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How are human rotaviruses generally transmitted?

How are human rotaviruses generally transmitted?


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I know rotaviruses are double stranded RNA viruses and i am wondering if the human transmission is similar to the modes of veterinary transmission.


Faecal-oral transmission. Ref from https://en.wikipedia.org/wiki/Rotavirus


How are human rotaviruses generally transmitted? - Biology

Mechanisms of Infection and Spread of Viruses through the Body

(pages 595-614 in your book)

Viral pathogenesis = the entire process by which viruses cause disease

Virulence = pathogenicity = the capacity of a virus to cause disease

  • Large particles (10 µm and above) are filtered out on mucocilliary layer of nasal turbinates. Then swept down into esophagus
  • Intermediate particles (5-10 µm) are usually trapped on mucocilliary layer of trachea and bronchioles. From there they are swept into esophagus.
  • Smaller particles often make it to the alveoli of lungs where they can set up infection or be destroyed by alveolar macrophages.
  • lungs and other mucosal tissue are sites of secretory immunoglobulin (IgA) which will facilitate viral killing
  • thick layer of esophagus
  • secretory antibodies (IgA)
  • chemicals - bile, stomach acid, proteases

C. Skin, genital tract, and conjunctiva

Skin: Tough outer layer is nearly impenetrable - entry is through cuts, scrapes, bites (insect or animal), iatrogenic (human intervention - needles)

Some viruses produce localized infection in skin (papilloma), but most move through the skin and into deeper layers and eventually into bloodstream (viremia).

Gential tract: genital tract is route of entry for important pathogens such as HSV, papilloma, HIV, HTLV, Hepatitis B and C. Sexual activity can cause minute tears in vagina and urethra, through which the virus may enter. Some varies stay local (papillomavirus), others spread systemically (HIV, HepB and C, HTLV)

Eyes: Conjunctiva has protective mechanisms (lysozyme in tears, washing, eyelid wiping, etc) and is not usually a route of infection. A few viruses, however, can infect here. Usually the infection is through a small tear in the conjunctiva and even then the infection is usually initiated by direct inoculation (physically touching something that has the virus on it).

A. Viruses have the choice of setting up infection at the point they entered the body or entering the blood stream and setting up an infection at another point.

The directionality of budding is very important to how a virus spreads. If it spreads at the apical surface it is usually released into a lumen where it can spread quickly on the lumenal epithelial surface, or even be shed to the exterior of the host. If it buds basolaterally, it will encounter slow movement and a myriad of host defenses. In many cases the budding dictates the type of infection that is set up.

B. Local Spread on Epithelial Surfaces

This does not happen much on skin because it is difficult for the virus to be transported without the aid of water. Papillomaviruses infect the basal layer of the epidermis but the viruses do not mature until the cells move toward the outer surface of the skin and become keratanized. At this point, virus matures and produces warts. Some poxviruses, such as molluscum contagiosum, orf and tanapox remain localized in skin, spread cell to cell, and cause lumps (points of infection) in the skin. Other poxviruses, such as smallpox, enter lymphatic system and are spread throughout the body.

In internal epithelium the surface is coated with water and this make spread much easier. Therefore these infections tend to have a shorter incubation time. In the case of paramyxoviruses, influenza virus, and rotavirus the epithelial tissue is infected but there is no invasion beyond this layer -- possibly because of lack of cellular receptors in the deeper tissue layers, or possibly due to higher temperatures in the deeper cellular tissue. However, they can still be quite severe.

C. Subepithelial Invas ion and Lymphatic Spread

Lymph system is a system of ducts, vessels, and glands that lies just below the basement membrane of the skin. The major purpose in in immunosurveillance -- detecting and getting rid of foreigh invaders. Many immune cells can be found in lymph nodes and lymph fluid. Macrophages are probably the primary defenders. They eat the viruses and use the protein parts to activate the immune response.

Viruses evade the lymph system in two primary ways. They can directly infect the immune cells (which eventually find their way into the bloodstream), or they can pass quickly through the lymph system (evading the macrophages) and into the blood stream.

D. Primary and Secondary Viremia

First entry of virus into the bloodstream is primary viremia (can be active or passive). This viremia may be subclinical and is the route by which viruses get to their sites of infection. After the infection occurs, then a secondary viremia can take place because of shedding of virus from the infected organ. This secodary viremia can then be the cause of infection at yet another site of the body.

Viruses may circulate freely in the blood (hepadnaviruses, togaviruses, flaviviruses, and enteroviruses), or they may associate with leukocytes (WBC), platelets, or erythrocytes and be harbored by them (HIV, Rift Valley Fever, Colorado tick fever). The latter viral infections are more difficult to clear and tend to be more persistent infections.

Macrophages have a lot to do with the type of infection that may be caused after a primary viremia. The factors that are important are the area of the body in which the infection occurs (different types of macrophages in different parts of the body), the susceptibility of the macrophages to infection, the state of their activation, and the age and genetics of the host. In most cases, macrophages are efficient destroyers of virus, but in some cases, as in dengue fever, they may serve as a host and carry the virus to different parts of the body.

Infection at a site after primary viremia has a lot to do with the nature of the vascular endothelial cells at that site and the amount of blood flow through the site. Virions tend to attach better in areas where the blood flow is slower. The viruses may get through the endothelials cells by squeezing between cells, or by directly infecting them and moving from cell to cell.

Because your immune system is constantly fighting viruses in the bloodstream there must be some sort of mechanism to constantly put out virus to maintain a viremia. This is particularly important in spread to certain parts of the body such as the central nervous system, where a constant viremia is necessary for the virus to be able to cross the blood/brain barrier. The viremia is usually maintained by either direct infection of blood cells (leukocytes usually) or infection of another organ which constantly is shedding virus into the bloodstream.

E. Secondary sites of infection.

Skin - this usually results in some sort of rash made up of macules, papules, vesicles or pustules.

CNS - spread is usually from blood vessels in meninges and choroid plexus and infection of neurons in cerebrospinal fluid, or directly from blood vessels of the brain and spinal cord. Spread is usually either by infection of endothelial cells or transport directly through the endothelial layer. Rarely by infected leukocytes moving into brain.

Another important route is travel of virus up neurons (rabies, varicella, herpes simplex)

Meningitis is infection of lining of brain and CNS (meninges)

Encephalitis is infection of brain

Other organs - liver (hepatitis), heart (carditis), lungs (pneumonia), salivary glands (mumps), testes (orchitis)

Fetus - 1) teratogenic effects (CMV and rubella) such as deafness, blindness, congenital heart and brain defects, 2) fetal death (smallpox, parvovirus 19)

The basis for tropism

  • cellular receptors
  • transcription factors - some enhancer elements only work for specific cell transcriptional factors (hep B in liver, papilloma 11 in keratinocytes)
  • cellular proteases - presence of cellular protease necessary to cleave viral proteins to make mature virus - influenza HA and tryptase Clara

The site of entry often dictates the mode of spread and the severity of the disease - Rabies.

Necessary for maintenance of infection in poulation.

A. Repiratory and oropharyngeal secreations

mucus or saliva from coughing sneezing and talking - measles. chickenpox, rubella. direct transmission of saliva or mucus - herpesviruses, CMV, EBV

B. Feces

enteric viruses - can often persist for longer periods of time (nonenveloped)

C. Skin

direct contact needed for transmission - molluscum contagiosum, warts, genital herpes, poxviruses.

D. Urine

Viruria is principal mode of shedding in arenavirus infections of rodents. Mumps virus and CMV in humans

E. Milk

CMV in mother's milk

F. Genital secretions

HIV, HSV I, HSV II, papillomaviruses, hepatitis B and C, HTLV

G. Blood and body fluids

Heptitis B, C, D, HIV, HTLV. Luckily some of the more fatal hemorrhagic fevers can only be transmitted this way.

H. No Shedding -- the Kuru story


Rotavirus outsources cellular protein CK1-alpha to assemble virus factories

Transmission electron micrograph of intact rotavirus particles, double-shelled Transmission electron micrograph of intact rotavirus particles, double-shelled. Credit: CDC

Rotaviruses, like all viruses, reproduce inside living cells. Making new viruses requires assembling replication factories via a complex, little known process that involves both viral and cellular components. A report in the Proceedings of the National Academy of Sciences by a multidisciplinary team led by researchers at Baylor College of Medicine reveals that the formation of rotavirus factories depends on a cellular protein called CK1α, which chemically modifies viral component NSP2, thus triggering its localization and assembly into the virus factory, an essential step in the formation of new viruses.

"One of the interests of our labs is to better understand the process of assembling rotavirus factories," said first co-author Dr. Jeanette M. Criglar, staff scientist of molecular virology and microbiology at Baylor College of Medicine and a graduate of the program.

In the process of investigating this, Criglar and her colleagues discovered that a cellular protein called CK1α is required to assemble rotavirus factories. "When we silenced CK1α in cells before infection with rotavirus, we knocked down the replication of the virus by more than 90 percent, suggesting that CK1α largely controls the formation of rotavirus factories," Criglar said.

CK1α is a enzyme with the ability to modify other proteins and their functions chemically by adding phosphate groups to them. The researchers discovered that CK1α mediates its effect on the formation of rotavirus replication factories by adding a phosphate group to a rotavirus protein called NSP2. This phosphate modification triggers the assembly of NSP2 octameric units into a crystal-like structure and appears to be required for the formation of rotavirus factories.

"CK1α normally takes care of housekeeping tasks within the cell. Rotavirus takes advantage of this protein's activity, 'outsourcing' it to assemble the virus factories," said corresponding author Dr. Mary K. Estes, Cullen Foundation Endowed Professor Chair of Human and Molecular Virology at Baylor College of Medicine and emeritus founding director of the Texas Medical Center Digestive Diseases Center.

In addition, the team discovered that rotavirus protein NSP2 can add phosphate groups to itself, thus modifying its activity and affecting other proteins involved in virus assembly. This is a surprising finding, Estes explains, because this function had not been described before for this viral protein.

"Taken together, our findings suggest that a cascade of phosphate chemical modifications, which is mediated in part by CK1α and NSP2, is essential for the formation of rotavirus factories," said co-author Dr. B V Venkataram Prasad, professor and Alvin Romansky Chair in Biochemistry and Molecular Biology, and member of the Dan L Duncan Comprehensive Cancer Center at Baylor. "These findings provide new insights that could lead to previously unsuspected ways to fight the disease in the future." "It is possible that our findings may also shed light on the assembly of virus factories for other viruses that also require CK1α, such as hepatitis C, or that also form cytoplasmic virus factories like West Nile and dengue virus," Criglar said. "If we can understand how other viruses assemble their factories, perhaps using similar mechanisms to rotavirus, we could advance the understanding of those diseases as well."


Diagnosis and Tests

How is rotavirus diagnosed?

If your child has signs of rotavirus, contact your healthcare provider. Providers can often diagnose rotavirus based on symptoms and a physical examination. In some cases, they may take a stool (poop) sample to test it for rotavirus. But, this step usually isn’t needed.

If you do need to take a stool sample, your provider will give you a sterile (germ-free) container. You collect some of your child’s stool in the container. A lab analyzes the stool for rotavirus.


Contents

Enteroviruses are members of the picornavirus family, a large and diverse group of small RNA viruses characterized by a single positive-strand genomic RNA. All enteroviruses contain a genome of approximately 7,500 bases and are known to have a high mutation rate due to low-fidelity replication and frequent recombination. [4] [5] After infection of the host cell, the genome is translated in a cap-independent manner into a single polyprotein, which is subsequently processed by virus-encoded proteases into the structural capsid proteins and the nonstructural proteins, which are mainly involved in the replication of the virus. [6]

RNA recombination appears to be a major driving force in the evolution of enteroviruses as well as in the shaping of their genetic architecture. [7] [5] The mechanism of recombination of the RNA genome likely involves template strand switching during RNA replication, a process known as copy choice recombination. [7] RNA recombination is considered to be an adaptation for dealing with RNA genome damage and a source of genetic diversity. [8] It is also a source of concern for vaccination strategies, because live attenuated/mutated strains used for vaccination could potentially recombine with wild-type related strains, as has been the case with circulating Vaccine Derived PolioViruses (cVDPDs) [9] [10] .The capsid region and especially VP1 is a recombination coldspot, [5] and this is one of the main reasons to use this region for genotyping [2] .However, the 5'UTR - capsid junction and the beginning of the P2 region have been observed to recombine very frequently, although recombinations do occur in the rest of the genome as well. [5] Interestingly, the enterovirus species EV-A, EV-B, EV-C, EV-D have not been observed so far to exchange genomic regions among them, with the exception of the 5'UTR. [5] [11] [12] Rather, genomic regions of the ORF are exchanged among different genotypes of the same species, with certain genotypes like EV71 and CVA6 from EV-A, E30 and E6 from EV-B, PV1 and PV2 from EV-C playing a key role as recombination hubs. [5] In addition, a recombination analysis of

3000 Enterovirus genomes identified many recombination events where one of the recombination partners has not been sequenced yet, thus revealing that there exists a large, yet undetected enterovirus genetic reservoir that may lead to new recombination events and the emergence of new strains, genotypes and pathogens. [5]

Enterovirus A - L Edit

Enteroviruses are a group of ubiquitous viruses that cause a number of infections which are usually mild. The genus picornavirus includes enteroviruses and rhinoviruses. Enterovirus A include coxsackievirus A2, A3, A4, A5, A6, A7, A8, A10, A12, A14, A16 and enterovirus A71, A76 A89, A89, A90, A91, A92, A144, A119, A120, A121, A122 (simian virus 19), A123 (simian virus 43), A124 (simian virus 46), A125 (baboon enterovirus A13). [13] Some viruses initially reported as novel have been found to be misidentified. Thus, coxsackievirus A23 is the same serotype as echovirus 9, and coxsackievirus A15 is the same serotype as coxsackievirus A11 and coxsackievirus A18 is the same serotype as coxsackievirus A13.

Coxsackie A16 virus causes human hand, foot and mouth disease.

Enterovirus B includes coxsackievirus B1,2,3,4,5,6 coxsackievirus A9 echovirus 1-33 and enterovirus B69-113. [13] Coxsackie B viruses are found world wide and can cause myocarditis (inflammation of the heart) pericarditis (inflammation of the sac surrounding the heart) meningitis (inflammation of the membranes that line the brain and spinal cord) and pancreatitis (inflammation of the pancreas). The Coxsackie B viruses are also reported to cause a spastic paralysis due to the degeneration of neuronal tissue and muscle injury. Infections usually occur during warm summer months with symptoms including exanthema, pleurodynia, flu-like illness consisting of fever, fatigue, malaise, myalgia, nausea, abdominal pain and vomiting. [14] Echoviruses are a cause of many of the nonspecific viral infections that can range from minor illness to severe, potentially fatal conditions such as aseptic meningitis, encephalitis, paralysis and myocarditis. [15] It is mainly found in the intestine, and can cause nervous disorders. [16] Type B enteroviruses are responsible for a vast number of mild and acute infections. They have been reported to remain in the body causing persistent infections contributing to chronic diseases such as type I diabetes. [17]

Enterovirus C consists of polioviruses 1,2 and 3 coxsackieviruses A1, A11, A13, A18, A17, 20, A21, A22, A24 and enterovirus C95, C96, C99, C102, C104, C105, C109, C113, C118. The three serotypes of poliovirus, PV-1, PV-2, and PV-3 each have a slightly different capsid protein. Capsid proteins define cellular receptor specificity and virus antigenicity. PV-1 is the most common type to cause infection in humans however, all three forms are extremely contagious spreading through person-to-person contact. Poliovirus causes Polio, or Poliomyelitis, which is a disabling and life threatening disease that causes paresthesia, meningitis and permanent paralysis. [18] Symptoms can include sore throat, fever, tiredness, nausea, headache and stomach pain although 72% of those that get infected will not display visible symptoms. [18] There are two types of vaccines available to prevent polio: inactivated poliovirus vaccine given as an injection in the leg (IPV) or arm and oral poliovirus vaccine (OPV). The polio vaccine is highly efficacious giving protection to 99 out of 100 children vaccinated. [18]

Non-cytolytic (non-cytopathic) enterovirus Edit

Enteroviruses are usually only capable of producing acute infections that are rapidly cleared by the adaptive immune response. [19] [20] However genome mutations, which enterovirus B serotypes may acquire in the host during the acute phase, may transform these viruses into the non-cytolytic form (also known as non-cytopathic or defective enterovirus). This is a mutated quasispecies [19] of enterovirus, which can cause persistent infection in human cardiac tissues especially in some patients with myocarditis or dilated cardiomyopathy. [21] [19] In persistent infections viral RNA is present only on very low levels and is not believed to contribute to any ongoing myocardial disease being a fading remnant of a recent acute infection [20] although some scientists think otherwise. [22]

Enterovirus D68 Edit

EV-D68 first was identified in California in 1962. Compared with other enteroviruses, it has been rarely reported in the U.S. in the past 40 years. Most people who get infected are infants, children, and teens. EV-D68 usually causes mild to severe respiratory illness however, the full spectrum of EV-D68 illness is not well-defined. Most start with common cold symptoms of runny nose and cough. Some, but not all, may also have fever. For more severe cases, difficulty breathing, wheezing or problems catching your breath may occur. As of October 4, 2014, there has been one death in New Jersey directly linked to EV-D68, [23] as well as one death in Rhode Island [ citation needed ] attributed to a combination of EV-D68 and sepsis caused by an infection of staphylococcus aureus. [24] [25]

Enterovirus A71 Edit

Enterovirus A71 (EV-A71) is notable as one of the major causative agents for hand, foot and mouth disease (HFMD), and is sometimes associated with severe central nervous system diseases. [26] EV-A71 was first isolated and characterized from cases of neurological disease in California in 1969. [27] [28] To date, little is known about the molecular mechanisms of host response to EV-A71 infection, but increases in the level of mRNAs encoding chemokines, proteins involved in protein degradation, complement proteins, and proapoptotis proteins have been implicated. [29]

Poliovirus Edit

There are three serotypes of poliovirus, PV-1, PV-2, and PV-3 each with a slightly different capsid protein. Capsid proteins define cellular receptor specificity and virus antigenicity. PV-1 is the most common form encountered in nature however, all three forms are extremely infectious. [30] Poliovirus can affect the spinal cord and cause poliomyelitis.

Polioviruses were formerly classified as a species belonging to the genus Enterovirus in the family Picornaviridae. The Poliovirus species has been eliminated from the genus Enterovirus. The following serotypes, Human poliovirus 1, Human poliovirus 2, and Human poliovirus 3, were assigned to the species Human enterovirus C, in the genus Enterovirus in the family Picornaviridae. The type species of the genus Enterovirus was changed from Poliovirus to Human enterovirus C. This has been ratified in April 2008. [31] The 39th Executive Committee (EC39) of the International Committee on Taxonomy of Viruses (ICTV) met in Canada during June 2007 with new taxonomic proposals. [32]

Two of the proposals with three changes were:

  • Code 2005.261V.04: To remove the following species Poliovirus from the existing genus Enterovirus in the family Picornaviridae.
  • Code 2005.262V.04: To assign the viruses PV-1, PV-2, PV-3 to the existing species Human enterovirus C in the genus Enterovirus in the family Picornaviridae. [33]
  • Code 2005.263V.04: To change the type species Poliovirus from the existing genus Enterovirus in the family Picornaviridae to the type species Human enterovirus C. [34]

Proposals approved at the (EC39) meeting of 2007, were sent to members of ICTV via email for ratification and have become official taxonomy. There have been a total of 215 taxonomic proposals, which have been approved and ratified since the 8th ICTV Report of 2005. [35]

The ratification process was performed by email. The proposals were sent electronically via email on March 18, 2008, to ICTV members with a request to vote on whether to ratify the taxonomic proposals, with a 1-month deadline. The following are two of the taxonomic proposals with three changes that were ratified by ICTV members in April 2008:

  • 2005.261V.04: To remove the following species from the existing genus Enterovirus in the family Picornaviridae: Poliovirus. (Note: Poliovirus hereby loses its status as a virus species.)
  • 2005.262V.04: To assign the following viruses to the species Human enterovirus C in the existing genus Enterovirus in the family Picornaviridae: Human poliovirus 1, Human poliovirus 2, Human poliovirus 3. (This is not strictly necessary as a taxonomic proposal because it concerns entities below the species level, but it is left in to clarify this reorganization of the Picornaviridae.)
  • 2005.263V.04: To change the type species of the genus Enterovirus in the family Picornaviridae, from Poliovirus to Human enterovirus C. [31]

Enteroviruses cause a wide range of symptoms, and while their long list of signs and symptoms should put them on the differential diagnosis list of many illnesses, they often go unnoticed. Enteroviruses can cause anything from rashes in small children, to summer colds, to encephalitis, to blurred vision, to pericarditis. Enteroviral infections have a great range in presentation and seriousness. Non polio enteroviruses cause 10–15 million infections and tens of thousands of hospitalizations in the US each year. [37] Enteroviruses can be identified through cell culture or PCR assay, collected from fecal or respiratory specimens. [38] Below are common enterovirus related diseases, including poliomyelitis.

    primarily via the fecal-oral route found in children who tested positive for enterovirus 68. [39][40]
  • Nonspecific febrile illness is the most common presentation of enterovirus infection. Other than fever, symptoms include muscle pain, sore throat, gastrointestinal distress/abdominal discomfort, and headache. [41] In newborns the picture may be that of sepsis, however, and can be severe and life-threatening.
  • Enteroviruses are by far the most common causes of aseptic meningitis in children. In the United States, enteroviruses are responsible for 30,000 to 50,000 meningitis hospitalizations per year as a result of 10–15 million infections. [42] or epidemic pleurodynia is characterized by severe paroxysmal pain in the chest and abdomen, along with fever, and sometimes nausea, headache, and emesis. and/or myocarditis are typically caused by enteroviruses symptoms consist of fever with dyspnea and chest pain. Arrhythmias, heart failure, and myocardial infarction have also been reported. can be caused by enteroviruses. is caused by Coxsackie A virus, and causes a vesicular rash in the oral cavity and on the pharynx, along with high fever, sore throat, malaise, and often dysphagia, loss of appetite, back pain, and headache. It is also self-limiting, with symptoms typically ending in 3–4 days. is a childhood illness most commonly caused by infection by Coxsackie A virus or EV71. is rare manifestation of enterovirus infection when it occurs, the most frequent enterovirus found to be causing it is echovirus 9. is characterized by inflammation of the myocardium (cardiac muscle cells). Over the last couple of decades, numerous culprits have been identified as playing a role in myocarditis pathogenesis in addition to the enterovirus, which at first was the most commonly implicated virus in this pathology. [43] One of the most common enteroviruses found to be responsible for causing Myocarditis is the Coxsackie B3 virus. [44]
  • A 2007 study suggested that acute respiratory or gastrointestinal infections associated with enterovirus may be a factor in chronic fatigue syndrome. [45]

Suspected diseases Edit

Possible correlations being studied Edit

Enterovirus has been speculated to be connected with Type 1 diabetes. [47] [48] [49] [50] It has been proposed that type 1 diabetes is a virus-triggered autoimmune response in which the immune system attacks virus-infected cells along with the insulin-producing beta cells in the pancreas. [51] A team working at University of Tampere, Finland has identified a type of enterovirus that has a possible link to type 1 diabetes (which is an autoimmune disease). [52] [53]

Most people who contract enterovirus have mild symptoms lasting about a week. Those with higher risk may have more complications, sometimes becoming fatal. [54] The most common sign of enterovirus is a common cold. More intense symptoms of enterovirus include hypoxia, aseptic meningitis, conjunctivitis, hand, foot and mouth disease, and paralysis.

Treatment for enteroviral infection is mainly supportive. In cases of pleurodynia, treatment consists of analgesics to relieve the severe pain that occurs in patients with the disease in some severe cases, opiates may be needed. Treatment for aseptic meningitis caused by enteroviruses is also mainly symptomatic. In patients with enteroviral carditis, treatment consists of the prevention and treatment of complications such as arrhythmias, pericardial effusion, and cardiac failure. Other treatments that have been investigated for enteroviral carditis include intravenous immunoglobulin. [55]


How are human rotaviruses generally transmitted? - Biology

In Spain, diarrhea remains a major cause of illness among infants and young children. To determine the prevalence of rotavirus genotypes and temporal and geographic differences in strain distribution, a structured surveillance study of hospitalized children <5 years of age with diarrhea was initiated in different regions of Spain during 2005. Rotavirus was detected alone in samples from 362 (55.2%) samples and as a coinfection with other viruses in 41 samples (6.3%). Enteropathogenic bacterial agents were detected in 4.9% of samples astrovirus and norovirus RNA was detected in 3.2% and 12.0% samples, respectively and adenovirus antigen was detected in 1.8% samples. Including mixed infections, the most predominant G type was G9 (50.6%), followed by G3 (33.0%) and G1 (20.2%). Infection with multiple rotavirus strains was detected in >11.4% of the samples studied during 2005.

Group A rotaviruses are a major cause of severe diarrhea in infants. In developing countries, severe diarrhea caused by human rotavirus results in an estimated 500,000 to 608,000 childhood deaths annually worldwide, it results in ≈2 million hospitalizations (1,2).

Rotaviruses belong to the Reoviridae family. Viral particles are nonenveloped, and triple-layered protein capsids enclose the genome of 11 dsRNA segments. The major protein in the central layer of the viral capsid is VP6, which determines 7 different groups of rotaviruses (A–G). The outer layer of the viral capsid is composed of 2 structural proteins, VP4 (encoded by gene 4) and VP7 (encoded by gene 7, 8, or 9, depending on the strain) (3). These 2 proteins carry the major antigenic determinants, which elicit neutralizing antibodies and are thought to be type specific. Group A rotaviruses are widespread in humans and animals and are subdivided into distinct genotypes, G and P (4). Epidemiologic studies of rotavirus infections are increasingly showing that a great diversity of rotavirus strains are cocirculating in the human population throughout the world. The most common genotypes of group A rotaviruses (≈90%), which cause dehydrating gastroenteritis in infants and young children worldwide, were G1P[8], G2P[4], G3P[8], and G4P[8] G1P[8] is the most prevalent worldwide (5). However, other G genotypes are epidemiologically important, such as G5 in Brazil (6,7), G9 and G10 in India (8,9), and G8 in Malawi (10).

In Spain, diarrhea remains an important cause of illness among infants and young children. A study conducted from 1998 through 2002 detected rotavirus in 1,155 (31%) of 3,760 specimens tested. G1 was the predominant genotype detected (53%), followed by G4 (24%), G2 (14%), G9 (6%), and G3 (2%) (11). The distribution of genotypes indicated a genotypic shift over time: G4 strains predominated (57%) from 1998 through 2000, whereas G1 gradually increased to account for 75% from 2000 through 2002 (11). Similar studies conducted in other regions of Spain indicated similar shifts in the prevalence of rotavirus genotypes (12,13).

We conducted structured surveillance among children with diarrhea who were hospitalized in 6 hospitals in Spain our primary goals were to determine the prevalence of rotavirus diarrhea in hospitalized children, the G and P types among infecting rotavirus strains, and the temporal and geographic differences in strain distribution throughout the regions.

Materials and Methods

Hospitals and Patients

Stool samples were collected from children attending 6 public hospitals located in different healthcare areas throughout Spain. These hospitals intentionally represented the geographic, climatic, and ethnic diversity of Spain. Their respective catchment areas are shown in Table 1. The study was conducted between January 2005 and January 2006 and included children <5years of age who were hospitalized with acute gastroenteritis and from whom a stool sample was obtained.

Acute gastroenteritis was defined as >3 looser-than-normal stools within a 24-hour period or an episode of forceful vomiting and any loose stool. To enable reporting of test results to hospitals, stool specimens were labeled with the date of collection and a unique surveillance identification number. Permission for enrollment in the study was obtained from children's legal guardians, and ethical approval was obtained from the institutional review board of the Hospital de La Ribera.

Specimen Collection and Testing

Whole stool specimens were collected and transported immediately to hospital laboratories and stored at 4°C until processing. All fecal samples were screened for enteropathogenic bacterial agents by conventional culture methods previously described (14).

Each month, specimens were sent to the reference laboratory (Viral Gastroenteritis Unit, National Center for Microbiology, Instituto de Salud Carlos III, Madrid, Spain). A 10% suspension in 0.1 mol/L phosphate-buffered saline (pH 7.2) was prepared and tested by reverse transcription (RT)-PCR for rotavirus, astrovirus, norovirus, and sapovirus (11,15,16) and by an immunochromatographic method for enteric adenoviruses (14).

Nucleic Acid Extraction and G/P Rotavirus Typing

Viral RNA was extracted from 250 μL of the 10% fecal suspension by using the guanidine isothiocyanate method and the Rnaid Spin Kit (BIO 101, Anachem Bioscience, Bedfordshire, UK) according to the manufacturer's instructions, with slight modifications (16). RNA was eluted in 50 μL of RNase-free distilled water and stored at –20°C. To determine the G/P type patterns present in children hospitalized from 2005 through 2006, a total of 98 rotavirus strains were P typed. G and P rotavirus genotyping were performed by using RT-PCR methods as previously reported (11,17).

DNA Sequencing and Analysis

Rotavirus amplicons were genetically characterized by nucleotide sequencing of both strands of the amplified PCR products. These products were purified by using QIAquick PCR Purification kit (Qiagen, Valencia, CA, USA) and then sequenced using an ABI PRISM BigDye Terminator Cycle Sequencing Ready Reaction Kit (Applied Biosystems, Foster City, CA, USA) on an ABI automated sequencer (Applied Biosystems, model 3700). Data analysis was performed by using Clustal for multiple alignments and neighbor-joining and maximum parsimony methods for phylogenetic analysis (Bionumerics, Kortrijk, Belgium). Spanish strains were submitted to GenBank under accession numbers DQ440613 through DQ440624.

Results

Microbiology

A total of 656 hospitalized children were enrolled. Enteropathogenic bacterial strains were detected in 5.0% of samples (Table 2). Astrovirus and norovirus RNA was detected in 3.2% and 12.0% samples, respectively, and adenovirus antigen in 1.8% samples.

A total of 403 rotavirus strains were detected. Rotavirus was found alone in 362 (55.2%) samples but was found in another 41 samples (6.3%) as a coinfection with other viruses. The percentage of children with gastroenteritis caused by rotavirus as unique agent ranged from 36.7% in Leon to 68.2% in Valencia (Table 2).

Rotavirus Characterization

G typing RT-PCR for rotavirus alone was performed on 362 samples positive for rotavirus but could not be determined in 10 (2.8%) samples. The G types detected, including mixed infections with multiple rotavirus strains, are shown in Table 3. Briefly, the most predominant G type was G9 (50.6%), followed by G3 (33.0%), G1 (20.2%), and G2 (7.1%) the least common G type was G4 (0.6%). G1, previously reported as the most common G type in Spain, was found in only 20.2% of rotavirus infections. With the exceptions of Valencia and Albacete, where G1 and G3, respectively, were the predominant G types, the results from all other regions showed a predominance of G9. However, even in these 2 areas, G9 was the second most common strain detected when cases with coinfection were added (26.7% and 31.6%, respectively).

Common G/P combinations, infrequent patterns, and mixed-infection combinations were all detected (Table 4). G9P[8] (40%) and G3P[8] (31%) were the most common combinations detected, but G types in combination with P[6] and P[9] were also detected.

Using DNA sequencing and phylogenetic analysis of partial sequences of the gene encoding VP7, we compared 2 G3 strains from this study with 9 G3 strains isolated previously in Spain. All G3 strains from Spain shared >99.0% homology and were more closely related to each other than to strains isolated in Italy, United Kingdom, India, and China.

Discussion

Genetically and antigenically diverse rotavirus strains cocirculate in humans. The prevalence of rotavirus genotypes varies according to location and time. Throughout the world, genotyping and serotyping studies have identified common cocirculating rotavirus types, and G1P[8], G2P[4], G3P[8], and G4P[8] are the predominant strains. However, from time to time, other less common genotypes, such as G9P[8], G5P[8], and G8P[6], have been predominant in various countries (5).

In Spain, previous studies have identified G1P[8] and G4P[8] as the predominant cocirculating strains from 1996 through 2004 (11,17,18) (Table 5). However, in our study, conducted in 2005 and 2006, a major shift in the predominant strains was detected. G9P[8] and G3P[8] have become the predominant genotypes cocirculating in several regions of Spain, and infection with multiple rotavirus strains was detected in 11.4% of the cases studied.

Since its widespread introduction into the human population in 1995, G9P[8] has become one of the predominant viruses worldwide. In 2 separate studies conducted in Thailand (19,20), this genotype has been reported as the predominant virus circulating from 2000 through 2002 and in Brazil from 1999 through 2002 (21). G3P[8] has recently been reported as the predominant strain circulating in the Japanese population (22).

Less common G- and P-type combinations were also detected in this study. This finding may suggest either an earlier reassortment between animal and human strains, resulting in the emergence of strains such as G2P[6] and G3P[9], or zoonotic transmission to humans of an animal strain, as possibly occurred with G9P[6]. The VP4-genotypes P[6] and P[9] are reported to be associated with infection in pigs and cats, respectively. Although animal rotavirus strains replicate poorly in humans and person-to-person transmission is rare, the relatively high frequency of multiple infections detected in this study suggests that the opportunity for dual infection of a cell, and therefore reassortments, exists (23).

The main limitations of this study are having only 1 year of data, the minimal variations in the sampling schemes in each institution (frequency of sampling, test procedures, motivations of investigators), and the small sample size collected. Although the sampling strategy enabled monitoring for rotavirus in a large number of children, future studies with hospital-based surveillance should be initiated in different areas of Spain, and even Europe, with larger samples.

Morbidity rates worldwide and morbidity and mortality rates caused by diarrhea in developing countries remain high despite efforts to improve sanitary conditions, water quality, and the healthcare infrastructure. These high rates have driven efforts to develop a safe and effective rotavirus vaccine, and the World Health Organization has recognized that developing a vaccine is a priority for reducing infant deaths in developing countries. The level and type of protection in rotavirus disease is poorly understood, although neutralizing antibody responses are thought to be type specific. Because these responses are associated with VP7 and VP4 viral proteins, establishing the G and P genotypes of strains circulating in the human population is important. Currently, 2 candidate rotavirus vaccines are undergoing clinical trials. A multivalent vaccine directed against G1, G2, G3, G4, and P[8] and a monovalent vaccine to G1P[8] have been developed (24,25). Homotypic protection has been demonstrated for both vaccines, but the degree to which they cross-protect against less common G- and P-type combinations not included in the vaccine formulations has yet to be established, and the importance of genotype-specific protection against rotavirus disease is still under discussion (26,27). Considering that G9 rotavirus type has emerged as one of the most common rotavirus genotypes in humans around the world, and it is becoming very prevalent in some countries, future rotavirus vaccine candidates will need to provide adequate protection against disease caused by G9 viruses. Therefore, surveillance of regional networks must be maintained to document rotavirus strain distribution and prevent the appearance of new strains or new variants that could escape immune protection induced by an outdated vaccine.

Dr Sánchez-Fauquier is the head of the Viral Gastroenteritis Unit, National Center for Microbiology, Instituto de Salud Carlos III, Majadahonda, Madrid. Her primary research interests are the epidemiology, immunology, pathogenesis, and molecular biology of viral gastroenteritis. She also is coordinator of the Spanish Viral Gastroenteritis Network (VIGESS-Net).


Management

Regardless of the infecting agent, children presenting with diarrhoea are assessed for dehydration and treated accordingly. A mild case of rotavirus disease, where the child is active, shows no signs of dehydration, has had between zero and two vomiting episodes within 12 hours, has had a few loose or low output watery stools per day and has no fever or a low-grade fever, requires only observation. Symptoms can last for 1–5 days, but if they last for >1 week, medical consultation should be sought. Increasing and/or intense vomiting and repeated episodes of watery diarrhoea (for example, >1 episode per hour, especially if abundant) are the main features that indicate the need for specific treatment. In low-income countries, the goal of treatment is avoiding or rapidly treating severe dehydration and maintaining protein–calorie intake to prevent death or worsening malnutrition, whereas in middle-income and high-income countries, reducing hospitalization and the duration of diarrhoea are the main goals. Key treatment concepts including fluid and electrolyte management (including ORS and intravenous rehydration), dietary management and the use of probiotics, anti-emetics, antisecretory drugs and antiviral drugs are discussed below comprehensive reviews of acute diarrhoea management can be found elsewhere 135,136 .

Fluid and electrolyte management

One of the most important medical advancements in the past 50 years that has saved millions of infant lives was that administration of ORS resulted in glucose-coupled sodium and water absorption in the small intestine 137 . Oral rehydration therapy has been used safely and successfully to prevent and treat dehydration due to diarrhoeal pathogens, including rotavirus, in infants and young children 138 . Clinical scales that consider the presence of signs and symptoms are available to assess for dehydration 139,140 , and a thirsty, restless or fatigued child with a dry mouth should alert caretakers to ongoing dehydration. Prompt replacement of fluids and electrolytes, spoon by spoon if necessary, with hypo-osmolar ORS (containing 60–75 mmol per litre of sodium in addition to glucose, potassium, chloride and citrate) 141 is the cornerstone of treatment for children without dehydration but with intense and repeated vomiting and/or diarrhoea episodes and for children with mild to moderate dehydration. If ORS is not available, homemade solutions can be prepared using water, sugar and salt. Plain water, soda, chicken broth and apple juice should be avoided in children with dehydration, especially in infants, as they are hyperosmolar solutions and do not sufficiently restore potassium, bicarbonate and sodium levels 142 . Intravenous fluids can be used in cases of severe dehydration, hyperemesis, oral rehydration therapy failure or severe electrolyte imbalances. Importantly, most children, even those with severe dehydration, can be managed effectively with ORS to prevent severe complications, including death.

Dietary management

Dietary management is an important factor in the care of children with acute diarrhoea 143 . Breastfeeding should be encouraged and is never contraindicated. In patients with dehydration, food withdrawal is advised for only 4–6 hours after initiating rehydration therapy 136,144 . The administration of repetitive, small portions of regular undiluted milk formulas is recommended for infants and children >6 months of age. The administration of lactose-free formulas might reduce the duration of treatment and the risk of treatment failure 143 and can be considered for selected children, such as those requiring hospitalization 136 . Importantly, the maintenance of adequate protein–calorie intake during the diarrhoea episode using home-available, age-appropriate foods should be encouraged, especially in low-income settings 143 . In addition, zinc supplementation can improve the outcome of acute diarrhoea in low-income regions, in which malnutrition is common. Although the mechanisms of the efficacy of zinc supplementation are unclear, data from animal studies suggest zinc has anti-inflammatory properties 145 and antisecretory effects 146 , among others. Zinc deficiency is common in low-income countries and can occur in children with acute gastroenteritis due to intestinal fluid loss. For children living in low-income regions, the WHO recommends daily zinc supplementation for infants and children for 10–14 days, starting as soon as the diarrhoea episode has been diagnosed 147 . However, zinc supplementation can increase vomiting after the initial dose 148 .

Probiotics

Commonly used probiotics for the treatment of acute diarrhoea are lactic acid-producing bacteria, such as Lactobacillus rhamnosus, Lactobacillus plantarum, several strains of Bifidobacteria and Enterococcus faecium (the SF68 strain), and yeast, such as Saccharomyces boulardii 149 . Most meta-analyses suggest a modest benefit of probiotics in reducing the duration of diarrhoea by ∼ 1 day and up to 2 days for rotavirus-induced diarrhoea, although studies have been performed largely in middle-income and high-income countries 3 , and some studies did not report a clear benefit 150,151 . The mechanisms underlying this have been postulated to include the activation of antigen-presenting cells, a reduction in the levels of pro-inflammatory cytokines, the modulation of effector T cell and regulatory T cell immune responses, innate immune signalling (through interactions with several TLRs) and the promotion of enterocyte proliferation and/or migration 152 . In low-income regions, treatment with probiotics has a positive immunomodulatory effect (that is, an increased anti-rotavirus IgG response in individuals who received treatment compared with individuals who received placebo), improves intestinal function in children with rotavirus infection and might decrease repeat episodes of rotavirus diarrhoea 153,154 . However, probiotics are not included in the standard of care for children with rotavirus diarrhoea globally.

Other drugs

Antiviral therapy for rotavirus infection has been studied but remains mostly in preclinical stages. One exception is nitazoxanide, a broad-spectrum antiviral drug 155 that has been reported to reduce the duration of diarrhoea and the duration of hospitalization of children with acute rotavirus diarrhoea 155–157 . Nitazoxanide inhibits the replication of rotavirus by interfering with viral morphogenesis 158 . One study in hospitalized children 5 months to 7 years of age reported a significant reduction in the median time to the resolution of all rotavirus-associated gastrointestinal symptoms from 75 hours in children who received placebo treatment to 31 hours in children who received a 3-day course of nitazoxanide treatment 156 .

Recommendations for the use of anti-emetics (such as metoclopramide, dimenhydrinate and ondansetron) for children with rotavirus disease have progressed from ‘not recommended’ to ‘possibly recommended’ owing to their effects of reducing the number of vomiting episodes and reducing the need for intravenous rehydration and hospitalization 150,159 . Indeed, one dose of ondansetron reduces the likelihood of needing intravenous rehydration, although this can increase diarrhoea output. Importantly, repeated doses do not provide an additional benefit over one dose. The largest benefit can be gained when ondansetron is used early in the clinical course of children with rotavirus infection and intense vomiting.

Other potential therapies for rotavirus gastroenteritis include racecadotril and smectite. Racecadotril (an intestinal enkephalinase inhibitor that reduces the secretion of water and electrolytes into the gut 160 ) has been shown to significantly decrease diarrhoea output at 48 hours after treatment and did not increase the frequency of adverse effects 161 . However, treatment with racecadotril did not reduce the proportion of patients with diarrhoea 5 days after treatment 161 . In addition, one meta-analysis of seven clinical trials reported that racecadotril treatment is more effective than placebo or no intervention at reducing the duration of illness and stool output in children with acute diarrhoea 162 . However, in Kenya, racecadotril did not alter the number of stools after 48 hours, the duration of hospital stay or the duration of diarrhoea in children with severe gastroenteritis who received ORS and zinc 163 and was not effective in Indian children with acute diarrhoea and vomiting 164 . Thus, racecadotril can be considered for the management of children with severe secretory diarrhoea, but the efficacy is variable. Smectite (a natural adsorbent that binds to endotoxins, exotoxins, bacteria and viral particles) has been reported to decrease the duration of acute diarrhoea by 18–29% in a meta-analysis of mostly open-label trials in children with acute diarrhoea. In addition, smectite has been shown to increase the cure rate at day 5, without any increase in the risk of adverse events and accordingly could be beneficial in some individuals with rotavirus disease 165,166 .

Combination trials evaluating the simultaneous use of several treatments are lacking 99 . Indeed, improvements in treatment strategies are needed, especially in regions where rotavirus-associated deaths occur and where vaccines are underutilized.


Rotavirus Infection

Rotavirus is a virus that infects the bowels, causing severe inflammation of the stomach and bowels (known as gastroenteritis). Rotavirus is the most common cause of severe diarrhea among infants and children throughout the world and causes the death of about 500,000 children worldwide annually. The name rotavirus comes from the characteristic wheel-like appearance of the virus when viewed by electron microscopy (the name rotavirus comes from the Latin rota, meaning "wheel").

Since 2006, vaccines have been available for rotavirus infection. Before the availability of a rotavirus vaccine, rotavirus infected almost all children by their third birthday. Repeat infections with different viral strains are possible, and most children had several episodes of rotavirus infection in the first years of life. After several infections with different strains of the virus, children acquire immunity to rotavirus. Babies and toddlers between 6-24 months of age are at the greatest risk for developing severe disease from rotavirus infection. Adults sometimes become infected, but the resulting illness is usually mild.

Worldwide, rotavirus infection is still a significant cause of death in infants and children. Rotavirus affects populations in all socioeconomic groups and is equally prevalent in industrialized and developing countries, so differences in sanitation practices or water supply are not likely to affect the incidence of the infection.

In the U.S., rotavirus infections usually peak in the fall months in the Southwest and spread to the Northeast by spring, so infections are most common during the winter months from November to May. However, infection with rotavirus can occur at any time of the year.

Rotavirus Infection

Childhood Illnesses Every Parent Should Know Slideshow

Rotavirus infection is responsible for significant morbidity and mortality in children in less developed countries where access to the rotavirus vaccine is limited. The infection causes significant fever, vomiting, and diarrhea in children. This can often lead to serious problems with dehydration, especially in very young children and infants.

What are rotavirus infection symptoms and signs?

Symptoms of the disease include fever, vomiting, and watery diarrhea. Abdominal pain may also occur, and infected children may have profuse watery diarrhea up to several times per day. Symptoms generally persist for three to nine days. Immunity from repeated infection is incomplete after a rotavirus infection, but repeated infections tend to be less severe than the original infection.

Rotavirus infection can be associated with severe dehydration in infants and children. Severe dehydration can lead to death in rare cases, so it is important to recognize and treat this complication of rotavirus infection. In addition to the symptoms of rotavirus infection discussed above, parents should be aware of the symptoms of dehydration that can occur with rotavirus infection or with other serious conditions.

Symptoms of dehydration include

  • lethargy,
  • dry, cool skin,
  • absence of tears when crying,
  • dry or sticky mouth,
  • sunken eyes or sunken fontanel (the soft spot on the head of infants), and
  • extreme thirst.

What causes rotavirus infections?

The rotavirus is a member of the Reoviridae family of viruses and contains double-stranded RNA enclosed by a double-shelled outer layer (capsid). Infection with different strains of the virus is possible, so it is common to have several separate rotavirus infections in childhood. Adults may also become infected, but the resulting illness is usually less severe than that in infants and young children.

Rotavirus vs. norovirus

Norovirus is the most common cause of gastroenteritis in the U.S. Noroviruses cause about 50%-70% of cases of gastroenteritis in adults, whereas rotavirus most typically affects young children. Like rotavirus, norovirus is highly contagious and spreads rapidly. Contaminated food and liquids can transmit noroviruses, as can touching objects contaminated with norovirus and then placing the hands or fingers in the mouth, direct contact with an infected individual, and contact with infected individuals and objects in day care centers and nursing homes.

What are risk factors for rotavirus infection?

Rotavirus most commonly infects infants and children. Since rotavirus infection is highly contagious, those who are around infected people are at high risk of infection. For this reason, children in group day care settings are at risk. However, rotavirus infects most children by 3 years of age.

Can adults get a rotavirus infection?

Yes, it is possible for anyone to develop a rotavirus infection. However, most adults who become infected have only minor symptoms, or may not have symptoms at all. Since neither vaccination nor previous infection provides full immunity, it is possible to get rotavirus infection more than once. The first infection tends to produce more severe symptoms than subsequent infections, and vaccination is very effective in infants in preventing severe symptoms (see below).

SLIDESHOW

Is rotavirus contagious? How long is rotavirus contagious?

Rotavirus infection is highly contagious. Contamination of hands or surfaces with the stool of an infected person and then touching the mouth is the main method of spread. Rotavirus infection is contagious (can be spread to other people) from the time before diarrhea develops until up to 10 days after symptoms have disappeared.

How does rotavirus spread?

The primary mode of transmission of rotavirus is the passage of the virus in stool to the mouth of another child, known as a fecal-oral route of transmission. Children can transmit the virus when they forget to wash their hands before eating or after using the toilet. Touching a surface contaminated with rotavirus and then touching the mouth area can result in infection.

There also have been cases of low levels of rotavirus in respiratory-tract secretions and other body fluids. Because the virus is stable (remains infective) in the environment, transmission can occur through ingestion of contaminated water or food and contact with contaminated surfaces. Rotavirus can survive for days on hard and dry surfaces, and it can live for hours on human hands.

What is the incubation period for rotavirus?

The time from initial infection to symptoms (incubation period) for rotavirus disease is typically around two days, but varies from one to three days.


How are human rotaviruses generally transmitted? - Biology

Infection with a rare G3P[19] rotavirus A strain was identified in an immunosuppressed patient in Italy. The strain showed a P[19] viral protein 4 gene and a complete AU-1–like genomic constellation. Phylogenetic analyses showed high nucleotide identity between this strain and G3P[19] rotavirus A strains from Asia, indicating possible reassortment events.

Group A rotavirus (RVA) is the leading cause of acute gastroenteritis in children <5 years of age worldwide, causing ≈450,000 deaths annually. The RVA genome is composed of 11 double-stranded RNA segments, encoding 6 structural viral (VP) and 5 nonstructural (NS) proteins (1). The outer capsid proteins, VP7 and VP4, elicit neutralizing antibodies. The genes encoding these proteins specify at least 27 G and 37 P genotypes, which are used for RVA binary classification.

Most RVA human infections worldwide are related to 5 major genotypes: G1P[8], G2P[4], G3P[8], G4P[8], and G9P[8] (2). Genome segment reassortment between human strains or human and animal strains during co-infections can generate viruses with novel genotype combinations, possibly influencing the virus phenotype (2). Some human and animal RVA strains possess unusual genotype combinations (3,4), and some strains might partially escape vaccine-induced immune protection (5).

Since 2007, the RVA surveillance network RotaNet-Italy has confirmed circulation of common RVA genotypes among children in Italy, despite sporadic uncommon, exotic, or zoonotic genotypes (6,7). We describe infection with a rare G3P[19] RVA strain in an immunosuppressed adult patient in Italy who had severe diarrhea.

The Study

In 2012, a 35-year-old woman who was hospitalized in the Hematology Unit of Rome University Hospital “Agostino Gemelli” in Rome, Italy she experienced acute gastroenteritis after a bone marrow allotransplant. Stool samples were collected and tested for classic bacterial, viral, and parasitic enteropathogens. The study was performed in compliance with informed consent guidelines in Italy.

Viral RNA was extracted by using the Viral RNeasy MiniKit (QIAGEN/Westburg, Milan, Italy) and stored at −80°C until use. Rotavirus G- and P-genotyping were performed by reverse transcription nested PCR by using VP7 or VP4 primer mixtures described previously (8,9). Nucleotide sequencing was performed by Macrogen, Inc. (Seoul, South Korea) by using the PCR primers. After analysis in Chromas Pro 2.23 (http://www.technelysium.com.au), consensus sequences were obtained by using SeqMan II (http://www.dnastar.com/t-seqmanpro.aspx). Multiple sequence alignments were carried out, and phylogenetic trees were created by using MEGA5 software (http://www.megasoftware.net) (10), using the maximum-likelihood method and Kimura 2- (NS 4–5) or Tamura 3- (all other genes) parameter tests. Strain sequences from this study were deposited in GenBank (accession nos. KF729023–729032).

The patient had Down syndrome, acute lymphatic leukemia, and blood type A Rh+ CCDeekk phenotype a transcranial Doppler scane did not show any abnormalities . She had received a stem cell allotransplant, followed by immunosuppressive treatment. Acute gastroenteritis began 2 days after immunosuppression, on day 10 after admission to the Hematology Unit. Diarrhea was nonbloody and watery, not accompanied by vomiting and fever, and lasted 3 days, during which rehydration therapy was administered. The patient was released from the hospital in stable condition she died of systemic complications 3 months later.

Stool samples were collected at diarrhea onset and tested for bacterial and viral enteric pathogens. Results were negative for Salmonella, Shigella, Campylobacter, Yersinia, Escherichia coli, staphylococci, Giardia, norovirus, and adenovirus. Only rotavirus and Klebsiella pneumoniae were detected because the patient did not exhibit chronic/bloody diarrhea or other systemic pathologies typically related to K. pneumoniae infection, this pathogen was not investigated further.

Figure 1. Phylogenetic trees of rotavirus A (RVA) isolates based on the open reading frames of genes coding for the viral protein (VP) regions. A) VP1 (nt 73–390) B) VP2 (nt 1–425) C).

Figure 2. Phylogenetic trees of rotavirus A (RVA) isolates based on the open reading frames of genes coding for the nonstructural protein (NS) regions. A) NS1 (nt 67–1087), B) NS2 (nt 47–1012), C).

The rotavirus strain, RVA/human-wt/ITA/ROMA116/2012/G3P[19] (ROMA116), was characterized by analyzing its 11 genomic RNA segment sequences in RotaC Tool (http://rotac.regatools.be/). The strain showed the genotype constellation of G3-P[19]-I3-R3-C3-M3-A3-N3-T3-E3-H3. Phylogenetic analyses confirmed a full AU-1–like genomic constellation, associated with the P[19] VP4 gene (Figures 1, 2). The strain clustered strictly with RVA/human-tc/CHN/L621/2006/G3P[9] from China (11), sharing 98%–99% nucleotide identities for most genes except VP1 (identity 91%), and the VP4 and NS5 genes, which belonged to different genotypes (Figures 1, 2). ROMA116 also showed high nucleotide identities (98%–99%) in VP2, VP6–7, and NS1–4 genes with strain RVA/human-wt/THA/CU365-KK/2008/G3P[9] from Thailand (12).

The VP7 tree (Figure 1, panel D) revealed strict clustering of ROMA116 with G3 strains from China, Thailand, and Hong Kong, all associated with P[9] VP4. However, other G3 RVA strains from Italy reported in humans or cats grouped in the same cluster. The VP4 tree (Figure 1, panel E) shows the correlation of the ROMA116 P[19] sequence with P[19] sequences detected in human and swine strains from 1994–2010, suggesting possible human-pig reassortment at the origin of ROMA116 VP4. Further evidence of reassortment resulted from both VP1 and NS5 tree analyses. In VP1, ROMA116 showed the highest nucleotide identity (95%) with simian strain TUCH (Figure 1, panel A) in NS5, the uncommon H3 genotype of ROMA116 clustered with strains detected in or derived from animals (Figure 2, panel E).

The phylogenetic trees show the divergence of ROMA116 from the constellation 3 putative ancestor AU-1 (13), characterized during the 1980s. ROMA116 shared relatively high nucleotide sequence conservation of only the NS1 gene with AU-1, but all other genes analyzed clustered more closely with RVA strains detected in Asia. This mixed genomic pattern probably was generated by previous reassortment events between strains circulating in that area. Analysis of the VP1, VP4, and NS5 gene trees together indicates that ROMA116 may have evolved through multiple reassortment events involving RVA strains of different animal origins.

Conclusions

The G3P[19] RVA strain we identified represents a single sporadic detection among >7,000 human RVA strains investigated in Italy during a 7-year period, which suggests either a recent introduction or a low ability of this strain to spread among humans. However, the phylogenetic analysis shows that the overall genome of ROMA116 is more similar to those reported for human strains than for animal strains, suggesting that the strain has a lower fitness for replicating in animal hosts than in humans. A study in Thailand (14) reported an outbreak of diarrhea in piglets caused by G3P[19] RVA, but no information was available for the other genes of that strain.

The possible importation of an apparently exotic rotavirus strain such as ROMA116 into Italy is not surprising the country’s geographic position favors massive migratory flows of persons from developing countries. Although rare, similar events have been suggested previously (7). The source of this infection was not identified no additional case was reported among hospital ward patients and personnel or in the patient’s family. The patient’s parents had been cleared to assist their daughter daily after the transplant, but strict control measures for opportunistic infectious agents were otherwise enforced. The patient’s family lived in a rural area where swine, bovine, and ovine farming activities occur in close proximity to human residential settlements, which may favor the circulation and zoonotic transmission of viruses from domestic animals to a higher extent than is possible inside urban settings such as Rome. The G3P[19] RVA strain may have been transmitted by an asymptomatic but infected relative, or the patient may have been harboring the strain in the gut before hospital admission, with active viral replication and disease occurring after immunosuppressive treatment.

Because no other enteropathogens were detected among the large panel of bacteria, viruses, and parasites investigated, it is likely that rotavirus was directly involved in causing illness in the patient, whose clinical symptoms were compatible with acute watery rotavirus diarrhea. It is possible that this RVA genotype may not cause disease in immunocompetent persons and that the compromised immune status of this patient played a critical role. Even if G3P[19] RVA, as with other uncommon viral strains, does not present a direct risk for public health in Italy, it could nonetheless be a donor of atypical RVA genes that might reassort into novel epidemic strains that could escape existing herd immunity in humans. In this view, RVA surveillance of both farmed and pet animals could be of valuable support to human surveillance of severe cases in hospitals (15), particularly in the postvaccine globalized world.

Dr Ianiro works as a postdoctoral researcher in the National Center for Immunobiologicals Research and Evaluation and the Department of Veterinary Public Health and Food Safety, Istituto Superiore di Sanità, Rome. His main research areas are molecular biology and epidemiology of human and animal rotaviruses.


Conclusion

Efforts to help alleviate the burden of rotavirus disease in sub-Saharan Africa and other developing countries have increased significantly in recent years. In this study, we evaluated the possibility of producing rotavirus VLPs using a plant expression system to produce a vaccine specifically adapted to the sub-Saharan African regions. We had partial success in demonstrating the capacity of the transient plant expression system to express specific rotavirus proteins. Despite the fact that no VLPs were observed for our fusion proteins, expression was detected for all chimeric proteins engineered, illustrating the versatility of plant-based systems. While this work is preliminary, we believe that it will serve as a solid basis for future studies on plant-made rotavirus vaccines for Africa.


Characterization of a Novel P[25],G11 Human Group A Rotavirus

FIG. 1 . Neighbor-joining phylogenetic tree based on nucleotide sequences of the VP7 encoding genes (nt 49-1026) for Dhaka6 and other established rotavirus G types. BO, bovine HU, human PO, porcine EQ, equine AV, avian. The VP7 sequences were obtained from published reports and the GenBank database. The GenBank accession numbers of the following strains are given in parentheses: Wa (KO2033), HU5 (A01028), SA11 (K02028), ST3 (X13603), OSU (X04613), NCDV (M12394), PA151 (L20881), Se584 (AJ311740), Ch2 (X56784), B37 (J04334), B223 (X57852), YM (M23194), L26 (M58290), L333 (D13549), FI23 (M61876), and Hg18 (AF237666). The VP7 sequence of WI61 was obtained from Green et al. (16). FIG. 2 . Comparison of the amino acid sequences of antigenic regions of Dhaka6 and other rotavirus G types. Dots indicate amino acids identical to the respective amino acids of Dhaka6. FIG. 3 . Neighbor-joining phylogenetic tree based on the nucleotide sequences (nt 44-762) of the VP8* fragments of the VP4 genes for Dhaka6 and other established rotavirus P types. BO, bovine HU, human PO, porcine EQ, equine SI, simian OV, ovine MU, murine RH, rhesus LA, lupine. The VP4 sequences and their GenBank accession numbers are as follows: A5 (D13395), SA11 (X14204), HCR3 (L19712), RV5 (M32559), UK ST3 (L33895), OSU (X13190), Wa (L34161), AU1 (D10970), 69 M (M60600), 116E (L94072), H2 (L04638), MDR13 (L07886), Mc35 (D14032), Lp14 (L11599), Eb (L18992), 993/83 (D16352), L338 (D13399), 4F (L10359), EHP (U08424), Hg18 (AF237665) 160/01 (AF528202), A34 (L35059), and TUCH (AY596179).