Rotavirus typing methods and algorithms

Genomic analysis of an acute gastroenteritis outbreak caused by rotavirus C in Hebei, China

Rotavirus group C is an important cause of sporadic cases and outbreaks of gastroenteritis worldwide. Whole-Genome sequences of human rotavirus C (RVC) in public databases are limited. We performed genome sequencing to analyze a RVC outbreak of acute gastroenteritis in China. Samples from 22 patients were screened for pathogens using RT-PCR, and six samples were positive for rotavirus. Whole-Genome sequencing analysis showed that the outbreak strain SJZ217 belongs to the G4-P[2]-I2-R2-C2-M3-A2-N2-T2-E2-H2 genotype and shares almost identical genomic sequences with Chungnam isolated in Korea. Phylogenetic analysis revealed strain SJZ217 also fell into a cluster with rotavirus C strains from Japan and Europe. Reassortment in the VP4 fragment was observed. These results helped to understand the genetic diversity and possible spread of RVC strains.

Global Infection Rate of Rotavirus C during 1980-2022 and Analysis of Critical Factors in the Host Range Restriction of Virus VP4

Information on rotavirus C (RVC) infection is lacking, partly because the prevalence of RVC among humans and animals worldwide is undefined. Data on the characteristics of the P genotype among RVC strains are also required. We performed systematic searches on the infection rates of RVC since 1980 based on the literature and gene sequences of the PubMed and GenBank databases. A phylogenetic tree of VP4 genes was constructed to evaluate the distribution of the P genotype of RVC from various hosts. The specific mutation motifs in VP8* with P [2]/P [4]/P [5] specificity were analyzed to elucidate their roles in host range restriction. The rate of RVC infection in humans has fallen from 3% before 2009 to 1%, whereas in animals it has risen from 10% to 25%. The P genotype of RVC showed strict host species specificity, and current human RVC infections are exclusively caused by genotype P [2]. In the VP8* hemagglutinin domain of the P [4]/P [5] genotype of swine RVC, specific insertion or deletion were found relative to the human P [2] genotype, and these motifs are a possible critical factor for host range restriction. Our findings highlight the need for further epidemiological surveillance, preventive strategies, and elucidation of the factors involved in the specific host range restriction of RVC-circulating strains.

Microbial health risks associated with rotavirus and enteric bacteria in River Ala in Akure, Nigeria

AIM

This study was carried out to determine the microbial health risks associated with a surface water commonly used for bathing, drinking, domestic and irrigational activities in Akure, Nigeria.

METHODS AND RESULTS

Water samples were collected from the river from March to June, 2018. The load of enteric bacteria, somatic coliphages and rotavirus in the water samples were determined using culture-based methods and molecular technique. The physicochemical characteristics of the water samples were determined using standard methods. The risks of rotavirus, Salmonella and Shigella infections resulting from ingestion of the water from the river were estimated using dose-response model. Redundancy analysis revealed that the levels of E. coli and Salmonella were highly associated with salinity and turbidity. The risks of infection associated with rotavirus (3.3 × 10^-3 ) was higher than those associated with Salmonella (1.3 × 10^-4 ) and Shigella (1.3 × 10^-3 ), and were all above the WHO acceptable risk limit (10^-4 ).

CONCLUSION

Accidental or intentional ingestion of water from the river may pose potential risks of gastrointestinal illness to humans.

SIGNIFICANCE AND IMPACT OF STUDY

Quantitative microbial risk assessment is essential in establishing adequate water management practices that must be strictly followed in order to protect human health.

Group A Rotavirus G1P[6] Associated Fatalities in Diarrheic Nigerian Infants, Possible Impact of Enterovirus Environmental Enteric Dysfunction, and Implications for Rota-Vaccinology

Group A rotavirus (RVA) diarrhea disease and mortality are yet unabated, particularly in developing countries. As global knowledge of specific strains associated with infant mortality is crucial for successful vaccination efforts, candidate RVA strains detected in mortality and fatal cases of severely diarrheic hospitalized infants in Akure, Nigeria were investigated.

Fecal samples from comatose patients were tested for RVAs, other diarrhea viruses, and enteric bacterial pathogens. Genomic dsRNA was extracted from 10% rotavirus positive stool suspension, the VP4 and VP7 genes were reverse transcribed and amplified by one-step reverse transcription polymerase chain reaction (PCR) and genotyped by seminested multiplex PCR. Amplicons were sequenced, aligned by ClustalW, and phylogenetic analyses were conducted in MEGA6. Sequences data were deposited to GenBank and DDBJ.

Medical examination and microbiological analyses upheld viral diarrhea. EIA revealed RVA and enterovirus. PCR identified virulent RVA strain GIP[6] whose VP7 nucleotide sequences shared a common cluster with Cuban isolate G1P[6], while the VP4 P[6] sequences were related to Asian strains. Reassortant RVA G1P[6] was found in fatal diarrhea cases and mortality of a Nigerian child. RVA coinfection with enterovirus and associated biomarkers of environmental enteric dysfunction in infantile diarrhea should henceforth be evaluated. Current rotavirus vaccines may fare badly against the prevailing virulent strains. The disease severity and outcome necessitates a wider epidemiological study, a review and inclusion of the P[6] genotype in future rotavirus vaccines.

Distribution of Rotavirus Genotypes Ccirculating in Ahvaz, Iran in 2016

Background

Group A rotavirus (RVA) mainly causes acute gastroenteritis, exclusively in young children in developing countries. The prevalence and determination of the molecular epidemiology of rotavirus genotypes will determine the dominant rotavirus genotypes in the region and provide a strategy for the development of appropriate vaccines.

Methods

A total of 100 fecal samples were collected from children below five years with acute gastroenteritis who referred to Aboozar Children’s Hospital of Ahvaz city during October 2015 to March 2016. All samples were screened by latex agglutination for the presence of rotavirus antigen. Rotavirus-positive samples were further analyzed by the semi-multiplex RT-PCR, and the sequencing was performed for G/P genotyping.

Results

Findings showed that 32% of the specimens were RVA-positive. Among the 32 VP7 genotyped strains, the predominant G genotype was G9 (37.5%), followed by G2 (21.9%), G1 (12.5%), G12 (9.4%), G4 (9.4%), G2G9 (6.3%), and G3 (3.1%). Among the 31 VP4 genotyped strains, P[8] genotype was the dominant (62.5%), followed by P[4] (31.3%) and P[4] P[8] (3.1%). The genotypes for G and P were identified for 31 rotaviruses (96.87%), but only one strain, G9, remained non-typeable for the P genotype. The most prevalent G/P combination was G9P[8] (28.5%), followed by G2P[4] (18.8%), G1P[8] (9.4%), G12P[8] (9.4%), G4P[8] (9.4%), G2G9P[4] (6.3%), G9P[4] P[8] (3.1%), G3P[8] (3.1%), G9P[4] (3.1%), G2P[8] (3.1%), and G9P[non-typeable] (3.1%).

Conclusion

A novel rotavirus strain, G12, was detected, for the first time, in patients from the southwest of Iran. Comprehensive investigations are required to evaluate the emergence of this strain.

Detection of rotavirus in clinical specimens using an immunosensor prototype based on the photon burst counting technique

In this study, a sensitive fluorescence sensor was developed for the detection of small, fluorescence-labeled particles dispersed in a solution. The prototype system comprises of a laser confocal optical system and a mechanical sample stage to detect photon bursting of fluorescence-labeled small particles in sample volumes less than 5 μL within 3 minutes. To examine the feasibility of the prototype system as a diagnostic tool, assemblages of rotavirus and fluorescence-labeled antibody were analyzed. The detection sensitivity for rotavirus was 1 × 10⁴ pfu/mL. Rotavirus in stool samples from patients with acute gastroenteritis was also detected. The advantages and disadvantages of this immunosensor with respect to ELISA and RT-PCR, the current gold standards for virus detection, are discussed.

One-step multiplex real-time RT-PCR assay for detecting and genotyping wild-type group A rotavirus strains and vaccine strains (Rotarix® and RotaTeq®) in stool samples

Background. Group A rotavirus (RVA) infection is the major cause of acute gastroenteritis (AGE) in young children worldwide. Introduction of two live-attenuated rotavirus vaccines, RotaTeq® and Rotarix®, has dramatically reduced RVA associated AGE and mortality in developed as well as in many developing countries. High-throughput methods are needed to genotype rotavirus wild-type strains and to identify vaccine strains in stool samples. Quantitative RT-PCR assays (qRT-PCR) offer several advantages including increased sensitivity, higher throughput, and faster turnaround time. Methods. In this study, a one-step multiplex qRT-PCR assay was developed to detect and genotype wild-type strains and vaccine (Rotarix® and RotaTeq®) rotavirus strains along with an internal processing control (Xeno or MS2 RNA). Real-time RT-PCR assays were designed for VP7 (G1, G2, G3, G4, G9, G12) and VP4 (P[4], P[6] and P[8]) genotypes. The multiplex qRT-PCR assay also included previously published NSP3 qRT-PCR for rotavirus detection and Rotarix® NSP2 and RotaTeq® VP6 qRT-PCRs for detection of Rotarix® and RotaTeq® vaccine strains respectively. The multiplex qRT-PCR assay was validated using 853 sequence confirmed stool samples and 24 lab cultured strains of different rotavirus genotypes. By using thermostable rTth polymerase enzyme, dsRNA denaturation, reverse transcription (RT) and amplification (PCR) steps were performed in single tube by uninterrupted thermocycling profile to reduce chances of sample cross contamination and for rapid generation of results. For quantification, standard curves were generated using dsRNA transcripts derived from RVA gene segments. Results. The VP7 qRT-PCRs exhibited 98.8-100% sensitivity, 99.7-100% specificity, 85-95% efficiency and a limit of detection of 4-60 copies per singleplex reaction. The VP7 qRT-PCRs exhibited 81-92% efficiency and limit of detection of 150-600 copies in multiplex reactions. The VP4 qRT-PCRs exhibited 98.8-100% sensitivity, 100% specificity, 86-89% efficiency and a limit of detection of 12-400 copies per singleplex reactions. The VP4 qRT-PCRs exhibited 82-90% efficiency and limit of detection of 120-4000 copies in multiplex reaction. Discussion. The one-step multiplex qRT-PCR assay will facilitate high-throughput rotavirus genotype characterization for monitoring circulating rotavirus wild-type strains causing rotavirus infections, determining the frequency of Rotarix® and RotaTeq® vaccine strains and vaccine-derived reassortants associated with AGE, and help to identify novel rotavirus strains derived by reassortment between vaccine and wild-type strains.

Sequence Diversity of VP4 and VP7 Genes of Human Rotavirus Strains in Saudi Arabia

Group A rotavirus is responsible for inducing severe diarrhea in young children worldwide. Rotavirus vaccines are used to control the disease in many countries. In the current study, the sequences of human rotavirus G and P types in Saudi Arabia are reported and compared to different relevant published sequences. In addition, the VP4 and VP7 genes of the G1P[8] strains are compared to different antigenic epitopes of the rotavirus vaccines. Stool samples were collected from children under 2 years suffering from severe diarrhea. Screening of the rotavirus-positive samples was performed with rapid antigen detection kit. RNA was amplified from rotavirus-positive samples by reverse transcriptase polymerase chain reaction assay for both VP4 and VP7 genes. Direct sequencing of the VP4 and VP7 genes was conducted and the obtained sequences were compared to each other and to the rotavirus vaccines. Both G1P[8] G1P[4] genotypes were detected. Phylogenetic analysis revealed that the detected strains belong to G1 lineage 1 and 2, P[8] lineage 3, and to P[4] lineage 5. Multiple amino acid substitutions were detected between the Saudi RVA strains and the commonly used vaccines. The current findings emphasize the importance of the continuous surveillance of the circulating rotavirus strains, which is crucial for monitoring virus evolution and helping in predicting the protection level afforded by rotavirus vaccines.

Multiplexed one-step RT-PCR VP7 and VP4 genotyping assays for rotaviruses using updated primers

The current two-step VP7 and VP4 genotyping RT-PCR assays for rotaviruses have been linked consistently to genotyping failure in an estimated 30% of RVA positive samples worldwide. We have developed a VP7 and VP4 multiplexed one-step genotyping assays using updated primers generated from contemporary VP7 and VP4 sequences. To determine assay specificity and sensitivity, 17 reference virus strains, 6 non-target gastroenteritis viruses and 725 clinical samples carrying the most common VP7 (G1, G2, G3, G4, G9, and G12) and VP4 (P[4], P[6], P[8], P[9] and P[10]) genotypes were tested in this study. All reference RVA strain targets yielded amplicons of the expected sizes and non-target genotypes and gastroenteritis viruses were not detected by either assay. Out of the 725 clinical samples tested, the VP7 and VP4 assays were able to assigned specific genotypes to 711 (98.1%) and 714 (98.5%), respectively. The remaining unassigned samples were re-tested for RVA antigen using EIA and qRT-PCR assays and all were found to be negative. The overall specificity, sensitivity and limit of detection of the VP7 assay were in the ranges of 99.0-100%, 94.0-100% and 8.6×10(1) to 8.6×10(2) copies of RNA/reaction, respectively. For the VP4 assay, the overall specificity, sensitivity and limit of detection assay were in the ranges of 100%, 94.0-100% and ≤1 to 8.6×10(2) copies of RNA/reaction, respectively. Here we report two highly robust, accurate, efficient, affordable and documentable gel-based genotyping systems which are capable of genotyping 97.8% of the six common VP7 and 98.3% of the five common VP4 genotypes of RVA strains which are responsible for approximately 88.2% of all RVA infections worldwide.

PCR-based approach to distinguish group A human rotavirus genotype 1 vs. genotype 2 genes

Group A rotaviruses (RVs) are eleven-segmented, double-stranded RNA viruses and important causes of severe diarrhea in children. A full-genome classification system is readily used to describe the genetic makeup of individual RV strains. In this system, each viral gene is assigned a specific genotype based upon its nucleotide sequence and established percent identity cut-off values. However, a faster and more cost-effective approach to determine RV gene genotypes is to utilize specific oligonucleotide primer sets in RT-PCR/PCR. Such primer sets and PCR-based genotyping methods have already been developed for the VP7-, VP6-, VP4- and NSP4-coding gene segments. In this study, primers were developed for the remaining seven RV gene segments, which encode proteins VP1, VP2, VP3, NSP1, NSP2, NSP3, and NSP5/6. Specifically, primers were designed to distinguish the two most common human RV genotypes (1 vs. 2) for these genes and were validated on several cell culture-adapted human and animal RV strains, as well as on human RVs from clinical fecal specimens. As such, primer sets now exist for all eleven genes of common human RVs, allowing for the identification of reassortant strains with mixed constellations of both genotype 1 and 2 genes using a rapid and economical RT-PCR/PCR method.

Inaccurate identification of rotavirus genotype G9 as genotype G3 strains due to primer mismatch

Reverse transcription (RT)-PCR is now the standard method for typing group A rotaviruses (RVA) to monitor the circulating genotypes in a population. Selection of primers that can accurately type the circulating genotypes is crucial in the context of vaccine introduction and correctly interpreting the impact of vaccination on strain distribution. To our knowledge this study is the first report from Asia of misidentification of genotype G9 as G3 due to a primer-template mismatch. We tested two published G-genotype specific primers sets, designed by Gouvea and colleagues (Set A) and Iturriza‐Gomara and colleagues (Set B) on RVA from Hong Kong and Sri Lanka. Among 52 rotaviruses typed as G3 by set A primers, 36 (69.2%) were identified as G9 by nucleotide sequencing and set B primers. Moreover, of 300 rotaviruses tested, 28.3% were untypable by set A primers whereas only 12.3% were untypable by set B primers. Our findings reinforce the need to periodically monitor the primers used for RVA genotyping.

Imaging of central nervous system viral diseases

Viral infections of the central nervous system (CNS) are commonly encountered and there has been continued emergence of new neurotropic viruses which are being frequently recognized. These may present clinically as encephalitis, meningitis, encephalomyelitis, and encephalomyeloradiculitis. The clinical manifestations are usually nonspecific and diagnosis is usually based on the laboratory investigations. Imaging plays a role in its early detection and at times suggests the specific diagnosis that may help in early institution of appropriate therapy. In this review, we summarize the pathology, clinical, and imaging features of the common viral infections that affect the CNS.

The burden of rotavirus disease in Denmark 2009-2010

BACKGROUND

This study sought to determine the incidence and the burden of severe diarrheal disease in Denmark with emphasis on rotavirus (RV) disease.

METHODS

This study was designed as a national prospective disease surveillance of children <5 years of age hospitalized for acute gastroenteritis in Denmark during March 2009 to April 2010, using rapid RV and adenovirus antigen detection.

RESULTS

A total of 3100 hospitalizations annually among Danish children <5 years of age can be attributed to acute gastroenteritis and 1210 (39%) of these to RV disease. The majority of RV-associated hospitalizations occur among children ≤ 24 months of age (RV-associated hospitalization rate: 7.7/1000 children ≤ 24 months of age and 3.8/1000 children <5 years of age). Although the well-known seasonal pattern of RV was evident with a peak during the spring months of March through April, our active surveillance demonstrated RV-associated hospitalizations throughout the year. Genotyping of a subset of RV-samples demonstrated high frequency of G1 (39%) and G4 (32%). Adenovirus was detected in 350 acute gastroenteritis-associated hospitalizations (11.2%).

CONCLUSION

In conclusion, we present national disease burden data on severe cases of gastroenteritis and specifically RV-associated disease and demonstrate that RV is indeed ubiquitous in the population and can be considered a major health burden among young Danish children.

Ovine rotavirus strain LLR-85-based bovine rotavirus candidate vaccines: construction, characterization and immunogenicity evaluation

Group A bovine rotaviruses (BRVs) are the most important cause of diarrheal diseases in neonatal calves and cause significant morbidity and mortality in the young animals, and epidemiologic surveillance of bovine rotavirus G genotypes conducted in various cattle populations throughout the world has shown that approximately 90% of the bovine rotavirus isolates belong to G6 and G10. Based on the modified Jennerian approach to immunization, we constructed and characterized a reassortant rotavirus stain, which bears a single bovine rotavirus VP7 gene encoding G genotype 6 specificity while the remaining 10 genes are derived from the ovine attenuated rotavirus LLR-85. The reassortant rotavirus strain, named as R191, and its parental virus strain LLR-85 were combined as bivalent vaccine candidates to inoculate the colostrums-deprived neonatal calves for evaluation of the immunogenicity. The calves were orally inoculated with the reassortant R191 (group 1), the parental rotavirus LLR-85 (group 2), or combined the R191 and LLR-85 (group 3), and serum specimens were detected to determine the immune response of IgG and IgA antibodies. Results showed that seroconversion to positivity for IgG and IgA antibodies occurred at postinoculation day (PID) 10 in all of the inoculated calves, and the highest titers of the serum IgG (range 1:800 to 1:6400) and IgA (range 1:800 to 1:3200) antibodies were obtained at PID 21 for all calves. Meanwhile, virus shedding was detected after inoculation, showing that the inoculated virus was positive in 2 of 77 fecal specimens (2.6%) collected from the inoculated calves during the first 7 days of oral inoculation with the rotavirus vaccine candidates. The results suggested that the rotavirus strains R191 and LLR-85 are promising bivalent vaccine candidates for the prevention of bovine G6 and G10 rotavirus infection.

Trends and Perspectives of Biosensors for Food and Environmental Virology

Food and environmental virology has become a very important and interesting area of research because of food safety and public health concerns. During the last few decades, increasing foodborne diseases and environmental generated illnesses are considered to be highly challenging issues. Biosensor technology holds great promise for the healthcare market, and the security sector. Similar to clinical diagnostic tools, biosensors are being developed for the rapid, reliable, yet inexpensive identification and enumeration of pathogenic viruses which are adulterating environment, food and feed commodities. In this modern era, bio-and nano-technologies play a pivotal role in virological diagnostics of food industry, environmental and veterinary samples. This review covers the recent advances and future prospects of nanotechnology-based bioanalytical microsystems for food and environmental virology.

[Predominance of G9 rotavirus in Valencia and Castellón between 2005 and 2007]

INTRODUCTION

Rotavirus is the leading cause of acute gastroenteritis in young children worldwide. Effective vaccines to prevent rotavirus infections are currently available, although their clinical use is still limited, and rotavirus still causes many episodes of infantile gastroenteritis, mainly during the winter seasons.

OBJECTIVE

To characterise G (VP7) and P (VP4) genotypes of rotaviruses causing acute gastroenteritis in children and to determine the prevalence of genotype G9 rotavirus in three public health areas in the provinces of Valencia and Castellon.

PATIENTS AND METHODS

Five-hundred and forty-one stool samples were prospectively collected from infants and children with gastroenteritis in the period between October 2005 and September 2008. They were analysed for rotavirus by ELISA or by immunochromatography. G and P genotyping was performed by reverse transcription and PCR (RT-PCR).

RESULTS

G and P rotavirus genotypes were characterised in a total of 525 faecal samples (97%), resulting in a global predominance of strains G9P[8] (56.5%) and G1P[8] (29.9%). During the period of time studied, G9P[8] was the G/P combination most frequently detected during the rotavirus seasons 2005-2006 and 2006-2007, being present in 81.2% and 64.7% of the patients, respectively. However, during the 2007-2008 season, G1P[8] strains were the most frequently found (68.8%), with a sharp decrease in G9P[8] strains to 7.2% of the samples.

CONCLUSIONS

Rotavirus G9P[8] have spread rapidly and widely during the 2005-2006 and 2006-2007 seasons, replacing other previously dominant genotypes (G1, G4) in our geographic area. Its incidence has declined sharply in 2007-2008, in which G1P[8] was again the predominating genotype.

[Detection of a rotavirus G9P[8] outbreak causing gastroenteritis in a geriatric nursing home]

INTRODUCTION

The aim of this study was to describe an outbreak of gastroenteritis due to rotavirus in a geriatric nursing home.

METHOD

Stool samples from 8 patients were studied. Antigen detection was carried out by ELISA, and molecular typing was performed by RT-PCR.

RESULTS

Rotavirus antigen was detected in 6 patients. Typing demonstrated a common genotype (G9P[8]).

CONCLUSION

The outbreak detected in elderly persons suggests a loss of immunity with age or a lack of protection against an emergent genotype.

Emergence of G12 rotavirus strains in Delhi, India, in 2000 to 2007

The prospect that rotavirus diarrhea in children may soon be prevented by vaccines has placed a new priority on understanding the diversity of rotavirus strains and the mechanism by which these strains evolve over time. We have characterized a total of 465 rotavirus strains collected in North India from 2000 to 2007 for G and P types by reverse transcription-PCR and sequencing. The novel G12 rotavirus strains recently detected in other countries were first detected in India in 2001 and have emerged as the predominant strains in Delhi, India, during 2005 to 2007. While the VP7 sequence was highly homologous among G12 strains isolated in Delhi, suggesting recent emergence from a common ancestor, the strains had a diverse constellation of other gene segments, demonstrating substantial reassortment. For the entire period, the common rotavirus G types G1 (26%), G2 (25%), and G9 (14%) comprised 65% of the strains, and common P types, P[4] (19%), P[6] (22%), and P[8] (35%), comprised 76% of the total P types. Of note, we detected a high percentage of unusual (17%) strains and fecal specimens with mixed (12% G and 15% P) rotavirus infections having a variety of genomic constellations. For the first time, we identified two novel rotavirus strains with unusual G/P combinations, G2P[11] and G3P[11], in patients with diarrhea. The study highlights the great diversity among rotaviruses isolated from Indian children, the opportunity for genetic reassortment between strains, and the emergence of a novel G12 strain in our country. Due to the demonstrated effect of antigenic diversity on rotavirus vaccines, it will be important to continue careful monitoring of these strains as rotavirus vaccine programs are implemented in India.

Development of a microtiter plate hybridization-based PCR-enzyme-linked immunosorbent assay for identification of clinically relevant human group A rotavirus G and P genotypes

A microtiter plate hybridization-based PCR-enzyme-linked immunosorbent assay (PCR-ELISA) has been used for the detection and identification of a variety of microorganisms. Here, we report the development of a PCR-ELISA for the identification of clinically relevant human rotavirus VP7 (G1 to G6, G8 to G10, and G12) and VP4 (P[4], P[6], P[8], P[9], and P[14]) genotypes. The G and P types of reference human and animal rotavirus strains for which specific probes were available were correctly identified by the PCR-ELISA. In addition, reference strains bearing G or P genotypes for which specific probes were unavailable, such as G11, G14, P[3], P[10], and P[11], did not display any cross-reactivity to the probes. The usefulness of the assay was further evaluated by analyzing a total of 396 rotavirus-positive stool samples collected in four countries: Brazil, Ghana, Japan, and the United States. The results of this study showed that the PCR-ELISA was sensitive and easy to perform without the use of any expensive and sophisticated equipment, the reagents used are easy to obtain commercially and advantageous over multiplex PCR since more than one type-specific probe is used and the selection of probes is more flexible.

Genetic diversity of the VP4 and VP7 genes affects the genotyping of rotaviruses: analysis of Paraguayan strains

The introduction of different multiplex RT-PCR strategies for the characterization of field rotavirus strains has led to improvements of surveillance systems worldwide. Nevertheless, the failure or incorrect characterization of rotavirus strains by these PCR strategies, mainly due to accumulation of point mutations in the VP4 and VP7 genes, has been reported. In this work, sequence analyses of the VP4 and VP7 genes from Paraguayan G1P[8] and G4P[8] strains revealed that the high degree of similarity with the primers pNCDV and ET10 could lead to the incorrect characterization of these strains as P[1] and G10 types. Moreover, the nucleotide diversity of the VP4 gene at the 1T-1 primer binding site could be one, although not the only, reason of the failure of the P[8] typing. Therefore, the typing methods utilized by surveillance programs should be constantly evaluated and sequencing of atypical strains should become a current practice in order to confirm their real nature.

Development and validation of DNA microarray for genotyping group A rotavirus VP4 (P[4], P[6], P[8], P[9], and P[14]) and VP7 (G1 to G6, G8 to G10, and G12) genes

Previously, we reported the development of a microarray-based method for the identification of five clinically relevant G genotypes (G1 to G4 and G9) (V. Chizhikov et al., J. Clin. Microbiol. 40:2398-2407, 2002). The expanded version of the rotavirus microarray assay presented herein is capable of identifying (i) five clinically relevant human rotavirus VP4 genotypes (P[4], P[6], P[8], P[9], and P[14]) and (ii) five additional human rotavirus VP7 genotypes (G5, G6, G8, G10, and G12) on one chip. Initially, a total of 80 cell culture-adapted human and animal reference rotavirus strains of known P (P[1] to P[12], P[14], P[16], and P[20]) and G (G1-6, G8 to G12, and G14) genotypes isolated in various parts of the world were employed to evaluate the new microarray assay. All rotavirus strains bearing P[4], P[6], P[8], P[9], or P[14] and/or G1 to G6, G8 to G10, or G12 specificity were identified correctly. In addition, cross-reactivity to viruses of genotype G11, G13, or G14 or P[1] to P[3], P[5], P[7], P[10] to P[12], P[16], or P[20] was not observed. Next, we analyzed a total of 128 rotavirus-positive human stool samples collected in three countries (Brazil, Ghana, and the United States) by this assay and validated its usefulness. The results of this study showed that the assay was sensitive and specific and capable of unambiguously discriminating mixed rotavirus infections from nonspecific cross-reactivity; the inability to discriminate mixed infections from nonspecific cross-reactivity is one of the inherent shortcomings of traditional multiplex reverse transcription-PCR genotyping. Moreover, because the hybridization patterns exhibited by rotavirus strains of different genotypes can vary, this method may be ideal for analyzing the genetic polymorphisms of the VP7 or VP4 genes of rotaviruses.

Prevention of rotavirus disease: guidelines for use of rotavirus vaccine

On February 3, 2006, a bovine-based pentavalent rotavirus vaccine (RotaTeq, Merck & Co Inc, Whitehouse Station, NJ) was licensed by the US Food and Drug Administration for use in infants in the United States. The American Academy of Pediatrics recommends routine immunization of infants with 3 doses of pentavalent rotavirus vaccine administered orally at 2, 4, and 6 months of age. The first dose should be administered between 6 and 12 weeks of age; immunization should not be initiated for infants older than 12 weeks of age. Subsequent doses should be administered at 4- to 10-week intervals, and all 3 doses of vaccine should be administered by 32 weeks of age. Pentavalent rotavirus vaccine can be coadministered with other childhood vaccines. Pentavalent rotavirus vaccine is contraindicated for infants with a serious allergic reaction to any vaccine component or to a previous dose of vaccine.

Rotavirus as a significant cause of prolonged diarrhoeal illness and morbidity following allogeneic bone marrow transplantation

Infective diarrhoea is common among allogeneic stem cell transplant (SCT) recipients, frequently caused by viruses and may be difficult to differentiate from acute graft-versus-host disease (GVHD). Viral pathogens may directly or indirectly impact upon transplant-related mortality. Rotavirus is one of the most common causes of diarrhoea worldwide, but one of the least studied causes of diarrhoea post SCT. In this retrospective study we describe 21 cases of confirmed rotavirus infection in allogeneic SCT recipients. Most of these cases may occur in clusters during the winter and spring period. Symptoms of rotaviral infection were diarrhoea (95%), vomiting (62%), abdominal pain (38%), weight loss and loss of appetite in 38 and 29% of the cases, respectively. Possible extraintestinal manifestations of rotavirus infection were observed. The duration of the symptoms in this series ranged from 4 days to 4 months with median of 15 days. Patients with rotavirus infection were invariably lymphopenic and/or on immunosuppression for GVHD. Of the patients diagnosed with rotavirus, 86% required hospitalisation. In 57% of the cases, other viral pathogens were isolated near to the rotavirus infection period. Rotavirus infection is an important cause of prolonged diarrhoea post SCT, causing significant morbidity and frequently requiring hospitalisation.

Predominance of rotavirus genotype G9 during the 1999, 2000, and 2002 seasons among hospitalized children in the city of Salvador, Bahia, Brazil: implications for future vaccine strategies

Two hundred eight of 648 (32%) diarrheal stool samples collected from hospitalized children under 5 years of age during a 3-year period (1999, 2000, and 2002) in the city of Salvador, in the state of Bahia, Brazil, were rotavirus positive. One hundred sixty-four of 208 (78.8%) rotavirus-positive samples had genotype G9 specificity, predominantly in association with P[8]. Other specificities detected were G1 (12.0%) and G4 (1.4%). Viruses with G2, G3, or P[4] specificity were not detected. Rotavirus genotype G9 predominated during each of the three seasons studied; it represented 89.2% of rotavirus strains detected in 1999, 85.3% in 2000, and 74.5% in 2002. G1 viruses (the globally most common G type) have a unique epidemiological characteristic of maintaining predominance during multiple consecutive rotavirus seasons. We have shown in this study for the first time that the G9 viruses also have a similar epidemiological characteristic, albeit for a shorter period of surveillance. The next generation of rotavirus vaccines will need to provide adequate protection against disease caused by G9 viruses.

Porcine rotavirus strain Gottfried-based human rotavirus candidate vaccines: Construction and characterization

Rotavirus gastroenteritis remains the leading cause of severe diarrheal disease in infants and young children worldwide, and thus, a safe and effective rotavirus vaccine is urgently needed in both developing and developed countries. Various candidate rotavirus vaccines that were developed by us and others have been or are being evaluated in different populations in various parts of the world. We have recently confirmed that a porcine rotavirus Gottfried strain bears a P (VP4) serotype (P2B[6]) closely related to human rotavirus P serotype 2A[6] which is of epidemiologic importance in some regions of the world. Based on the modified Jennerian approach to immunization, we have constructed 11 Gottfried-based single VP7 or VP4 gene substitution reassortant vaccine candidates which could provide: (i) an attenuation phenotype of a porcine rotavirus in humans; and (ii) antigenic coverage for G serotypes 1-6 and 8-10 and P serotype 1A[8], 1B[4] and 2A[6]. In addition, following immunization of guinea pigs with Gottfried VP4, we found low but consistent levels of neutralizing antibodies to VP4 with P1A[8] or P1B[4] specificity, both of which are of global epidemiologic importance. Thus, porcine-based VP7 reassortant rotavirus vaccines may provide an advantage over rhesus- or bovine-based VP7 reassortant vaccines since the VP4s of the latter vaccines do not evoke antibodies capable of neutralizing the viruses bearing P1A[8], P1B[4] or P2A[6] VP4.

Global distribution of rotavirus serotypes/genotypes and its implication for the development and implementation of an effective rotavirus vaccine

A safe and effective rotavirus vaccine is urgently needed, particularly in developing countries. Critical to vaccine development and implementation is a knowledge base concerning the epidemiology of rotavirus G and P serotypes/genotypes throughout the world. The temporal and geographical distribution of human rotavirus G and P types was reviewed by analysing a total of 45571 strains collected globally from 124 studies reported from 52 countries on five continents published between 1989 and 2004. Four common G types (G1, G2, G3 and G4) in conjunction with P[8] or P[4] represented over 88% of the strains analysed worldwide. In addition, serotype G9 viruses associated with P[8] or P[6] were shown to have emerged as the fourth globally important G type with the relative frequency of 4.1%. When the global G and/or P type distributions were divided into five continents/subcontinents, several characteristic features emerged. For example, the P[8]G1 represented over 70% of rotavirus infections in North America, Europe and Australia, but only about 30% of the infections in South America and Asia, and 23% in Africa. In addition, in Africa (i) the relative frequency of G8 was as high as that of the globally common G3 or G4, (ii) P[6] represented almost one-third of all P types identified and (iii) 27% of the infections were associated with rotavirus strains bearing unusual combinations such as P[6]G8 or P[4]G8. Furthermore, in South America, uncommon G5 virus appeared to increase its epidemiological importance among children with diarrhea. Such findings have (i) confirmed the importance of continued active rotavirus strain surveillance in a variety of geographical settings and (ii) provided important considerations for the development and implementation of an effective rotavirus vaccine (e.g. a geographical P-G type adjustment in the formulation of next generation multivalent vaccines).

A review of viral gastroenteritis

PURPOSE OF REVIEW

Since Kapakian first identified a virus in the stool of a patient with diarrhoea in 1972, many viruses have been described that cause diarrhoea directly or indirectly. It is now appreciated that viruses are the most common cause of diarrhoeal illness worldwide. Although bacteria and other pathogens cause significant numbers of gastroenteritis, it is the viruses that are dealt with in this review. The viruses responsible will be discussed individually.

RECENT FINDINGS

Rotavirus remains the leading cause of diarrhoeal disease overall, with the newly designated calicivirus family causing the most outbreaks in the industrialized nations. As diagnostic techniques improve, however, the importance of astrovirus and other previously under-reported pathogens is becoming more apparent and the number of viruses associated with gastroenteritis continues to increase. The emergence of severe acute respiratory syndrome coronavirus, arguably the most important emerging infection of recent years and a cause of significant gastrointestinal disease, is also discussed.

SUMMARY

No effective treatments have been developed for viral gastroenteritis. Current efforts are targeted at the development of suitable vaccines and the implementation of infection control measures.