Isolation and characterization of two distinct human rotavirus strains with G6 specificity

Human transmission and outbreaks of feline-like G6 rotavirus revealed with whole-genome analysis of G6P[9] feline rotavirus

Group A rotaviruses (RVAs) are generally highly species-specific; however, some strains infect across species. Feline RVAs sporadically infect humans, causing gastroenteritis. In 2012 and 2013, rectal swab samples were collected from 61 asymptomatic shelter cats at a public health center in Mie Prefecture, Japan, to investigate the presence of RVA and any association with human infections. The analysis identified G6P[9] strains in three cats and G3P[9] strains in two cats, although no feline RVA sequence data were available for the former. A whole-genome analysis of these G6P[9] strains identified the genotype constellation G6-P[9]-I2-R2-C2-M2-A3-N2-T3-E3-H3. The nucleotide identity among these G6P[9] strains exceeded 99.5% across all 11 gene segments, indicating the circulation of this G6P[9] strain among cats. Notably, strain RVA/Human-wt/JPN/KF17/2010/G6P[9], previously detected in a 3-year-old child with gastroenteritis, shares high nucleotide identity (>98%) with Mie20120017f, the representative G6P[9] strain in this study, across all 11 gene segments, confirming feline RVA infection and symptomatic presentation in this child. The VP7 gene of strain Mie20120017f also shares high nucleotide identity with other sporadically reported G6 RVA strains in humans. This suggests that feline-origin G6 strains as the probable source of these sporadic G6 RVA strains causing gastroenteritis in humans globally. Moreover, a feline-like human G6P[8] strain circulating in Brazil in 2022 was identified, emphasizing the importance of ongoing surveillance to monitor potential global human outbreaks of RVA.

Genetic diversity of rotavirus A in Argentina during 2019-2022: detection of G6 strains and insights regarding its dissemination

One of the challenges associated with introducing a vaccine is monitoring its impact through clinical and molecular surveillance. The aims of this study were to analyze the genetic diversity of rotavirus A in Argentina between 2019 and 2022 and to assess the phylogenetic and phylodynamic features of the unusual G6 strains detected. A significant decline in the Wa-like genogroup strains was observed, and G6 strains were detected for the first time in Argentina, in association with P[8] and P[9]. Spatiotemporal analysis showed that the G6-lineage I strains detected recently in Argentina and Brazil might have emerged from European strains. This study provides recent evidence of the genetic diversity of rotaviruses in isolated cases. It is considered important to support continuous surveillance of rotavirus in the post-vaccine scenario, mainly to evaluate potential changes that may occur after the COVID-19 pandemic.

Rotavirus A during the COVID-19 Pandemic in Brazil, 2020-2022: Emergence of G6P[8] Genotype

Rotavirus A (RVA) remains a leading cause of acute gastroenteritis (AGE) hospitalizations in children worldwide. During the COVID-19 pandemic, a reduction in vaccination coverage in Brazil and elsewhere was observed, and some reports have demonstrated a reduction in AGE notifications during the pandemic. This study aims to investigate the diversity and prevalence of RVA genotypes in children and adults presenting with AGE symptoms in Brazil during the COVID-19 pandemic between 2020 and 2022. RVA was screened using RT-qPCR; then, G and P genotypes were characterized using one-step multiplex RT-PCR. A total of 2173 samples were investigated over the three-year period, and we detected RVA in 7.7% of samples (n = 167), being 15.5% in 2020, 0.5% in 2021, and 13.8% in 2022. Higher RVA prevalence was observed in the Northeastern region (19.3%) compared to the Southeastern (6.1%) and Southern regions (5.5%). The most affected age group was children aged between 0 and 6 months old; however, this was not statistically significant. Genotyping and phylogenetic analysis identified the emergence of G6P[8] during the period; moreover, it was detected in 10.6% of samples in 2020 and in 83.5% in 2022. In contrast, the prevalence of G3P[8], the previous dominant genotype, decreased from 72.3% in 2020 to 11.3% in 2022. We also identified unusual strains, such as G3P[9] and G9P[4], being sporadically detected during the period. This is the first report on the molecular epidemiology and surveillance of RVA during the COVID-19 pandemic period in Brazil. Our study provides evidence for the importance of maintaining high and sustainable levels of vaccine coverage to protect against RVA disease. Furthermore, it highlights the need to maintain nationwide surveillance in order to monitor future trends and changes in the epidemiology of RVA in Brazil.

Genetic diversity and Genomic analysis of G3P[6] and equine-like G3P[8] in Children Under-five from Southern Highlands and Eastern Tanzania

Rotavirus group A genomic characterization is critical for understanding the mechanisms of rotavirus diversity, such as reassortment events and possible interspecies transmission. However, little is known about the genetic diversity and genomic relationship of the rotavirus group A strains circulating in Tanzania. The genetic and genomic relationship of RVA genotypes was investigated in children under the age of five. A total of 169 faecal samples were collected from under-five with diarrhea in Mbeya, Iringa and Morogoro regions of Tanzania. The RVA were screened in children under five with diarrhea using reverse transcription PCR for VP7 and VP4, and the G and P genotypes were determined using Sanger dideoxynucleotide cycle sequencing. Whole-genome sequencing was performed on selected genotypes. The overall RVA rate was 4.7% (8/169). The G genotypes were G3 (7/8) and G6 (1/8) among the 8 RVA positives, while the P genotypes were P[6] (4/8) and P[8] (2), and the other two were untypeable. G3P[6] and G3P[8] were the identified genotype combinations. The genomic analysis reveals that the circulating G3P[8] and G3P[6] isolates from children under the age of five with diarrhea had a DS-1-like genome configuration (I2-R2-C2-M2-Ax-N2-T2-E2-H2). The phylogenic analysis revealed that all 11 segments of G3P[6] were closely related to human G3P[6] identified in neighboring countries such as Uganda, Kenya, and other African countries, implying that G3P[6] strains descended from a common ancestor. Whereas, G3P[8] were closely related to previously identified equine-like G3P[P8] from Kenya, Japan, Thailand, Brazil, and Taiwan, implying that this strain was introduced rather than reassortment events. We discovered amino acid differences at antigenic epitopes and N-linked glycosylation sites between the wild type G3 and P[8] compared to vaccine strains, implying that further research into the impact of these differences on vaccine effectiveness is warranted. The phylogenic analysis of VP7 also identified a bovine-like G6. For the first time in Tanzania, we report the emergence of novel equine-like G3 and bovine-like G6 RVA strains, highlighting the importance of rotavirus genotype monitoring and genomic analysis of representative genotypes.

Full genotype constellations analysis of unusual DS-1-like G12P[6] and G6P[8] rotavirus strains detected in Brazil, 2019

Rotavirus A (RVA) is a major cause of acute gastroenteritis (AGE) in children worldwide. We report unusual RVA G12P[6] and G6P[8] strains isolated from fecal samples from Brazilian children hospitalized for AGE. The characterized RVA have genome segments backbone: G12-P[6]/ G6-P[8]-I2-R2-C2-M2-A2-N2-T2-E2-H2 of DS-1-like genogroup. Our study describes the first identification of G6P[8], a DS-1-like genogroup strain. Nucleotide analysis of VP7 and VP4 genes revealed that all G12 Brazilian strains clustered into the sub-lineages IIIB, mostly associated with P[6] lineage I. Additionally, our G6 lineage I strains were closely related to German G6 genotypes, bound with P[8] lineage III, differing from both vaccine strains. The comparative sequence analysis of our strains with vaccine strains revealed amino acid substitutions located in immunodominant regions of VP7 and VP4 proteins. Continuous monitoring of RVA genotypes is essential to evaluate the impact of vaccination on the dynamic nature of RVA evolution.

Phylogenetic analysis of open reading frame of 11 gene segments of novel human-bovine reassortant RVA G6P[1] strain in Pakistan

Multiple Rotavirus A (RVA) strains are linked with gastrointestinal infections in children that fall in age bracket of 0 to 60 months. However, the problem is augmented with emergence of unique strains that reassort with RVA strains of animal origin. The study describes the sequence analysis of a rare G6P[1] rotavirus strain isolated from a less than 1 year old child, during rotavirus surveillance in Rawalpindi district, Pakistan in 2010. Extracted RNA from fecal specimen was subjected to high throughput RT-PCR for structural and nonstructural gene segments. The complete rotavirus genome of one isolate RVA/Human-wt/PAK/PAK99/2010/G6P[1] was sequenced for phylogenetic analysis to elucidate the evolutionary linkages and origin. Full genome examination of novel strain RVA/Human-wt/PAK/PAK99/2010/G6P[1] revealed the unique genotype assemblage: G6-P[1]-I2-R2-C2-M2-A3-N2-T6-E2-H1. The evolutionary analyses of VP7, VP4, NSP1 and NSP3 gene segments revealed that PAK99 clustered with bovine, or cattle-like rotavirus strains from other closely related species, in the genotypes G6, P[1], A3 and T6 respectively. Gene segments VP6, VP1, VP2, VP3, NSP2 and NSP4 all possessed the DS-1-like bovine genotype 2 and bovine (-like) RVA strains instead of RVA strains having human origin. However, the NSP5 gene was found to cluster closely with contemporary human Wa-like rotavirus strains of H1 genotype. This is the first report on bovine-human (Wa-like reassortant) genotype constellation of G6P[1] strain from a human case in Pakistan (and the second description worldwide). Our results emphasize the significance of incessant monitoring of circulating RVA strains in humans and animals for better understanding of RV evolution.

Next-generation sequencing of a human-animal reassortant G6P[14] rotavirus A strain from a child hospitalized with diarrhoea

We previously reported the VP4 and the VP7 genotypes of the first G6P[14] rotavirus strain (RVA/Human-wt/GHA/M0084/2010/G6P[14]) from the stool of an infant with diarrhoea in Ghana. In the current study, we obtained the complete genome sequences using Illumina MiSeq next-generation sequencing to enable us to determine the host species origin of the genes by phylogenetic analysis. The genotype constellation was G6-P[14]-I2-R2-C2-M2-A11-N2-T6-E2-H3. Phylogenetic analysis showed that M0084 was a reassortant strain from RVAs of both artiodactyl and human host species origin. The level of sequence identity of the individual genes of M0084 to other sequences in the GenBank ranged from 95.2 to 99.5%; however, there was no single strain from the GenBank database with a complete genome sequence that was highly similar to that of M0084. To help trace the source of such unique gene pools being introduced into human RVAs, it will be useful to examine RVA sequences from potential reservoirs such as sheep and goats, which are common domestic animals in this locality.

A Multiplex PCR/LDR Assay for Viral Agents of Diarrhea with the Capacity to Genotype Rotavirus

Rotavirus and noroviruses are major causes of diarrhea. Variable rotavirus vaccination efficacy in Africa and Asia is multifactorial, including the diversity of circulating strains and viral co-infection. We describe a multiplexed assay that detects and genotypes viruses from stool specimens. It includes a one-step reverse transcriptase PCR reaction, a ligase detection reaction (LDR), then hybridization of fluorescent products to micro-beads. In clinical samples it detects rotavirus, caliciviruses (sapovirus and norovirus), mixed infections, and genotypes or genogroups of rotaviruses and noroviruses, respectively. The assay also has the capacity to detect hepatitis A. The assay was validated on reference isolates and 296 stool specimens from the US and Ghana. The assay was 97% sensitive and 100% specific. The genogroup was concordant in 100% of norovirus, and the genotype in 91% and 89% of rotavirus G- and P-types, respectively. Two rare rotavirus strains, G6P[6] and G6P[8], were detected in stool specimens from Ghana. The high-throughput assay is sensitive, specific, and may be of utility in the epidemiological surveillance for rare and emerging viral strains post-rotavirus vaccine implementation.

Evidence for presumable feline origin of sporadic G6P[9] rotaviruses in humans

Species A rotaviruses are highly diverse and impose a substantial burden to human and animal health. Interspecies transmission between livestock, domestic animals and humans is commonly observed, but spread of animal-like rotaviruses within the human population is limited. During the continued monitoring of rotavirus strains in Germany, an unusual G6P[9] rotavirus strain was detected in feces of a child. The complete rotavirus coding sequences revealed a unique G6-P[9]-I2-R2-C2-M2-A3-N2-T3-E2-H3 genotype constellation. The virus was phylogenetically related to feline G3P[9] strains and other human G6P[9] rotaviruses of presumable zoonotic origin. Analysis of primer binding sites of G6 specific genotyping revealed further evidence of a G6P[9] feline reservoir. Moreover, substantial deficits of conventional semi-nested PCR genotyping approaches in detecting contemporary G6P[9] were revealed. Rotavirus strain GER29-14 most likely resulted from a direct or recent interspecies transmission from a cat to human. Further studies could assess nucleic acid sequences and genotype constellations of feline rotavirus to confirm the likely feline origin of sporadic human G6P[9] strains.

Detection of the first G6P[14] human rotavirus strain in an infant with diarrhoea in Ghana

BACKGROUND

Rotaviruses with G6P[14] specificity are mostly isolated in cattle and have been established as a rare cause of gastroenteritis in humans. This study reports the first detection of G6P[14] rotavirus strain in Ghana from the stool of an infant during a hospital-based rotavirus surveillance study in 2010.

METHODS

Viral RNA was extracted and rotavirus VP7 and VP4 genes amplified by one step RT-PCR using gene-specific primers. The DNA was purified, sequenced and genotypes determined using BLAST and RotaC v2.0. Phylogenetic tree was constructed using maximum likelihood method in MEGA v6.06 software and statistically supported by bootstrapping with 1000 replicates. Phylogenetic distances were calculated using the Kimura-2 parameter model.

RESULTS

The study strain, GHA-M0084/2010 was characterised as G6P[14]. The VP7 gene of the Ghanaian strain clustered in G6 lineage-III together with artiodactyl and human rotavirus (HRV) strains. It exhibited the highest nucleotide (88.1 %) and amino acid (86.9 %) sequence identity with Belgian HRV strain, B10925. The VP8* fragment of the VP4 gene was closely related to HRV strains detected in France, Italy, Spain and Belgium. It exhibited the strongest nucleotide sequence identity (87.9 %) with HRV strains, PA169 and PR/1300 (Italy) and the strongest amino acid sequence identity (89.3 %) with HRV strain R2775/FRA/07 (France).

CONCLUSION

The study reports the first detection of G6P[14] HRV strain in an infant in Ghana. The detection of G6P[14], an unusual strain pre-vaccine introduction in Ghana, suggests a potential compromise of vaccine effectiveness and indicates the necessity for continuous surveillance in the post vaccine era.

Continuous detection and genetic diversity of human rotavirus A in sewage in eastern China, 2013-2014

BACKGROUND

Rotavirus is the leading viral agent for pediatric gastroenteritis. However, the case-based surveillance for rotavirus is limited in China, and its circulation in the environment is not well investigated.

METHODS

From 2013 to 2014, rotavirus was detected in raw sewage samples of Jinan and Linyi by quantitative PCR (qPCR) and conventional reverse transcription PCR (RT-PCR). After sequenced and genotyped, sequences analysis was conducted.

RESULTS

A total of 46 sewage samples were collected monthly for the detection of rotavirus, and rotavirus was positive in 43 samples (93.5 %, 43/46). By quantitative assessment, the concentrations of rotavirus in raw sewage ranged from 4.1 × 10(3) to 1.3 × 10(6) genome copies (GC)/L in Jinan, and from 1.5 × 10(3) to 3.0 × 10(5) GC/L in Linyi. A total of 318 sequences of 5 G-genotypes and 318 sequences of 5 P-genotypes were obtained. G9 (91.8 %, 292/318) and P[8] (56.0 %, 178/318) were the most common G- and P-genotype, respectively. Multiple transmission lineages were recognized in these genotypes. Interestingly, an intragenic recombination event between two G9 lineages was observed.

CONCLUSIONS

This study provided the first report of comprehensive environmental surveillance for rotavirus in China. The results suggest that the concentration of rotavirus in raw sewage was high, and multiple rotavirus transmission lineages continuously co-circulated in Shandong.

Whole Genomic Analysis of an Unusual Human G6P[14] Rotavirus Strain Isolated from a Child with Diarrhea in Thailand: Evidence for Bovine-To-Human Interspecies Transmission and Reassortment Events

An unusual rotavirus strain, SKT-27, with the G6P[14] genotypes (RVA/Human-wt/THA/SKT-27/2012/G6P[14]), was identified in a stool specimen from a hospitalized child aged eight months with severe diarrhea. In this study, we sequenced and characterized the complete genome of strain SKT-27. On whole genomic analysis, strain SKT-27 was found to have a unique genotype constellation: G6-P[14]-I2-R2-C2-M2-A3-N2-T6-E2-H3. The non-G/P genotype constellation of this strain (I2-R2-C2-M2-A3-N2-T6-E2-H3) is commonly shared with rotavirus strains from artiodactyls such as cattle. Phylogenetic analysis indicated that nine of the 11 genes of strain SKT-27 (VP7, VP4, VP6, VP2-3, NSP1, NSP3-5) appeared to be of artiodactyl (likely bovine) origin, while the remaining VP1 and NSP2 genes were assumed to be of human origin. Thus, strain SKT-27 was found to have a bovine rotavirus genetic backbone, and thus is likely to be of bovine origin. Furthermore, strain SKT-27 appeared to be derived through interspecies transmission and reassortment events involving bovine and human rotavirus strains. Of note is that the VP7 gene of strain SKT-27 was located in G6 lineage-5 together with those of bovine rotavirus strains, away from the clusters comprising other G6P[14] strains in G6 lineages-2/6, suggesting the occurrence of independent bovine-to-human interspecies transmission events. To our knowledge, this is the first report on full genome-based characterization of human G6P[14] strains that have emerged in Southeast Asia. Our observations will provide important insights into the origin of G6P[14] strains, and into dynamic interactions between human and bovine rotavirus strains.

Increased detection of G3P[9] and G6P[9] rotavirus strains in hospitalized children with acute diarrhea in Bulgaria

Rotavirus severe disease in children is now vaccine-preventable and the roll-out of vaccination programs globally is expected to make a significant impact in the reduction of morbidity and mortality in children <5 years of age. Rotavirus is also a pathogen of other mammals and birds, and its segmented RNA genome can lead to the emergence of new or unusual strains in human population via interspecies transmission and reassortment events. Despite the efficacy and impact of rotavirus vaccine in preventing severe diarrhea, the correlates of protection remain largely unknown. Therefore, rotavirus strain surveillance before, during and after the introduction of immunization programs remains a crucial for monitoring rotavirus vaccine efficacy and impact. In this context, molecular characterization of 1323 Bulgarian rotavirus strains collected between June 2010 and May 2013 was performed. A total of 17 strains of interest were analyzed by partial sequence analysis. Twelve strains were characterized as G3P[9] and G6P[9] of potential animal origin. Phylogenetic analysis and comparisons with the same specificity strains detected sporadically between 2006 and 2010 revealed the constant circulation of these unusual human strains in Bulgaria, although in low prevalence, and their increased potential for person-to-person spread.

Molecular epidemiology of rotavirus in cats in the United Kingdom

Rotaviruses are leading causes of gastroenteritis in the young of many species. Molecular epidemiological studies in children suggest that interspecies transmission contributes to rotavirus strain diversity in people. However, population-based studies of rotaviruses in animals are few. We investigated the prevalence, risk factors for infection, and genetic diversity of rotavirus A in a cross-sectional survey of cats housed within 25 rescue catteries across the United Kingdom. Morning litter tray fecal samples were collected during the winter and summer in 2012 from all pens containing kittens and a random sample of those housing adult cats. Group A rotavirus RNA was detected by real-time reverse transcription-PCR, and positive samples were G and P genotyped using nested VP4 and VP7 PCR assays. A total of 1,727 fecal samples were collected from 1,105 pens. Overall, the prevalence of rotavirus was 3.0% (95% confidence interval [CI], 1.2 to 4.9%). Thirteen out of 25 (52%; 95% CI, 31.3 to 72.2%) centers housed at least one rotavirus-positive cat. The prevalence of rotavirus was associated with season (odds ratio, 14.8 [95% CI, 1.1 to 200.4]; P = 0.04) but not age or diarrhea. It was higher during the summer (4.7%; 95% CI, 1.2 to 8.3%) than in winter (0.8%; 95% CI, 0.2 to 1.5%). Asymptomatic epidemics of infection were detected in two centers. G genotypes were characterized for 19 (33.3%) of the 57 rotavirus-positive samples and P genotypes for 36 (59.7%). Two rotavirus genotypes were identified, G3P[9] and G6P[9]. This is the first population-based study of rotavirus in cats and the first report of feline G6P[9], which questions the previous belief that G6P[9] in people is of bovine origin.

Whole genomic analysis of porcine G10P[5] rotavirus strain P343 provides evidence for bovine-to-porcine interspecies transmission

Porcine group A rotavirus (RVA) strain P343 (RVA/Pig-tc/THA/P343/1991/G10P[5]) was suggested to have VP7 and VP4 genes of bovine origin. In order to obtain precise information on the exact origin and evolution of this unusual porcine strain, the remaining nine genes (VP6, VP1-3, and NSP1-5) of strain P343 were sequenced and analyzed in the present study. On whole genomic analysis, strain P343 was found to have a bovine RVA-like genotype constellation (G10-P[5]-I2-R2-C2-M2-A3-N2-T6-E2-H3) different from those of typical porcine RVA strains. Furthermore, on phylogenetic analysis, each of the 11 genes of strain P343 appeared to be of bovine origin. Therefore, strain P343 was suggested to be a bovine RVA strain that was transmitted to pigs.

Genetic characterization of a rare bovine-like human VP4 mono-reassortant G6P[8] rotavirus strain detected from an infant in Bangladesh

During an ongoing diarrhea etiology surveillance in Mirzapur, Bangladesh, a rare human G6P[8] RVA strain (RVA/Human-wt/BGD/KH2288/2011/G6P[8]) was detected in a stool sample of a 7-month-old infant with acute diarrhea. Complete genotype analyses revealed that KH2288 possessed the G6-P[8]-I2-R2-C2-M2-A11-N2-T6-E2-H3 genotype constellation. Sequence analysis of the VP7 gene revealed a close phylogenetic relationship with bovine G6 strains from India, whereas, the VP4 gene segment was nearly identical to typical human P[8] strain circulating in Bangladesh and the rest of the world. Phylogenetic analysis of the remaining nine gene segments revealed a close relatedness to either animal or animal derived human RVA strain. We speculated that, strain KH2288 was a monoreassortant between a human RVA strain and a RVA strain typically infecting member of the Artiodactyla, such as cattle, goat or sheep. To our knowledge, this is the first complete genotyping report of a naturally occurring G6P[8] RVA strain, worldwide.

Genomic analysis of human rotavirus strains G6P[14] and G11P[25] isolated from Kolkata in 2009 reveals interspecies transmission and complex reassortment events

In a community based case-control study in Kolkata, India, in 2009, two human rotaviruses with uncommon genotypes G6P[14] and G11P[25] were identified, having bovine and porcine characteristics respectively. Strain N-1/2009 with G6P[14] and strain N-38/2009 with G11P[25] genotypes, were isolated from a 13months aged boy who was asymptomatic and a 10months old girl with severe diarrhea respectively. The remaining 9 gene segments of these two strains were analyzed to find the exact origin of these unusual rotaviruses, and the origin of these two strains from bovine/porcine rotaviruses was apparent. This study identifies zoonotic transmission and single and multiple reassortment events as mechanisms driving the diversity of human rotaviruses. This study indicates interspecies transmission between human and animal rotaviruses causes single or multiple reassortment and thus contribute to the genetic diversity of rotavirus.

Identification by full-genome analysis of a bovine rotavirus transmitted directly to and causing diarrhea in a human child

The genome of rotaviruses consists of 11 segments of double-stranded RNA, and each genome segment has multiple genotypes. Thus, the genotype constellation of an isolate is often indicative of its host species. Albeit rarely, interspecies transmission occurs either by virions with nonreassorted or reassorted genomic segments. A rotavirus with the G6P[1] genotype, Ro8059, was isolated from the stool of a 1-year-old child during routine characterization of diarrheal specimens from a sentinel clinic in Israel in 1995. Since genotype G6P[1] is generally associated with bovine rotaviruses, and the child developed diarrhea within days of his first contact with calves at an urban farm, the aim of this study was to characterize the whole genomic constellation of Ro8059 and four G6P[1] bovine strains, BRV101, BRV105, BRV106, and CR231/39, by RNA-RNA hybridization and full genome sequencing to determine whether some or all of the segments were of bovine origin. The genome constellations of all four bovine G6P[1] strains were G6-P[1]-I2-R2-C2-M2-A3-N2-T6-E2-H3 for VP7-VP4-VP6-VP1-VP2-VP3-NSP1-NSP2-NSP3-NSP4-NSP5, respectively. Ro8059 shared the same genotype constellation with these bovine strains, with high nucleotide sequence identities (95.84 to 100%) for each of the 11 segments indicating that Ro8059 represented a direct interspecies whole-genome transmission of a nonreassorted rotavirus from a calf to a human infant. We conclude that this was the earliest example with a complete epidemiological link in which an entirely bovine rotavirus directly infected a human child and caused a symptomatic diarrheal illness. Thus, not all bovine rotaviruses are always naturally attenuated to the human host.

Molecular characterization of the NSP4 gene of human group A rotavirus strains circulating in Tunisia from 2006 to 2008

Non-structural protein 4 (NSP4), encoded by group A rotavirus (RVA) genome segment 10, is a multifunctional protein and the first recognized virus-encoded enterotoxin. Recently, a new classification system for RVAs was proposed and a total of 14 NSP4 genotypes (E1-E14) are currently described. The most common NSP4 genotypes in humans are Wa-like E1 and DS-1-like E2. This report represents the first investigation on the genetic diversity of RVA NSP4 genes in Tunisia from 2006 to 2008. In the present study, the NSP4-encoding genes of human RVA strains with different G/P-genotype combinations were analyzed. NSP4 genes of 261 RVA-positive fecal samples were analyzed using a semi-nested reverse transcriptase-polymerase chain reaction and in addition the NSP4 gene of 46 representative RVA strains were sequenced. Phylogenetic analysis of the Tunisian NSP4 nucleotide sequences revealed the presence of two NSP4 genotypes. Genotype E1 was found to be associated with G1P[8], G3P[6], G3P[8], G4P[6] and G4P[8], whereas genotype E2 was associated with G2P[4], G2P[6] and G6P[9] samples. These results support the hypothesis that P[8] carrying RVA strains usually possess the E1 genotype, whereas P[4] carrying RVA strains usually possess the E2 genotype. P[6] carrying strains were found with both E1 and E2. The unusual G6P[9] strains possessed a E2 genotype with a possible animal origin. These results underline the need for further investigations to assess the validity of NSP4 as a suitable target for epidemiologic surveillance of RVA infections and vaccine development.

Whole-genomic analysis of rotavirus strains: current status and future prospects

Studies on genetic diversity of rotaviruses have been primarily based on the genes encoding the antigenically significant VP7 and VP4 proteins. Since the rotavirus genome has 11 segments of RNA that are vulnerable to reassortment events, analyses of the VP7 and VP4 genes may not be sufficient to obtain conclusive data on the overall genetic diversity, or true origin of strains. In the last few years following the advent of the whole-genome-based genotype classification system, the whole genomes of at least 167 human group A rotavirus strains have been analyzed, providing a plethora of new and important information on the complex origin of strains, inter- and intra-genogroup reassortment events, animal–human reassortment events, zoonosis, and genetic linkages involving different group A rotavirus gene segments. In addition, the whole genomes of a limited number of human group B, C and novel group rotavirus strains have been analyzed. This article briefly reviews the available data on whole-genomic analysis of human rotavirus strains. The significance and future prospects of whole-genome-based studies are also discussed.

Detection of the first G6P[14] human rotavirus strain from a child with diarrhea in Egypt

We report the first detection of a G6P[14] rotavirus strain in Egypt from the stool of a child participating in a hospital-based diarrhea surveillance study conducted throughout the year 2004. Rotavirus infection was initially detected using a rotavirus group A VP6 enzyme immunoassay; the P (VP4) and G (VP7) genotypes of the strain were identified by RT-PCR. We sequenced the VP7 gene and the VP8* portion of the VP4 gene and the strain displayed the strongest identity to the VP7 [>94% nucleotides (nt), >97% amino acids (aa)] and VP4 (>93% nt, >98% aa) sequences of PA169, a novel G6P[14] strain first isolated from a child in Italy during the winter of 1987. Additional sequencing and analysis of the other remaining structural (VP1-VP3, VP6) and non-structural (NSP1-NSP5) proteins support this animal-to-human reassortment theory. According to the full genome classification system, the G6P[14] strain (EGY3399) was assigned to G6-P[14]-I2-R2-C2-M2-A11-N2-T6-E2-H3 genotypes. The greatest similarity of EGY3399 NSP4 and NSP5 gene sequences were to those of ovine and simian origin, respectively. Coupled with other observations, our results suggest G6P[14] isolates rarely cause severe diarrhea in Egyptian children, and support other studies that indicate animal rotavirus contribute to the genetic diversity of rotavirus detected from humans through interspecies transmission and single or multiple segments reassortment.

Intestinal epithelia activate anti-viral signaling via intracellular sensing of rotavirus structural components

Rotavirus (RV), a leading cause of severe diarrhea, primarily infects intestinal epithelial cells (IECs) causing self-limiting illness. To better understand innate immunity to RV, we sought to define the extent to which IEC activation of anti-viral responses required viral replication or could be recapitulated by inactivated RV or its components. Using model human intestinal epithelia, we observed that RV-induced activation of signaling events and gene expression typically associated with viral infection was largely mimicked by administration of ultraviolet (UV)-inactivated RV. Use of anti-interferon (IFN) neutralizing antibodies revealed that such replication-independent anti-viral gene expression required type I IFN signaling. In contrast, RV-induction of nuclear factor-κB-mediated interleukin-8 expression was dependent on viral replication. The anti-viral gene expression induced by UV-RV was not significantly recapitulated by RV RNA or RV virus-like particles although the latter could enter IEC. Together, these results suggest that RV proteins mediate viral entry into epithelial cells leading to intracellular detection of RV RNA that generates an anti-viral response.

The global spread of rotavirus G10 strains: Detection in Ghanaian children hospitalized with diarrhea

From October 2003 through September 2004, a total of 289 stool samples were collected from children <5 years of age who had severe diarrhea at admission to or when visiting the emergency department at the Navrongo War Memorial Hospital in rural Ghana during a study on rotavirus disease burden. Rotavirus antigen was detected in 115 stool samples (39.8%) tested for rotavirus. Four rotavirus-positive samples were found to bear G10P[6] specificity by reverse-transcription polymerase chain reaction, polymerase chain reaction-enzyme-linked immunosorbent assay, and oligonucleotide microarray hybridization. Two of these strains further exhibited serotype G10 specificity by neutralization and subgroup II specificity by enzyme immunoassay and possessed long electropheretic patterns by polyacrylamide gel electrophoresis. Their VP7 genes shared a much closer nucleotide identity with other African human G10 strains (>97%) than with human G10 strain from Asia or South America (<86%) or animal strains (<85%). The VP8* genes of the Ghanaian G10 strains exhibited >94% identity to that of human P[6] virus strains and belonged to the P[6] lineage 1a. The deduced VP7 amino acid sequence showed that the Ghanaian strains were more closely related to human G10 strains than to animal G10 strains. The possession of the typical human subgroup II specificity and the P[6] specificity (frequently found in Ghana and the rest of Africa) and the marked similarity in the VP7 antigenic sites suggest that these G10 strains may have evolved through genetic reassortment between bovine and human strains.

Rotavirus disease and vaccination: impact on genotype diversity

Temporal and spatial fluctuations in the genotype distribution of human rotaviruses are continuously observed in surveillance studies. New genotypes, such as G9 and G12, have emerged and spread worldwide in a very short time span. In addition, reassortment events have the potential to contribute substantially to genetic diversity among human and animal rotaviruses. With the recent introduction of the two rotavirus vaccines, RotaTeq and Rotarix, in many countries, it appears that the total number of hospitalizations due to rotavirus infections is being reduced, at least in developed countries that implemented a universal immunization program. However, continued surveillance is warranted, especially regarding the long-term effects of the vaccines. No data analyses are available to clarify whether rotavirus vaccine introduction would allow other rotavirus P and G genotypes, which are not covered by the current vaccines, to emerge into the human population and fill the apparent gap. This kind of data analysis is essential, but its interpretation is hampered by natural and cyclical genotype fluctuations.

Characterization of full-length VP4 genes of OP354-like P[8] human rotavirus strains detected in Bangladesh representing a novel P[8] subtype

The G1 and G9 rotavirus strains MMC71 and MMC38 (subgroup II, NSP4 genogroup B), respectively, isolated from children in Bangladesh, were analyzed genetically. Full-length VP4 genes of these strains had 98.9% identity to each other and showed 83.9-89.4% identity to those of the P[4] and P[8] rotaviruses. Phylogenetic analysis of VP4 nucleotide sequences revealed that strains MMC38 and MMC71 were located in a lineage of P[8] strains. However, the cluster was highly divergent from the previously established P[8] strains. The VP8* portions of strains MMC38 and MMC71 showed more than 93.9% nucleotide sequence identity to OP354-like P[8] strains, and these strains were clustered into the same lineage. These findings indicate that the VP4 of these strains should be classified into a subtype of the P[8] genotype (P[8]b) that is distinct from that of common P[8] rotaviruses (P[8]a).

Europe, the bull and the Minotaur: the biological legacy of a Neolithic love story

The European cattle was domesticated 10 000 years ago in eastern Turkey, 1000 years later pottery‐associated milk fats identify cattle‐based dairy activity in western Turkey. Subsequently, the Indo‐European language, domesticated animals and plants travel as a Neolithic package along two major routes across Europe. A striking south‐east to north‐west gradient of a mutation in the current European population (lactase persistence into adulthood) documents the expansion of a Neolithic dairy culture into a Mesolithic hunter society. Using oral tradition (myths), archaeological and written historical evidence and biological data, it is asked whether highly transmissible viral diseases like measles and smallpox entered during the Neolithic from domesticated animals into the human population. The bovine origin of paramyxovirus infections is likely; smallpox comes from camels or from rodents via cattle while mycobacteria and Helicobacter infected humans already before the Neolithic. Microbes adapt constantly and quickly to changing ecological situations. The current global environmental changes will lead to another highly dynamic phase of viral transmissions into the human population.

Are human P[14] rotavirus strains the result of interspecies transmissions from sheep or other ungulates that belong to the mammalian order Artiodactyla?

A limited number of human G6P[14] rotavirus strains that cause gastroenteritis in humans have been isolated in Europe and Australia. The complete genome sequences were determined for five of these human strains--B10925-97 (isolated in Belgium in 1997), 111/05-27 (Italy, 2005), PA169 (Italy, 1987), MG6 (Australia, 1993), and Hun5 (Hungary, 1997)--and their genetic relatedness to animal rotavirus strains was evaluated by sequencing the complete genome of the sheep rotavirus OVR762 (G8P[14]; Spain, 2002), the guanaco (Lama guanicoe) rotavirus strains Arg/Chubut/99 and Arg/Río Negro/98 (G8P[14] and G8P[1], respectively; Argentina, 1999 and 1998), the sable antelope strain RC-18/08 (G6P[14]; South Africa, 2008), and the bovine rotavirus strain Arg/B383/98 (G15P[11]; Argentina, 1998). These analyses revealed an overall consensus genomic constellation (G6/G8)-P[14]-I2-(R2/R5)-C2-M2-(A3/A11)-N2-T6-(E2/E12)-H3, together with a few gene reassortments, and the phylogenetic analyses confirmed that the P[14] human strains evaluated in this study were closely related to rotavirus strains isolated from sheep, cattle, goats, guanacos, and antelopes and to rabbits (albeit to a lesser extent), suggesting that one (or more) of these animal species might be the source of the human G6P[14] strains. The main feature of the genotype and phylogenetic analyses was the close overall genomic relatedness between the five human G6P[14] rotavirus strains and the ovine and antelope rotavirus strains. Taken together, these data strongly suggest a common origin for the human P[14] strains and those of the even-toed ungulates belonging to the mammalian order Artiodactyla, with sheep probably playing a key role in the interspecies transmission responsible for the introduction of P[14] rotavirus strains into the human population.

Two out of the 11 genes of an unusual human G6P[6] rotavirus isolate are of bovine origin

In 2003, we described the first human G6P[6] rotavirus strain (B1711). To investigate further the molecular origin of this strain and to determine the possible reassortments leading to this new gene constellation, the complete genome of strain B1711 was sequenced. SimPlot analyses were conducted to compare strain B1711 with other known rotavirus gene segments, and phylogenetic dendrograms were constructed to analyse the origin of the eleven genome segments of strain B1711. Our analysis indicated that strain B1711 acquired its VP1-, VP2-, VP4-, VP6- and NSP1–5-encoding gene segments from human DS-1-like P[6] rotavirus strains, and its VP3 and VP7 gene segments from a bovine rotavirus strain through reassortment. The introduction of animal–human reassortant strains, which might arise in either of the hosts, into the human rotavirus population is an important mechanism for the generation of rotavirus diversity, and might be a challenge for the current rotavirus vaccines and vaccines under development.

Diversity in Indian equine rotaviruses: identification of genotype G10,P6[1] and G1 strains and a new VP7 genotype (G16) strain in specimens from diarrheic foals in India

Rotaviruses causing severe diarrhea in foals in two organized farms in northern India, during the period from 2003 to 2005, were characterized by electropherotyping, serotyping, and sequence analysis of the genes encoding the outer capsid proteins. Of 137 specimens, 47 (34.31%) were positive for rotavirus and exhibited at least five different electropherotypes (E), E1 to E5. Strains belonging to different electropherotypes exhibited either a different serotype/genotype specificity or a lack of reactivity to typing monoclonal antibodies (MAbs) used in this study. Strains belonging to E1, E2, and E5 exhibited genotype G10,P6[1], G3, and G1 specificities and accounted for 19.0, 42.9, and 9.5% of the isolates, respectively. Though they possessed G10-type VP7, the E1 strains exhibited high reactivity with the G6-specific MAb, suggesting that the uncommon combination of the outer capsid proteins altered the specificity of the conformation-dependent antigenic epitopes on VP7. E3 and E4 strains accounted for 28.6% of the isolates and were untypeable. Sequence analysis of VP7 from E4 strains (Erv92 and Erv99) revealed that they represent a new VP7 genotype, G16. The detection of unexpected bovine rotavirus-derived G10,P6[1] reassortants, G1 serotype strains, and a new genotype (G16) strain in two distant farms reveals an interesting epidemiological situation and diversity of equine rotaviruses in India.

Molecular characterization of novel G5 bovine rotavirus strains

Group A rotaviruses are a major cause of acute gastroenteritis in young children as well as many domestic animals. The rotavirus genome is composed of 11 segments of double-stranded RNA and can undergo genetic reassortment during mixed infections, leading to progeny viruses with novel or atypical phenotypes. The aim of this study was to determine if the bovine group A rotavirus strains KJ44 and KJ75, isolated from clinically infected calves, share genetic features with viruses obtained from heterologous species. All 11 genes sequences of the KJ44 and KJ75 strains were sequenced and analyzed. The KJ44 VP4 had 91.7% to 96.3% deduced amino acid identity to the bovine related P[1] strain, whereas the KJ75 strain was most closely related to the bovine related P[5] strain (91.9% to 96.9% amino acid identity). Both KJ44 and KJ75 strains also contained the bovine related VP3 gene. The remaining 9 segments were closely related to porcine group A rotaviruses. The KJ44 and KJ75 strains showed high amino acid identity to the G5 rotaviruses, sharing 90.4% to 99.0% identity. In addition, these strains belonged to the NSP4 genotype B, which is typical of porcine rotaviruses and subgroup I, with the closest relationship to the porcine JL-94 strain. These results strongly suggest that bovine rotavirus strains with the G5 genotype occur in nature as a novel G genotype in cattle as a result of a natural reassortment between bovine and porcine strains.

Full genomic analysis of human rotavirus strain B4106 and lapine rotavirus strain 30/96 provides evidence for interspecies transmission

The Belgian rotavirus strain B4106, isolated from a child with gastroenteritis, was previously found to have VP7 (G3), VP4 (P[14]), and NSP4 (A genotype) genes closely related to those of lapine rotaviruses, suggesting a possible lapine origin or natural reassortment of strain B4106. To investigate the origin of this unusual strain, the gene sequences encoding VP1, VP2, VP3, VP6, NSP1, NSP2, NSP3, and NSP5/6 were also determined. To allow comparison to a lapine strain, the 11 double-stranded RNA segments of a European G3P[14] rabbit rotavirus strain 30/96 were also determined. The complete genome similarity between strains B4106 and 30/96 was 93.4% at the nucleotide level and 96.9% at the amino acid level. All 11 genome segments of strain B4106 were closely related to those of lapine rotaviruses and clustered with the lapine strains in phylogenetic analyses. In addition, sequence analyses of the NSP5 gene of strain B4106 revealed that the altered electrophoretic mobility of NSP5, resulting in a super-short pattern, was due to a gene rearrangement (head-to-tail partial duplication, combined with two short insertions and a deletion). Altogether, these findings confirm that a rotavirus strain with an entirely lapine genome complement was able to infect and cause severe disease in a human child.

Identification of a novel VP4 genotype carried by a serotype G5 porcine rotavirus strain

Rotavirus genome segment 4, encoding the spike outer capsid VP4 protein, of a porcine rotavirus (PoRV) strain, 134/04-15, identified in Italy was sequenced, and the predicted amino acid (aa) sequence was compared to those of all known VP4 (P) genotypes. The aa sequence of the full-length VP4 protein of the PoRV strain 134/04-15 showed aa identity values ranging from 59.7% (bovine strain KK3, P8[11]) to 86.09% (porcine strain A46, P[13]) with those of the remaining 25 P genotypes. Moreover, aa sequence analysis of the corresponding VP8* trypsin cleavage fragment revealed that the PoRV strain 134/04-15 shared low identity, ranging from 37.52% (bovine strain 993/83, P[17]) to 73.6% (porcine strain MDR-13, P[13]), with those of the remaining 25 P genotypes. Phylogenetic relationships showed that the VP4 of the PoRV strain 134/04-15 shares a common evolutionary origin with porcine P[13] and lapine P[22] rotavirus strains. Additional sequence analyses of the VP7, VP6, and NSP4 genes of the PoRV strain 134/04-15 revealed the highest VP7 aa identity (95.9%) to G5 porcine strains, a porcine-like VP6 within VP6 genogroup I, and a Wa-like (genotype B) NSP4, respectively. Altogether, these results indicate that the PoRV strain 134/04-15 should be considered as prototype of a new VP4 genotype, P[26], and provide further evidence for the vast genetic and antigenic diversity of group A rotaviruses.

Serotype diversity and reassortment between human and animal rotavirus strains: implications for rotavirus vaccine programs

The development of rotavirus vaccines that are based on heterotypic or serotype-specific immunity has prompted many countries to establish programs to assess the disease burden associated with rotavirus infection and the distribution of rotavirus strains. Strain surveillance helps to determine whether the most prevalent local strains are likely to be covered by the serotype antigens found in current vaccines. After introduction of a vaccine, this surveillance could detect which strains might not be covered by the vaccine. Almost 2 decades ago, studies demonstrated that 4 globally common rotavirus serotypes (G1-G4) represent >90% of the rotavirus strains in circulation. Subsequently, these 4 serotypes were used in the development of reassortant vaccines predicated on serotype-specific immunity. More recently, the application of reverse-transcription polymerase chain reaction genotyping, nucleotide sequencing, and antigenic characterization methods has confirmed the importance of the 4 globally common types, but a much greater strain diversity has also been identified (we now recognize strains with at least 42 P-G combinations). These studies also identified globally (G9) or regionally (G5, G8, and P2A[6]) common serotype antigens not covered by the reassortant vaccines that have undergone efficacy trials. The enormous diversity and capacity of human rotaviruses for change suggest that rotavirus vaccines must provide good heterotypic protection to be optimally effective.

Serological characterization of novel P11[14],G8 bovine group A rotavirus, Sun9, isolated in Japan

In this study, a novel bovine group A rotavirus (BoRV-A), Sun9, isolated from calf diarrhea in Tochigi Prefecture, Japan, was serologically characterized by a cross-neutralization assay, and serological surveillance by using its reassortant was performed on cattle bred in Japan. The G serotype of Sun9 was identified as G serotype 8 based on the one- or two-way serological relationships observed in Sun9 and other G8 strains. The P serotype of Sun9 was identified as P serotype 11 based on the one- or two-way serological relationships observed in Sun9, its reassortants, and the P11 lapine group A rotavirus R-2. The serological surveillance data indicated that 2.4% of the specimens appeared to possess antibodies against the P11[14] antigen. Few P11[14] bovine group A rotaviruses may exist in the Japanese cattle population.

Molecular characterizations of human and animal group a rotaviruses in the Netherlands

To gain more insight into interspecies transmission of rotavirus group A, human and animal fecal samples were collected between 1997 and 2001 in The Netherlands. A total of 110 human stool samples were successfully P and G genotyped by reverse transcriptase PCR. All strains belonged to the main human rotavirus genotypes G1 to G4, G9, [P4], [P6], [P8], and [P9]. [P8]G1 was predominant, and 5.5% belonged to the G9 genotype. Eleven percent of all P[8] genotypes could be genotyped only by a recently published modified primer. Rotavirus-positive fecal samples from 28 calf herds were genotyped by DNA sequencing. Genotypes G6 and G10 predominated; G6 and G10 were detected in 22 (78.6%) and 16 (57.1%) of the rotavirus-positive calf herds, respectively. In 12 (42.9%) calf herds, we found mixed infections. Genotype G8 was not found. Genotype G6 bovine rotaviruses were divided into three clusters: UK-like, VMRI-29-like, and Hun4-like. DNA sequencing of a part of the VP7 gene was shown to be useful as a quick determination of uncommon or novel strains of which the genotyping cannot be done by genotyping PCR. Of equine strains, both VP4 and VP7 genes could be used for genotyping: two [P12]G3 and four [P12]G14 equine rotaviruses were determined. We did not find indications for rotavirus interspecies transmissions, although the recently published human G6-Hun4 is genetically related to our G6 bovine isolates. All bovine, porcine, and equine rotaviruses were within genotypes previously reported for these animal species.

Sequence analysis of the VP7 and VP4 genes identifies a novel VP7 gene allele of porcine rotaviruses, sharing a common evolutionary origin with human G2 rotaviruses

During an epidemiological survey encompassing several porcine herds in Saragoza, Spain, the VP7 and VP4 of a rotavirus-positive sample, 34461-4, could not be predicted by using multiple sets of G- and P-type-specific primers. Sequence analysis of the VP7 gene revealed a low amino acid (aa) identity with those of well-established G serotypes, ranging between 58.33% and 88.88%, with the highest identity being to human G2 rotaviruses. Analysis of the VP4 gene revealed a P[23] VP4 specificity, as its VP8* aa sequence was 95.9% identical to that of the P14[23],G5 porcine strain A34, while analysis of the VP6 indicated a genogroup I, that is predictive of subgroup I specificity. Analysis of the 10th and 11th RNA segments revealed close identity to strains of porcine and human origin, respectively. The relatively low overall aa sequence conservation (<89% aa) to G2 human rotaviruses, the lack of N-glycosylation sites that are usually highly conserved in G2 rotaviruses, and the presence of several amino acid substitutions in the major antigenic hypervariable regions hampered an unambiguous classification of the porcine strain 34461-4 as G2 serotype on the basis of sequence analysis alone. The identification of a borderline, G2-like, VP7 gene allele in pigs, while reinforcing the hypotheses of a tight relationship in the evolution of human and animal rotaviruses, provides additional evidence for the wide genetic/antigenic diversity of group A rotaviruses.

Crystallization and preliminary X-ray diffraction analysis of the sialic acid-binding domain (VP8*) of porcine rotavirus strain CRW-8

Rotavirus recognition and attachment to host cells involves interaction with the spike protein VP4 that projects outwards from the surface of the virus particle. An integral component of these spikes is the VP8* domain, which is implicated in the direct recognition and binding of sialic acid-containing cell-surface carbohydrates and facilitates subsequent invasion by the virus. The expression, purification, crystallization and preliminary X-ray diffraction analysis of VP8* from porcine CRW-8 rotavirus is reported. Diffraction data have been collected to 2.3 A resolution, enabling the determination of the VP8* structure by molecular replacement.

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.

Molecular characterization of novel P[14],G8 bovine group A rotavirus, Sun9, isolated in Japan

In this study, a novel bovine group A rotavirus (RV-A), Sun9, isolated from calf diarrhea in the Tochigi Prefecture, Japan, was characterized genetically by the sequence analysis of the genome segments encoding VP4 and VP7. The nucleotide and deduced amino acid sequences of the genome segments encoding VP4 and VP7 of Sun9 revealed high homology with P[14] human and lapine RV-As (80.2-88.7% and 90.9-94.8%) and G8 bovine and human RV-As (83.1-95.5% and 92.3-98.2%). Sun9 was also classified into P[14] and G8 in the phylogenetic analysis of the nucleotide sequences of the genome segments encoding VP4 and VP7. Although previous reports have suggested that P[14],G8 human RV-As isolated until now were obtained from the reassortment between human and bovine RV-As, or the interspecies transmission of bovine RV-A to human, no P[14],G8 bovine RV-A has yet been reported. Sun9 may be initial direct evidence of the above hypothesis.

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).

Dominating prevalence of P[8],G1 and P[8],G9 rotavirus strains among children admitted to hospital between 2000 and 2003 in Budapest, Hungary

Group A rotaviruses are the main cause of acute dehydrating diarrhea in children, responsible for high mortality in developing countries and a significant socio-economic burden associated with treating the disease in developed countries. Two rotavirus vaccine candidates predicated on either homotypic or heterotypic protection have undergone clinical trials recently and await licensure for routine use. In anticipation of a future vaccination campaign in Hungary, the diversity of rotaviruses collected from Budapest between 2000 and 2003 were analyzed by polyacrylamide gel electrophoresis (PAGE) of the viral genome and by serotyping and genotyping of the outer capsid genes, VP7 and VP4. Among 2,763 rotavirus positive specimens available for analysis, we were able to determine the electropherotype of 2,227, and, of these, 1,517 (68.1%) were subjected to G typing and 1,173 (52.7%) were subjected to P typing. We successfully G typed 1,481 (97.6%) and P typed 1,130 (96.3%) strains, respectively. A total of six G types (G1, 50.2%; G2, 2.2%; G3, 1.7%; G4, 5.8%; G6, 0.6%; and G9, 34.4%) and four P types (P[4], 3.0%; P[6], 0.7%; P[8], 89.9%; and P[9], 1.7%) were identified in nine individual combinations (P[8],G1; P[4],G2; P[8],G3; P[8],G4; P[8],G9; P[6],G4; P[4],G1; P[9],G3; and P[9],G6). The prevalence of VP7 and VP4 specificities varied from year to year. In this regard, a shift in serotype predominance from G1 in 2000-2001 (61.8%) and 2001-2002 (69.7%) to G9 in 2002-2003 (51.3%) was an intriguing observation that has been reported recently in some other countries, as well. The emergence of serotype G9 rotaviruses in Hungary and other parts of the world may have implications for future vaccine development and use, particularly, if current vaccine candidates cannot confer adequate homotypic or heterotypic protection against these strains.