Molecular characterization of unusual human G5P[6] rotaviruses identified in China

Recent Molecular Characterization of Porcine Rotaviruses Detected in China and Their Phylogenetic Relationships with Human Rotaviruses

Porcine rotavirus A (PoRVA) is an enteric pathogen capable of causing severe diarrhea in suckling piglets. Investigating the prevalence and molecular characteristics of PoRVA in the world, including China, is of significance for disease prevention. In 2022, a total of 25,768 samples were collected from 230 farms across China, undergoing porcine RVA positivity testing. The results showed that 86.52% of the pig farms tested positive for porcine RVA, with an overall positive rate of 51.15%. Through the genetic evolution analysis of VP7, VP4 and VP6 genes, it was revealed that G9 is the predominant genotype within the VP7 segment, constituting 56.55%. VP4 genotypes were identified as P[13] (42.22%), P[23] (25.56%) and P[7] (22.22%). VP6 exhibited only two genotypes, namely I5 (88.81%) and I1 (11.19%). The prevailing genotype combination for RVA was determined as G9P[23]I5. Additionally, some RVA strains demonstrated significant homology between VP7, VP4 and VP6 genes and human RV strains, indicating the potential for human RV infection in pigs. Based on complete genome sequencing analysis, a special PoRVA strain, CHN/SD/LYXH2/2022/G4P[6]I1, had high homology with human RV strains, revealing genetic reassortment between human and porcine RV strains in vivo. Our data indicate the high prevalence, major genotypes, and cross-species transmission of porcine RVA in China. Therefore, the continuous monitoring of porcine RVA prevalence is essential, providing valuable insights for virus prevention and control, and supporting the development of candidate vaccines against porcine RVA.

Full genome-based characterization of an Asian G3P[6] human rotavirus strain found in a diarrheic child in Japan: Evidence for porcine-to-human zoonotic transmission

Human rotavirus strains having the unconventional G3P[6] genotype have been sporadically detected in diarrheic patients in different parts of the world. However, the full genomes of only three human G3P[6] strains from Asian countries (China, Indonesia, and Vietnam) have been sequenced and characterized, and thus the exact origin and evolution of G3P[6] strains in Asia remain to be elucidated. Here, we sequenced and characterized the full genome of a G3P[6] strain (RVA/Human-wt/JPN/SO1199/2020/G3P[6]) found in a stool sample from a 3-month-old infant admitted with acute gastroenteritis in Japan. On full genomic analysis, strain SO1199 was revealed to have a unique Wa-like genogroup configuration: G3-P[6]-I5-R1-C1-M1-A8-N1-T1-E1-H1. VP6 genotype I5 and NSP1 genotype A8 are commonly found in porcine rotavirus strains. Furthermore, phylogenetic analysis demonstrated that all 11 genes of strain SO1199 were closely related to those of porcine and/or porcine-like human rotaviruses and thus appeared to be of porcine origin. Thus, strain SO1199 was shown to possess a porcine-like genomic backbone and thus is likely to be the result of interspecies transmission of a porcine rotavirus strain. Of note is that all 11 genes of strain SO1199 were phylogenetically located in clusters, distinct from those of the previously identified porcine-like human G3P[6] strains from around the world including Asia, suggesting the occurrence of independent porcine-to-human zoonotic transmission events. To our knowledge, this is the first report on full genome-based characterization of a human G3P[6] strain that has emerged in Japan. Our findings revealed the diversity of unconventional human G3P[6] strains in Asia, and provide important insights into the origin and evolution of G3P[6] strains.

Genetic heterogeneity of group A rotaviruses: a review of the evolutionary dynamics and implication on vaccination

INTRODUCTION

Human rotavirus remains a major etiology of acute gastroenteritis among under 5-year children worldwide despite the availability of oral vaccines. The genetic instability of rotavirus and the ability to form different combinations from the different G- and P-types reshapes the antigenic landscape of emerging strains which often display limited or no antigen identities with the vaccine strain. As evidence also suggests, the selection of the antigenically distinct novel or rare strains and their successful spread in the human population has raised concerns regarding undermining the effectiveness of vaccination programs.

AREAS COVERED

We review aspects related to current knowledge about genetic and antigenic heterogeneity of rotavirus, the mechanism of genetic diversity and evolution, and the implication of genetic change on vaccination.

EXPERT OPINION

Genetic changes in the segmented genome of rotavirus can alter the antigenic landscape on the virion capsid and further promote viral fitness in a fully vaccinated population. Against this background, the potential risk of the appearance of new rotavirus strains over the long term would be better predicted by a continued and increased close monitoring of the variants across the globe to identify any change associated with disease dynamics.

Development of Genotype-Specific Anti-Bovine Rotavirus A Immunoglobulin Yolk Based on a Current Molecular Epidemiological Analysis of Bovine Rotaviruses A Collected in Japan during 2017-2020

Bovine rotavirus A (RVA), a major causative pathogen of diarrhea in dairy and Japanese beef calves, has led to severe economic losses in numerous countries. A dual genotyping system based on genomic segments encoding VP7 (G genotype) and VP4 (P genotype), comprising the outer layer of the virion, has been used to understand the epidemiological dynamics of RVAs at the national and global levels. This study aimed to investigate occurrence frequency of G and P genotypes for multiple bovine RVAs from calf diarrheic samples collected in Japan from 2017 to 2020. After we produced anti-bovine RVA immunoglobulin yolks (IgYs) from hens immunized with the two RVAs with different genotypes (G6P[5] and G10P[11]) selected on the basis of the current epidemiological survey, we investigated cross-reactivity against bovine RVAs with different G and P combinations owing to establish a useful strategy to protect calves from RVA infections using the two IgYs. Consequently, the two produced anti-bovine IgYs showed strong cross-reactivity against bovine RVAs with the same G and/or P genotypes in neutralization assay, respectively. Therefore, our data suggest the possibility of a passive immunization to protect calves from a bovine RVA infections epidemic in Japan via oral administration of the two IgYs into calves. The findings presented herein will provide important information that IgY is one of the effective tools to prevent infections of various pathogens.

Molecular Characterisation of a Rare Reassortant Porcine-Like G5P[6] Rotavirus Strain Detected in an Unvaccinated Child in Kasama, Zambia

A human-porcine reassortant strain, RVA/Human-wt/ZMB/UFS-NGS-MRC-DPRU4723/2014/G5P[6], was identified in a sample collected in 2014 from an unvaccinated 12 month old male hospitalised for gastroenteritis in Zambia. We sequenced and characterised the complete genome of this strain which presented the constellation: G5-P[6]-I1-R1-C1-M1-A8-N1-T1-E1-H1. The genotype A8 is often observed in porcine strains. Phylogenetic analyses showed that VP6, VP7, NSP2, NSP4, and NSP5 genes were closely related to cognate gene sequences of porcine strains (e.g., RVA/Pig-wt/CHN/DZ-2/2013/G5P[X] for VP7) from the NCBI database, while VP1, VP3, VP4, and NSP3 were closely related to porcine-like human strains (e.g., RVA/Human-wt/CHN/E931/2008/G4P[6] for VP1, and VP3). On the other hand, the origin of the VP2 was not clear from our analyses, as it was not only close to both porcine (e.g., RVA/Pig-tc/CHN/SWU-1C/2018/G9P[13]) and porcine-like human strains (e.g., RVA/Human-wt/LKA/R1207/2009/G4P[6]) but also to three human strains (e.g., RVA/Human-wt/USA/1476/1974/G1P[8]). The VP7 gene was located in lineage II that comprised only porcine strains, which suggests the occurrence of independent porcine-to-human reassortment events. The study strain may have collectively been derived through interspecies transmission, or through reassortment event(s) involving strains of porcine and porcine-like human origin. The results of this study underline the importance of whole-genome characterisation of rotavirus strains and provide insights into interspecies transmissions from porcine to humans.

Full genomic characterization of a porcine rotavirus strain detected in an asymptomatic piglet in Accra, Ghana

Background

The introduction of rotavirus A vaccination across the developing world has not proved to be as efficacious as first hoped. One cause of vaccine failure may be infection by zoonotic rotaviruses that are very variable antigenically from the vaccine strain. However, there is a lack of genomic information about the circulating rotavirus A strains in farm animals in the developing world that may be a source of infection for humans. We therefore screened farms close to Accra, Ghana for animals sub-clinically infected with rotavirus A and then sequenced the virus found in one of these samples.

Results

6.1% of clinically normal cows and pigs tested were found to be Rotavirus A virus antigen positive in the faeces. A subset of these (33.3%) were also positive for virus RNA. The most consistently positive pig sample was taken forward for metagenomic sequencing. This gave full sequence for all open reading frames except segment 5 (NSP1), which is missing a single base at the 5′ end. The virus infecting this pig had genome constellation G5-P[7]-I5-R1-C1-M1-A8-N1-T7-E1-H1, a known porcine genotype constellation.

Conclusions

Farm animals carry rotavirus A infection sub-clinically at low frequency. Although the rotavirus A genotype discovered here has a pig-like genome constellation, a number of the segments most closely resembled those isolated from humans in suspected cases of zoonotic transmission. Therefore, such viruses may be a source of variable gene segments for re-assortment with other viruses to cause vaccine breakdown. It is recommended that further human and pig strains are characterized in West Africa, to better understand this dynamic.

Genome analysis of a G9P[23] group A rotavirus isolated from a dog with diarrhea in China

Genotype G9 is an emerging genotype among species A rotavirus (RVA) circulating in humans and pigs worldwide. In this study, an RVA strain designated RVA/Dog-tc/CHN/SCCD-A/2017/G9P[23] was isolated in cell culture from a pet dog stool sample with acute diarrhea, and its whole genome was sequenced. The genotype constellation of SCCD-A was G9-P[23]-I5-R1-C1-M1-A8-N1-T1-E1-H1. All genome segments except the VP1 gene were closely related to the genes from porcine RVA strains or porcine-like human RVA strains. On the other hand, the VP1 gene clustered in a distinct lineage only with that of a G5P[6] porcine-like human RVA, preventing the identification of the exact host species origin, but very unlikely to be originated from human RVA. In addition, phylogenetic analysis showed that the G9 VP7 gene of SCCD-A clustered into a novel sublineage within the lineage III of G9. This first isolation of a G9P[23] RVA from a pet dog may justify the exploration of the role dogs play in the interaction of RVA circulating in pigs and humans.

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First identified G9P[23] group A rotavirus from dog and the genome of RVA/Dog-tc/CHN/SCCD-A/2017/G9P[23]was determined.

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The strain’s genotype constellation as G9-P[23]-I5-R1-C1-M1-A8-N1-T1-E1-H1.

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G9P[23] from dog may justify the exploration of the role dogs play in the interaction of RVA circulating in pigs and humans.

Whole genome characterisation of a porcine-like human reassortant G26P[19] Rotavirus A strain detected in a child hospitalised for diarrhoea in Nepal, 2007

A rare G26 Rotavirus A strain RVA/Human-wt/NPL/07N1760/2007/G26P[19] was detected in a child hospitalised for acute diarrhoea in Kathmandu, Nepal. The complete genome of 07N1760 was determined in order to explore its evolutionary history as well as examine its relationship to a Vietnamese strain RVA/Human-wt/VNM/30378/2009/G26P[19], the only G26 strain whose complete genotype constellation is known. The genotype constellation of 07N1760 was G26-P[19]-I12-R1-C1-M1-A8-N1-T1-E1-H1, a unique constellation identical to that of the Vietnamese 30378 except the VP6 gene. Phylogenetic analysis revealed that both strains were unrelated at the lineage level despite their similar genotype constellation. The I12 VP6 gene of 07N1760 was highly divergent from the six currently deposited I12 sequences in the GenBank. Except for its NSP2 gene, the remaining genes of 07N1760 shared lineages with porcine and porcine-like human RVA genes. The NSP2 gene belonged to a human RVA N1 lineage which was distinct from typical porcine and porcine-like human lineages. In conclusion, the Nepali G26P[19] strain 07N1760 was a porcine RVA strain which derived an NSP2 gene from a human Wa-like RVA strain by intra-genotype reassortment probably after transmission to the human host.

Novel G9 rotavirus strains co-circulate in children and pigs, Taiwan

Molecular epidemiologic studies collecting information of the spatiotemporal distribution of rotavirus VP7 (G) and VP4 (P) genotypes have shown evidence for the increasing global importance of genotype G9 rotaviruses in humans and pigs. Sequence comparison of the VP7 gene of G9 strains identified different lineages to prevail in the respective host species although some of these lineages appear to be shared among heterologous hosts providing evidence of interspecies transmission events. The majority of these events indicates the pig-to-human spillover, although a reverse route of transmission cannot be excluded either. In this study, new variants of G9 rotaviruses were identified in two children with diarrhea and numerous pigs in Taiwan. Whole genome sequence and phylogenetic analyses of selected strains showed close genetic relationship among porcine and human strains suggesting zoonotic origin of Taiwanese human G9 strains detected in 2014-2015. Although the identified human G9P[19] and G9P[13] rotaviruses represented minority strains, the repeated detection of porcine-like rotavirus strains in Taiwanese children over time justifies the continuation of synchronized strain surveillance in humans and domestic animals.

The Public Health Burden of Rotavirus Disease in Children Younger Than Five Years and Considerations for Rotavirus Vaccine Introduction in China

BACKGROUND

Rotavirus is the leading cause of severe diarrhea among young children worldwide. Rotavirus vaccines have demonstrated substantial benefits in many countries that have introduced vaccine nationally. In China, where rotavirus vaccines are not available through the national immunization program, it will be important to review relevant local and global information to determine the potential value of national introduction. Therefore, we reviewed evidence of rotavirus disease burden among Chinese children younger than 5 years to help inform rotavirus vaccine introduction decisions.

METHODS

We reviewed scientific literature on rotavirus disease burden in China from 1994 through 2014 in China National Knowledge Infrastructure, Wanfang and PubMed. Studies were selected if they were conducted for periods of 12 month increments, had more than 100 patients enrolled and used an accepted diagnostic test.

RESULTS

Overall, 45 reports were included and indicate that rotavirus causes ~40% and ~30% of diarrhea-related hospitalizations and outpatient visits, respectively, among children younger than 5 years in China. Over 50% of rotavirus-related hospitalizations occur by age 1 year; ~90% occur by age 2 years. Regarding circulating rotavirus strains in China, there has been natural, temporal variation, but the predominant local strains are the same as those that are globally dominant.

CONCLUSIONS

These findings affirm that rotavirus is a major cause of childhood diarrheal disease in China and suggest that a vaccination program with doses given early in infancy has the potential to prevent the majority of the burden of severe rotavirus disease.

A scoping review of the evidence for public health risks of three emerging potentially zoonotic viruses: hepatitis E virus, norovirus, and rotavirus

Emerging zoonoses are defined as those newly recognized, or increasing in incidence or geographic range. Hepatitis E virus (HEV), norovirus (NoV), and rotavirus (RV), while well known to be transmitted person-person, have also been hypothesized to be emerging zoonoses. Our objective was to investigate their potential public health risks from animal reservoirs. Given the diversity of evidence sources, a scoping review incorporating a mixed methods synthesis approach was used. A broad search was conducted in five electronic databases. Each citation was appraised independently by two reviewers using screening tools designed and tested a priori. Level 1 relevance screening excluded irrelevant citations; level 2 confirmed relevance and categorized. At level 3 screening, data were extracted to support a risk profile. A stakeholder group provided input on study tools and knowledge translation and transfer. Level 1 screening captured 2471 citations, with 1270 advancing to level 2 screening, and 1094 to level 3. We defined criteria for case attribution to zoonosis for each virus. Using these criteria, we identified a small number of zoonotic cases (HEV n=3, NoV=0, RV=40 (zoonoses=3; human-animal re-assortants=37)) categorized as 'likely'. The available evidence suggests the following potential HEV human exposure sources: swine, other domestic animals, wildlife, surface waters, and asymptomatic human shedders. Possible at-risk groups include the immunocompromised and the elderly. Reports of NoV intergenogroup recombinants suggest potential for human-animal recombination. Greatest public health impact for RV zoonoses may be the potential effect of human-animal reassortants on vaccination efficacy.

Rotaviruses: is their surveillance needed?

Rotaviruses, a major cause of gastroenteritis in children worldwide accounts for around 0.5 million deaths annually. Owing to their segmented genome and frequently evolving capability, these display a wide variation in their genotypes. In addition to commonly circulating genotypes (G1, G2, G3, G4, G9, P[4] and P[8]), a number of infrequent genotypes are being continuously reported to infect humans. These viral strains exhibit variation from one geographical setting to another in their distribution. Though the introduction of vaccines (RotaTeq and Rotarix) proved to be very effective in declining rotavirus associated morbidity and mortality, the number of infections remained same. Unusual genotypes significantly contribute to the rotavirus associated diarrhoeal burden, may reduce the efficacy of the vaccines in use and hence vaccinated individuals may not be benefited. Vaccine introduction may bring about a notable impact on the distribution and prevalence of these viruses due to selection pressure. Moreover, there is a sudden emergence of G2 and G3 in Brazil and United States, respectively, during the years 2006-2008 post-vaccination introduction; G9 and G12 became predominant during the years 1986 through 1998 before the vaccine introduction and now are commonly prevalent strains; and disparity in the predominance of strains after introduction of vaccines and their natural fluctuations poses a vital question on the impact of vaccines on rotavirus strain circulation. This interplay between vaccines and rotavirus strains is yet to be explored, but it certainly enforces the need to continuously monitor these changes in strains prevalence in a particular region. Furthermore, these fluctuations should be considered while administration or development of a vaccine, if rotavirus associated mortality is ever to be controlled.

The prevalence and genetic diversity of group A rotaviruses on pig farms in the Mekong Delta region of Vietnam

Group A rotaviruses (ARoVs) are a common cause of severe diarrhea among children worldwide and the cause of approximately 45% of pediatric hospitalizations for acute diarrhea in Vietnam. ARoVs are known to cause significant economic losses to livestock producers by reducing growth performance and production efficiencies, however little is known about the implications of asymptomatic endemic circulation of ARoV. We aimed to determine the prevalence and predominant circulating genotypes of ARoVs on pig farms in a southern province of Vietnam. We found overall animal-level and farm-level prevalence of 32.7% (239/730) and 74% (77/104), respectively, and identified six different G types and 4 P types in various combinations (G2, G3, G4, G5, G9, G11 and P[6], P[13], P[23], and P[34]). There was no significant association between ARoV infection and clinical disease in pigs, suggesting that endemic asymptomatic circulation of ARoV may complicate rotavirus disease attribution during outbreaks of diarrhea in swine. Sequence analysis of the detected ARoVs suggested homology to recent human clinical cases and extensive genetic diversity. The epidemiological relevance of these findings for veterinary practitioners and to ongoing pediatric ARoV vaccine initiatives in Vietnam merits further study.

A Case of Mild Encephalopathy with a Reversible Splenial Lesion Associated with G5P[6]Rotavirus Infection

We report a case of mild encephalopathy with a reversible splenial lesion (MERS) associated with acute gastroenteritis caused by rotavirus (RV) infection. The patient (male, 4 years and 3 months old) was admitted to our hospital for diarrhea and afebrile seizures. Head MRI revealed a hyperintense signal in the splenium of the corpus callosum on DWI and a hypointense signal on the ADC-map. After awakening from sedation, the patient's disturbance of consciousness improved. On day 5 after admission of the illness, the patient was discharged from the hospital in a good condition. Electroencephalography on day 2 after admission was normal. On day 8 of admission, head MRI revealed that the splenial lesion had disappeared. RV antigen-positive stools suggested that RV had caused MERS. This RV genotype was considered to be G5P[6]; it may have spread to humans as a strain reassortment through substitution of porcine RV into human RV gene segments. This extremely rare genotype was detected first in Japan and is not covered by existing vaccines; this is the first sample isolated from encephalopathy patients. Few reports have investigated RV genotypes in encephalopathy; we believe that this case is valuable for studying the relationship between genotypes and clinical symptoms.

Identification of circulating porcine-human reassortant G4P[6] rotavirus from children with acute diarrhea in China by whole genome analyses

P[6] group A rotavirus (RVA) strains identified in four stool specimens collected from children with acute diarrhea in Guangxi Province, southern China in 2010, with unknown G type were further analyzed by full genomic analysis. It was revealed by whole genome sequencing that 11 genomic cognate gene segments of these P[6] RVA strains shared almost 100% nucleotide identities and all exhibited an identical G4-P[6]-I1-R1-C1-M1-A8-N1-T1-E1-H1 genotype constellation. Phylogenetic analyses of VP7, VP1-VP4, NSP1, NSP2, NSP4 and NSP5 genes revealed that these Guangxi G4P[6] RVA strains were closely related to porcine and porcine-like human RVAs, while VP6 and NSP3 were closely related to those of common human RVAs. Interestingly, the four infants from whom these specimens were collected had come from different villages and/or towns. They had not contacted with each other and had had acute diarrhea before admitted into the same hospital. The genomic analyses and the clinical data revealed that these four Guangxi G4P[6] RVA strains from China were reassortants possessing VP6 and NSP3 gene segments of human origin yet all other nine gene segments of porcine origin. It is the first report on porcine-human reassortant G4P[6] RVA with identical genome configuration circulating in children.

Whole genomic analysis of a porcine-like human G5P[6] rotavirus strain isolated from a child with diarrhoea and encephalopathy in Japan

An unusual rotavirus strain, Ryukyu-1120, with G5P[6] genotypes (RVA/Human-wt/JPN/Ryukyu-1120/2011/G5P[6]) was identified in a stool specimen from a hospitalized child aged 4 years who showed diarrhoea and encephalopathy. In this study, we sequenced and characterized the complete genome of strain Ryukyu-1120. On whole genomic analysis, this strain was found to have a unique genotype constellation: G5-P[6]-I5-R1-C1-M1-A8-N1-T1-E1-H1. The VP6 and NSP1 genotypes I5 and A8 are those commonly found in porcine strains. Furthermore, phylogenetic analysis indicated that each of the 11 genes of strain Ryukyu-1120 appeared to be of porcine origin. Thus, strain Ryukyu-1120 was found to have a porcine rotavirus genetic backbone and is likely to be of porcine origin. To our knowledge, this is the first report of whole-genome-based characterization of the emerging G5P[6] strains in Asian countries. Our observations will provide important insights into the origin of G5P[6] strains and the dynamic interactions between human and porcine rotavirus strains.

The first identification of rare human group A rotavirus strain G3P[10] with severe infantile diarrhea in eastern India

During an ongoing surveillance for diarrheal pathogens, an unusual human group A rotavirus strain G3P[10] (RVA/Human-wt/IND/mcs60/2011/G3P[10]) was detected in a stool sample of a 14 months old girl child with acute diarrhea in Kolkata, eastern India. The VP7 nucleotide sequence of this strain revealed a close phylogenetic relationship to the prototype G3 strain AU-1 and Australian feline strain Cat2, whereas, the VP4 gene segment was closely related to the G8P[10] rotavirus 69M from Indonesia. Analysis of 11 gene segments of this unusual G3P[10] strain demonstrates a complex evolutionary pattern, with genes possibly derived from the group A rotaviruses of human DS-1-like and AU-1-like strains of simian and caprine host species. To our knowledge, this is the first complete genotyping report of any G3P[10] rotavirus, worldwide.

Detection of rare reassortant G5P[6] rotavirus, Bulgaria

During the ongoing rotavirus strain surveillance program conducted in Bulgaria, an unusual human rotavirus A (RVA) strain, RVA/Human/BG/BG620/2008/G5P[6], was identified among 2200 genotyped Bulgarian RVAs. This strain showed the following genomic configuration: G5-P[6]-I1-R1-C1-M1-A8-N1-T1-E1-H1. Phylogenetic analysis of the genes encoding the neutralization proteins and backbone genes identified a probable mixture of RVA genes of human and porcine origin. The VP1, VP6 and NSP2 genes were more closely related to typical human rotavirus strains. The remaining eight genes were either closely related to typical porcine and unusual human-porcine reassortant rotavirus strains or were equally distant from reference human and porcine strains. This study is the first to report an unusual rotavirus isolate with G5P[6] genotype in Europe which has most likely emerged from zoonotic transmission. The absence of porcine rotavirus sequence data from this area did not permit to assess if the suspected ancestral zoonotic porcine strain already had human rotavirus genes in its genome when transmitted from pig to human, or, the transmission was coupled or followed by gene reassortment event(s). Because our strain shared no neutralization antigens with rotavirus vaccines used for routine immunization in children, attention is needed to monitor if this G-P combination will be able to emerge in human populations. A better understanding of the ecology of rotavirus zoonoses requires simultaneous monitoring of rotavirus strains in humans and animals.

Genetic diversity and novel combinations of G4P[19] and G9P[19] porcine rotavirus strains in Thailand

Several epidemiological studies reported the detection of rotavirus strains bearing unusual combinations of genetic background of human and porcine rotaviruses. This observation supports the hypothesis of interspecies transmission of rotaviruses in humans and pigs. The aims of this study were to investigate the genotypes and molecular characteristics of rotaviruses in piglets with diarrhea in several farms from two provinces in Thailand. A total of 207 fecal specimens collected from diarrheic piglets were screened for the presence of groups A, B, and C rotaviruses. Group A rotaviruses were detected in 41 out of 207 (19.8%) fecal specimens tested. A wide variety of G-P combination rotavirus strains were detected in this study. The G4P[6] was identified as the most prevalent genotype (39.0%), followed by G4P[23] (12.2%), G3P[23] (7.3%), G4P[19] (7.3%), G3P[6] (4.9%), G3P[13] (4.9%), G3P[19] (4.9%), G9P[13] (4.9%), G9P[19] (4.9%), G5P[6], and G5P[13] each of 2.4%. Furthermore, G5 and G9 in combinations with P-nontypeable strains were also found at each consisting of 2.4% (n=1) of the collection. It was interesting to note that among diversified porcine rotavirus strains, novel combinations of G4P[19] and G9P[19] strains were detected for the first time in this study. Nucleotide sequences of VP4 and VP7 of these strains were closely related to human rotaviruses reported previously. The data implies that these porcine rotaviruses were probably generated in nature from the reassortment between the viruses of human and porcine origin. This study provides valuable epidemiological information and molecular characteristics of porcine rotaviruses circulating in piglets with diarrhea in northern Thailand.

Full-length genomic analysis of porcine G9P[23] and G9P[7] rotavirus strains isolated from pigs with diarrhea in South Korea

Group A rotaviruses (RVAs) are agents causing severe gastroenteritis in infants and young animals. G9 RVA strains are believed to have originated from pigs. However, this genotype has emerged as the fifth major human RVA genotype worldwide. To better understand the relationship between human and porcine RVA strains, complete RVA genome data are needed. For human RVA strains, the number of complete genome data have grown exponentially. However, there is still a lack of complete genome data on porcine RVA strains. Recently, G9 RVA strains have been identified as the third most important genotype in diarrheic pigs in South Korea in combinations with P[7] and P[23]. This study is the first report on complete genome analyses of 1 G9P[7] and 3 G9P[23] porcine RVA strains, resulting in the following genotype constellation: G9-P[7]/P[23]-I5-R1-C1-M1-A8-N1-T1-E1-H1. By comparisons of these genotype constellations, it was revealed that the Korean G9P[7] and G9P[23] RVA strains possessed a typical porcine RVA backbone, similar to other known porcine RVA strains. However, detailed phylogenetic analyses revealed the presence of intra-genotype reassortments among porcine RVA strains in South Korea. Thus, our data provide genetic information of G9 RVA strains increasingly detected in both humans and pigs, and will help to establish the role of pigs as a source or reservoir for novel human RVA strains.

Identification of porcine rotavirus-like genotype P[6] strains in Taiwanese children

The molecular characterization of genotype P[6] rotavirus strains collected from children admitted to hospital with acute dehydrating diarrhoea during a 6-year surveillance period in Taiwan is described in this study. In total, three G4P[6] strains, one G5P[6] and one G12P[6] were characterized by sequencing and phylogenetic analysis of the VP4, VP7, VP6 and NSP4 genes. Whilst all four genes of the single Taiwanese G12P[6] strain clustered with the respective genes of globally common human rotavirus strains, the G4 and G5 strains showed remarkable similarities to porcine rotavirus strains and putative porcine-origin human P[19] strains reported previously from Taiwan. The overall proportion of porcine rotavirus-like strains in Taiwan remains around 1 % among hospitalized children; however, the circulation and sporadic transmission of these heterotypic strains from pigs to humans could pose a public-health concern. Therefore, continuation of strain monitoring is needed in the vaccine era to detect any possible vaccine breakthrough events associated with the introduction of such heterologous rotavirus strains.

Identification of lineage III of G12 rotavirus strains in diarrheic children in the Northern Region of Brazil between 2008 and 2010

This study reports on the surveillance for rotavirus genotypes and the identification of G12 human rotavirus in the Northern Region of Brazil. Rotavirus-positive samples were collected from children <5 years of age with acute diarrhea from January 2008 to October 2010. G2P[4] was the most prevalent genotype, accounting for 45.6% (126/303) of cases. Five rotavirus strains bearing G12P[6] genotype specificity were detected. Phylogenetic analysis of the VP7 gene showed that G12 strains clustered into lineage III. This is the first detection of G12 strains from lineage III in Latin America, broadening the current evidence for the worldwide emergence of this genotype.

Changing patterns of rotavirus genotypes in Turkey

To describe the circulation dynamics of human rotavirus genotypes and to understand the epidemiological changes of rotavirus infection in Turkey, one of the countries where the highest mortality rates are seen due to rotavirus in Europe. Stool samples of children under 5 years of age which gave positive results for rotavirus antigen were stored at -20°C and then genotyped using multiplex reverse transcription polymerase-chain reaction. Of the 494 stool samples, 137 (28.1%) were positive for rotavirus antigen and 100 (73%) samples which could be genotyped successfully were included in the study. 42 (42%) samples were from inpatients, and 58 (58%) were from outpatients. The median age of the children was 16 months (5 days-59 months). G9 and P[8] were the most frequent G and P genotypes, and were detected in 30 (30%) and 55 patients (55%), respectively. In 90 samples for which both G and P genotypes could be determined, 34 different combinations were found. G9P[8] was the most frequent genotype detected in 19 patients (19%), followed by G1P[8] and G4P[6] each in 7 (7%) patients. The incidence of mixed infection was found to be 26%. Novel strains like P2A[6] and P[5] and unusual reassortant strains were detected. Distribution of rotavirus genotypes exhibited distinctive changes in this study. When the ever-changing epidemiology of rotaviruses is taken into account, ongoing surveillance studies are important before the inclusion of rotavirus vaccines in national immunization program of Turkey.

Diverse origin of P[19] rotaviruses in children with acute diarrhea in Taiwan: Detection of novel lineages of the G3, G5, and G9 VP7 genes

We previously reported the detection of genotype P[19] rotavirus strains from children hospitalized with acute dehydrating diarrhea during a 5-year surveillance period in Taiwan. The characterization of five P[19] strains (0.4% of all typed), including three G3P[19], a novel G5P[19], and a unique G9P[19] genotype is described in this study. Phylogenetic analysis of the VP4, VP7, VP6, and NSP4 genes was performed, which demonstrated novel lineages for respective genotypes of the VP4 and the VP7 genes. The sequence similarities of the P[19] VP4 gene among Taiwanese human strains was higher (nt, 91.5-96.2%; aa, 93.7-97.6%) than to other P[19] strains (nt, 83.5-86.6%; aa, 89.4-94.1%) from different regions of the world. The VP7 gene of the three G3P[19] Taiwanese strains shared up to 93.4% nt and 97.5% aa identity to each other but had lower similarity to reference strain sequences available in GenBank (nt, <90.1%; aa, <95.6%). Similarly, the VP7 gene of the novel G5P[19] strain was only moderately related to the VP7 gene of reference G5 strains (nt, 82.2-87.3%; aa, 87.0-93.1%), while the VP7 gene of the single G9P[19] strain was genetically distinct from other known human and animal G9 rotavirus strains (nt, ≤ 92.0%; aa, ≤ 95.7%). Together, these findings suggest that the Taiwanese P[19] strains originated by independent interspecies transmission events. Synchronized surveillance of human and animal rotaviruses in Taiwan should identify possible hosts of these uncommon human rotavirus strains.

VP7 Gene of human rotavirus A genotype G5: Phylogenetic analysis reveals the existence of three different lineages worldwide

Group A rotavirus (RV-A) genotype G5, which is common in pigs, was also detected in children with severe diarrhea in Brazil, Argentina, Paraguay, Cameroon, China, Thailand, and Vietnam. To evaluate the evolutionary relationship among RV-A G5 strains, the VP7 and VP4 genes of 28 Brazilian RV-A G5 human strains, sampled between 1986 and 2005, were sequenced and compared with other RV-A G5 strains currently circulating worldwide in animals and humans. The phylogenetic analysis of RV-A G5 VP7 gene strains demonstrates the existence of three main lineages: (a) Lineage I: Brazilian strains grouped with three porcine strains from Thailand; (b) Lineage II: porcine, bovine, and equine strains from different regions; (c) Lineage III: human strains isolated in Asia and Africa, and two porcine strains from Argentina. The VP8* (*non-typable) subunit of VP4 gene sequencing showed that all P[8] strains fell into three major genetic lineages: P[8]-1; P[8]-2; and P[8]-3. These results showed that the RV-A G5 strains circulating in humans are the result of two independent zoonotic transmission events, most likely from pigs.

Full genomic analyses of human rotavirus G4P[4], G4P[6], G9P[19] and G10P[6] strains from North-eastern India: evidence for interspecies transmission and complex reassortment events

In hospitalized patients with acute gastroenteritis in Manipur, India, four rotavirus strains were found to possess VP7 and/or VP4 genes with porcine or bovine characteristics. Considering the animal-like nature of these strains, the remaining eight gene segments were analysed to decipher their exact origin. Analyses of full genome of these strains exhibited their origin from porcine/bovine rotaviruses. This study suggests single or multiple events of reassortment involving multiple gene segments of more than one host type among the strains and emphasizes the significance of complete genetic characterization of unusual strains in regions with high incidence and mortality rates.

Full genomic analysis of a porcine-bovine reassortant G4P[6] rotavirus strain R479 isolated from an infant in China

During the 2004 surveillance of rotaviruses in Wuhan, China, a G4P[6] rotavirus strain R479 was isolated from a stool specimen collected from a 2-year-old child with diarrhea. The strain R479 had an uncommon subgroup specificity I + II, and analysis of the VP6 gene suggested that it was related to porcine rotaviruses. In the present study, full-length nucleotide sequences of all the RNA segments of R479 were determined and analyzed phylogenetically to identify the origin of individual RNA segments. According to the rotavirus genotyping system based on 11 RNA segments, the genotype of R479 was expressed as G4-P[6]-I5-R1-C1-M1-A1-N1-T7-E1-H1. This genotype includes the porcine-like VP6 genotype (I5) and bovine-like NSP3 genotype (T7). Phylogenetic analysis revealed that R479 genes encoding VP1, VP2, VP3, VP6, VP7, VP8*, NSP1, NSP4, and NSP5 were more closely related to those of porcine rotaviruses than human or other animal rotaviruses. In contrast, it was remarkable that the NSP3 gene of R479 was genetically closely related to only a bovine rotavirus strain UK. The NSP2 gene of R479 was also unique and clustered with only the G5P[8] human strain IAL28 and G3P[24] simian strain TUCH. These results suggested that R479 may be a reassortant virus having the NSP3 gene from a bovine rotavirus in the genetic background of a porcine rotavirus, with an NSP2 gene related to the porcine-human reassortant strain IAL28. To our knowledge, R479 is the first porcine-bovine reassortant rotavirus isolated from a human.

Detection and characterisation of group A rotavirus in asymptomatic piglets in southern Ireland

Porcine group A rotaviruses (GARV) are causative agents of enteritis in piglets and are a large reservoir of genetic material for the diversification of human GARVs. Accumulation of information on the genetic heterogeneity of porcine viruses is pivotal for readily characterising unusual human strains. Screening of 292 fecal samples, collected from 4-5- to 8-9-week-old asymptomatic pigs from four herds in Ireland between 2005 and 2007 resulted in 19 (6.5%) samples testing positive by reverse-transcription PCR (RT-PCR) for GARV. The strains were molecularly characterized to collate data on the VP7 and partial VP4 outer capsid genes. By sequence analysis of the VP7 gene, the Irish strains were identified as G2, G4, G5, G9 and G11 viruses. The G11 strains were closely related to other human and porcine G11 strains, while the G2 strains resembled porcine G2 viruses detected recently in Europe and southern Asia. The G4 strains were distantly related to other G4 human and animal strains, constituting a separate G4 VP7 lineage. Analysis of the G5 strains revealed that they were similar to a selection of G5 human and porcine strains, while the G9 strains resembled other porcine G9 viruses. By sequence analysis of the VP8* fragment of the VP4, the Irish viruses were characterised as P[6], P[7], P[13], P[13]/[22], P[26] and P[32].

Molecular epidemiology of rotaviruses among healthy calves in Japan: isolation of a novel bovine rotavirus bearing new P and G genotypes

A total of 171 fecal specimens collected from healthy calves on a beef farm in Gifu Prefecture, Japan in 2006-2007 were examined for group A rotaviruses by RT-semi-nested PCR targeting the coding region for VP8*. Nine specimens were positive for rotavirus. G and P genotyping indicated that one strain was G10P[11]-like and six strains were considered to be the same unknown G and P genotypes. Among these six untypeable strains, one strain, AzuK-1, was adapted to cell culture and analyzed. Sequence and phylogenetic analyses of the full lengths of VP4 and VP7 genes revealed that AzuK-1 strain is a novel bovine rotavirus bearing new G21 and P[29] genotypes as confirmed by the RCWG. Furthermore, we detected G21P[29] rotaviruses in fecal specimens collected from healthy calves in Hokkaido, Japan during the period from 1997 to 1998. These findings suggest that novel G21P[29] rotaviruses have been widely prevalent among cattle for over 10 years in Japan.

Full genomic analysis of a human group A rotavirus G9P[6] strain from Eastern India provides evidence for porcine-to-human interspecies transmission

Deduced amino acid sequence and phylogenetic analyses of a group A rotavirus G9P[6] strain (designated as mcs/13-07), detected from a 3-year-old child in Eastern India, revealed a VP8* closely related to porcine P[6] strains (P[6] sublineage 1D), and the VP7 clustered with G9 lineage-III strains. To our knowledge, this is the first report of human P[6] strain clustering in sublineage Id. Thus, to further characterize the evolutionary diversity of strain mcs/13-07, all gene segments were analyzed. VP6 and NSP4 exhibited genetic relatedness to Wa-like human subgroup II strains, while VP1-3, NSP1-3 and NSP5 were closely related to porcine strains. Based on the new classification system of rotaviruses, mcs/13-07 revealed a G9-P[6]-I1-R1-C1-M1-A8-N1-T1-E1-H1 genotype with close similarity to human Wa-like and porcine Gottfried strains. Therefore, considering the porcine-like or porcine origin of multiple gene segments, it might be tempting to assume that strain mcs/13-07 represents a rare instance of whole-virus transmission from pig to human, after which the virus evolved with time. Alternatively, it is possible that strain mcs/13-07 resulted from multiple reassortment events involving human subgroup II and porcine P[6] strains. Nevertheless, detection of strain mcs/13-07 provides further evidence for complex interspecies transmission events, which are frequent in developing countries.

Recommendations for the classification of group A rotaviruses using all 11 genomic RNA segments

Recently, a classification system was proposed for rotaviruses in which all the 11 genomic RNA segments are used (Matthijnssens et al. in J Virol 82:3204-3219, 2008). Based on nucleotide identity cut-off percentages, different genotypes were defined for each genome segment. A nomenclature for the comparison of complete rotavirus genomes was considered in which the notations Gx-P[x]-Ix-Rx-Cx-Mx-Ax-Nx-Tx-Ex-Hx are used for the VP7-VP4-VP6-VP1-VP2-VP3-NSP1-NSP2-NSP3-NSP4-NSP5/6 encoding genes, respectively. This classification system is an extension of the previously applied genotype-based system which made use of the rotavirus gene segments encoding VP4, VP7, VP6, and NSP4. In order to assign rotavirus strains to one of the established genotypes or a new genotype, a standard procedure is proposed in this report. As more human and animal rotavirus genomes will be completely sequenced, new genotypes for each of the 11 gene segments may be identified. A Rotavirus Classification Working Group (RCWG) including specialists in molecular virology, infectious diseases, epidemiology, and public health was formed, which can assist in the appropriate delineation of new genotypes, thus avoiding duplications and helping minimize errors. Scientists discovering a potentially new rotavirus genotype for any of the 11 gene segments are invited to send the novel sequence to the RCWG, where the sequence will be analyzed, and a new nomenclature will be advised as appropriate. The RCWG will update the list of classified strains regularly and make this accessible on a website. Close collaboration with the Study Group Reoviridae of the International Committee on the Taxonomy of Viruses will be maintained.