Genotyping of non-polio enteroviruses associated with acute flaccid paralysis in Thailand in 2013 and 2014.

BACKGROUND: Acute flaccid paralysis (AFP) surveillance was conducted as part of the World Health Organization's strategy for completely eradicating poliomyelitis and leaving non-polio enteroviruses NPEVs as one of the main potential causes of AFP. We aimed to detect NPEV in association with AFP. METHODS: We used 459 isolates reported to be Negative Polio and some NPEVs by the World Health Organization Polio Regional Reference Laboratory (Thailand), which had been obtained during polio surveillance programmes conducted in Thailand in 2013-2014. Of 459 isolates, 35 belonged to the genus Enterovirus by RT-PCR and genotyping by DNA sequencing. RESULTS: This study found 17 NPEV genotypes, with 3, 13 and 1 belonging to enterovirus (EV) species A (EV-A), EV-B, and EV-C, respectively. The EV-A types identified included coxsackievirus A2 (CA2), CA4, and EV71, typically associated with hand, foot and mouth diseases. EV-B is the most prevalent cause of AFP in Thailand, while CA21 was the only type of EV-C detected. The EV-B species (13/35; 76.5%) constituted the largest proportion of isolates, followed by EV-A (3/35; 17.6%) and EV-C (1/35; 5.9%). For the EV-B species, Echovirus (E) 30 and CVB were the most frequent isolates. E30, CVB, E14, and E6 were considered endemic strains. CONCLUSION: NPEVs, e.g. CA4, are reported for the first time in Thailand. Despite some limitations to this study, this is the first report on the circulation patterns of NPEVs associated with AFP in Thailand. AFP surveillance has unearthed many unknown NPEVs and, the cases of death due to AFP occur annually. Therefore, it is important to study NPEVs in the wake of the eradication of poliovirus in the context of the continued incidence of paralysis.

Full genome-based characterization of G4P[6] rotavirus strains from diarrheic patients in Thailand: Evidence for independent porcine-to-human interspecies transmission events.

The exact evolutionary patterns of human G4P[6] rotavirus strains remain to be elucidated. Such strains possess unique and strain-specific genotype constellations, raising the question of whether G4P[6] strains are primarily transmitted via independent interspecies transmission or human-to-human transmission after interspecies transmission. Two G4P[6] rotavirus strains were identified in fecal specimens from hospitalized patients with severe diarrhea in Thailand, namely, DU2014-259 (RVA/Human-wt/THA/DU2014-259/2014/G4P[6]) and PK2015-1-0001 (RVA/Human-wt/THA/PK2015-1-0001/2015/G4P[6]). Here, we analyzed the full genomes of the two human G4P[6] strains, which provided the opportunity to study and confirm their evolutionary origin. On whole genome analysis, both strains exhibited a unique Wa-like genotype constellation of G4-P[6]-I1-R1-C1-M1-A8-N1-T1-E1-H1. The NSP1 genotype A8 is commonly found in porcine rotavirus strains. Furthermore, on phylogenetic analysis, each of the 11 genes of strains DU2014-259 and PK2015-1-0001 appeared to be of porcine origin. On the other hand, the two study strains consistently formed distinct clusters for nine of the 11 gene segments (VP4, VP6, VP1-VP3, and NSP2-NSP5), strongly indicating the occurrence of independent porcine-to-human interspecies transmission events. Our observations provide important insights into the origin of zoonotic G4P[6] strains, and into the dynamic interaction between porcine and human rotavirus strains.

High prevalence of equine-like G3P[8] rotavirus in children and adults with acute gastroenteritis in Thailand.

Group A rotavirus (RVA) is a major cause of acute gastroenteritis in infants and young children worldwide. This study aims to clarify the distribution of G/P types and genetic characteristics of RVAs circulating in Thailand. Between January 2014 and September 2016, 1867 stool specimens were collected from children and adults with acute gastroenteritis in six provinces in Thailand. RVAs were detected in 514/1867 (27.5%) stool specimens. G1P[8] (44.7%) was the most predominant genotype, followed by G3P[8] (33.7%), G2P[4] (11.5%), G8P[8] (7.0%), and G9P[8] (1.3%). Unusual G3P[9] (0.8%), G3P[10] (0.4%), G4P[6] (0.4%), and G10P[14] (0.2%) were also detected at low frequencies. The predominant genotype, G1P[8] (64.4%), in 2014 decreased to 6.1% in 2016. In contrast, the frequency of G3P[8] markedly increased from 5.5% in 2014 to 65.3% in 2015 and 89.8% in 2016. On polyacrylamide gel electrophoresis, most (135/140; 96.4%) of the G3P[8] strains exhibited a short RNA profile. Successful determination of the nucleotide sequences of the VP7 genes of 98 G3P[8] strains with a short RNA profile showed that they are all equine-like G3P[8] strains. On phylogenetic analysis of genome segments of two representative Thai equine-like G3P[8] strains, it was noteworthy that they possessed distinct NSP4 genes, one bovine-like and the other human-like. Thus, we found that characteristic equine-like G3P[8] strains with a short RNA electropherotype are becoming highly prevalent in children and adults in Thailand.

Identification and characterization of a human G9P[23] rotavirus strain from a child with diarrhoea in Thailand: evidence for porcine-to-human interspecies transmission.

An unusual rotavirus strain with the G9P[23] genotype (RVA/Human-wt/THA/KKL-117/2014/G9P[23]) was identified in a stool specimen from a 10-month-old child hospitalized with severe diarrhoea. In this study, we sequenced and characterized the complete genome of strain KKL-117. On full-genomic analysis, strain KKL-117 was found to have the following genotype constellation: G9-P[23]-I5-R1-C1-M1-A8-N1-T1-E1-H1. The non-G/P genotype constellation of this strain (I5-R1-C1-M1-A8-N1-T1-E1-H1) is commonly shared with rotavirus strains from pigs. Furthermore, phylogenetic analysis indicated that each of the 11 genes of strain KKL-117 appeared to be of porcine origin. Our observations provide important insights into the dynamic interactions between human and porcine rotavirus strains.

Predominant prevalence of human rotaviruses with the G1P[8] and G8P[8] genotypes with a short RNA profile in 2013 and 2014 in Sukhothai and Phetchaboon provinces, Thailand.

Of 2,754 stool specimens collected from children with acute gastroenteritis during 2013-2014 in Sukhothai and Phetchaboon provinces, Thailand, 666 (24.2%) were positive for rotavirus A (RVA) in polyacrylamide gel electrophoresis (PAGE). The G and P types of all RVA-positive specimens were determined by semi-nested RT-PCR. G1P[8] (56.5%) was most prevalent, followed by G2P[4] (22.1%). Unusual G8P[8] human RVAs (HuRVAs) were detected at a high frequency (20.0%). Interestingly, 171 of the 376 G1P[8] HuRVAs and all of the 133 G8P[8] HuRVAs showed a short RNA pattern in PAGE. Thus, it was shown that the properties of HuRVAs have been markedly unusual in recent years in Thailand. J. Med. Virol. 89:615-620, 2017. © 2016 Wiley Periodicals, Inc.

CaFÉ: A Sensitive, Low-Cost Filtration Method for Detecting Polioviruses and Other Enteroviruses in Residual Waters.

Acute flaccid paralysis (AFP) surveillance has been used to identify polio cases and target vaccination campaigns since the inception of the Global Poliovirus Eradication Initiative (GPEI) in 1988. To date, only Afghanistan and Pakistan have failed to interrupt wild poliovirus transmission. Circulation of vaccine-derived polioviruses (VDPV) continues to be a problem in high-risk areas of the Eastern Mediterranean, African, and Southeast Asian regions. Environmental surveillance (ES) is an important adjunct to AFP surveillance, helping to identify circulating polioviruses in problematic areas. Stools from AFP cases and contacts (>200,000 specimens/year) and ES samples (>642 sites) are referred to 146 laboratories in the Global Polio Laboratory Network (GPLN) for testing. Although most World Health Organization supported laboratories use the two-phase separation method due to its simplicity and effectiveness, alternative simple, widely available, and cost-effective methods are needed. The CAFÉ (Concentration and Filtration Elution) method was developed from existing filtration methods to handle any type of sewage or residual waters. At $10-20 US per sample for consumable materials, CAFÉ is cost effective, and all equipment and reagents are readily available from markets and suppliers globally. The report describes the results from a parallel study of CAFÉ method with the standard two-phase separation method. The study was performed with samples collected from five countries (Guatemala, Haïti, Thailand, Papua New Guinea, and the Philippines), run in three laboratories-(United States, Thailand and in the Philippines) to account for regional and sample-to-sample variability. Samples from each site were divided into two 500 ml aliquots and processed by both methods, with no other additional concentration or manipulation. The results of 338 parallel-tested samples show that the CAFÉ method is more sensitive than the two-phase separation method for detection of non-polio enteroviruses (p-value < 0.0001) and performed as well as the two-phase separation method for polioviruses detection with no significant difference (p-value > 0.05). The CAFÉ method is a robust, sensitive, and cost-effective method for isolating enteroviruses from residual waters.

Genomic characterization of a novel G3P[10] rotavirus strain from a diarrheic child in Thailand: Evidence for bat-to-human zoonotic transmission.

An unusual rotavirus strain with the G3P[10] genotype (RVA/Human-wt/THA/MS2015-1-0001/2015/G3P[10]) was identified in a stool sample from a hospitalized child aged 11 months with severe gastroenteritis in Thailand. In the current study, we sequenced and characterized the full genome of strain MS2015-1-0001. On full-genomic analysis, strain MS2015-1-0001 exhibited the following genotype configuration: G3-P[10]-I8-R3-C3-M3-A9-N3-T3-E3-H6, which is identical or closely related to those of bat and bat-like rotavirus strains (MYAS33-like). Furthermore, phylogenetic analysis revealed that all 11 genes of strain MS2015-1-0001 appeared to be of bat origin. Our findings provide evidence for bat-to-human interspecies transmission of rotaviruses and important insights into dynamic interactions between human and bat rotavirus strains.

Spread of genetically similar noroviruses in Bangkok, Thailand, through symptomatic and asymptomatic individuals.

Norovirus infection is a major cause of acute gastroenteritis, although some infected individuals are asymptomatic. GII.4 is the predominant genotype worldwide and, since 2000, has been the most prevalent in patients in Thailand with acute gastroenteritis. We screened stool samples for norovirus in 786 patients with acute gastroenteritis who were admitted to a hospital in Bangkok from 2017 to early 2019 and detected it in 136 specimens (17.3%). Eight and 124 specimens were positive for the GI and GII genogroups, respectively, and the remaining 4 specimens were double-positive. Nine genotypes (GI.3, GI.5, GII.2, GII.3, GII.4, GII.6, GII.8, GII.13, and GII.17) were identified from 140 strains, and 72 strains (51.4%) were GII.4. We had previously conducted a one-year survey of norovirus infection in residents of a community in Bangkok from May 2018 to April 2019 and found that a substantial portion of the residents were infected asymptomatically. The 9 genotypes identified in the patients were also commonly identified in the community residents. To investigate the relationship between noroviruses identified in the acute gastroenteritis patients and those identified in the community residents, phylogenetic tree analysis was conducted. Of the 9 genotypes, 8 showed similarities in both their genomic sequences and their deduced amino acid sequences. In addition, strain replacement of GI.3 was observed in both the patients and the community residents within the overlapping period. These results suggested that norovirus spreads efficiently to the community by simultaneously causing symptomatic and asymptomatic infections.

A long-term survey on the distribution of the human rotavirus G type in Thailand.

The distribution of the G type of human rotavirus was surveyed in Thailand between July 1993 and June 2007. A significant yearly change in the distribution of the G type distribution was found. From 1993-1994 to 1998-1999, the G1 type was the most dominant. In 1999-2000, G9 began to appear at a high frequency. In 2000-2001, 2001-2002, and 2002-2003, G9 was very common. In 2003-2004, G1 became the most prevalent type again, and since then it has been detected at the highest frequency. G12 strains, which were first detected in 1998-1999, were also found in 2004-2005 and 2006-2007. The G4 and G3 types were moderately prevalent in 2001-2002 and 2004-2005, respectively. Nucleotide sequence analysis of the VP7 genes of the G9 and G12 strains which reemerged in Thailand showed that they were each similar to the contemporary strains in other countries.

Full genome characterization of novel DS-1-like G9P[8] rotavirus strains that have emerged in Thailand.

The emergence and rapid spread of unusual DS-1-like intergenogroup reassortant rotaviruses having G1/3/8 genotypes have been recently reported from major parts of the world (Africa, Asia, Australia, Europe, and the Americas). During rotavirus surveillance in Thailand, three novel intergenogroup reassortant strains possessing the G9P[8] genotype (DBM2017-016, DBM2017-203, and DBM2018-291) were identified in three stool specimens from diarrheic children. In the present study, we determined and analyzed the full genomes of these three strains. On full-genomic analysis, all three strains were found to share a unique genotype constellation comprising both genogroup 1 and 2 genes: G9-P[8]-I2-R2-C2-M2-A2-N2-T2-E2-H2. Phylogenetic analysis demonstrated that each of the 11 genes of the three strains was closely related to that of emerging DS-1-like intergenogroup reassortant, human, and/or locally circulating human strains. Thus, the three strains were suggested to be multiple reassortants that had acquired the G9-VP7 genes from co-circulating Wa-like G9P[8] rotaviruses in the genetic background of DS-1-like intergenogroup reassortant (likely equine-like G3P[8]) strains. To our knowledge, this is the first description of emerging DS-1-like intergenogroup reassortant strains having the G9P[8] genotype. Our observations will add to the growing insights into the dynamic evolution of emerging DS-1-like intergenogroup reassortant rotaviruses through reassortment.

Characterization of an Unusual DS-1-Like G8P[8] Rotavirus Strain from Japan in 2017: Evolution of Emerging DS-1-Like G8P[8] Strains through Reassortment.

The emergence of unusual DS-1-like intergenogroup reassortant rotaviruses with a bovine-like G8 genotype (DS-1-like G8P[8] strains) has been reported in several Asian countries. During the rotavirus surveillance program in Japan in 2017, a DS-1-like G8P[8] strain (RVA/Human-wt/JPN/SO1162/2017/G8P[8]) was identified in 43 rotavirus-positive stool samples. Strain SO1162 was shown to have a unique genotype constellation, including genes from both genogroup 1 and 2: G8-P[8]-I2-R2-C2-M2-A2-N2-T2-E2-H2. Phylogenetic analysis revealed that the VP1 gene of strain SO1162 appeared to have originated from DS-1-like G1P[8] strains from Thailand and Vietnam, while the remaining 10 genes were closely related to those of previously reported DS-1-like G8P[8] strains. Thus, SO1162 was suggested to be a reassortant strain that acquired the VP1 gene from Southeast Asian DS-1-like G1P[8] strains on the genetic background of co-circulating DS-1-like G8P[8] strains. Our findings provide important insights into the evolutionary dynamics of emerging DS-1-like G8P[8] strains.

The dynamics of norovirus genotypes and genetic analysis of a novel recombinant GII.P12-GII.3 among infants and children in Bangkok, Thailand between 2014 and 2016.

Norovirus (NoV) is the leading cause of viral acute gastroenteritis among all age groups in the world. We performed a molecular epidemiological study of the NoVs prevalent in Bangkok between November 2014 and July 2016 to investigate the emergence of new NoV variants in Thailand. A total of 332 stool specimens were collected from hospitalized pediatric patients with acute gastroenteritis in Bangkok, Thailand. NoVs were detected by real-time PCR. The genome of the N-terminal/shell domain was amplified, the nucleotide sequence was determined, and phylogenetic analyses were performed. GII NoV was detected in 58 (17.5%) of the 332 specimens. GII.17, a genotype strain prevalent from 2014 to mid-2015, was hardly detected and replaced by the GII.3 genotype strain. Entire genome sequencing followed by phylogenetic analysis of the GII.3 genotype strains indicated that they are new recombinant viruses, because the genome encoding ORF1 is derived from a GII.12 genotype strain, whereas that encoding ORF2-3 is from a GII.3 genotype strain. The putative recombination breakpoints with the highest statistical significance were located around the border of 3Dpol and ORF2. The change in the prevalent strain of NoV seems to be linked to the emergence of new forms of recombinant viruses. These findings suggested that the swapping of the structural and non-structural proteins of NoV is a common mechanism by which new epidemic variants are generated in nature.

Characterization of a G10P[14] rotavirus strain from a diarrheic child in Thailand: Evidence for bovine-to-human zoonotic transmission.

An unusual rotavirus strain, DB2015-066 with the G10P[14] genotype (RVA/Human-wt/THA/DB2015-066/2015/G10P[14]), was detected in a stool sample from a child hospitalized with acute gastroenteritis in Thailand. Here, we sequenced and characterized the full-genome of the strain DB2015-066. On whole genomic analysis, strain DB2015-066 was shown to have a unique genotype constellation: G10-P[14]-I2-R2-C2-M2-A3-N2-T6-E2-H3. The backbone genes of this strain (I2-R2-C2-M2-A3-N2-T6-E2-H3) are commonly found in rotavirus strains from artiodactyls such as cattle. Furthermore, phylogenetic analysis indicated that each of the 11 genes of strain DB2015-066 could be of artiodactyl (likely bovine) origin. Thus, strain DB2015-066 appeared to be derived from through zoonotic transmission of a bovine rotavirus strain. Of note, the VP7 gene of strain DB2015-066 was located in G10 lineage-6 together with ones of bovine and bovine-like rotavirus strains, away from the clusters comprising other G10P[14] strains in G10 lineage-2/4/5/9, suggesting the occurrence of independent bovine-to-human interspecies transmission events. Our observations provide important insights into the origins of rare G10P[14] strains, and into dynamic interactions between artiodactyl and human rotavirus strains.

Monthly Distribution of Norovirus and Sapovirus Causing Viral Gastroenteritis in Thailand.

A total of 1,141 rotavirus-negative stool specimens collected from diarrheic children in 4 distinct regions under sentinel surveillance in Thailand between 2006 and 2008 were examined by reverse-transcription (RT)-PCR for norovirus (NoV) and sapovirus (SaV). Three hundred 3 specimens (26.6%) were positive for NoV, with 34 and 269 belonging to genogroup I (GI) and genogroup II (GII), respectively. Twelve specimens (1.1%) were positive for SaV. Mixed infections were found in 5 specimens: 3 samples indicated the presence of both NoV GI and GII, and 2 samples indicated the presence of both NoV GII and SaV. Analysis of the monthly distribution of NoV and SaV revealed that NoV GII was clustered between September and February, while NoV GI was detected mainly in June and July; SaV was found in May, June, and July. In addition, 3 outbreaks of acute gastroenteritis at 2 junior high schools in Phichit and Bangkok, and at a university in Phitsanulok, Thailand in 2006 were found to have been caused by NoV infection. Sequence analysis of NoVs from sporadic cases and outbreaks showed them to be genotypes GII.4 and GII.6.

Reassortment of Human and Animal Rotavirus Gene Segments in Emerging DS-1-Like G1P[8] Rotavirus Strains.

The emergence and rapid spread of novel DS-1-like G1P[8] human rotaviruses in Japan were recently reported. More recently, such intergenogroup reassortant strains were identified in Thailand, implying the ongoing spread of unusual rotavirus strains in Asia. During rotavirus surveillance in Thailand, three DS-1-like intergenogroup reassortant strains having G3P[8] (RVA/Human-wt/THA/SKT-281/2013/G3P[8] and RVA/Human-wt/THA/SKT-289/2013/G3P[8]) and G2P[8] (RVA/Human-wt/THA/LS-04/2013/G2P[8]) genotypes were identified in fecal samples from hospitalized children with acute gastroenteritis. In this study, we sequenced and characterized the complete genomes of strains SKT-281, SKT-289, and LS-04. On whole genomic analysis, all three strains exhibited unique genotype constellations including both genogroup 1 and 2 genes: G3-P[8]-I2-R2-C2-M2-A2-N2-T2-E2-H2 for strains SKT-281 and SKT-289, and G2-P[8]-I2-R2-C2-M2-A2-N2-T2-E2-H2 for strain LS-04. Except for the G genotype, the unique genotype constellation of the three strains (P[8]-I2-R2-C2-M2-A2-N2-T2-E2-H2) is commonly shared with DS-1-like G1P[8] strains. On phylogenetic analysis, nine of the 11 genes of strains SKT-281 and SKT-289 (VP4, VP6, VP1-3, NSP1-3, and NSP5) appeared to have originated from DS-1-like G1P[8] strains, while the remaining VP7 and NSP4 genes appeared to be of equine and bovine origin, respectively. Thus, strains SKT-281 and SKT-289 appeared to be reassortant strains as to DS-1-like G1P[8], animal-derived human, and/or animal rotaviruses. On the other hand, seven of the 11 genes of strain LS-04 (VP7, VP6, VP1, VP3, and NSP3-5) appeared to have originated from locally circulating DS-1-like G2P[4] human rotaviruses, while three genes (VP4, VP2, and NSP1) were assumed to be derived from DS-1-like G1P[8] strains. Notably, the remaining NSP2 gene of strain LS-04 appeared to be of bovine origin. Thus, strain LS-04 was assumed to be a multiple reassortment strain as to DS-1-like G1P[8], locally circulating DS-1-like G2P[4], bovine-like human, and/or bovine rotaviruses. Overall, the great genomic diversity among the DS-1-like G1P[8] strains seemed to have been generated through reassortment involving human and animal strains. To our knowledge, this is the first report on whole genome-based characterization of DS-1-like intergenogroup reassortant strains having G3P[8] and G2P[8] genotypes that have emerged in Thailand. Our observations will provide important insights into the evolutionary dynamics of emerging DS-1-like G1P[8] strains and related reassortant ones.

Full Genome Characterization of Novel DS-1-Like G8P[8] Rotavirus Strains that Have Emerged in Thailand: Reassortment of Bovine and Human Rotavirus Gene Segments in Emerging DS-1-Like Intergenogroup Reassortant Strains.

The emergence and rapid spread of unusual DS-1-like intergenogroup reassortant rotavirus strains have been recently reported in Asia, Australia, and Europe. During rotavirus surveillance in Thailand in 2013-2014, novel DS-1-like intergenogroup reassortant strains having G8P[8] genotypes (i.e., strains KKL-17, PCB-79, PCB-84, PCB-85, PCB-103, SKT-107, SWL-12, NP-130, PCB-656, SKT-457, SSKT-269, and SSL-55) were identified in stool samples from hospitalized children with severe diarrhea. In this study, we determined and characterized the complete genomes of these 12 strains (seven strains, KKL-17, PCB-79, PCB-84, PCB-85, PCB-103, SKT-107, and SWL-12, found in 2013 (2013 strains), and five, NP-130, PCB-656, SKT-457, SSKT-269, and SSL-55, in 2014 (2014 strains)). On full genomic analysis, all 12 strains showed a unique genotype constellation comprising a mixture of genogroup 1 and 2 genes: G8-P[8]-I2-R2-C2-M2-A2-N2-T2-E2-H2. With the exception of the G genotype, the unique genotype constellation of the 12 strains (P[8]-I2-R2-C2-M2-A2-N2-T2-E2-H2) was found to be shared with DS-1-like intergenogroup reassortant strains. On phylogenetic analysis, six of the 11 genes of the 2013 strains (VP4, VP2, VP3, NSP1, NSP3, and NSP5) appeared to have originated from DS-1-like intergenogroup reassortant strains, while the remaining four (VP7, VP6, VP1, and NSP2) and one (NSP4) gene appeared to be of bovine and human origin, respectively. Thus, the 2013 strains appeared to be reassortant strains as to DS-1-like intergenogroup reassortant, bovine, bovine-like human, and/or human rotaviruses. On the other hand, five of the 11 genes of the 2014 strains (VP4, VP2, VP3, NSP1, and NSP3) appeared to have originated from DS-1-like intergenogroup reassortant strains, while three (VP7, VP1, and NSP2) and one (NSP4) were assumed to be of bovine and human origin, respectively. Notably, the remaining two genes, VP6 and NSP5, of the 2014 strains appeared to have originated from locally circulating DS-1-like G2P[4] human rotaviruses. Thus, the 2014 strains were assumed to be multiple reassortment strains as to DS-1-like intergenogroup reassortant, bovine, bovine-like human, human, and/or locally circulating DS-1-like G2P[4] human rotaviruses. Overall, the great genomic diversity among the DS-1-like intergenogroup reassortant strains seemed to have been generated through additional reassortment events involving animal and human strains. Moreover, all the 11 genes of three of the 2014 strains, NP-130, PCB-656, and SSL-55, were very closely related to those of Vietnamese DS-1-like G8P[8] strains that emerged in 2014-2015, indicating the derivation of these DS-1-like G8P[8] strains from a common ancestor. To our knowledge, this is the first report on full genome-based characterization of DS-1-like G8P[8] strains that have emerged in Thailand. Our observations will add to our growing understanding of the evolutionary patterns of emerging DS-1-like intergenogroup reassortant strains.

Whole genomic analysis of bovine group A rotavirus strains A5-10 and A5-13 provides evidence for close evolutionary relationship with human rotaviruses.

Bovine group A rotavirus (RVA) is an important cause of acute diarrhea in calves worldwide. In order to obtain precise information on the origin and evolutionary dynamics of bovine RVA strains, we determined and analyzed the complete nucleotide sequences of the whole genomes of six archival bovine RVA strains; four Thai strains (RVA/Cow-tc/THA/A5-10/1988/G8P[1], RVA/Cow-tc/THA/A5-13/1988/G8P[1], RVA/Cow-tc/THA/61A/1989/G10P[5], and RVA/Cow-tc/THA/A44/1989/G10P[11]), one American strain (RVA/Cow-tc/USA/B223/1983/G10P[11]), and one Japanese strain (RVA/Cow-tc/JPN/KK3/1983/G10P[11]). On whole genomic analysis, the 11 gene segments of strains A5-10, A5-13, 61A, A44, B223, and KK3 were found to be considerably genetically diverse, but to share a conserved non-G/P genotype constellation except for the NSP1 gene (I2-R2-C2-M2-(A3/11/13/14)-N2-T6-E2-H3), which is commonly found in RVA strains from artiodactyls such as cattle. Furthermore, phylogenetic analysis revealed that most genes of the six strains were genetically related to bovine and bovine-like strains. Of note is that the VP1, VP3, and NSP2 genes of strains A5-10 and A5-13 exhibited a closer relationship with the cognate genes of human DS-1-like strains than those of other RVA strains. Furthermore, the VP6 genes of strains A5-10 and A5-13 appeared to be equally related to both human DS-1-like and bovine strains. Thus, strains A5-10 and A5-13 were suggested to be derived from the same evolutionary origin as human DS-1-like strains, and were assumed to be examples of bovine RVA strains that provide direct evidence for a close evolutionary relationship between bovine and human DS-1-like strains. Our findings will provide important insights into the origin of bovine RVA strains, and into evolutionary links between bovine and human RVA strains.

Emergence and Characterization of Unusual DS-1-Like G1P[8] Rotavirus Strains in Children with Diarrhea in Thailand.

The emergence and rapid spread of unusual DS-1-like G1P[8] rotaviruses in Japan have been recently reported. During rotavirus surveillance in Thailand, three DS-1-like G1P[8] strains (RVA/Human-wt/THA/PCB-180/2013/G1P[8], RVA/Human-wt/THA/SKT-109/2013/G1P[8], and RVA/Human-wt/THA/SSKT-41/2013/G1P[8]) were identified in stool specimens from hospitalized children with severe diarrhea. In this study, we sequenced and characterized the complete genomes of strains PCB-180, SKT-109, and SSKT-41. On whole genomic analysis, all three strains exhibited a unique genotype constellation including both genogroup 1 and 2 genes: G1-P[8]-I2-R2-C2-M2-A2-N2-T2-E2-H2. This novel genotype constellation is shared with Japanese DS-1-like G1P[8] strains. Phylogenetic analysis revealed that the G/P genes of strains PCB-180, SKT-109, and SSKT-41 appeared to have originated from human Wa-like G1P[8] strains. On the other hand, the non-G/P genes of the three strains were assumed to have originated from human DS-1-like strains. Thus, strains PCB-180, SKT-109, and SSKT-41 appeared to be derived through reassortment event(s) between Wa-like G1P[8] and DS-1-like human rotaviruses. Furthermore, strains PCB-180, SKT-109, and SSKT-41 were found to have the 11-segment genome almost indistinguishable from one another in their nucleotide sequences and phylogenetic lineages, indicating the derivation of the three strains from a common origin. Moreover, all the 11 genes of the three strains were closely related to those of Japanese DS-1-like G1P[8] strains. Therefore, DS-1-like G1P[8] strains that have emerged in Thailand and Japan were assumed to have originated from a recent common ancestor. To our knowledge, this is the first report on whole genome-based characterization of DS-1-like G1P[8] strains that have emerged in an area other than Japan. Our observations will provide important insights into the evolutionary dynamics of emerging DS-1-like G1P[8] rotaviruses.