A novel and unusual strain of porcine rotavirus (PoRV) CMP034 was isolated from a 7-week-old piglet during the epidemiological survey of porcine rotavirus infection in Chiang Mai province, Thailand from June 2000 to July 2001. Molecular characterization of gene VP4 by sequence analysis showed a low level of amino acid sequence identity, ranging from 56.7% to 76.6%, while comparison of VP8* portion showed 41.8% to 69.9% identity, with the 26 P genotypes recognized to date. Phylogenetic analysis of the VP4 sequence revealed that CMP034 was only distantly related to the other 26 P genotypes and was located in a separate branch. Sequence analysis of gene VP7 showed the highest level of amino acid identity (94.7%) with the PoRV G2-like reference strain 34461-4 but a lower level of identity with those of human G2 rotaviruses, ranging from 87.7% to 88.0%. Phylogenetic analysis of gene VP7 revealed two major lineages among G2 rotavirus strains based on the host origin. PoRV strain CMP034 clustered exclusively with G2-like PoRV strain 34461-4 in a novel lineage that is distinct from the major G2 human lineage. Moreover, strain CMP034 displayed a porcine-like VP6 and NSP5/6 with subgroup I specificity, while bearing an NSP4 with some genetic group B human-like characteristics. These findings provide evidence that CMP034 should be considered as a novel VP4 genotype P[27].

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Human group A rotavirus is a major contagious virus causing gastroenteritis in children. Molecular epidemiological study of group A rotavirus infections in hospitalized children was performed by multiplex RT-PCR during 2015-2016 in Chiang Rai, Thailand. G- and P-genotypes of positive rotavirus samples were further analyzed by one-step and two-step multiplex RT-PCR methods. Among 270 fecal specimens tested, rotavirus was the most prevalent (33.7%), followed by norovirus GII (4.1%), adenovirus (3%), and astrovirus (1.5%). Infection was common in patients aged 12-23 months (45.1%) and occurred mostly in children under 3 years of age (85.7%). The highest peak was in a hot month, March (64.8%). G9P[8] emerged as the most predominant (79.1%), followed by G3P[8] (13.2%), G1P[8] (3.3%), and mixed G-types (4.4%). Interestingly, Chiang Rai G9 strains were clustered within a distinct lineage VII including G9 recently reported since 2010-2015. G9-VII also contained four to five unique amino acid substitutions in the VP7 proteins compared with those of the G9 candidate vaccine strain RVA/Human-tc/IND/116E/1985/G9P[11] and the prototype RVA/Human-wt/USA/WI61/1983/G9P[8], defining the G9-VII as a novel variant. G3 strains were closely related to the "new G3P[8] reassortant variant" with an equine-like VP7 gene that emerged in several countries. This study contributes to the understanding of the genetic diversity, providing scientific support for future vaccine strategies to reduce the morbidity and mortality.

Of 477 stool specimens, which had been screened for rotavirus, adenovirus, norovirus, sapovirus and astrovirus, collected from infants and children with acute gastroenteritis in pediatric clinics encompassing five localities (Sapporo, Tokyo, Maizuru, Osaka, and Saga) in Japan from July 2007 to June 2008, 247 negative samples (51.7%) were subjected to screening for human parechovirus. Human parechovirus (HPeV) was detected by RT-PCR using a primer pair to amplify 5'UTR region of its genome and was genotyped by sequencing of the VP1 gene. HPeV was detected in 20 of 247 specimens tested, and the detection rate was found to be 8.1%. Seventeen of the 20 strains that tested positive for HPeV were sequenced successfully the VP1 gene. The majority of the HPeV strains (n = 15) could be identified as HPeV1, and the remaining 2 strains could be typed as HPeV3. By phylogenetic and identical matrix analyses of HPeV VP1 sequences, HPeV1 should be divided into two lineages, and all of the Japanese studied HPeV1 strains belong to the lineage 2 accordingly. This is the first report of the circulation of HPeV, especially HPeV1 in Japan.

Norovirus (NoV) is recognized as one of the most common causative agents of diarrhea disease in young children. A total of 187 fecal specimens collected from non-hospitalized children with acute gastroenteritis in Shizuoka, Japan during July 2008 to June 2009 were investigated for the presence of diarrhea viruses by a multiplex RT-PCR. Diarrhea viruses were overall detected in 158 of 187 (84.5%). Of the viruses detected, NoV was the most prevalent (55.6%). Most of the NoV sequences belonged to GII.4 (53.8%). NoV GII.6 emerged as the second most common strain (40.4%). The full-length capsid sequences of five representative Shizuoka GII.6 strains were compared with all 12 GII.6 strains available in GenBank database between 1990 and 2009. At least three distinct GII.6 subclusters (a-c) appeared in different parts of the world. Shizuoka GII.6 strains formed their own subcluster c, distinct from other complete GII.6 reference sequences. The Shizuoka strains had significant amino acid divergence, particularly in the P2 domain up to 10.9-17.5% and contained eight unique mutations in the P domains, compared with subcluster a and b viruses. The homology model showed that the eight mutations were predicted to be located at the surface-exposed P1 and P2 domains. The data suggest the emergence of a new NoV GII.6 variant in Shizuoka, with a high level of genetic variation.

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