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Stool specimens from hospitalized infants with sporadic gastroenteritis in Chiang Mai, Thailand, between July 2000 and July 2001 were examined for norovirus and sapovirus by reverse transcription-PCR and sequence analysis. These viruses were identified in 13 of 105 (12%) specimens. One strain was found to be a recombinant norovirus

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A molecular epidemiological study on common diarrheal viruses was conducted in Ho Chi Minh City, Vietnam between October 2002 and September 2003. Fecal samples were collected from 1,010 hospitalized children with acute gastroenteritis. Those samples were screened for groups A, B, and C rotavirus, adenovirus, genogroups I and II norovirus (NoV), sapovirus (SaV), and human astrovirus (HAstV) by RT-multiplex PCR, and the positive specimens were characterized further by ELISA, nested PCR, or sequencing. Among the diarrheal viruses detected, group A rotavirus was the most common, with a proportion of 67.4%, whereas NoV GII, adenovirus, SaV, and HAstV were also found in 5.5, 3.2, 0.8, and 0.6%, respectively. It is noteworthy that the group C rotavirus was first reported in Vietnam, with a proportion of 0.5% in this study. Fifty-six of 1,010 (5.5%) samples were found positive with more than one viral agent, in which 25 samples contained both group A rotavirus and NoV GII. Group A rotavirus could be identified throughout year with the peaks in both the dry and rainy season, whereas other viruses prevailed mainly in the rainy season. G-typing for the group A rotavirus showed that genotype 1 was still the most prevailing (33.0%), but interestingly, serotype 9 was emergent and became the third most common rotavirus G-type in these samples (13.7%). The four most common G-P combinations globally, G1P[8], G2P[4], G3P[8], and G4P[8] were found in 46.8% of rotavirus-positive samples, and it is of interest that one unusual rotavirus G9P[19] strain was first detected in Vietnam. The majority of NoV strains belonged to GII/4, and SaV strains mainly clustered with the Manchester strain (GI/1). Twenty-seven out of 32 adenovirus strains were identified as serotype 41. All HAstVs belonged to genotype 1. The results indicated clearly the impact of viral agents causing gastroenteritis and the importance of vaccination against diarrhea in Vietnam.

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].