Molecular analysis of G3 rotavirus among infants and children in Dhaka City, Bangladesh after 1993

Between 2004 and 2005, 917 fecal specimens were collected from children below age 5 who presented to Child Health Institute for treatment of diarrhoea in Dhaka City, Bangladesh. The specimens were screened by RT-PCR for the presence of group A rotavirus and positive stools genotyped. Group A rotavirus was detected in 307 stools and serotype G3P[8] strains were detected in nine specimens. Sequence analysis clustered the G3 strains into one distinct lineage (lineage I) with other Asian G3 strains. In addition, one amino acid change at position 96 in antigenic region A, similar to lineage II G3 Chinese strains, was noted. To our knowledge this is the first report of serotype G3 strains in Bangladesh since 1993 and the first report of the molecular characterization of these strains.     

Molecular characterization of VP4, VP6, VP7, NSP4, and NSP5/6 genes identifies an unusual G3P[10] human rotavirus strain

An unusual strain of human rotavirus G3P[10] (CMH079/05) was detected in a stool sample of a 2‐year‐old child admitted to the hospital with severe diarrhea in Chiang Mai, Thailand. Analysis of the VP7 gene sequence revealed highest identities with unusual human rotavirus G3 strain CMH222 at 98.7% on the nucleotide and 99.6% on the amino acid levels. Phylogenetic analysis of the VP7 sequence confirmed that the CMH079/05 strain formed a cluster with G3 rotavirus reference strains and showed the closest lineage with the CMH222 strain. Analysis of partial VP4 gene of CMH079/05 revealed highest degree of sequence identities with P[10] rotavirus prototype strain 69M at nucleotide and amino acid levels of 92.9% and 94.6%, respectively. Phylogenetic analysis of the VP4 sequence revealed that CMH079/05 and 69M clustered closely together in a monophyletic branch separated from other rotavirus genotypes. To our knowledge, this is a novel G–P combination of G3 and P[10] genotypes. In addition, analyses of VP6, NSP4, and NSP5/6 genes revealed these uncommon genetic characteristics: (i) the VP6 gene differed from the four other known subgroups; (ii) the NSP4 gene was identified as NSP4 genetic group C, an uncommon group in humans; and (iii) the NSP5/6 gene was most closely related with T152, a G12P[9] rotavirus previously isolated in Thailand. The finding of uncommon G3P[10] rotavirus in this pediatric patient provided additional evidence of the genetic diversity of human group A rotaviruses in Chiang Mai, Thailand. J. Med. Virol. 81:176–182, 2009. © 2008 Wiley‐Liss, Inc.     

Evolutionary consequences of G9 rotaviruses circulating in Thailand

Infection with group A rotaviruses is the main cause of acute gastroenteritis in infants and young children worldwide. Rotavirus G9 is recognized as the fifth most predominant G genotype that spreads throughout the world. In this study, we describe the changing distribution of rotavirus G9 genotype in Chiang Mai, Thailand, from 1989 to 2005. Molecular genetic evolutionary analysis of the G9 rotavirus VP7 gene was performed. The G9 rotavirus in Thailand was first detected in Chiang Mai in 1989 with a low prevalence of 1.98%, but in 2000 and 2001 it had become the most predominant genotype, reaching prevalence of 75% and 92.2%, respectively. Then, the prevalence of G9 reached a peak of 100% in 2002 and decreased abruptly over the next 3 years, i.e. 16.7% in 2003, 32.1% in 2004, and 4.7% in 2005. Our phylogenetic analysis demonstrates that all the G9 rotaviruses circulating in Thailand belonged to lineage III, and clustered closely together based on the year of virus isolation. One amino acid change from Thr to Ile was observed in antigenic region C at position 208 between the G9 strains isolated in 1989 and the strains of 1997–2005. These findings provide the overall picture and genomic data of G9 rotaviruses circulating in Chiang Mai, Thailand.     

Emergence of a new norovirus GII.6 variant in Japan, 2008-2009

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.     

Intergenogroup Recombinant Sapovirus in Japan, 2007�C2008

We investigated the incidence of sapovirus (SaV)–associated gastroenteritis in infants and children in Japan during 2007–2008 and characterized the diversity of SaV-positive strains. SaV was detected in 19 (4%) of 477 fecal specimens. The leading genogroup (79%, 15 cases) comprised intergenogroup recombinant SaVs (GII/GIV).     

Molecular and epidemiological trend of rotavirus infection among infants and children in Japan

This study investigated the prevalence of group A, B, and C rotavirus (RAV, RBV, RCV) and adenovirus (AdV) infections in infants and children with acute gastroenteritis in Japan from July 2006 to June 2007. A total of 628 fecal specimens collected from infants and children with acute gastroenteritis in five different places (Maizuru, Tokyo, Sapporo, Saga and Osaka) in Japan during the period of July 2006–June 2007 were examined for RAV, RBV, RCV and AdV by RT-multiplex PCR. RAV was further characterized to G-typing and P-typing by RT-multiplex PCR and sequencing method. It was found that 123 (19.6%) fecal specimens were positive for RAV followed by AdV of 4.5%. RBV and RCV could not be detected in this study. Serotype G1 (58.5%) was identified at high levels followed by G9 (20.3%), G2 (11.4%), and G3 (7.3%). P genotyping revealed P[8] as predominant (84.6%) followed by P[4] (13.8%) and P[6] (1.6%). During the 2006/2007 rotavirus season, G1P[8] strains were most common with G9P[8], G2P[4], G3P[8], G1P[4] and G9P[6] also detected. It is clear from this study that RAV is still the cause of diseases in Japan. To our knowledge, this is the first report of RV P[6] strain in humans in Japan.