Aichi virus is a new member of the family Picornaviridae, genus Kobuvirus, and is associated with human gastroenteritis. This study detected Aichi virus in 28 of 912 fecal specimens which were negative for rotavirus, adenovirus, norovirus, sapovirus, and astrovirus and were collected in Japan, Bangladesh, Thailand, and Vietnam during 2002 to 2005.Aichi virus, a small round virus about 30 nm in diameter, was first recognized in 1989 as the cause of oyster-associated nonbacterial gastroenteritis in humans (8-10). The virus was classified into a new genus named Kobuvirus of the family Picornaviridae (11), which contains nine genera, Aphthovirus, Cardiovirus, Enterovirus, Erbovirus, Hepatovirus, Kobuvirus (which includes Aichi virus and bovine kobuvirus), Parechovirus, Rhinovirus, and Teschovirus. The complete Aichi virus genome was determined in 1998 and proved to be a singlestranded positive-sense RNA molecule with 8,251 bases, excluding a poly(A) tail; it contains a large open reading frame with 7,302 nucleotides that encodes a potential polyprotein precursor of 2,433 amino acids (11). In 2000, a reverse transcription (RT)-PCR method for the detection of Aichi virus was developed and a genetic analysis was performed with the 519-base RNA sequences at the putative junction between the C terminus of 3C and the N terminus of 3D. As a result, Aichi virus isolates have been divided into groups 1 (genotype A) and 2 (genotype B) (12).Studies on Aichi virus were subsequently performed, and it was also detected in Brazil and Germany (2-7). However, there has been limited knowledge about the epidemiology of Aichi virus infection in Asian countries other than Japan and Pakistan. This study was performed to determine the prevalence of Aichi virus in Bangladesh, Thailand, Vietnam, and also in Japan and to provide a better understanding of the epidemiology and genetic relationships between the Aichi virus strains in the present study and the strains previously reported.A total of 912 stored, extracted RNA samples from fecal specimens known to be negative for rotavirus, adenovirus, norovirus, sapovirus, and astrovirus by RT-PCR that were collected from patients with acute gastroenteritis in Japan (215 samples collected

A total of 82 fecal specimens which were known to be negative for rotavirus, adenovirus, norovirus, sapovirus, and astrovirus and which were collected from infants and children with acute gastroenteritis in Chiang Mai, Thailand, from January to December 2005 were screened for human parechovirus (HPeV). HPeV was detected by reverse transcription-PCR with a primer pair that amplified the 5 untranslated region of its genome and was genotyped by sequencing of the VP1 region. HPeV was detected in 12 of 82 specimens tested, and the detection rate was found to be 14.6%. The capsid VP1 gene was successfully sequenced from nine of the HPeV strains detected. The HPeV strains studied clustered into four different genotypes, HPeV genotype 1 (HPeV1) to HPeV4, and the majority of the strains studied (five strains) belonged to HPeV1. This is the first finding of HPeV from children with acute gastroenteritis in Thailand. In addition, the diversity of the Thai HPeV strains was also noted.

Of 362 fecal specimens collected from infants and children hospitalized with acute gastroenteritis in Sri Lanka from September 2005 to August 2006, 30 (8.3%) were positive for human parechovirus (HPeV). Six different HPeV genotypes, including HPeV1, -3, -4, -5, -10, and -11, were identified, of these, HPeV11 was reported for the first time.

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.

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Sequence analysis of the capsid gene of Aichi viruses was performed on 12 strains detected in Japan, Bangladesh, Thailand, and Vietnam during 2002-2005. The phylogenetic tree constructed from 17 nucleotide sequences of the capsid gene of the strains studied and reference strains demonstrated that Aichi virus strains clustered into two branches. A classification of Aichi viruses based on the capsid gene was proposed, in which lineage I consists of the Aichi virus strains detected from Japan, Thailand, Vietnam, and Germany, and lineage II includes Bangladeshi strains and a Brazilian strain.

Multiplex RT-PCR method using five sets of panel primers was developed for the detection of diarrheal viruses, including rotavirus A, B, and C, adenovirus, astrovirus, norovirus GI and GII, sapovirus, Aichi virus, parechovirus, enterovirus, cosavirus, bocavirus, and Saffold virus. The sensitivity of the method was evaluated and tested with 751 fecal specimens collected from Japanese children with acute diarrhea. Several kinds of viruses were detected in 528 out of 751 (70.3%) fecal specimens. Mixed-infection with different viruses in clinical specimens could also be effectively detected. The method proved to be reliable with highly sensitive and specific and useful for routine diagnosis. J. Med. Virol. 89:818-824, 2017. © 2016 Wiley Periodicals, Inc.

A total of 329 fecal specimens, which had been known to be negative for rotavirus, adenovirus, norovirus, sapovirus, and astrovirus, and which were collected from infants and children with acute gastroenteritis in Japan and Thailand during 2005-2008 were screened for human bocavirus (HBoV). HBoV was detected by PCR with a primer pair that amplified the NP1 region of its genome and was genotyped by sequencing of the VP1/VP2 region. Of the 329 samples tested, 6 (1.8%) were positive for HBoV. Of these, five samples were collected from Japan and one sample was from Thailand, and the detection rates of HBoV in each country were 2% and 1.2%, respectively. For the detected HBoV, the capsid VP1/VP2 gene of all HBoV strains was successfully sequenced. Four Japanese HBoV strains studied were clustered into group 1, while the remaining Japanese strain and a unique Thai strain belonged to group 2. No severe acute gastroenteritis associated with HBoV was noted. This study provides better understanding on the epidemiology of HBoV infections in children with acute gastroenteritis in Japan and Thailand.