Aichivirus C is the third species in the genus Kobuvirus, family Picornaviridae, and the virus is... more Aichivirus C is the third species in the genus Kobuvirus, family Picornaviridae, and the virus is circulating in pigs worldwide. Aichivirus A in humans and Aichivirus B in cows have been shown to associate with diarrheal diseases, however, the pathogenesis of Aichivirus C has not been demonstrated clearly. In this study, the full genome nucleotide sequence of the Thai strain, CMP06/2007/THA collected from stool sample of a diarrheal piglet was analyzed and identified as a variant type with a 90-nt deletion in the 2B-coding region. In addition, molecular characterization of nucleotide sequences of the 2B-coding region of Aichivirus C strains from six diarrheal and six healthy piglets in Thailand, and four strains from healthy pigs in Japan revealed that all of the strains in this study were variant types. These findings indicate that variant strains of Aichivirus C are circulating in Asian countries such as China, Thailand and Japan, and deletion of tandem repeat of 2B-region is unlikely to associate with the pathogenesis of the virus.
A total of 329 fecal specimens, which had been known to be negative for rotavirus, adenovirus, no... more 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.
Human caliciviruses, including norovirus (NoV) and sapovirus (SaV), are recognized as common path... more Human caliciviruses, including norovirus (NoV) and sapovirus (SaV), are recognized as common pathogens that cause acute viral gastroenteritis in children and adults throughout the world. To gain an overview of molecular epidemiology of human caliciviruses in children hospitalized with acute gastroenteritis in Chiang Mai, Thailand, from 2002 to 2004, NoV and SaV were detected and characterized molecularly for identification of their genotypes. From a total of 248 fecal specimens collected, 35 (14.1%) were positive for NoV GII genogroup. Among the 35 NoV GII, GII/4 was the most predominant genotype (22 strains), followed by GII/3 (7 strains), GII/1 (2 strains), GII/7 (2 strains), GII/2 (1 strain), and GII/16 (1 strain). In addition, only three specimens (1.2%) were positive for SaV, each of which was classified into two different genogroups. One isolate was clustered with GIV genogroup, while the other two belonged to two distinct genotypes of the SaV GI cluster, GI/1 and GI/2 genotypes. This study demonstrated that human caliciviruses are important enteric viruses that caused acute gastroenteritis in the hospitalized children in Chiang Mai, Thailand from 2002 to 2004. Moreover, a great genetic diversities of NoV and SaV were observed.
Human cosavirus (HCoSV) is a newly discovered virus in Picornaviridae family. At present it is no... more Human cosavirus (HCoSV) is a newly discovered virus in Picornaviridae family. At present it is not clear whether HCoSV is associated with diseases, including gastroenteritis in humans, as epidemiological data is limited. Epidemiological surveillance of HCoSV was conducted on 150 fecal specimens collected from children and 150 samples from adults with diarrhea in Thailand by RT-PCR screening. HCoSV was found in a single adult specimen and not in any of the fecal specimens from children. This represents the first report of HCoSV infection in patients with diarrhea in Thailand. Extensive epidemiological surveillance of novel viruses associated with diarrhea in other populations may provide a better understanding of the distribution, genetic diversity, and association of the viral agents associated with acute gastroenteritis in humans.
An increasing trend of sapovirus (SaV) infections in Japanese children during 2009−2019, particul... more An increasing trend of sapovirus (SaV) infections in Japanese children during 2009−2019, particularly after the introduction of the voluntary rotavirus (RV)‐vaccination program has been observed. Herein, we investigated the epidemiological situation of SaV infections from 2019 to 2022 when people adopted a precautionary lifestyle due to the emergence of the COVID‐19 pandemic, and RV vaccines had been implemented as routine vaccines. Stool samples were collected from children who attended outpatient clinics with acute gastroenteritis and analyzed by reverse transcriptase‐polymerase chain reaction to determine viral etiology. Among 961 stool samples, 80 (8.3%) were positive for SaV: 2019−2020 (6.5%), 2020−2021 (0%), and 2021−2022 (12.8%). The trend of SaV infection in Japanese children yet remained upward with statistical significance (p = 0.000). The major genotype was GI.1 (75%) which caused a large outbreak in Kyoto between December 2021 and February 2022. Phylogenetic, gene sequence and deduced amino acid sequence analyses suggested that these GI.1 strains detected in the outbreak and other places during 2021−2022 or 2019−2020 remained genetically identical and widely spread. This study reveals that SaV infection is increasing among Japanese children which is a grave concern and demands immediate attention to be paid before SaV attains a serious public health problem.
Journal of Infection and Public Health, Mar 1, 2022
BACKGROUND Human sapovirus (SaV) is an important etiologic agent of childhood diarrhea. This stud... more BACKGROUND Human sapovirus (SaV) is an important etiologic agent of childhood diarrhea. This study aims to investigate the burden of SaV infection in childhood diarrhea in Japan from 2009-2019, to understand the changes in SaV infection after the introduction of rotavirus (RV) vaccination in Japan in 2011. METHODS Stool samples were collected from children aged ≤ 12 years old with acute gastroenteritis (AGE) who visited outpatient clinics of six prefectures in Japan. The viral RNA was detected by RT-PCR and genogroups and genotypes were determined through sequence-based analysis. RESULTS Among 5697 stool samples, 318 (5.6%) samples remained SaV-positives showing the highest prevalence in June and 12-24 month aged children. The most predominant genotype was GI.1 (56.8%), followed by GI.2 (19.2%), GII.1 (10.8%), GIV.1 (9.4%), GI.3 (1.7%), GII.2 (1.4%), GII.3 and GII.5 (0.3%). Importantly, an increasing trend (P = 0.016) of SaV infection was observed during this period. In particular, SaV-detection rate was increased significantly (P = 0.033) from 4.3% in pre-rotavirus (RV)-vaccination era to 6.1% in post-RV-vaccination era. We provided evidence that this increase in SaV infection was mainly attributed by coinfections. CONCLUSIONS The upward trend of SaV infection, particularly after the introduction of RV-vaccination, is an emerging concern. Attention should be paid to control this upward trend of SaV infection to ensure maximum benefits of implementation of RV vaccines towards reducing overall childhood diarrhea worldwide.
This study describes the detection and molecular characterization of two rare G8P[14] and G3P[3] ... more This study describes the detection and molecular characterization of two rare G8P[14] and G3P[3] rotavirus strains, which were collected from children with acute gastroenteritis in 2014 in Japan. Among 247 rotaviruses, one G8P[14] (strain 12,597) and one G3P[3] (strain 12,638) rotaviruses were detected. The genotypes of 11 gene segments of these two rotavirus strains (RVA/Human-wt/JPN/12597/2014/G8P[14] and RVA/Human-wt/JPN/12638/2014/G3P[3]) were characterized. The genotype constellation of strain 12,597 was assigned to G8-P[14]-I2-R2-C2-M2-A3-N2-T9-E2-H3, and this strain possessed a rare T9 genotype of NSP3 gene which has never been reported previously in combination with G8 genotype of VP7 gene. Molecular characterization and phylogenetic analysis suggested that the strain 12,597 had the consensus G8P[14] backbone that originated from the rotaviruses of animal origins such as cows, deer, dogs, and cats. The genotype constellation of strain 12,638 was identified as G3-P[3]-I3-R3-C3-M3-A9-N2-T3-E3-H6. The VP7 and VP4 genotypes of strain 12,638 was similar to those of the Cat97-like strains, but the VP1, VP2, and VP3 were closely related to those of the AU-1-like strain. Interestingly, the NSP1 to NSP3 genes shared highest identities with those of a bat rotavirus (RVA/Bat-wt/ZMB/LUS12-14/2012/G3P[3] strain). These findings indicated that the strain 12,638 was an intra-genotype reassortant strain among the AU-1-like strains, the Cat97-like strains and the bat strain. Interestingly, the strains 12,597 and 12,638 possessed the same N2 genotype of NSP2 gene. The results of this study support the possible roles of interspecies transmission and multiple reassortment events for generating the genetic diversity of rotavirus in human.
Abstract Astroviruses are members of the large and growing family Astroviridae. The viruses can i... more Abstract Astroviruses are members of the large and growing family Astroviridae. The viruses can infect both humans and a wide variety of mammals and avian species, including lambs, sheep, calves, pigs, dogs, cats, deer, mice, minks, bats, cheetahs, sea lions, dolphins, rats, rabbits, chickens, ducks, turkeys, and pigeons. In humans, astroviruses cause acute gastroenteritis and mainly affect children under 2 years old with general prevalence rates of up to 10%. Using advanced diagnostic assays, recent epidemiological studies have highlighted the impact of astrovirus-associated gastroenteritis, with additional novel astroviruses MLB and VA being discovered in human stool samples. Continued surveillance studies and the molecular characterization of the viral genome will permit the identification of new strains and potential zoonotic transmission of astroviruses in different host species.
BACKGROUND Global distribution of human bocavirus (HBoV) has been known to associate with viral g... more BACKGROUND Global distribution of human bocavirus (HBoV) has been known to associate with viral gastroenteritis in pediatric population. This study was conducted in Chiang Mai, Thailand from 2012 to 2018 to investigate epidemiology and genotype distribution of HBoV in pediatric patients less than 5 years old hospitalized with diarrhea. METHODS A total of 2727 fecal specimens were investigated for the presence of HBoV using nested-PCR targeting partial VP1 capsid region. The detected HBoV strains were further characterized by nucleotide sequencing and phylogenetic analysis. RESULTS Detection rate of HBoV infection in pediatric patients with acute diarrhea was 5.2%. Three genotypes of HBoV were detected with the most predominance of HBoV1 (50.4%), followed by HBoV2 (42.5%), and HBoV3 (7.1%). The majority of HBoV positive cases were children of 1 to <2 years old (31.9%) with high detection rate of HBoV1 and HBoV2. HBoV infection occurred all year-round. Phylogenetic analysis revealed that majority of HBoV1 displayed the genetic relationship with HBoV1 strains reported previously from Asia whereas only a few were related to the strains from Europe, South America, and Middle East. The HBoV2 and HBoV3 were also mainly closely related to the strains reported from Asia and a few from South America and North Africa. CONCLUSIONS This study highlights distribution of HBoV genotypes circulating in pediatric patients with acute gastroenteritis in Chiang Mai, Thailand. Overall, three genotypes of HBoV were detected with equally high prevalence of HBoV1 and HBoV2 whereas HBoV3 was detected with much lower prevalence.
Aichivirus C is the third species in the genus Kobuvirus, family Picornaviridae, and the virus is... more Aichivirus C is the third species in the genus Kobuvirus, family Picornaviridae, and the virus is circulating in pigs worldwide. Aichivirus A in humans and Aichivirus B in cows have been shown to associate with diarrheal diseases, however, the pathogenesis of Aichivirus C has not been demonstrated clearly. In this study, the full genome nucleotide sequence of the Thai strain, CMP06/2007/THA collected from stool sample of a diarrheal piglet was analyzed and identified as a variant type with a 90-nt deletion in the 2B-coding region. In addition, molecular characterization of nucleotide sequences of the 2B-coding region of Aichivirus C strains from six diarrheal and six healthy piglets in Thailand, and four strains from healthy pigs in Japan revealed that all of the strains in this study were variant types. These findings indicate that variant strains of Aichivirus C are circulating in Asian countries such as China, Thailand and Japan, and deletion of tandem repeat of 2B-region is unlikely to associate with the pathogenesis of the virus.
A total of 329 fecal specimens, which had been known to be negative for rotavirus, adenovirus, no... more 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.
Human caliciviruses, including norovirus (NoV) and sapovirus (SaV), are recognized as common path... more Human caliciviruses, including norovirus (NoV) and sapovirus (SaV), are recognized as common pathogens that cause acute viral gastroenteritis in children and adults throughout the world. To gain an overview of molecular epidemiology of human caliciviruses in children hospitalized with acute gastroenteritis in Chiang Mai, Thailand, from 2002 to 2004, NoV and SaV were detected and characterized molecularly for identification of their genotypes. From a total of 248 fecal specimens collected, 35 (14.1%) were positive for NoV GII genogroup. Among the 35 NoV GII, GII/4 was the most predominant genotype (22 strains), followed by GII/3 (7 strains), GII/1 (2 strains), GII/7 (2 strains), GII/2 (1 strain), and GII/16 (1 strain). In addition, only three specimens (1.2%) were positive for SaV, each of which was classified into two different genogroups. One isolate was clustered with GIV genogroup, while the other two belonged to two distinct genotypes of the SaV GI cluster, GI/1 and GI/2 genotypes. This study demonstrated that human caliciviruses are important enteric viruses that caused acute gastroenteritis in the hospitalized children in Chiang Mai, Thailand from 2002 to 2004. Moreover, a great genetic diversities of NoV and SaV were observed.
Human cosavirus (HCoSV) is a newly discovered virus in Picornaviridae family. At present it is no... more Human cosavirus (HCoSV) is a newly discovered virus in Picornaviridae family. At present it is not clear whether HCoSV is associated with diseases, including gastroenteritis in humans, as epidemiological data is limited. Epidemiological surveillance of HCoSV was conducted on 150 fecal specimens collected from children and 150 samples from adults with diarrhea in Thailand by RT-PCR screening. HCoSV was found in a single adult specimen and not in any of the fecal specimens from children. This represents the first report of HCoSV infection in patients with diarrhea in Thailand. Extensive epidemiological surveillance of novel viruses associated with diarrhea in other populations may provide a better understanding of the distribution, genetic diversity, and association of the viral agents associated with acute gastroenteritis in humans.
An increasing trend of sapovirus (SaV) infections in Japanese children during 2009−2019, particul... more An increasing trend of sapovirus (SaV) infections in Japanese children during 2009−2019, particularly after the introduction of the voluntary rotavirus (RV)‐vaccination program has been observed. Herein, we investigated the epidemiological situation of SaV infections from 2019 to 2022 when people adopted a precautionary lifestyle due to the emergence of the COVID‐19 pandemic, and RV vaccines had been implemented as routine vaccines. Stool samples were collected from children who attended outpatient clinics with acute gastroenteritis and analyzed by reverse transcriptase‐polymerase chain reaction to determine viral etiology. Among 961 stool samples, 80 (8.3%) were positive for SaV: 2019−2020 (6.5%), 2020−2021 (0%), and 2021−2022 (12.8%). The trend of SaV infection in Japanese children yet remained upward with statistical significance (p = 0.000). The major genotype was GI.1 (75%) which caused a large outbreak in Kyoto between December 2021 and February 2022. Phylogenetic, gene sequence and deduced amino acid sequence analyses suggested that these GI.1 strains detected in the outbreak and other places during 2021−2022 or 2019−2020 remained genetically identical and widely spread. This study reveals that SaV infection is increasing among Japanese children which is a grave concern and demands immediate attention to be paid before SaV attains a serious public health problem.
Journal of Infection and Public Health, Mar 1, 2022
BACKGROUND Human sapovirus (SaV) is an important etiologic agent of childhood diarrhea. This stud... more BACKGROUND Human sapovirus (SaV) is an important etiologic agent of childhood diarrhea. This study aims to investigate the burden of SaV infection in childhood diarrhea in Japan from 2009-2019, to understand the changes in SaV infection after the introduction of rotavirus (RV) vaccination in Japan in 2011. METHODS Stool samples were collected from children aged ≤ 12 years old with acute gastroenteritis (AGE) who visited outpatient clinics of six prefectures in Japan. The viral RNA was detected by RT-PCR and genogroups and genotypes were determined through sequence-based analysis. RESULTS Among 5697 stool samples, 318 (5.6%) samples remained SaV-positives showing the highest prevalence in June and 12-24 month aged children. The most predominant genotype was GI.1 (56.8%), followed by GI.2 (19.2%), GII.1 (10.8%), GIV.1 (9.4%), GI.3 (1.7%), GII.2 (1.4%), GII.3 and GII.5 (0.3%). Importantly, an increasing trend (P = 0.016) of SaV infection was observed during this period. In particular, SaV-detection rate was increased significantly (P = 0.033) from 4.3% in pre-rotavirus (RV)-vaccination era to 6.1% in post-RV-vaccination era. We provided evidence that this increase in SaV infection was mainly attributed by coinfections. CONCLUSIONS The upward trend of SaV infection, particularly after the introduction of RV-vaccination, is an emerging concern. Attention should be paid to control this upward trend of SaV infection to ensure maximum benefits of implementation of RV vaccines towards reducing overall childhood diarrhea worldwide.
This study describes the detection and molecular characterization of two rare G8P[14] and G3P[3] ... more This study describes the detection and molecular characterization of two rare G8P[14] and G3P[3] rotavirus strains, which were collected from children with acute gastroenteritis in 2014 in Japan. Among 247 rotaviruses, one G8P[14] (strain 12,597) and one G3P[3] (strain 12,638) rotaviruses were detected. The genotypes of 11 gene segments of these two rotavirus strains (RVA/Human-wt/JPN/12597/2014/G8P[14] and RVA/Human-wt/JPN/12638/2014/G3P[3]) were characterized. The genotype constellation of strain 12,597 was assigned to G8-P[14]-I2-R2-C2-M2-A3-N2-T9-E2-H3, and this strain possessed a rare T9 genotype of NSP3 gene which has never been reported previously in combination with G8 genotype of VP7 gene. Molecular characterization and phylogenetic analysis suggested that the strain 12,597 had the consensus G8P[14] backbone that originated from the rotaviruses of animal origins such as cows, deer, dogs, and cats. The genotype constellation of strain 12,638 was identified as G3-P[3]-I3-R3-C3-M3-A9-N2-T3-E3-H6. The VP7 and VP4 genotypes of strain 12,638 was similar to those of the Cat97-like strains, but the VP1, VP2, and VP3 were closely related to those of the AU-1-like strain. Interestingly, the NSP1 to NSP3 genes shared highest identities with those of a bat rotavirus (RVA/Bat-wt/ZMB/LUS12-14/2012/G3P[3] strain). These findings indicated that the strain 12,638 was an intra-genotype reassortant strain among the AU-1-like strains, the Cat97-like strains and the bat strain. Interestingly, the strains 12,597 and 12,638 possessed the same N2 genotype of NSP2 gene. The results of this study support the possible roles of interspecies transmission and multiple reassortment events for generating the genetic diversity of rotavirus in human.
Abstract Astroviruses are members of the large and growing family Astroviridae. The viruses can i... more Abstract Astroviruses are members of the large and growing family Astroviridae. The viruses can infect both humans and a wide variety of mammals and avian species, including lambs, sheep, calves, pigs, dogs, cats, deer, mice, minks, bats, cheetahs, sea lions, dolphins, rats, rabbits, chickens, ducks, turkeys, and pigeons. In humans, astroviruses cause acute gastroenteritis and mainly affect children under 2 years old with general prevalence rates of up to 10%. Using advanced diagnostic assays, recent epidemiological studies have highlighted the impact of astrovirus-associated gastroenteritis, with additional novel astroviruses MLB and VA being discovered in human stool samples. Continued surveillance studies and the molecular characterization of the viral genome will permit the identification of new strains and potential zoonotic transmission of astroviruses in different host species.
BACKGROUND Global distribution of human bocavirus (HBoV) has been known to associate with viral g... more BACKGROUND Global distribution of human bocavirus (HBoV) has been known to associate with viral gastroenteritis in pediatric population. This study was conducted in Chiang Mai, Thailand from 2012 to 2018 to investigate epidemiology and genotype distribution of HBoV in pediatric patients less than 5 years old hospitalized with diarrhea. METHODS A total of 2727 fecal specimens were investigated for the presence of HBoV using nested-PCR targeting partial VP1 capsid region. The detected HBoV strains were further characterized by nucleotide sequencing and phylogenetic analysis. RESULTS Detection rate of HBoV infection in pediatric patients with acute diarrhea was 5.2%. Three genotypes of HBoV were detected with the most predominance of HBoV1 (50.4%), followed by HBoV2 (42.5%), and HBoV3 (7.1%). The majority of HBoV positive cases were children of 1 to <2 years old (31.9%) with high detection rate of HBoV1 and HBoV2. HBoV infection occurred all year-round. Phylogenetic analysis revealed that majority of HBoV1 displayed the genetic relationship with HBoV1 strains reported previously from Asia whereas only a few were related to the strains from Europe, South America, and Middle East. The HBoV2 and HBoV3 were also mainly closely related to the strains reported from Asia and a few from South America and North Africa. CONCLUSIONS This study highlights distribution of HBoV genotypes circulating in pediatric patients with acute gastroenteritis in Chiang Mai, Thailand. Overall, three genotypes of HBoV were detected with equally high prevalence of HBoV1 and HBoV2 whereas HBoV3 was detected with much lower prevalence.
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Papers by Niwat Maneekarn