Genetic recombination and genotype diversity of norovirus GI in children with acute gastroenteritis in Thailand, 2015-2021.

BACKGROUND: Human norovirus is a predominant etiological agent responsible for acute gastroenteritis across all age groups. Recently, norovirus recombinant strains have been reported as the cause of norovirus outbreaks in several settings and the strains that cause outbreaks mostly belong to the norovirus GII. However, yet, the norovirus GI recombinant strains have never been reported previously in Thailand. The aims of this study were to investigate the genetic recombination and genotype diversity of norovirus GI strains in children hospitalized with acute gastroenteritis in Chiang Mai, Thailand during a period of seven years from 2015 to 2021. METHODS: A total of 2829 stool specimens were screened for norovirus GI by real-time PCR, and the polymerase and capsid genes were sequenced and analyzed. RESULTS: Of 2829 specimens tested, 12 (0.4%) were positive for norovirus GI. Of these, 7 out of 12 (58.3%) strains were identified as norovirus GI recombinant strains. Among 7 norovirus GI recombinant strains, 3, 3, and 1 were identified as GI.3[P13], GI.5[P4], and GI.6[P11], respectively. The remaining five strains were identified as non-recombinant strains of the GI.4[P4], GI.5[P5], and GI.6[P6] genotypes. CONCLUSIONS: The findings highlight the genetic diversity and multiple intergenotype recombinant strains of norovirus GI circulating in children with acute gastroenteritis in Chiang Mai, Thailand from 2015 to 2021. The detection of multiple intergenotype norovirus GI recombinant strains further underscore the complexity of norovirus GI strains circulating in this region.

Distribution and molecular characterization of saffold virus and human cosavirus in children admitted to hospitals with acute gastroenteritis in Thailand, 2017-2022.

Saffold virus (SAFV) and human cosavirus (HCoSV) are emerging viruses of the Picornaviridae family. They have been shown to associate with gastrointestinal infection and more recently these viruses have also been demonstrated to associate with other clinical infections such as the respiratory tract, cardiovascular system, and the cerebral ventricular system. In this study, 2459 stool specimens collected from pediatric patients admitted to hospitals with acute gastroenteritis from January 2017 to December 2022, were screened for SAFV and HCoSV utilizing reverse transcription-polymerase chain reaction. Positive samples were then characterized into genotypes via nucleotide sequencing and bioinformatic analysis. Of the 2459 samples, 21 and 39 were positive for SAFV (0.9%) and HCoSV (1.6%), respectively. Three genotypes of SAFV were identified-SAFV-1 (38%), SAFV-2 (24%), and SAFV-3 (38%). Two genetic groups of HCoSV were identified-HCoSV-C (97%) and HCoSV-A (3%), demonstrating a large increase of HCoSV-C as compared to those reported previously from the same geographical region in Thailand. This study provides the prevalence of SAFV and HCoSV genotypes in Chiang Mai, Thailand during a period of 6 years from 2017 to 2022.

Molecular detection and characterization of SARS-CoV-2 in wastewater in Thailand during 2020-2022.

BACKGROUND: SARS-CoV-2 has been detected in feces of infected individuals and in wastewater in many countries, which indicates that wastewater may be used to monitor contamination of the virus in community. However, information about the presence of SARS-CoV-2 in different types of environmental water and their genetic characterization are still limited. The purpose of this study was to investigate the presence of SARS-CoV-2 contaminating in environmental water in Thailand. METHODS: We collected 600 water samples from 10 different sampling sites in Chiang Mai city, Thailand twice a month from July 2020 to December 2022. The SARS-CoV-2 RNA was detected by real-time RT-PCR and further amplified for ORF1a and S genes to investigate their genetic relationship to the reference strains by phylogenetic analysis. RESULTS: SARS-CoV-2 was detected at 0.17% in the wastewater sample collected in the vicinity of fresh market where the outbreak of COVID-19 cases were simultaneously reported. The detected SARS-CoV-2 strain (W323/21) had nucleotide and amino acid sequences identical to SARS-CoV-2 Delta variant. Amino acid sequence alignment of spike protein revealed that the W323/21 strain carried a mutation of D950N as it was demonstrated in Delta variant reference strains. CONCLUSIONS: The findings indicated that SARS-CoV-2 Delta variant was detected in wastewater in Chiang Mai, Thailand during the outbreak of COVID-19, suggesting a circulation of the virus in environmental water and in the community during the outbreak.

Diverse genotypes of human enteric and non-enteric adenoviruses circulating in children hospitalized with acute gastroenteritis in Thailand, from 2018 to 2021.

Human adenovirus (HAdV) is a common viral pathogen that causes diarrhea in children worldwide. The aim of this study was to investigate the prevalence and genotype diversity of HAdV strains circulating in children admitted to the hospitals with acute gastroenteritis (AGE) in Chiang Mai, Thailand, from 2018 to 2021. A total of 1,790 stool samples were screened for HAdV by PCR method, and 80 (4.5%) were positive for HAdV. Of these, children under 5 years of age accounted for 90.0% of HAdV-positive cases with the highest infection rate at the age group of 48-60 months old. The infection rate was not significantly different between boys and girls. The HAdV infection was detected sporadically throughout the year without a discrete seasonal pattern. Five species of both enteric and non-enteric HAdVs (A, B, C, E, and F) with 10 different genotypes, including HAdV-F41 (25.0%), HAdV-B3 (17.5%), HAdV-F40 (16.3%), HAdV-C1 (15.0%), HAdV-C5 (7.5%), HAdV-C2 (6.3%), HAdV-B7 (5.0%), HAdV-A12 (3.8%), HAdV-E4 (2.5%), and HAdV-B11 (1.3%), were detected in this study. In conclusion, our study reported the prevalence and seasonality of HAdV infection with a wide variety of HAdV genotypes circulating in children hospitalized with AGE during a period of 2018-2021 in Chiang Mai, Thailand. IMPORTANCE In the present study, the prevalence of human adenovirus (HAdV) infection in children with acute gastroenteritis (AGE) in Chiang Mai, Thailand, from 2018 to 2021 was detected at 4.5%. Diverse species and genotypes of HAdVs (HAdV-A12, HAdV-B3, HAdV-B7, HAdV-B11, HAdV-C1, HAdV-C2, HAdV-C5, HAdV-E4, HAdV-F40, and HAdV-F41) had been identified. The highest infection rate was found in children aged 48-60 months old. The HAdV infection was detected sporadically throughout the year. These findings imply that a wide variety of HAdV genotypes circulate in pediatric patients with AGE in Chiang Mai, Thailand.

Triple Intergenotype Recombination of Human Astrovirus 5, Human Astrovirus 8, and Human Astrovirus 1 in the Open Reading Frame 1a, Open Reading Frame 1b, and Open Reading Frame 2 Regions of the Human Astrovirus Genome.

Human astrovirus (HAstV) strains exhibit high levels of genetic diversity, and many recombinant strains with different recombination patterns have been reported. The aims of the present study were to investigate the emergence of HAstV recombinant strains and to characterize the recombination patterns of the strains detected in pediatric patients admitted to the hospital with acute gastroenteritis in Chiang Mai, Thailand. A total of 92 archival HAstV strains detected in 2011 to 2020 were characterized regarding their open reading frame 1a (ORF1a) genotypes in comparison with their ORF1b genotypes to identify recombinant strains. The recombination breakpoints of the putative recombinant strains were determined by whole-genome sequencing and were analyzed by SimPlot and RDP software. Three HAstV strains (CMH-N178-12, CMH-S059-15, and CMH-S062-15) were found to be recombinant strains of three different HAstV genotypes, i.e., HAstV5, HAstV8, and HAstV1 within the ORF1a, ORF1b, and ORF2 regions, respectively. The CMH-N178-12 strain displayed recombination breakpoints at nucleotide positions 2681 and 4357 of ORF1a and ORF1b, respectively, whereas the other two recombinant strains, CMH-S059-15 and CMH-S062-15, displayed recombination breakpoints at nucleotide positions 2612 and 4357 of ORF1a and ORF1b, respectively. This is the first study to reveal nearly full-length genome sequences of HAstV recombinant strains with a novel recombination pattern of ORF1a-ORF1b-ORF2 genotypes. This finding may be useful as a guideline for identifying other recombinant HAstV strains in other geographical regions and may provide a better understanding of their genetic diversity, as well as basic knowledge regarding virus evolution. IMPORTANCE Recombination is one of the mechanisms that plays a crucial role in the genetic diversity and evolution of HAstV. We wished to investigate the emergence of HAstV recombinant strains and to analyze the whole-genome sequences of the putative HAstV recombinant strains detected in pediatric patients with acute gastroenteritis in 2011 to 2020. We reported 3 novel intergenotype recombinant strains of HAstV5-HAstV8-HAstV1 at the ORF1a-ORF1b-ORF2 regions of the HAstV genome. The hot spots of recombination occur frequently near the ORF1a-ORF1b and ORF1b-ORF2 junctions of the HAstV genome. The findings indicate that intergenotype recombination of HAstV occurs frequently in nature. The emergence of a novel recombinant strain allows the new virus to adapt and successfully escape from the host immune system, eventually emerging as the predominant genotype to infect human populations that lack herd immunity against novel recombinant strains. The virus may cause an outbreak and needs to be monitored continually.

The emergence of recombinant norovirus GII.12[P16] and predominance of GII.3[P12] strains in pediatric patients with acute gastroenteritis in Thailand, 2019-2020.

Norovirus (NoV) and sapovirus (SaV) are important pathogens that cause acute gastroenteritis (AGE) in all age groups, commonly in children worldwide. Recently, a number of studies have reported a wide variety of NoV recombinant strains. This study aimed to investigate the distribution of NoV and SaV recombinant strains circulating in Chiang Mai, Thailand, during 2019-2020. One hundred and twenty-four NoV and seven SaV strains detected in children admitted to the hospital with AGE were included in this study. The partial RNA-dependent RNA-polymerase (RdRp)/VP1 regions of these NoV and SaV strains were analyzed by phylogenetic analysis, Simplot, and RDP software. Overall, eight recombination patterns of NoV were detected. NoV GII.4[P16] was the most common strain detected (39.1%), followed by GII.3[P12] (25.0%), GII.4[P31] (17.2%), and other recombinant strains were detected at a lower rate. NoV GII.12[P16] strains were detected for the first time in Thailand. For SaV, none of the recombinant strains was detected. All SaV strains, GI.1/GI.1, GI.2/GI.2, and GII.5/GII.5, exhibited VP1 genotype corresponded to RdRp genotype. In conclusion, this study demonstrates the distribution and diversity of NoV and SaV recombinant strains circulating in pediatric patients with AGE in Chiang Mai, during 2019-2020 with the emergence of NoV GII.3[P12] and GII.12[P16].

Molecular epidemiology and characterization of norovirus and sapovirus in pediatric patients with acute diarrhea in Thailand, 2019-2020.

BACKGROUND: Human enteric pathogens in the family Caliciviridae including norovirus (NoV) and sapovirus (SaV) are associated with acute diarrheal disease globally and are considered as one of the viruses with high genetic diversity. METHODS: In order to investigate the epidemiology of NoV and SaV in pediatric patients with acute diarrhea in Chiang Mai, Thailand from January 2019 to December 2020, a total of 675 stool specimens were collected and examined for the presence of NoV and SaV by RT-multiplex PCR. RESULTS: 126 (18.7 %) and 6 (0.9 %) stool samples were positive for NoV and SaV, respectively. Mixed infection of NoV and SaV was detected in one patient (0.2 %). Among 10 different NoV strains detected in this study, NoV genogroup II genotype 4 (GII.4) Sydney 2012 was the most predominant genotype (51.2 %) followed by GII.3, GII.2, GII.6, GII.12, GII.7, GII.17, GI.4, GII.14, and GI.3. Interestingly, monthly distribution of NoV genotypes revealed that NoV GII.3 increased dramatically in August 2019, suggesting an outbreak of NoV GII.3 might occur in the community. In addition, 3 genotypes of SaV were detected in this study with SaV GI.1 being the most common genotype (71.4 %) followed by GI.2 and GII.5 (each at 14.3 %). CONCLUSIONS: This study demonstrates the prevalence and genetic diversity of NoV and SaV circulating in pediatric patients with acute gastroenteritis in Chiang Mai, Thailand during 2019-2020 and shows an emergence of NoV GII.3 infection in 2019.

Changing Predominance of Norovirus Recombinant Strains GII.2[P16] to GII.4[P16] and GII.4[P31] in Thailand, 2017 to 2018.

Human norovirus is a major virus that causes acute gastroenteritis in all age groups. Recently, norovirus recombinant strains have been reported as the cause of norovirus outbreaks. This study has investigated the distribution of norovirus genotypes and recombinant strains circulating in children hospitalized with diarrhea in Chiang Mai, Thailand from 2017 to 2018. A total of 882 stool specimens were tested for the presence of norovirus GI and GII by reverse transcription-PCR (RT-PCR) assay. Genotypes of the viruses were assessed by partial VP1 nucleotide sequencing and the representative strains were further characterized for norovirus recombinant strains by amplification of ORF1 (RdRp)/ORF2 (VP1 capsid) junction region. From a total of 882 stool samples, 131 (14.9%) were positive for norovirus, of which the majority of norovirus genogroups were norovirus GII, and only one was identified as norovirus GI. A wide variety of norovirus genotypes were detected in this study, including GI.5, GII.2, GII.3, GII.4, GII.6, GII.7, GII.13, GII.14, and GII.17 with the predominance of GII.2 (62.5%) in 2017 and GII.4 (57.0%) in 2018. Nevertheless, it should be noted that GII.4 remained the most predominant genotype (50.4%) in overall prevalence. Analysis of norovirus recombination revealed that several norovirus recombinant strains (GII.2[P16], GII.3[P16], GII.4[P16], GII.4[P31], GII.6[P7], GII.13[P16], and GII.14[P7]) had been identified with the predominance of GII.2[P16] in 2017 and changed to GII.4[P16] and GII.4[P31] in 2018. In conclusion, this study reported the detection of a wide variety of norovirus genotypes and several norovirus recombinant strains in Chiang Mai, Thailand from 2017 to 2018. IMPORTANCE In the present study, the prevalence of norovirus infection in children with acute gastroenteritis in Chiang Mai, Thailand between 2017 and 2018 was 14.9%. A variety of norovirus genotypes were detected, including GI.5, GII.2, GII.3, GII.4, GII.6, GII.7, GII.13, GII.14, and GII.17 with the predominance of GII.4 genotype. In addition, several norovirus recombinant strains (GII.2[P16], GII.3[P16], GII.4[P16], GII.4[P31], GII.6[P7], GII.13[P16], and GII.14[P7]) had been identified. Our results revealed that GII.2[P16] was a predominant strain till the end of 2017 and then was replaced by GII.4[P16] and GII.4[P31] in 2018. The findings imply that norovirus recombinant strains emerged in Chiang Mai, Thailand and that circulating strains changes over time.

Emergence of Multiple Novel Inter-Genotype Recombinant Strains of Human Astroviruses Detected in Pediatric Patients With Acute Gastroenteritis in Thailand.

Objective: Human astrovirus (HAstV) is recognized as an important cause of acute gastroenteritis in children. Recombination between different genotypes of HAstV can contribute to diversity and evolution of the virus. This study aimed to investigate the emergence of HAstV recombinant strains in pediatric patients hospitalized with acute gastroenteritis in Chiang Mai, Thailand, spanning 2011-2020. Methods: A total of 92 archival HAstV strains collected from pediatric patients with acute gastroenteritis during 2011-2020 were further characterized to identify the recombinant strains. The ORF1b and ORF2 junction region of each strain was amplified and sequenced. The obtained sequences were analyzed in comparison with the reference sequences retrieved from GenBank database. Their genotypes were assigned using MEGA X software based on the partial ORF1b (RdRp) and ORF2 (capsid) regions, and the recombination breakpoints of recombinant strains were determined by SimPlot and RDP4 analyses. Results: Five inter-genotype recombinant strains with three recombination patterns of ORF1b/ORF2 of classic HAstV, HAstV8/HAstV1, HAstV8/HAstV3, and HAstV3/HAstV2, were detected. The recombination breakpoints of all strains were located at the 3'-end region of ORF1b close to the ORF1b/ORF2 junction. Conclusion: Several novel inter-genotype recombinant strains of classic HAstV genotypes were detected in pediatric patients with acute gastroenteritis in Chiang Mai, Thailand, during the period of 10 years from 2011 to 2020.

Contamination of Human Bocavirus Genotypes 1, 2, 3, and 4 in Environmental Waters in Thailand.

Human bocavirus (HBoV) has been recognized as one of the common pathogens which cause respiratory disease and acute gastroenteritis in children worldwide. Recently, our studies reported the detection of HBoV in children with acute gastroenteritis and in oysters in Thailand. However, studies on the presence of HBoV in environmental waters in Thailand have not yet been conducted. In this study, 126 environmental water samples collected from November 2016 to July 2018 were investigated. Detection of HBoV was based on amplification of the VP1/VP2 region of the HBoV genome by nested PCR followed by nucleotide sequencing and phylogenetic analysis. HBoV was detected in 34 out of 126 samples (27.0%). All four HBoV genotypes, HBoV1 to HBoV4, were detected. HBoV2 was the most frequently detected genotype (61.8%), followed by HBoV1 (23.5%), HBoV4 (8.8%), and HBoV3 (5.9%). The highest detection rate of HBoV was observed during the warmest months in Thailand: April 2017 and March 2018. Phylogenetic analysis of VP1/VP2 nucleotide sequences of HBoV genotypes revealed that all four of the genotypes detected in environmental waters were closely related to genotypes detected in patients with acute gastroenteritis, which had been reported previously in the same geographical area. This study reports the existence of multiple HBoV genotypes in environmental waters and provides evidence of a considerably high magnitude of HBoV contamination in these waters. These findings demonstrate the potential risk of waterborne transmission of HBoV to humans. IMPORTANCE Recently, we reported the detection of HBoV genotypes 1, 2, and 3 in pediatric patients with acute gastroenteritis, and the detection of HBoV1 and 2 in oysters in Thailand. In this study, we reported the detection of HBoV1, 2, 3, and 4 contamination in environmental waters within the same geographic area. Phylogenetic analysis demonstrated that the HBoV genotypes detected in environmental waters and in oysters were closely related to HBoV detected in patients. These findings imply that HBoV contamination in oysters and in environmental waters could be a potential sources of foodborne and waterborne transmission to humans.

High divergence of human astrovirus genotypes circulating in pediatric patients hospitalized with acute gastroenteritis in Chiang Mai, Thailand, 2017-2020.

Human astrovirus (HAstV) is one of the common causes of acute gastroenteritis in children. The investigation of molecular epidemiology of HAstV is essential for monitoring the emergence and/or re-emergence of new HAstV genotypes, as well as understanding the evolution of HAstV circulating in children suffering from acute gastroenteritis. The present study aimed to investigate the prevalence and distribution of HAstVs strains circulating in children hospitalized with acute gastroenteritis in Chiang Mai, Thailand during 2017-2020. A total of 1500 fecal specimens collected from children with acute gastroenteritis were screened for HAstV by RT-PCR that targeted the partial RdRp in ORF1b and strains were characterized by sequencing and phylogenetic analysis. Of the 1500 fecal samples, 39 (2.6%) were positive for HAstV. Of these, both classic and novel HAstV genotypes, including classic HAstV1-HAstV5, novel HAstV-MLB1, MLB2, and HAstV-VA2, were detected. The data in this study revealed a high divergence of HAstV genotypes circulating in pediatric patients admitted to the hospitals with acute gastroenteritis in Chiang Mai, Thailand during 2017-2020.

Epidemiology and genetic diversity of group A rotavirus in pediatric patients with acute gastroenteritis in Thailand, 2018-2019.

Group A rotaviruses (RVAs) are the major viruses that cause acute gastroenteritis in young children worldwide. The objective of this study was to investigate the prevalence and genotype diversity of RVAs circulating in children with acute gastroenteritis in Thailand in 2018-2019. A total of 1170 stool specimens were obtained from children admitted to hospitals with diarrhea and screened for RVAs by nested RT-PCR. The RVA genotypes were determined by multiplex-PCR or nucleotide sequencing and phylogenetic analysis. Out of 1170 stool specimens, 209 (17.9%) were positive for RVAs. The RVA G9P[8] genotype (24.4%) was the most dominant genotype, followed by G3P[8] (22.9%), G8P[8] (22.0%), G1P[8] (16.7%), G2P[4] (6.7%), G1P[6] (2.3%), G1P[4] (1.0%), G3P[4] (1.0%), G9P[4] (1.0%), mixed-infections of G1P[4] + G1P[8] (1.0%), and GXP[8] (0.5%). Moreover, an uncommon RVA G3P[10] genotype (0.5%), bearing bat-like VP7 and VP4 genes, was detected. This study reveals the prevalence and genetic diversity of RVA genotypes in children with acute gastroenteritis in Thailand. The knowledge obtained from this study is helpful for understanding the epidemiology of rotavirus in Thailand. The emergence of uncommon RVA strain G3P[10] provides an evidence for interspecies transmission of human and animal rotaviruses.

Prevalence and Genetic Characterization of Aichivirus in Environmental Waters in Thailand.

Aichivirus 1 (AiV-1) is an enteric virus that has been documented to be the causative agent of diarrhea in humans. It is transmitted by fecal-oral route, through person-to-person contact, consumption of contaminated food or water, or recreation of contaminated water. AiV-1 is highly prevalent in water samples and has been proposed as a potential indicator of fecal contamination in water reservoirs. This study aimed to investigate the prevalence and genetic diversity of AiV-1 in environmental water samples in Thailand. A total of 126 samples were collected monthly from November 2016 to July 2018 from various sources of environmental water including irrigation water, reservoir, river, and wastewater. The presence of AiV-1 was detected by RT-nested PCR of the 3CD region and further analyzed by phylogenetic analysis. The AiV-1 was detected in 28 out of 126 (22.2%) of tested samples. A high frequency of AiV-1 detection was in wastewater (52.4%). All 28 AiV-1 strains detected in this study belonged to the genotype B and were closely related to AiV strains detected previously in environmental waters and in humans worldwide. This study demonstrated, for the first time, the contamination of AiV-1 in various sources of water samples in Thailand and provided a better insight into the prevalence of AiV-1 in environmental waters and its potential risk of human health.

Molecular detection and genetic characterization of Salivirus in environmental water in Thailand.

Salivirus (SalV), also known as klassevirus, is a newly discovered member of the Picornaviridae family, which has been proposed to be a potential causative agent of acute gastroenteritis. This study aimed to provide further insight into the currently limited epidemiological data of SalV in environmental water in Thailand, which could be a potential source of human infection. A total of 95 water samples were collected from six locations in Chiang Mai province, northern Thailand, between November 2016 and February 2018. The molecular screening for SalV was performed by the nested polymerase chain reaction. The SalV genotypes were then determined through nucleotide sequencing and phylogenetic analysis. SalV was detected in 31 out of the 95 (32.6%) water samples and all belonged to the A1 genotype, based on phylogenetic analysis of the 5'UTR and 3D regions. The SalV-A1 strains detected in the environmental water were closely related to the SalV-A1 detected in a patient with diarrhoea in the same geographical area, based on the nucleotide sequence identities of the 5'UTR and 3D regions ranging from 91 to 99% and 96-99%, respectively. This study reports the prevalence of SalV-A1 contamination in environmental water in Chiang Mai, Thailand.

Increasing predominance of G8P[8] species A rotaviruses in children admitted to hospital with acute gastroenteritis in Thailand, 2010-2013.

Rotavirus A is a well-known etiological cause of acute gastroenteritis in infants and young children worldwide. In this study, we investigated the prevalence and distribution of RVA genotypes circulating in children with acute gastroenteritis in Thailand from 2010 to 2013. A total of 1,032 fecal specimens were collected from children with an age range from neonatal to 15 years of age and tested for RVA by RT-PCR. Of these, 184 (17.8%) were positive for RVA. The highest detection rate of RVA was found in children aged between 12 and 24 months. The G1P[8] genotype was identified as the most dominant genotype (57.6%), followed by G2P[4] (12.5%), G8P[8] (10.4%), G9P[8] (7.1%), G3P[8] (4.9%), G1P[4] (2.2%), G2P[8] (1.7%), and mixed-infections of G1 and G3 in combination with P[8] (0.5%). In addition, the uncommon human rotavirus strains G4P[6] (1.1%), G9P[19] (0.5%), G12P[4] (0.5%), and G12P[6] (0.5%) were also detected in this study. Interestingly, the unusual G8P[8] strains were detected at a relatively high frequency, and phylogenetic analysis revealed that these G8 strains were genetically closely related to bovine and bovine-like human G8 rotavirus strains reported previously from Thailand, Japan, Vietnam, India and Taiwan. These G8P[8] strains displayed the DS-1-like genotype constellation of G8-P[8]-I2-R2-C2-M2-A2-N2-T2-E2-H2 (in the order VP7-VP4-VP6-VP1-VP2-VP3-NSP1-NSP2-NSP3-NSP4-NSP5/6, respectively). Overall, the data indicated a high degree of diversity of RVA genotypes, with the emergence of several uncommon RVA strains in children with acute gastroenteritis in Thailand.

Salivirus infection in children with diarrhea, Thailand.

A new member of the Picornaviridae family named salivirus, and also known as klassevirus, was identified recently from the feces of children with gastroenteritis. At present, it remains unclear whether salivirus is associated with gastroenteritis in humans and epidemiological data are very limited. To investigate the prevalence of salivirus in Thailand, we performed molecular screening of fecal samples from children hospitalized with acute gastroenteritis in Chiang Mai, Thailand during 2015-2016 through the application of RT-nested PCR. Salivirus was detected in 1 out of 229 (0.44%) fecal samples tested and it belonged to genotype A1, based on nucleotide sequences of the 5'UTR, VP1, and 3D regions. This is the first report of salivirus infection in young children with acute diarrhea in Thailand.

Wide variety of recombinant strains of norovirus GII in pediatric patients hospitalized with acute gastroenteritis in Thailand during 2005 to 2015.

Norovirus (NoV) has been reported as being a common cause of acute gastroenteritis both in children and adults worldwide. Of the many variants, NoV GII.4 is the most predominant genotype. One of the mechanisms that drives the evolution and emergence of new variants of NoV is homologous recombination. This study describes the genetic recombination involved in cases of NoV GII detected in pediatric patients with acute gastroenteritis in Chiang Mai, Thailand during 2005 to 2015. From a total of 1938 stool samples, 3 (0.15%) were positive for NoV GI and 298 (15.38%) were identified as NoV GII. The genotypes detected in this study were GI.6, GI.14, GII.1, GII.2, GII.3, GII.4, GII.6, GII.7, GII.12, GII.13, GII.14, GII.15, GII.16, GII.17, GII.20, and GII.21. The NoV recombinant strains were verified by analysis of the partial sequence of ORF1 (RdRp)/ORF2 (capsid) junction. Phylogenetic analyses of partial ORF1 and ORF2 regions resulted in the identification of 21 (6.98%) NoV recombinant strains. Among these, 9 recombination patterns were detected in this study; GII.Pe/GII.4, GII.Pg/GII.1, GII.Pg/GII.12, GII.P7/GII.6, GII.P7/GII.14, GII.P12/GII.4, GII.P16/GII.2, GII.P16/GII.13, and GII.P21/GII.3. The findings demonstrated the wide variety of recombinant strains of NoV GII strains detected in pediatric patients admitted to the hospitals with acute gastroenteritis in Chiang Mai, Thailand during the past decade.

Prevalence of human cosavirus and saffold virus with an emergence of saffold virus genotype 6 in patients hospitalized with acute gastroenteritis in Chiang Mai, Thailand, 2014-2016.

Human cosavirus and saffold virus are both newly discovered members of the Picornaviridae family. It has been suggested that these viruses may be the causative agents of acute gastroenteritis. In this study, 1093 stool samples collected from patients with acute gastroenteritis between January 2014 and December 2016, were screened for cosavirus and saffold virus using reverse transcription-polymerase chain reaction. The viral genotypes were then established via nucleotide sequencing. Here, cosavirus was detected in 16 of 1093 stool samples (1.5%) and saffold virus was detected in 18 of 1093 stool samples (1.6%). The saffold virus genotypes 1 (16.7%), 2 (50%) and 6 (33.3%), and the cosavirus genetic groups A (87.5%), C (6.25%) and D (6.25%), were all identified across the three-year study period. Interestingly, saffold virus genotype 6 has now been detected for the first time in Thailand. The present study provides the prevalence of cosavirus and saffold virus with the emergence of saffold virus genotype 6 in Thailand.

Detection and molecular characterization of porcine kobuvirus in piglets in 2009-2013 in northern Thailand.

A total of 636 fecal samples collected from piglets with and without diarrhea during 2009 to 2013 were tested for porcine kobuvirus by RT-PCR. From a total of 528 fecal samples collected from piglets with diarrhea and 108 from healthy controls, 505 (95.6%) and 104 (96.3%) were positive for porcine kobuvirus, respectively. The detection rates of porcine kobuvirus were remarkable equally high in both diarrheic and healthy piglets. Phylogenetic analysis revealed that porcine kobuvirus strains detected in both symptomatic and asymptomatic piglets were genetically closely related to each other and also to other porcine kobuviruses reported worldwide. It was interesting to point out that one of the porcine kobuvirus strains isolated from piglet in our study was similar to a porcine-like bovine kobuvirus reference strain isolated previously in South Korea. This finding provided the evidence to support the interspecies transmission of kobuviruses between cattle and swine.