Detection and characterization of Aichi virus 1 in pediatric patients with diarrhea in Thailand

A Comparative Study of Acute Gastroenteritis Symptoms in Single- versus Multiple-Virus Infections

Many different enteric viruses can cause acute gastroenteritis in humans worldwide. While a single virus can indeed cause disease, multiple-virus infections are commonly reported. However, data regarding a comparison between single- and multiple-virus infections upon clinical manifestations of acute gastroenteritis are relatively limited. In this study, a total of 2383 fecal specimens were collected from children with acute gastroenteritis during June 2014-July 2017 in a pediatric clinic in Japan and tested for 11 viruses by multiplex RT-PCR. At least 1 virus was found in 1706 (71.6%) specimens and norovirus GII was the most frequent agent, followed by rotavirus A and other viruses. Multiple-virus infections were identified in 565 cases (33.1%). While major clinical symptoms were found to be significantly different in some single- vs. multiple-virus infections, the disease severity was statistically non-significant. Our study highlights the burden of multiple-virus infections for acute gastroenteritis and the clinical features of patients with multiple-virus infections.

Enteropathogen Changes After Rotavirus Vaccine Scale-up

OBJECTIVES

To inform next steps in pediatric diarrhea burden reduction by understanding the shifting enteropathogen landscape after rotavirus vaccine implementation.

METHODS

We conducted a case-control study of 1788 medically attended children younger than 5 years, with and without gastroenteritis, after universal rotavirus vaccine implementation in Peru. We tested case and control stools for 5 viruses, 19 bacteria, and parasites; calculated coinfection-adjusted attributable fractions (AFs) to determine pathogen-specific burdens; and evaluated pathogen-specific gastroenteritis severity using Clark and Vesikari scales.

RESULTS

Six pathogens were independently positively associated with gastroenteritis: norovirus genogroup II (GII) (AF 29.1, 95% confidence interval [CI]: 28.0-32.3), rotavirus (AF 8.9, 95% CI: 6.8-9.7), sapovirus (AF 6.3, 95% CI: 4.3-7.4), astrovirus (AF 2.8, 95% CI: 0.0-4.0); enterotoxigenic Escherichia coli heat stable and/or heat labile and heat stable (AF 2.4, 95% CI: 0.6-3.1), and Shigella spp. (AF 2.0, 95% CI: 0.4-2.2). Among typeable rotavirus cases, we most frequently identified partially heterotypic strain G12P[8] (54 of 81, 67%). Mean severity was significantly higher for norovirus GII-positive cases relative to norovirus GII-negative cases (Vesikari [12.7 vs 11.8; P < .001] and Clark [11.7 vs 11.4; P = .016]), and cases in the 6- to 12-month age range relative to cases in other age groups (Vesikari [12.7 vs 12.0; P = .0002] and Clark [12.0 vs 11.4; P = .0016]).

CONCLUSIONS

Norovirus is well recognized as the leading cause of pediatric gastroenteritis in settings with universal rotavirus vaccination. However, sapovirus is often overlooked. Both norovirus and sapovirus contribute significantly to the severe pediatric disease burden in this setting. Decision-makers should consider multivalent vaccine acquisition strategies to target multiple caliciviruses in similar countries after successful rotavirus vaccine implementation.

Whole genome analysis of Aichivirus A, isolated from a child, suffering from gastroenteritis, in Pakistan

Viruses are the primary cause of acute gastroenteritis in children all over the world. Understanding the emergence and genetic variation of these viruses may help to prevent infections. Aichivirus (AiV) is a member of the Kobuvirus genus, which currently contains six officially recognized species: Aichivirus A-F. The species AiV A contains six types including Aichivirus 1 (AiV 1) and eventually, three genotypes have been identified in the human AiV 1 (named A to C). The present study describes the identification and sequencing of the polyprotein gene of a human AiV 1 strain PAK419 via NGS in Pakistani children with acute gastroenteritis. Our study strain PAK419 was classified as AiV 1 genotype A, most commonly found in Japan and Europe, and closely related to non-Japanese and European strains on the phylogenetic tree. PAK419 showed 95-98 % nucleotide sequence identity with strains isolated from Ethiopia (ETH/2016/P4), Australia (FSS693) and China (Chshc7). On phylogenetic observation PAK419 formed a distinct cluster in the AiV 1 genotype A with the above mentioned and other human AiV strains detected around the world (Germany, Brazil, Japan, Thailand, Korea and Vietnam). The data clearly showed that Pakistani AiV strains and human strains identified from all over the world are distinct from Aichivirus strains found in bovine, swine, canine, feline, caprine, ferret, bat, and environmental samples. The distinguishing characteristics of the AiV genome showed a lower probability of inter-genotypic recombination events, which may support the lack of AiV serotypes. PAK419 also had a high content of C nucleotide (37.4 %), as found in previous studies, which could also restrict the possible genetic variation of AiV. This study demonstrate the power of NGS in uncovering unknown gastroenteric etiological agents circulating in the population.

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.

High Frequency of Aichivirus in Children With Acute Gastroenteritis in Iran

BACKGROUND

Initially, detection and isolation of Aichivirus as a new member of Picornaviridae family was documented in Japan. Aichivirus species belongs to genus Kobuvirus, including 3 genotypes A, B and C. In previous studies, it has been suggested that Aichivirus infect humans by fecal-oral route. To establish an investigation for the occurrence of Aichivirus among pediatric patients involved to acute gastroenteritis, we developed a reverse transcription quantitative polymerase chain reaction assay for detection and quantification of Aichivirus in stool specimens.

MATERIAL AND METHODS

In this study, a total of 160 stool samples from September 2018 to May 2019 were collected from pediatric patients presenting with acute gastroenteritis in Karaj hospital, Iran. After viral RNA extraction, the reverse transcription quantitative polymerase chain reaction was performed to amplify the 3CD junction region of Aichivirus genome and viral load was assessed. Aichivirus genomic RNA was detected in 13/160 (8.1%) of stool samples. The highest Aichivirus detection rate was in December (30.7%). The maximum viral load was determined to be 3.9 × 10 copies/g in one sample obtained from a 1-month-old patient. The co-infection of Aichivirus with salivirus and saffold virus was also assessed by reverse transcription quantitative polymerase chain reaction, among which frequent mixed infections by 2 or more viruses were identified.

CONCLUSIONS

This is the first documentation of Aichivirus detection in stool samples that demonstrates Aichivirus has been circulating among Iranian pediatric patients.

A Comprehensive Review on Human Aichi Virus

Although norovirus, rotavirus, adenovirus and Astrovirus are considered the most important viral agents transmitted by food and water, in recent years other viruses, such as Aichi virus (AiV), have emerged as responsible for gastroenteritis outbreaks associated with different foods. AiV belongs to the genus Kobuvirus of the family Picornaviridae. It is a virus with icosahedral morphology that presents a single stranded RNA genome with positive sense (8280 nucleotides) and a poly (A) chain. AiV was first detected from clinical samples and in recent years has been involved in acute gastroenteritis outbreaks from different world regions. Furthermore, several studies conducted in Japan, Germany, France, Tunisia and Spain showed a high prevalence of AiV antibodies in adults (between 80% and 99%), which is indicative of a large exposure to this virus. The aim of this review is to bring together all the discovered information about the emerging pathogen human Aichi virus (AiV), discussing the possibles routes of transmission, new detection techniques and future research. Although AiV is responsible for a low percentage of gastroenteritis outbreaks, the high seroprevalence shown by human populations indicates an evident role as an enteric agent. The low percentage of AiV detection could be explained by the fact that the pathogen is more associated to subclinical infections. Further studies will be needed to clarify the real impact of AiV in human health and its importance as a causative gastroenteritis agent worldwide.

Environmental monitoring of Aichi virus and human bocavirus in samples from wastewater treatment plant, drain, and River Nile in Egypt

Wastewater plays a major role in water pollution causing transmission of several viral pathogens, including Aichi virus (AiV) and human bocavirus (HBoV), associated with gastrointestinal illness in humans. In this study, we investigated the presence of AiV and HBoV in aquatic, sludge, sediment matrices collected from Abu-Rawash wastewater treatment plant (WWTP), El-Rahawy drain, Rosetta branch of the River Nile in Egypt by conventional polymerase chain reaction (PCR). AiV RNA was detected in 16.6% (2/12), 8.3% (1/12), 8.3% (1/12), 22% (16/72), 12.5% (3/24), 4% (1/24), and 0/24 (0%) of untreated raw sewage, treated sewage, sewage sludge, drainage water, drain sediment, river water, and river sediment, respectively. On the other hand, HBoV DNA was detected in 41.6% (5/12), 25% (3/12), 16.6% (2/12), 48.6% (35/72), 29% (7/24), 3/24 (12.5%), 4% (1/24) of untreated raw sewage, treated raw sewage, sewage sludge, drainage water, drain sediment, river water, and river sediment, respectively. This study provides data on the presence of these viruses in various types of water samples that are valuable to environmental risk assessment. In addition, the current study demonstrates the importance of environmental monitoring as an additional tool to investigate the epidemiology of AiV and HBoV circulating in a given community.

Aichi Virus Induces Antiviral Host Defense in Primary Murine Intestinal Epithelial Cells

The picornavirus Aichi virus (AiV) is a non-enveloped RNA virus that causes acute gastroenteritis symptoms, such as diarrhea, abdominal pain, nausea, vomiting, and fever. Antiviral host defense involves the fast response of type I interferon (IFN) and the secretion of inflammatory cytokines against pathogens. However, the intestinal inflammatory and antiviral response to AiV infection is poorly understood. This study evaluated the antiviral activity of intestinal epithelial cells (IECs), which form a single-cell layer separating the bowel wall from pathogens. Isolated primary mouse IECs were subjected to AiV infection and virion production, inducing the mRNA expression of type I/type III IFNs and inflammatory cytokines. The mechanism involved induced the expression of phospho-IFN regulatory factor 3 and mitochondrial antiviral-signaling protein of type I IFN signaling. These findings were also observed in AiV-infected human colon carcinoma cells. In summary, a viral productive and pathogenic infection of AiV in primary murine IECs is validated.

Molecular epidemiology and genetic diversity of human parechoviruses in children hospitalized with acute diarrhea in Thailand during 2011-2016

Little is known about human parechovirus (HPeV) infection in Thailand. The genotype distribution of HPeV strains in children admitted to hospitals with acute gastroenteritis was investigated using polymerase chain reaction (PCR) and nucleotide sequencing of the VP1 region as the detection and genotype identification methods, respectively. Of a total of 2,002 stool samples, 49 (2.4%) were positive for HPeV. Of these, HPeV-1 was the most predominant genotype (40.8%), followed by HPeV-3 (16.3%) and HPeV-14 (16.3%), while HPeV-5, -6, -2, -4, and -8 strains were less frequently detected, at 10.2%, 8.2%, 2%, 2%, and 2%, respectively. HPeV infections were detected throughout the year with the biannual peaks of infection in the rainy (Jun-Jul-Aug) and winter (Nov-Dec-Jan) months in Thailand. Based on VP1 amino acid sequence alignment, the arginyl-glycyl-aspartic acid (RGD) motif was found in HPeV-1, -2, -4, and -6 strains. Additionally, an amino acid insertion at the N-terminus of VP1 was observed in HPeV-4 and HPeV-5 strains. Phylogenetic analysis revealed that small clades of HPeV-1 and HPeV-3 strains emerged in 2016 and 2015, respectively, and dominated in the year of their emergence. The HPeV strains detected in Thailand in this study were most closely related to reference strains from Asia and Europe. The evolutionary rate of HPeV strains was 2.87 × 10^-4 (95% highest posterior density (HPD) 0.10-6.14 × 10^-4) substitutions/site/year. These findings provide information about the genetic diversity and evolutionary dynamics of HPeV genotypes circulating in pediatric patients with acute gastroenteritis in Thailand.

The First Molecular Detection of Aichi Virus 1 in Raw Sewage and Mussels Collected in South Africa

Aichi virus 1 (AiV-1) has a worldwide distribution and is associated with gastroenteritis in humans. In this study, raw sewage and mussel samples were analyzed for the presence of AiV-1 using reverse transcription-PCR (RT-PCR). Amplification and sequencing of the 3CD and VP1 genomic regions followed by phylogenetic analysis using selected genome sequences revealed the presence of AiV-1, genotype B. The results highlight the importance of further screening to evaluate the prevalence and epidemiology of this clinically important virus in South Africa.

Aichivirus in Children with Diarrhea in Northern Italy

OBJECTIVE

Since its discovery, Aichivirus (AiV) A has been detected, with an incidence of 0.9-4.1%, primarily when studying outbreaks of diarrhea in children or young adults. In this paper, we report the first detection of AiV in Piedmont, Italy, in pediatric patients.

METHODS

A total of 159 fecal specimens (from 96 males and 63 females) previously screened for rotaviruses, adenoviruses, noroviruses, human parechoviruses, saliviruses, and sapoviruses were collected from infants and children with acute gastroenteritis.

RESULTS

The most commonly detected virus was norovirus GII (33.80%), fol lowed by rotavirus (21.30%), astrovirus (18.87%), boca virus (13.92%), sapovirus (10.90%), parechovirus (8%), norovirus GI (6.70%), adenovirus (1%), and salivirus (0.52%). Real-time polymerase chain reaction detected AiV A in 1 (0.62%) case subjects. AiV A was detected in monoinfection only in January.

CONCLUSIONS

Our results indicate that AiV may be associated with a limited number of diarrhea cases in pediatric patients.

Molecular detection of human enteric viruses circulating among children with acute gastroenteritis in Valencia, Venezuela, before rotavirus vaccine implementation

Background

The role of rotavirus as main etiologic agent of diarrhea has been well documented worldwide, including in Venezuela. However, information about the prevalence of gastrointestinal viruses such as calicivirus, adenovirus and astrovirus is limited and the contribution of other agents as Aichi virus and klassevirus is largely unknown. To explore the etiological spectrum of diarrhea associated with agents other than rotaviruses, 227 stool samples from children under 5 years old with acute gastroenteritis, collected in Valencia (Venezuela) from 2001 to 2005, and previously tested as rotavirus-negative, were analyzed for caliciviruses, adenoviruses, astroviruses, Aichi viruses, klasseviruses, picobirnaviruses and enteroviruses by specific RT-PCRs.

Results

At least one viral agent was detected in 134 (59%) of the samples analyzed, mainly from children under 24 months of age and most of them belonging to the lowest socioeconomic status. Overall, enterovirus was identified as the most common viral agent (37.9%), followed by calicivirus (23.3%), adenovirus (11.5%), astrovirus (3.5%), klassevirus (1.3%) and Aichi virus (0.4%), while no picobirnavirus was detected. Klasseviruses were found during 2004 and 2005 and Aichi viruses only in 2005, indicating their circulation in Venezuela; meanwhile, the rest of the viruses were detected during the whole study period. Coinfections with two or more viruses were found in 39 (29.1%) of the infected children, most under 24 months of age. Adenovirus was involved as the coinfecting agent in at least 46.9% of the cases, but no differences concerning socio-demographic variables were observed between the coinfected and the single infected children.

Conclusions

The results show that various enteric viruses, including enteroviruses, caliciviruses and adenoviruses, accounted for a significant proportion of infantile diarrhea cases in Venezuela before rotavirus vaccine implementation. In addition, emerging viruses as Aichi virus and klassevirus were found, indicating the need to continue monitoring their spreading into the communities. Efforts are needed to develop more accurate methods to identify the major causes of diarrhea and to provide tools for more effective preventive measures.

Multiple enterovirus genotypes circulating in children hospitalized with acute gastroenteritis in Thailand

Enterovirus (EV) infection is widespread and can lead to a broad range of clinical symptoms, from mild to severe forms of disease. EVs are not always classified as pathogen and the epidemiological surveillance of EV infection in acute gastroenteritis cases in Thailand remains unexplored. This study aims to investigate the frequency, seasonality and molecular characteristics of EV circulating in children hospitalized with acute gastroenteritis in Chiang Mai, Thailand from 2010 to 2014. A total of 1266 fecal samples were included in this study. RT-PCR amplification of the 5'UTR was used for EV screening and phylogenetic analysis of the VP1 sequence was performed for EV genotyping. EV was detected in 5.8% of infections (73 out of 1266). Based on VP1 sequence analysis, over half (50.8%) of the identified EV cases were caused by species C, and the next two most frequent were species B and A (35.4% and 13.8%, respectively). This study identified 28 different EV genotypes, EV-C96 and coxsackievirus A24 were the most frequent genotype detected (12.3% each). EV was detected throughout the year with an increase of detection rate in December-January and May-June. In conclusion, this study reported the prevalence of EV infection with a wide variety of EV genotypes in children with acute diarrhea.

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.

Analysis of Aichi virus and Saffold virus association with pediatric acute gastroenteritis

BACKGROUND

Aichi virus (AiV) and Saffold virus (SAFV) have been reported in children with acute gastroenteritis and respiratory disease worldwide; however, their causative role in acute gastroenteritis remains ambiguous.

OBJECTIVES

To assess the clinical association of AiV and SAFV with acute gastroenteritis in the pediatric population.

STUDY DESIGN

A case-control study involving 461 paired stool samples from pediatric cases with diarrhea and healthy controls was conducted in China. Quantitative real-time reverse transcription polymerase chain reaction (RT-PCR) was used to screen AiV and SAFV.

RESULTS

In the 461 paired samples, AiV and SAFV were more prevalent among asymptomatic children than children with acute gastroenteritis (0.87% vs. 0.43% and 2.8% vs. 1.5%, respectively), with no significant differences between groups (p=0.142 and p=0.478, respectively). Cox regression model analysis revealed no correlation between AiV (odds ratio, OR=2.24; 95% confidence interval, CI, 0.76-6.54) or SAFV infection (OR=1.36; 95% CI, 0.86-2.15) and diarrhea. High viral loads were found in both AiV- and SAFV-positive groups, with no significant difference in viral load between the groups (p=0.507 and p=0.677, respectively). No other known enteric pathogens were found in the AiV-positive samples but common in SAFV-positive cases. Phylogenetic analysis revealed that all 6 AiV subjects clustered with genotype B. All 7 SAFV-positive cases and 8 of 13 SAFV-positive controls were genotyped successfully; the genotypes identified included SAFV-1, SAFV-2 SAFV-3, and SAFV-6.

CONCLUSION

Our study revealed no association of these viruses in acute gastroenteritis in children. These viruses may have the ability to replicate in humans; however, the infections are usually asymptomatic.