Determining effectiveness of rotavirus vaccine by immunochromatography and reverse transcriptase polymerase chain reaction: A comparison

The Emergence and Widespread Circulation of Enteric Viruses Throughout the COVID-19 Pandemic: A Wastewater-Based Evidence

Growing evidence shed light on the importance of wastewater-based epidemiology (WBE) during the pandemic, when the patients rarely visited the clinics despite the fact that the infections were still prevalent in the community as before. The abundance of infections in the community poses a constant threat of the emergence of new epidemic strains. Herein, we investigated enteric viruses in raw sewage water (SW) from Japan's Tohoku region and compared them to those from the Kansai region to better understand the circulating strains and their distribution across communities during the COVID-19 pandemic. Raw SW was collected between 2019 and 2022, concentrated by polyethylene-glycol-precipitation method, and investigated for major AGE viruses by RT-PCR. Sequence-based analyses were used to assess genotypes and evolutionary relationships. The most commonly detected enteric virus was rotavirus A (RVA) at 63.8%, followed by astrovirus (AstV) at 61.1%, norovirus (NoV) GII and adenovirus (AdV) at 33.3%, sapovirus (SV) at 25.0%, enterovirus (EV) at 19.4%, and NoV GI at 13.9%. The highest prevalence (46.0%) was found in the spring. Importantly, enteric viruses did not decline during the pandemic. Rather, several strains like NoV GII.2, DS-1-like human G3 (equine) RVA, MLB1 AstV, and different F41 HAdV emerged throughout the pandemic and spread widely over the Tohoku and Kansai regions. Tohoku's detection rate remained lower than that of the Kansai area (36 vs 58%). This study provides evidence for the emergence and spread of enteric viruses during the pandemic.

Sapovirus infections in Japan before and after the emergence of the COVID-19 pandemic: An alarming update

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.

Genotype Diversity of Enteric Viruses in Wastewater Amid the COVID-19 Pandemic

Viruses remain the leading cause of acute gastroenteritis (AGE) worldwide. Recently, we reported the abundance of AGE viruses in raw sewage water (SW) during the COVID-19 pandemic, when viral AGE patients decreased dramatically in clinics. Since clinical samples were not reflecting the actual state, it remained important to determine the circulating strains in the SW for preparedness against impending outbreaks. Raw SW was collected from a sewage treatment plant in Japan from August 2018 to March 2022, concentrated by polyethylene-glycol-precipitation method, and investigated for major gastroenteritis viruses by RT-PCR. Genotypes and evolutionary relationships were evaluated through sequence-based analyses. Major AGE viruses like rotavirus A (RVA), norovirus (NoV) GI and GII, and astrovirus (AstV) increased sharply (10-20%) in SW during the COVID-19 pandemic, though some AGE viruses like sapovirus (SV), adenovirus (AdV), and enterovirus (EV) decreased slightly (3-10%). The prevalence remained top in the winter. Importantly, several strains, including G1 and G3 of RVA, GI.1 and GII.2 of NoV, GI.1 of SV, MLB1 of AstV, and F41 of AdV, either emerged or increased amid the pandemic, suggesting that the normal phenomenon of genotype changing remained active over this time. This study crucially presents the molecular characteristics of circulating AGE viruses, explaining the importance of SW investigation during the pandemic when a clinical investigation may not produce the complete scenario.

Diagnostic accuracy of rotavirus antigen tests in children: A systematic review and meta-analysis

OBJECTIVES

Rotavirus infection is the leading cause of acute gastroenteritis (AGE) in children. Children with rotavirus infection may have symptoms such as diarrhoea or vomiting. Diarrheal diseases caused by rotavirus and other enteric pathogens cannot be differentiated on the basis of clinical symptoms. Therefore, diagnostic testing is essential to confirm a diagnosis of rotavirus infection. The aim of the meta-analysis is to evaluate the diagnostic accuracy of immunochromatographic rotavirus antigen tests in children.

METHODS

We searched the PubMed, Embase, Cochrane Library and Google Scholar databases for studies evaluating the diagnostic accuracy of antigen tests for rotavirus in children. We included studies that provided sufficient data to construct a 2 × 2 table on a per patient basis. The overall sensitivity and specificity of the antigen tests were determined using a bivariate random-effects model.

RESULTS

In total, 12 studies with 4407 participants were included in the study. The meta-analysis yielded a pooled sensitivity of 89.2% (95% confidence interval [CI]: 77.4%-95.3%) and pooled specificity of 93.2% (95% CI: 83.8%-97.3%). A subgroup analysis of such tests in children aged ≤5 years yielded a pooled sensitivity of 87.1% and pooled specificity of 91.8%. Another subgroup analysis of high-quality studies involving 820 participants yielded a pooled sensitivity of 92.3% and pooled specificity of 95.2%.

CONCLUSIONS

Rotavirus antigen tests have high sensitivity for the diagnosis of rotavirus infection in children with AGE. In addition, such tests may be effective for the identification and clinical management of rotavirus infection in children and the prevention of disease progression.

Detection of Rotavirus Strains in Freshwater Clams in Japan

Bivalve molluscan shellfish like clams and oysters, etc., are capable to bioaccumulate surrounding contaminants from waters into their digestive systems and posing serious threats of food poisoning. Detection of rotaviruses (RVs) in shellfish is of particular importance because RVs are prone to genome reassortment resulting in the emergence of new RV variants that may compromise vaccine safety. Herein, we have detected the wild-type RVs and Rotarix/RotaTeq vaccine strains in freshwater clams collected on the riverside, Kawasaki city, from July 2019 to January 2020 and correlated the detected genotypes with that of gastroenteritis cases of nearby clinics to understand the transmission of RVs in the environment. The wild-type RVs were detected in 62 (64.6%) out of 96 freshwater clams in every study month: July, September, November, and January that are considered as off-season for RV infections. The most frequent genotypes were G2 (42.9%), G8 (28.6%), G3 (14.3%), G1 (7.1%), and G10 (7.1%), which remained comparable with genotypic distribution found in the clinical samples over the last few years indicating that these RVs may accumulate in clams since a long time. However, G10 genotype was detected in clam but not in clinical samples suggesting the presence of asymptomatic infection or RVs could be carried out from a long distance. Importantly, vaccine strains, RotaTeq (1%) but not Rotarix (0%), were also detected in a clam. Attention must be paid to monitoring the potential transmission of wild-type and vaccine RV strains in the environment to prevent the emergence of new variants generated from genome reassortment with vaccine strains.

Distribution of rotavirus genotypes in Japan from 2015 to 2018: Diversity in genotypes before and after introduction of rotavirus vaccines

BACKGROUND

Diversity in group A rotavirus (RVA) strains after introduction of RV-vaccines remains an emerging concern worldwide. In this study, we investigated the prevalence and distribution of RVA genotypes in Japanese children with acute gastroenteritis (AGE) from 2015 to 2018. In addition, a comparison of the genotypes in pre-vaccination (2006-2012) and post-vaccination (2012-2018) periods was conducted to understand the impact of these vaccines on genotype distribution.

METHODS

Fecal samples were collected regularly from outpatient clinics in six localities: Hokkaido, Tokyo, Shizuoka, Osaka, Kyoto, and Saga. RVA were screened and genotyped by RT-PCR and sequence-based genotyping.

RESULTS

During the period 2015-2018, RVA was detected in 307 (19.7%) samples out of 1557 specimens: 29.9% (95% CI: 25.8% to 34.3%), 17.9% (95% CI: 14.7% to 21.5%), and 13% (95% CI: 10.3% to 16.0%) were detected RVA-positive in 2015-2016, 2016-2017 and 2017-2018, respectively. The average detection of RVA in pre-vaccination (2006-2012) and post-vaccination (2012-2018) era remained almost similar (18%-20%). The G2P[4]I2 (52.1%, 95% CI: 43.5%-60.6%) remained the most common genotype in 2015-2016, whereas G8P[8]I2 (55.9%, 95% CI: 45.2%-66.2%) dominated in 2016-2017. In 2017-2018, G9P[8]I2 (42.0%, 95% CI: 30.5%-53.9%) prevailed, followed by G9P[8]I1 (23.0%, 95% CI: 14.0%-34.2%). The detection rate of some common genotypes of pre-vaccination era like G1P[8] and G3P[8] has been reduced after introduction of RV-vaccine, whereas genotypes that were sporadic before the introduction of vaccines like G2P[4], G2P[8], G9P[8] and G8P[8] were emerged/reemerged in post-vaccination period.

CONCLUSIONS

Our study presented the diversity in circulating RVA genotypes in Japan before and after introduction of RV-vaccines. Sudden emergence of DS-1-like (I2) unusual strains in post-vaccination era remains alarming. Continuous monitoring of RVA genotypes is therefore indispensable to refine future vaccine strategy.