Genomic Expedition: Deciphering Human Adenovirus Strains from the 2023 Outbreak in West Bengal, India: Insights into Viral Evolution and Molecular Epidemiology.

Understanding the genetic dynamics of circulating Human Adenovirus (HAdV) types is pivotal for effectively managing outbreaks and devising targeted interventions. During the West Bengal outbreak of 2022-2023, an investigation into the genetic characteristics and outbreak potential of circulating HAdV types was conducted. Twenty-four randomly selected samples underwent whole-genome sequencing. Analysis revealed a prevalent recombinant strain, merging type 3 and type 7 of human mastadenovirus B1 (HAd-B1) species, indicating the emergence of recent strains of species B in India. Furthermore, distinctions in VA-RNAs and the E3 region suggested that current circulating strains of human mastadenovirus B1 (HAd-B1) possess the capacity to evade host immunity, endure longer within hosts, and cause severe respiratory infections. This study underscores the significance of evaluating the complete genome sequence of HAdV isolates to glean insights into their outbreak potential and the severity of associated illnesses.

Comprehensive full genome analysis of norovirus strains from eastern India, 2017-2021.

BACKGROUND: Worldwide, noroviruses are the leading cause of acute gastroenteritis (AGE) in people of all age groups. In India, norovirus rates between 1.4 to 44.4% have been reported. Only a very few complete norovirus genome sequences from India have been reported. OBJECTIVE: To perform full genome sequencing of noroviruses circulating in India during 2017-2021, identify circulating genotypes, assess evolution including detection of recombination events. METHODOLOGY: Forty-five archived norovirus-positive samples collected between October 2017 to July 2021 from patients with AGE from two hospitals in Kolkata, India were processed for full genome sequencing. Phylogenetic analysis, recombination breakpoint analysis and comprehensive mutation analysis were also performed. RESULTS: Full genome analysis of norovirus sequences revealed that strains belonging to genogroup (G)I were genotyped as GI.3[P13]. Among the different norovirus capsid-polymerase combinations, GII.3[P16], GII.4 Sydney[P16], GII.4 Sydney[P31], GII.13[P16], GII.16[P16] and GII.17 were identified. Phylogenetic analysis confirmed phylogenetic relatedness with previously reported norovirus strains and all viruses were analyzed by Simplot. GII[P16] viruses with multiple residue mutations within the non-structural region were detected among circulating GII.4 and GII.3 strains. Comprehensive mutation analysis and selection pressure analysis of GII[P16] viruses showed positive as well as negative selection sites. A GII.17 strain (NICED-BCH-11889) had an untypeable polymerase type, closely related to GII[P38]. CONCLUSION: This study highlights the circulation of diverse norovirus strains in eastern India. These findings are important for understanding norovirus epidemiology in India and may have implications for future vaccine development.

Molecular epidemiology of circulating human adenoviruses among acute respiratory infection patients seeking healthcare facilities in West Bengal, India.

Human adenovirus (HAdV) causes acute respiratory infections leading to mortality in children. This study analyzes the circulating respiratory HAdV genotypes in West Bengal, India during 2018-2022 among symptomatic patients. The overall positivity rate was 6.8%, out of which 26.4% were co-infected with other respiratory viruses. Children aged 2 to 5 years were mostly infected. Phylogenetic analysis revealed that the recombinant HAdV-B type 7/3, which has remarkable outbreak potential, predominantly circulated in this region followed by the non-recombinant HAdV-B type 3/3. Moreover, the amino acid sequences encoded by both the hexon and fiber genes of these two circulating strains possessed a few mutations that mostly diverged from the prototype strain, although the divergence was less pronounced in case of the amino acids encoded by the fiber gene of HAdV-B type 3/3. Overall, the results underscore the need for continuous surveillance of respiratory HAdV types to combat future possible epidemics.

Upsurge in hospitalization of pediatric patients with severe acute respiratory infections in Kolkata and surrounding districts caused by recombinant human respiratory adenovirus type B 7/3.

Globally, different genotypes of human adenoviruses are associated with outbreaks of acute respiratory infection (ARI) though such evidence is lacking from India. In the present study, we report a sudden increase in the positivity of respiratory adenovirus among hospitalized children with ARI from Kolkata and the surrounding districts of West Bengal, India, from December 2022 to date. A sharp rise in the positivity rate of respiratory adenovirus was found which ranged from 22.1% in early December 2022 to 52.6% in mid-March 2023. The overall positivity was 40.4% during the period and children in the 2 to <5 years (51.0%) age group were mostly affected. Single infection with adenovirus was found in 72.4% of cases while co-infection with rhinovirus was the maximum (9.4%). Around 97.5% of positive cases required hospitalization. Cough, breathlessness, and wheeze were the most common clinical features among positive patients. Phylogenetic analysis of the hexon and fiber gene of all the sequenced strains revealed HAdV-B 7/3 recombination with more than 99% homology within themselves. This report of a respiratory adenovirus outbreak in West Bengal, India causing severe illness in the pediatric population underscores the need for regular monitoring of the circulating strains.

Epidemiology of major entero-pathogenic viruses and genetic characterization of Group A rotaviruses among children (≤5 years) with acute gastroenteritis in eastern India, 2018-2020.

AIMS: This study was carried out from January 2018 to March 2020 in Kolkata, eastern India to determine the prevalence rates and epidemiological patterns associated with the major viral agents of gastroenteritis among children ≤5 years of age. Molecular characterization of GARV, the predominant agent of viral gastroenteritis, was done to understand their genotype diversity. METHODS AND RESULTS: 1284 of 3157 stool samples (~40%) from children (≤5 years) with acute gastroenteritis tested positive for one or more enteric viruses with positivity rates 25.11%, 8.74%, 6.62% and 6.11% for GARV, HAdV-F, AstV and NoV respectively. Co-infection was observed in 5.31% of cases. Associated clinical/meteorological variables like age, sex, symptoms, temperature and precipitation were assessed to find any correlation between these and enteric virus infection rates. >70% of viral gastroenteritis cases were observed in 6-24 months' age group. GARV and AstV infection occurred mostly during cooler months while HAdV-F infection mostly occurred during warmer periods. No definite seasonality was observed for NoV infections. Clinical severity associated with GARV infection was higher compared to other enteric viruses. Genotyping of rotavirus positive samples revealed G3P[8] was the predominantly circulating GARV genotype throughout the study period. CONCLUSIONS: GARV remained the predominant viral agent of acute gastroenteritis among children though its prevalence rates in this region declined significantly compared to the previous years (2010-2016). The prevalence of other enteric viruses was below 10%. SIGNIFICANCE AND IMPACT OF STUDY: This study provides valuable insights regarding the current burden of viral gastroenteritis in Eastern India. The 2-year study in children will provide the baseline data for future surveillance studies in evaluating the impact of the introduced GARV vaccine on the overall prevalence of viral gastroenteritis.

Emergence of a novel SARS-CoV-2 Pango lineage B.1.1.526 in West Bengal, India.

BACKGROUND: Since its inception in late 2019, SARS-CoV-2 has been evolving continuously by procuring mutations, leading to emergence of numerous variants, causing second wave of pandemic in many countries including India in 2021. To control this pandemic continuous mutational surveillance and genomic epidemiology of circulating strains is very important to unveil the emergence of the novel variants and also monitor the evolution of existing variants. METHODS: SARS-CoV-2 sequences were retrieved from GISAID database. Sequence alignment was performed with MAFT version 7. Phylogenetic tree was constructed by using MEGA (version X) and UShER. RESULTS: In this study, we reported the emergence of a novel variant of SARS-CoV-2, named B.1.1.526, in India. This novel variant encompasses 129 SARS-CoV-2 strains which are characterized by the presence of 11 coexisting mutations including D614G, P681H, and V1230L in S glycoprotein. Out of these 129 sequences, 27 sequences also harbored E484K mutation in S glycoprotein. Phylogenetic analysis revealed strains of this novel variant emerged from the GR clade and formed a new cluster. Geographical distribution showed, out of 129 sequences, 126 were found in seven different states of India. Rest 3 sequences were observed in USA. Temporal analysis revealed this novel variant was first collected from Kolkata district of West Bengal, India. CONCLUSIONS: The D614G, P618H and E484K mutations have previously been reported to favor increased transmissibility, enhanced infectivity, and immune invasion, respectively. The transmembrane domain (TM) of S2 subunit anchors S glycoprotein to the virus envelope. The V1230L mutation, present within the TM domain of S glycoprotein, might strengthen the interaction of S glycoprotein with the viral envelope and increase S glycoprotein deposition to the virion, resulting in more infectious virion. Therefore, the new variant having D614G, P618H, V1230L, and E484K may have higher infectivity, transmissibility, and immune invasion characteristics, and thus need to be monitored closely.