Human enteric adenovirus (HAdV) belonging to species F is one of the most common pathogens responsible for infantile gastroenteritis worldwide. This study was initiated to estimate prevalence and types of HAdV among children below 5 years of age seeking health care facility for treatment of diarrhea in Kolkata, Eastern India. A total of 1,562 stool specimens were tested during 2013-2014 and among them, 185 (11.8%) were positive for enteric HAdV. Maximum number of positive cases were observed among children between 6 and 12 months of age (13.9%). HAdV infection occurred at a low frequency throughout the year, with an increased incidence in the month of March-July in both the years. Among HAdV positive samples (n = 185), 44.8% showed coinfection with rotavirus. Genotyping based on hypervariable region of hexon and partial shaft region of fiber genes, revealed prevalence of HAdV-40 over HAdV-41 genotype during this study period. Nucleotide sequence analysis of HAdV-40 strains exhibited more than 99% similarity among themselves and 98.5% with the prototype strain Dugan. Sequence analysis of six hypervariable regions (HVRs) of hexon genes from all the HAdV-41 strains revealed co-circulation of both genome type cluster 1(GTC1) and GTC2. The presence of both types of GTCs reflects accumulation of amino acid (aa) mutations in HVR of hexon gene. A recombination event was evident in a subset of HAdV-41 strains where hexon gene belonged to GTC1 whereas, fiber gene clustered with GTC2. Sequence analysis of fiber gene shaft region of HAdV-41 strains revealed 15 aa deletion from the 15th repeat motif. J. Med. Virol. 89:606-614, 2017. © 2016 Wiley Periodicals, Inc.

The study highlights the high prevalence of RV in children with gastroenteritis in Kolkata. The circulating genotypes have changed over the time with predominance of G9 and G2 strains during 2011-2013. The current G2, G9 and G1 Kolkata strains shared low amino acid homologies with current vaccine strains. Although there is substantial evidence for cross protection of vaccines against a variety of strains, still the strain variation should be monitored post vaccine introduction to determine if it has any impact on vaccine effectiveness.

During the peak outbreak (July-September 2009), a total 1886 patients were screened in eastern India, of which 139 (7.37%) and 52 (2.76%) were positive for pH1N1 and seasonal H1N1, respectively. Full-length HA1, NA, NS1 and PB1-F2 genes of representative strains were sequenced. Phylogenetic analysis of deduced amino acid sequences of pH1N1 strains revealed HA1 and NS1 to be of North American swine lineage, and the NA gene of Eurasian swine lineage. Consistent with previous reports, the PB1-F2 gene of pH1N1 strains was unique due to a mutation resulting in a truncated protein of 11 aa. The HA, NA and NS1 genes of H1N1/2009 strains clustered with H1N1 strains of 2000-2009, whereas a subset of strains contained a pH1N1-like truncated PB1-F2. The truncated PB1-F2 may confer the advantage of lower pathogenicity but higher replication and infectivity to the human H1N1 strains. This is the first report of seasonal H1N1/2009 strains with a pH1N1/2009-like gene segment.

Noroviruses are significant etiological agents of acute gastroenteritis (AGE) across all age groups, especially in children under 5 years of age. Although the prevalence of norovirus infection is known to have increased in various countries, in India there are few reports pertaining to the norovirus disease burden. We investigated the epidemiology and molecular characteristics of noroviruses in children seeking health care at two hospitals in Kolkata, Eastern India. Faecal specimens were collected between January 2018 and December 2019 from 2812 children under 5 years of age with acute gastroenteritis. Noroviruses were detected in 6.04% (170/2812) of the samples, and 12.9% (22/170) of these were cases of coinfection with rotavirus. Among children (≤5 years), a higher infection rate (8.2%, n = 94/1152) was observed in the 6 to 12 month age group. GII.4 Sydney 2012 was the dominant norovirus capsid genotype (n = 75/90, 83.3%), followed by GII.3 (n = 10/90, 11.1%). Other capsid types GII.13 (n = 4/90, 4.4%) and GII.17 (n = 1/90; 1.1%) were also detected at low frequency. Phylogenetic analysis showed that the GII.P16 polymerase of strains in this region clustered with those of the phylogenetically distinct monophyletic clade of GII.P16 strains, whose members have been circulating worldwide since 2014. Inter-genotypic norovirus recombinants such as GII.P16-GII.3 (n = 10) and GII.P16-GII.13 (n = 4) were also observed among the circulating strains. In comparison to previous studies from eastern India, the present study shows a higher detection rate of norovirus infection in the paediatric population suffering from acute gastroenteritis. Continuous surveillance is required for predicting the emergence of novel genotypes and recombinant strains and for future vaccine development. Supplementary Information The online version contains supplementary material available at 10.1007/s00705-021-05197-6.

In developing countries, viruses causing respiratory disease are a major concern of public health. During January 2010-December 2011, 2,737 patients with acute respiratory infection from the outpatient departments as well as patients admitted to hospitals were screened for different respiratory viruses. Nasal and or throat swabs were collected and transported to the laboratory where initial screening of influenza A and influenza B viruses was performed. The samples were tested further for influenza C virus, parainfluenza viruses 1-4, human rhinovirus, metapneumovirus and respiratory syncytial virus by conventional RT- PCR. The study revealed that the majority of the patients were under 5 years of age; both due to their higher susceptibility to respiratory infections and presentation to hospitals. Out of 2,737 patients enrolled in this study, 59% were found positive for one or more respiratory viruses. Influenza B infection was detected in 12% of patients followed by influenza A (11.7%), respiratory syncytial virus (7.1%), parainfluenza virus-2 (6%), metapneumovirus (3%), parainfluenza virus-3 (1%), parainfluenza virus-4 (0.6%), parainfluenza virus-1 (0.3%), influenza C (0.2%) and human rhinovirus (0.2%). Distinct seasonal infection was observed only for influenza A and influenza B viruses.