Genetic characterisation of influenza A(H1N1)pdm09 viruses circulating in Assam, Northeast India during 2009-2015.

Introduction: Influenza A(H1N1)pdm09 virus, since its identification in April 2009, has continued to cause significant outbreaks of respiratory tract infections including pandemics in humans. In the course of its evolution, the virus has acquired many mutations with an ability to cause increased disease severity. A regular molecular surveillance of the virus is essential to mark the evolutionary changes that may cause a shift to the viral behavior. Materials and Methods: Samples of Throat/Nasal swabs were collected from a total of 3715 influenza-like illness cases and screened by Real-time Reverse Transcription-Polymerase Chain Reaction for influenza viruses. Nucleotide sequence analysis was done to identify changes in antigenicity of the virus strains. Results: The present study describes the molecular characteristics of influenza A(H1N1)pdm09 viruses detected in Assam of Northeast India during 2009-2015. Influenza A viruses were detected in 11.4% (425/3715), of which influenza A(H1N1)pdm09 viruses were detected in 41.4% (176/425). The nucleotide sequencing of influenza A(H1N1)pdm09 viruses revealed a total of 17 and 22 amino acid substitutions in haemagglutinin (HA) and neuraminidase (NA) genes of the virus, respectively, compared to contemporary vaccine strain A/California/07/2009. The important mutations detected in HA genes of A/Assam(H1N1)pdm09 strains included E391K, K180Q and S202T. Mutation 'N248D' which has an ability to develop oseltamivir resistance was also detected in NA gene of A/Assam(H1N1)pdm09 strains. Conclusions: Regular molecular surveillance of influenza A(H1N1)pdm09 is important to monitor the viral behavior in terms of increase virulence, drug resistance pattern and emergence of novel strains.

Outbreak of influenza-like illness investigated during August 2013 near Indo-China border of Arunachal Pradesh, Northeast India.

During August 2013, an outbreak of influenza-like illnesses (ILI) was investigated in Monigong area, near Indo-China border of Arunachal Pradesh, Northeast India. Influenza type A/H3N2 was detected by RT-PCR in 33.3% (8/24) of ILI cases. Sequence analysis of HA and NA genes revealed eight and five amino acid substitutions, respectively in Monigong H3N2 (Mo/H3N2) strains as compared to vaccine strain A/Victoria/361/2011. Four non-synonymous substitutions, three localizing at antigenic sites T144A, A; R158G, B; L173S, D, and one H9Y in close proximity to a potential glycosylation site aa8 in HA1 domain along with the substitution T329N in NA are likely to influence the antigenicity/virulence of Mo/H3N2 viruses. J. Med. Virol. 88:1999-2003, 2016. © 2016 Wiley Periodicals, Inc.

Analyses of clinical, pathological and virological features of human rotavirus strain, YO induced gastroenteritis in infant BALB/c mice.

Experimental studies of human rotavirus infections in mice are limited and there is lack of information on the quantitative assessment of rotaviral replication and its relationship with histological changes. In the present study, consequences of human rotavirus strain, YO induced gastroenteritis in infant BALB/c mice were analyzed for the occurrence of clinical symptoms, histopathology and virological events. The infected animals developed diarrhea and dehydration and showed accumulation of vacuolated enterocytes with lodging of the rotavirus antigens and shortening of villi in the intestine over a period of 5 days. The ileum was identified as the most susceptible and supportive part of small intestine for perpetuation of rotavirus infection in mice. Rotaviral antigen/RNA in stool and RNA in intestine were detected throughout the clinical disease period. At 48-72 h post inoculation, diarrhea was at the peak (90-95%) in the infected animals with increased load of viral RNA and intense pathological lesions suggesting it as the critical time point in the course of infection. The rising titers of antirotavirus neutralizing antibodies ascertained the replication of human rotavirus strain, YO in mice. These data may contribute to the understanding of pathophysiological, immunological and virological characteristics of rotavirus infections in mice.

VP6 capsid protein of chicken rotavirus strain CH2: sequence, phylogeny and in silico antigenic analyses.

The inner capsid protein VP6 of group A rotavirus possesses group and subgroup epitope specificities. Avian rotaviruses have a unique VP6 that is antigenically different from its mammalian counterpart. The lack of information on the VP6 protein of chicken rotavirus strain, CH2, at the genetic and antigenic level was a major motivation for this work. Sequencing of the complete cDNA of the VP6 gene of CH2, revealed a nucleotide (amino acid) identity that varied from 78.3 to 98.5% (86.4-98.2%) when compared with other avian rotaviruses. Regardless of its host origin dissimilarity, CH2 VP6 showed a close sequence homology (97.4-98.2%) with turkey and pigeon rotaviruses. Homology-based modeling of the CH2 VP6 from the corresponding crystal structure of the bovine rotavirus, RF strain, demonstrated that the hypervariable region (residue 228-240) does have a critical role in strain specific antigenic characteristics of avian and mammalian rotaviruses. A predicted conformational epitope encompasses experimentally characterized group and subgroup epitopes suggesting that it is a major antibody binding site on the VP6 protein. The VP6 structure modeling and conformational epitope prediction together with enzyme immuno assay of SG MAbs placed CH2 in SGI/II. The study may be helpful in designing peptides for group A rotavirus diagnostic assays and to achieve heterotypic protection against rotavirus serotypes.