Molecular characterization and phylogenetic analysis of H3N2 human influenza A viruses in Cheongju, South Korea

Abstract

To investigate the genetic characteristics of human influenza viruses circulating in Chungbuk province, we tested 510 clinical samples of nasopharyngeal suction from pediatric patients diagnosed with respiratory illness between June 2007 and June 2008. Genetic characterization of the HA genes of H3N2 isolates indicated the relative higher similarity to A/Virginia/04/07 (99.6%) rather than that of A/Wisconsin/67/2005 (98.4%), a Northern Hemisphere 2007-2008 vaccine strain, based on amino acid sequences. We found several altered amino acids at the H3 HA1 antigenic sites compared with the vaccine strain; K140I at site A, K158R at site B, and K173N (H471) or K173Q, and S262N at site E, but there was no antigenic shift among the H3N2 viruses. Interestingly, A/Cheongju/H383/08 and A/Cheongju/H407/08 isolates had single amino acid substitution at D151G on the catalytic site of the N2 NA while A/Cheongju/H412/08 and A/Cheongju/ H398/07 isolates had one amino acid deletion at residue 146. Furthermore, we found that 25% (3 out of 12 isolates) of the H3N2 subtype viruses had the amino acid substitution at position 31 on the M2 protein (Aspartic acid to Asparagine) and confirmed their drug-resistance by biological assays. Taken together, the results of this study demonstrated continuous evolutions of human H3N2 viruses by antigenic drift and also highlighted the need to closely monitor antigenic drug resistance in influenza A viruses to aid in the early detection of potentially pandemic strains, as well as underscore the need for new therapeutics.

Antigenic Site Variation in the Hemagglutinin of Pandemic Influenza A(H1N1)pdm09 Viruses between 2009–2017 in Ukraine

“…Importantly, substitution D222G is located in the receptor-binding pocket in the antigenic site Ca HA and may alter the properties of the RBS [21]. In addition, the K163I substitution observed in A/Zaporizza/417/2013 may impart altered antibody-binding properties [28,29].…”

Virulence and Genetic Compatibility of Polymerase Reassortant Viruses Derived from the Pandemic (H1N1) 2009 Influenza Virus and Circulating Influenza A Viruses

“…The human pandemic H1N1 virus, CA04 (H1N1), was obtained from St. Jude Children's Research Hospital. The human, avian, and swine influenza viruses, including the mammalian-passaged variants (Table 1), used in this study were from our repository of human and animal influenza viruses collected from the following sources: nasopharyngeal suctions of patients at the Chungbuk National University Hospital; lung tissue samples of swine from local pig farms; and fecal samples of birds from live bird markets, poultry farms, or the wild (2,3,29,48,55,56). After the sequences of the rescued viruses were confirmed, virus stocks were prepared in 10-day-old embryonated chicken eggs and titrated in MDCK cells.…”

Full genomic analysis of an influenza A (H1N2) virus identified during 2009 pandemic in Eastern India: evidence of reassortment event between co-circulating A(H1N1)pdm09 and A/Brisbane/10/2007-like H3N2 strains

“…Comparison of antigenic sites of HA1 region of our strain with A/Brisbane/59/2007 (the vaccine strain; which was used to clarify whether the vaccination could provide protection against this virus), A/Eastern India/2499/2009 (one of the influenza A(H1N1)pdm09 strain) and A/India/77251/2001(an H1N2 strain isolated in 2001-02 sessions) revealed that there is an insertion of a strong basic amino acid Lysine (K) at position 147. Such insertion might affect electrostatic interactions of HA with its antibodies [20]. The substitution of one nonpolar neutral amino acid with another nonpolar neutral one will not make any difference in making the hydrophobic interaction and proper conformation into the binding pocket [21] but the S152A substitution is polar to nonpolar whereas L174S and A207S show substitution of a nonpolar aa with a polar one.…”