title: Genetic characterization of circulating seasonal Influenza A viruses (2005-2009) revealed introduction of oseltamivir resistant H1N1 strains during 2009 in eastern India.
abstract: Influenza surveillance was implemented in Kolkata, eastern India in 2005 to identify the circulating subtypes and characterize their genetic diversity. Throat and nasal swabs were collected from outpatients with influenza-like illness (ILI). Of 2844 ILI cases identified at two referral hospitals during October 2005-September 2009, 309 (10.86%) were positive for Influenza A by real time RT-PCR, of which 110 (35.60%) were subtyped as H1N1 and 199 (64.40%) as H3N2. Comparison of the nucleotide (nt) and amino acid (aa) sequences of the HA1 gene for H1N1 and H3N2 strains showed that a subset of strains precede WHO recommended contemporary strains by 1-2 years. The Kolkata H1N1 strains clustered in Clade II, subgroup 2B with A/Brisbane/59/2007 but were distant from the corresponding vaccine strains (New Caledonia/20/99 and A/Solomon Island/3/06). The 2005-06 and 2007 H3N2 strains (15/17) clustered either A/Brisbane/10/2007-like (n=8) or A/Nepal/921/2006 like (n=7) strains, whereas 2008 strains (8/12) and 2009 strains (4/4) were similar to the 2010-11 vaccine strain A/Perth/16/2009. More aa substitutions were found in HA or NA genes of H3N2 than in H1N1 strains. No mutation conferring neuraminidase resistance was observed in any of the strain during 2005-08, however in 2009, drug resistant marker (H275Y) was present in seasonal H1N1, but not in co-circulating H3N2 strains. This is the first report of genetic characterization of circulating Influenza A strains from India. The results also highlight the importance of continuing Influenza surveillance in developing countries of Asia for monitoring unusual strains with pandemic potential and mutations conferring antiviral resistance.
authors.affiliation: Division of Virology, National Institute of Cholera and Enteric Diseases, P-33 C.I.T. Road, Scheme XM, Beliaghata, Kolkata, West Bengal, India.
authors.forename: Anurodh S
authors.initials: AS
authors.lastname: Agrawal
authors.forename: Mehuli
authors.initials: M
authors.lastname: Sarkar
authors.forename: Swati
authors.initials: S
authors.lastname: Ghosh
authors.forename: Tapasi
authors.initials: T
authors.lastname: Roy
authors.forename: Sekhar
authors.initials: S
authors.lastname: Chakrabarti
authors.forename: Renu
authors.initials: R
authors.lastname: Lal
authors.forename: Akhilesh C
authors.initials: AC
authors.lastname: Mishra
authors.forename: Mandeep S
authors.initials: MS
authors.lastname: Chadha
authors.forename: Mamta
authors.initials: M
authors.lastname: Chawla-Sarkar
mesh_terms: D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D000998:Antiviral Agents / Q000494:pharmacology* / Q000627:therapeutic use; D001483:Base Sequence; D024882:Drug Resistance, Viral; D014644:Genetic Variation; D019267:Hemagglutinin Glycoproteins, Influenza Virus / Q000235:genetics; D006801:Humans; D007194:India; D053118:Influenza A Virus, H1N1 Subtype / Q000187:drug effects* / Q000235:genetics* / Q000302:isolation & purification / Q000502:physiology; D053122:Influenza A Virus, H3N2 Subtype / Q000187:drug effects / Q000235:genetics* / Q000302:isolation & purification; D007251:Influenza, Human / Q000188:drug therapy / Q000453:epidemiology / Q000821:virology*; D008969:Molecular Sequence Data; D009439:Neuraminidase / Q000737:chemistry / Q000235:genetics; D053139:Oseltamivir / Q000494:pharmacology*; D010802:Phylogeny; D012367:RNA, Viral / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017423:Sequence Analysis, RNA; D014764:Viral Proteins / Q000235:genetics
chemical_list: D000998:Antiviral Agents; C543345:H1N1 virus hemagglutinin; D019267:Hemagglutinin Glycoproteins, Influenza Virus; D012367:RNA, Viral; D014764:Viral Proteins; C483468:hemagglutinin, human influenza A virus; D053139:Oseltamivir; D009439:Neuraminidase