Epidemiology and Molecular Characterization of Seasonal and Pandemic Influenza H1N1 2009 Viruses Screening for Drug Resistant Seasonal and H1N1 2009 Isolates and A Study on Antiviral Activity of Indigenous Herbs

Abstract

The laboratory confirmed cases of acute and chronic respiratory infections caused by seasonal influenza and influenza A (HIN1) pdm 2009 was evaluated in Chennai region, Tamilnadu. The study was conducted at department of virology, King Institute of Preventive Medicine and Research (KIPMandR) which is also regional referral center for influenza, Chennai. Among the samples received (n=2025), 169 samples (8.35%) showed positive for influenza viral infection. The number of cases positive for A (HIN1) pdm 2009, A (H3N2) and B subtype were 15 (8.88%), 82 (48.52%) and 72 (42.61%) respectively. Among the positive samples for influenza subtype B, newlineVictoria (BV) and Yamagata (BY) strains represented 38 (52.78%) and 34 (47.22%) cases respectively. It was observed that the positive samples of Seasonal Influenza viral infections including A (H3N2) and B subtypes were higher than the pandemic influenza infection A (HIN1) pdm 2009. It is to be noted that all serotypes are circulating in Chennai throughout the study period and the subtype s distribution varied significantly from year to year. The unpredictably of circulating strains over the years was evident as both influenza A and B viruses and their subtypes cocirculated throughout the surveillance period. It is to be noted that all the isolates had the genetic marker S31N in the M gene suggesting amantadine resistance. A single strain (gi|335058495|gb|JF807497. 1| Influenza A virus (A/Chennai/10/2009(H1N1)) of the 25 viral isolates showed oseltamivir resistance as this feature was identified by substitution of HIS by TYR (H275Y). Considering the increasing incidence of influenza virus and the ability of the virus to become drug resistance, medicinal plants to treat respiratory infections pose as promising alternatives to treat influenza. Further, the results presented in this study suggests that plants with reported antiviral properties with specific potent molecule could be a potential new avenue for anti-influenza molecule discovery for the mankind.