Journal of Antivirals & Antiretrovirals
Open Access

Abstract

Oseltamivir Resistant Influenza A (H1N1) Virus Infection in Mumbai, India

Devanshi Gohil, Sweta Kothari, Pramod Shinde, Anand Chintakrindi, Rhuta Meharunkar, Rajas Warke, Meena Kanyalkar, Abhay Chowdhary and Ranjana Deshmukh

Objectives: Oseltamivir is an important antiviral agent approved for treatment of infections caused by Influenza virus. The emergence of an Oseltamivir resistant seasonal Influenza A (H1N1) virus in 2007 in Norway and pandemic Influenza A (H1N1) virus in 2009 [Influenza A (H1N1) pdm 09] is of major concern. This study aimed for examining antiviral drug resistance of Influenza A viruses circulating during 2009 Influenza season in Mumbai. Methods: Nasopharyngeal swabs positive for Influenza A virus were inoculated on Madin-Darby canine kidney cell line for virus isolation. Molecular analysis of neuraminidase gene and matrix gene was carried out to detect known mutations contributing to resistance. Resistance to neuraminidase was assayed using a commercially available chemiluminescence based NA-Star assay kit. Results: Genotypically, a total of 47 isolates of Influenza A (H1N1) pdm 09 isolates were observed to harbor mutations known to confer resistance to Adamantane. However, no known mutations conferring resistance to neuraminidase (NA) inhibitors were detected. Resistance to Oseltamivir was observed in a single isolate of seasonal Influenza A (H1N1) isolate with an extremely high IC50 value of 1261 nM. Conversely, the isolate was sensitive to Adamantane. Phylogenetic analysis revealed that NA gene of this Oseltamivir-resistant isolate from Mumbai was antigenically related to human A (H1N1) A/Brisbane/59/2007 vaccine strain. Conclusions: Surveillance on drug susceptibility of circulating strains in Mumbai helped us to identify Oseltamivir resistance in seasonal Influenza virus. The study highlights the importance of continual surveillance on Influenza in India to ensure that antiviral prescribed by clinicians is effective when treating patients for Influenza infections.