Determination of Oseltamivir Resistance Level by an H275Y Genotyping Assay among Influenza A (H1N1) Viruses in Hamadan Province, Iran

Introduction: Epidemics and deaths caused by influenza viruses are an important concern worldwide. The use of neuraminidase inhibitors such as oseltamivir is an effective and valuable way to treat the diseases caused by these viruses. However, the mutation in several parts of the gene leads to the emergence of drug-resistant strains, and an ever-increasing rise in drug-resistant strains is a global problem. Histidine-to-tyrosine mutation at position 275 (H275Y) of neuraminidase protein is one of the most common oseltamivir resistance mutations. This study aimed to detect H275Y mutation in influenza A (H1N1) virus circulating in the Hamadan province of Iran using real-time polymerase chain reaction  (RT-PCR). Material & Methods: This cross-sectional study was conducted on 110 swab samples isolated from patients with suspected influenza virus infection between 2015 and 2016. Ribonucleic acid (RNA) was extracted from samples and the RT-PCR method was used to determine virus types and subtypes. The positive samples were evaluated for detection of H275Y mutation using RT-PCR. (Ethic code: IR.UMSHA.REC.1400.917) Findings: Out of 110 patients in this study, 50 (45%) were females and 60 (55%) were males. The mean±SD age of participants was 40.74±2.42 years. Influenza A (H1N1) virus was found in 22 (20%) out of 110 patients, including 9/50 (18%) females and 13/60 (21.7%) males. There was no significant relationship between the virus and gender (P=0.81). No drug resistance related to H275Y mutation was observed in 22 positive cases. Discussion & Conclusion: The findings indicated that no drug resistance mutations have occurred, and oseltamivir is still an appropriate option to treat infections caused by the influenza virus in Hamadan province, Iran. However, due to the increasing number of resistant strains, an annual review of oseltamivir resistance is recommended and further studies are needed in this regard.