Molecular analysis of human influenza virus in Tehran, Iran.

BACKGROUND: To date there are no reports of molecular and phylogenetic analyses of human influenza virus in Tehran, Iran. OBJECTIVES: We isolated and characterized circulating influenza viruses in a sample of patients in Tehran. METHODS: Nasal and pharyngeal swabs were collected from 57 individuals who were suspected of having influenza between October 2005 and January 2007. These samples were cultured and subsequently genotyped by RT-PCR and sequencing analyses. RESULTS: Twelve of 57 samples (21%) were positive for human influenza virus. Out of the 12 positive samples, 7 were A/H3N2 (58%), 3 were A/H1N1 (25%) and 2 were B subtypes (17%). The phylogenetic analysis of the hemagglutinin gene showed that the H1N1 isolates were close to the A/New Caledonia/20/99 and the H3N2 isolates were close to the A/Panama/2007/99 and A/Moscow/10/99 vaccine strains. CONCLUSION: In a sample of clinical patients in Tehran, Iran, the predominant subtype of human influenza virus was determined to be A/H3N2, followed by A/H1N1 and B. In addition, phylogenetic analysis on H1 showed some genetic drifts from vaccine strains, but the phylogeny of H3 demonstrated that these isolates were from the previous vaccine strains.