Genetic diversity of H۹N۲ avian influenza viruses in Iran over the past two decades

Numerous studies have explored the molecular epidemiology of H۹N۲ viruses in Iran; however, continuous monitoring remains vital for timely interventions to mitigate potential damage. This study examined the molecular characteristics and evolutionary features of Iranian H۹N۲ viruses by sequencing the complete genomes of two viruses, Marand and Baneh, isolated in ۱۹۹۸ and ۲۰۲۲, respectively, alongside other Iranian strains from GenBank. All Iranian viruses were identified as low-pathogenic avian influenza viruses, as evidenced by the presence of the di-basic motif K/RSSR cleavage site. Notably, all Iranian viruses isolated from ۲۰۰۹ onward had an L at position ۲۱۶ in the hemagglutinin receptor binding site, whereas earlier viruses exhibited a Q/L at the same position, an essential mutation that enhances replication in mammalian cells. The molecular evolutionary rates for the Iranian hemagglutinin (HA) and neuraminidase (NA) genes were estimated at ۴.۵۰ × ۱۰-۳ and ۳.۶۰ × ۱۰-۳ substitutions per site per year, respectively. Error-prone replication of H۹N۲ viruses has resulted in the continuous evolution of Iranian strains over two decades, characterized by three phases of population growth. Maximum likelihood phylogenetic analysis revealed that the HA and NA genes of H۹N۲ viruses from domestic chickens belonged to the G۱ sublineage. Additionally, the internal genes of some viruses displayed evidence of reassortment with other subtypes, indicating potential gene exchange with other viruses. These findings underscored the importance of ongoing surveillance of H۹N۲ viruses in both domestic and wild bird populations, given the human-like receptor-binding preference and the possibility of genetic reassortment with various viral subtypes.

کلیدواژه ها:

Avian influenza virus ، complete genome sequencing ، Evolutionary analysis ، Iran