Determination of genetic characterization and circulation pattern of Respiratory Syncytial Virus (RSV) in children with a respiratory infection, Tehran, Iran, during 2018-2019.

The RSV-associated disease accounts for a significant health burden particularly in infants and young children who need to be hospitalized. Since continuous surveillance of circulating RSV genotypes is crucial worldwide, this study aimed to investigate the genetic diversity of RSV circulating strains causing upper or lower acute respiratory infection. Our attention was geared towards studying the cases hospitalized or outpatient in children younger than 2 years of age in Iran during 2018/2019. In this study, nasopharyngeal swabs collected from 206 children who presented with respiratory infection symptoms, were admitted to the referral pediatric ward of Bahrami children's hospital in Tehran, Iran. RSV-positive samples were detected via Nested RT-PCR. The glycoprotein gene was sequenced, and virus genotypes were confirmed through phylogenetic analysis by the MEGA X program. A total of 74 (35.92%) samples tested positive for RSV. Among them, sequencing was done in 10 specimens from 2018 (RSV-A: RSV-B=4:6) and 19 specimens from 2019 (RSV-A: RSV-B=16:3). According to phylogenetic analysis, all RSV-A strains were assigned as ON1 genotype and RSV-B strains were assigned as BA9 genotype. A new N-glycosylation site in Iranian BA9 and positive selection in ON1 genotype was observed. Phylogenetic characterization of strains in the current study revealed co-circulation of ON1 and BA9 as the only prevalent genotypes of both RSV-A and -B groups.