Epidemiological and phylogenetic assessment of human respiratory syncytial virus among pediatric patients presenting acute respiratory infections in Shiraz, Iran during 2015-2016.

Background and Objectives: The pediatric population worldwide bears a significant morbidity and death burden due to acute respiratory infections (ARIs). Human Orthopneumovirus, sometimes referred to as the Human Respiratory Syncytial Virus (HRSV), is one of the main causes of ARIs in infants. The main goal of this study was to identify the genetic diversity of HRSV strains that were circulating in the Iranian population at a certain time of year. Materials and Methods: Two hundred youngsters less than 12 years old with acute respiratory infections had samples taken from their throat and pharynx secretions. Then, external and hemi-nested PCR were employed, using specific primers targeting the G gene region to detect HRSV. Subsequently, nine randomly selected positive samples were subjected to sequencing. The results were then compared with reference strains cataloged in GeneBank, and phylogenetic tree was constructed using Chromes and MEGA7. Results: Out of 200 samples, 34 were identified as containing HRSV. Subgroup A was predominant, accounting for 61.76% of cases, followed by subgroup BA (35.29%) and subgroup B (2.94%). Phylogenetic analysis revealed five samples associated with subtype B and four with genotype A. Genomic analysis showed three samples under the GA2 subgroup and one under GA1 for subtype A, and four samples in subgroup BA and one in GB2 for subtype B. Conclusion: In this study, subgroup A strains, particularly genotype GA2, exhibited a higher prevalence compared to subgroup B strains during the specific period under investigation, shedding light on the genetic landscape of HRSV in this region.