Molecular Characterization of G and F Protein Genes of Bovine Respiratory Syncytial Virus Detected from Dead Calves Caused by Severe Respiratory Syndrome: Emergence of Novel Mutations and Their Importance

Bovine respiratory syncytial virus (BRSV) is an important viral agent in bovine respiratory disease complex affecting young calves from asymptomatic to fatal. Although BRSV is widely prevalent in Türkiye as in other parts of the world, there are limited molecular studies on BRSV in Türkiye. Therefore, in order to better understand the characteristics of circulating BRSV in Türkiye, a study based on the molecular analysis of both F and G proteins was performed. For this purpose, the presence of BRSV was investigated in 20 calves that died as a result of severe respiratory syndrome in the western region of Türkiye in 2020. Nested PCR was performed for both gene regions, and the products were sequenced. Four samples detected as BRSV positive were identified as genotype III according to both gene regions in molecular analysis. However, they were separated into two distinct clusters due to significant differences in nucleotide (90.09–99.54