Molecular Epidemiology of Bovine Respiratory Syncytial Virus in Cattle in Niger State, North Central Nigeria

This study provides the first molecular epidemiological characterisation of bovine respiratory syncytial virus (BRSV) in cattle in Niger State, located in Nigeria's North Central geopolitical zone. BRSV is a major cause of respiratory disease in young cattle globally, causing bronchopneumonia, reduced growth rates, and mortality, and its presence and genetic diversity in Niger State are unknown. Using a cross-sectional design, nasal swabs and bronchoalveolar lavage samples were collected from 200 cattle presenting with respiratory signs across 20 farms in four local government areas. BRSV was detected by real-time RT-PCR, and positive samples were sequenced for partial G and F protein genes. Phylogenetic analysis was conducted against reference sequences to determine subgroup classification. Concurrent serological testing using ELISA was performed on 300 sera from clinically healthy cattle to estimate population-level exposure. Co-infection with bovine coronavirus (BCoV) and bovine parainfluenza virus type 3 (BPIV-3) was screened by multiplex PCR. The study fills a significant gap in respiratory virus diversity data for Nigerian cattle. Findings revealed BRSV detection in 28 percent of respiratory disease cases, with subgroup A the predominant phylogenetic clade. ELISA revealed serological evidence of prior BRSV exposure in 61 percent of healthy cattle. Co-infection with BCoV was detected in 15 percent of BRSV-positive samples. The study recommends respiratory disease surveillance expansion and evaluation of available BRSV vaccines against Nigerian circulating strains. Keywords: bovine respiratory syncytial virus, molecular epidemiology, cattle, Niger State, respiratory disease.