Prevalence and Molecular Characteristics of Bovine Respiratory Syncytial Virus in Beef Cattle in China

Abstract

Bovine respiratory syncytial virus (BRSV) is an important pathogen of the bovine respiratory disease complex (BRDC); however, its prevalence and molecular characteristics in China remain largely unknown. In this study, 788 nasal swabs from 51 beef cattle farms with BRDC outbreaks in 16 provinces and one municipality were collected from October 2020 to July 2022, and 18.65% (147/788) of samples from 23 farms across 11 provinces were detected as BRSV-positive by reverse transcription-insulated isothermal PCR (RT-iiPCR) assay. Further, 18 complete G gene sequences were classified into BRSV subgroup III, and 25 complete F gene sequences were obtained from 8 and 10 provinces. Compared to the known BRSV strains in GenBank, the G proteins and F proteins in this study shared several identical amino acid (aa) mutations. Moreover, five nearly complete genome sequences were obtained and clustered into a large branch with two America BRSV subgroup III strains (KU159366 and OM328114) rather than the sole Chinese strain (MT861050) but were located in an independent small branch. In conclusion, this study reveals that BRSV has a wide geographical distribution in China, and subgroup III strains, which have unique evolution characteristics, are the dominant strains. The results contribute to a better understanding of the prevalence and genetic evolution of BRSV.

Keywords: China; bovine respiratory syncytial virus; epidemic; molecular characteristics.

Figure 1

Map of China shows the geographical distribution of BRSV strains by province or municipality, Indicates the province or municipality of the sample collected in this study, Indicates provinces with BRSV positive-sample distribution.

Figure 2

Phylogenetic tree based on the complete nucleotide sequences of G gene. Sequences were compared and clustered by MEGA 7.0 software. The phylogenetic tree was constructed using the neighbor-joining method (1000 replicates). ● represents 18 G gene sequences of BRSV strains from this study, represents the G gene sequences of other strains in China.

Figure 3

Phylogenetic tree based on the complete nucleotide sequences of F gene. Sequences were compared and clustered by MEGA 7.0 software. The Phylogenetic tree was constructed using the neighbor-joining method (1000 replicates). ● represents 25 F Gene sequences of BRSV strains from this study, represents the F gene sequences of other isolates in China.

Figure 4

Phylogenetic tree based on the nucleotide sequences of the complete genome was compared and clustered by MEGA 7.0 software. The phylogenetic tree was constructed using the neighbor-joining method (1000 replicates). ● represents 5 complete genome sequences of BRSV strains from this study, represents the complete genome of other isolates in China.