Isolation and Genomic Characterization of a Chinese Genotype C Bovine Parainfluenza Virus Type 3 from Cattle and Its Pathogenicity in C57BL/6 Mice

Abstract

Bovine parainfluenza virus type 3 (BPIV-3), also known as bovine respirovirus 3, is a common respiratory pathogen associated with bovine respiratory disease (BRD). BPIV-3 has currently circulated worldwide; however, data on the prevalence and genetic characteristics of BPIV-3 are still scarce and limited. In this study, the BPIV-3 strain SC was identified and isolated from cattle presenting with clinical signs of BRD in China. Animal experiments indicated that BPIV-3 SC can successfully infect C57BL/6 mice and induce weight loss, lung inflammatory cell infiltration, and inflammatory cytokine expression in mice. In addition, the complete genome of BPIV-3 SC was obtained using next-generation sequencing and was 15,473 bp in length. Phylogenetic analysis indicated that BPIV-3 SC belonged to genotype C, which clustered in the same large clade consisting of a population of Chinese genotype C strains but was found to be different from the other strains upon further differentiation. Compared to other Chinese genotype C strains, the BPIV-3 SC showed 70 unique nucleotide mutations and 13 unique amino acid mutations in the HN, P, and L proteins, suggesting a unique genetic evolution of BPIV-3 SC. In conclusion, we isolated and characterized a differential Chinese genotype C BPIV-3, which contributed to an understanding of the prevalence and evolution of BPIV-3 in China.

Prevalence, Molecular Characteristics and Virulence Identification of Bovine Parainfluenza Virus Type 3 in China

“…The results showed that all guinea pigs developed significant respiratory symptoms and pathological lung changes after being intranasally inoculated with the isolates. Our findings differed from previous investigations [ 18 , 33 , 34 , 35 , 36 ], which may be related to the animal species and the virulence of the strains. Among three infection groups, guinea pigs inoculated with Hubei-03 had the most obvious clinical symptoms, the most obvious pathological changes, and the highest viral load in the lungs, which indicated that the pathogenicity of the Hubei-03 strain had the highest virulence among all the isolated viruses.…”

“…The one-step growth curve was conducted as follows: MDBK cells that had reached confluence were inoculated with BPIV-3 isolates at 0.1 MOI (multiplicity of infection). Virus samples were collected at 3,6,9,12,18,24,30,36,42,48,60, and 72 h after inoculation. The obtained virus was frozen and thawed three times before the viral titer was evaluated using TCID 50 .…”