Origin and transmission of bovine viral diarrhea virus type 1 in China revealed by phylodynamic analysis.

Bovine viral diarrhea virus type 1 (BVDV-1) is prevalent worldwide and causes significant economic loss in animal husbandry. Since its first report in the 1980s in China, several genotypes of BVDV-1 had been reported, but an in-depth phylogenetic analysis on the BVDV isolates from China is lacking. To investigate the molecular evolution and phylodynamics of BVDV-1 genotypes circulating in China, comprehensive phylogenetic and phylodynamic analyses were performed to reconstruct the origin and spatial-temporal distribution, and to trace main viral flows among different areas. BVDV-1 5'-UTR sequences from China and Mongolia were collected from Genbank, and the phylogeny was built using the maximum likelihood method. The Bayesian Skygrid was used to estimate the evolution and population dynamics of BVDV-1. Eight BVDV-1 genotypes were identified, of which 1b and 1 m are the main genotypes. The results indicated that BVDV-1 might be introduced in China in the 1960s, and after a long period of population growth, it gradually leveled off after 2010. The phylodynamic inference clearly shows a more steady BVDV-1 population growth, and the transmission of BVDV-1 may be confined to specific regions. This study will help to understand the molecular epidemiology and long-term evolutionary dynamics of BVDV-1 in China, therefore providing a scientific basis for the prevention and controlof the virus.