# Molecular Characteristics and Pathogenicity Analysis of Bovine Viral Diarrhea Virus Strain Isolated from Persistently Infected Cattle

## TL;DR

This study isolates and analyzes a new strain of bovine viral diarrhea virus from persistently infected cattle in China, examining its genetic features and pathogenicity in mice.

## Contribution

The study reports the isolation, molecular characterization, and pathogenicity analysis of a new BVDV-1b strain, HB2411, from persistently infected cattle in China.

## Key findings

- The HB2411 strain belongs to the BVDV-1b subtype and shares 96.7% homology with the U63479 strain.
- The E2 protein of HB2411 shows multiple amino-acid mutations, and recombination analysis suggests cross-geographical transmission.
- In BALB/c mice, the HB2411 strain caused high viral loads in the liver and increased inflammatory cytokine expression.

## Abstract

Bovine viral diarrhea is a contagious disease caused by infection with the bovine viral diarrhea virus, one of the major infectious diseases that seriously threaten the global cattle industry. BVDV belongs to the genus Pestivirus within the family Flaviviridae and can infect various domestic animals, including cattle. In this study, a BVDV strain was isolated and identified from a cattle herd in Hebei Province, China. The complete genome of the newly isolated strain was subjected to phylogenetic analysis, recombination analysis, and sequence analysis of the E2 region. Furthermore, its pathogenicity was evaluated in BALB/c mice.

Bovine viral diarrhea virus (BVDV) primarily causes bovine viral diarrhea/mucosal disease, an infectious disease having a significant economic impact on the cattle-farming industry globally. Comprehensive monitoring and in-depth studies of the pathological characteristics of viruses are crucial in formulating effective prevention and control strategies. The isolation, identification, molecular characterization, and pathogenicity analysis of a BVDV strain isolated from persistently infected cattle ear tissue samples are reported in this study. This newly isolated strain is a noncytopathogenic BVDV, which we named HB2411. Homology between the HB2411 and U63479 strains was determined to be 96.7%, and the phylogenetic tree indicated that HB2411 belongs to the BVDV-1b subtype. Genetic variation analysis of the E2 protein of the HB2411 strain revealed multiple amino-acid mutation sites. Recombination analysis of the newly isolated HB2411 strain suggested a potential cross-geographical transmission event. BALB/c mice were intraperitoneally inoculated with the BVDV strain to evaluate the pathogenicity and virulence of BVDV-1b HB2411. BVDV was detected in multiple organs of BALB/c mice, with the highest viral load in the liver. BVDV infection promoted the expression of inflammatory cytokines in mice livers, necessitating further studies on the virulence and pathogenic mechanisms of this new strain to reduce economic losses caused to the animal husbandry industry.