# Identification, Pathogenicity, and Reverse Genetics System Construction of a Pseudorabies Virus Isolate from Pigs in China

## TL;DR

A new deadly strain of pseudorabies virus was isolated in China, and a genetic system was developed to study its behavior and create safer vaccines.

## Contribution

A novel PRV strain was isolated and a reverse genetics system was developed for creating recombinant PRV strains.

## Key findings

- PRV-HL-2021 is highly lethal to mice, indicating strong pathogenicity.
- Recombinant PRV strains with EGFP and gene deletions were successfully created and showed similar growth to the original strain.
- The reverse genetics system provides tools for studying PRV functions and developing vaccines.

## Abstract

Pseudorabies virus (PRV) is a highly contagious virus that primarily affects pigs but can also infect other animals, including humans. In this study, a novel PRV strain, PRV-HL-2021, was isolated from an outbreak in Heilongjiang, China. This strain was found to be highly lethal to mice, highlighting its pathogenicity. A reverse genetics system was established using a fosmid library of PRV-HL-2021’s genome, enabling the creation of recombinant PRV strains, including one expressing enhanced green fluorescent protein (EGFP) and another with deletions in key viral genes (US9, gI, and gE). These recombinant strains were used to study viral replication, pathogenesis, and gene functions. The successful isolation of PRV-HL-2021 and the development of this reverse genetics system provide valuable tools for understanding PRV’s genetic diversity and for developing safer vaccines and antiviral strategies. These advancements will help control PRV outbreaks in pigs and reduce the risk of transmission to humans and other animals.

Pseudorabies virus (PRV) is a highly contagious pathogen in swine that can cross species barriers and infect other mammals, including humans. Given the potential for interspecies transmission and its threat to public health, understanding the molecular biology of PRV strains is essential for developing effective control measures and preparing for future pandemics. In this study, a novel PRV strain, PRV-HL-2021, was isolated from an outbreak in Heilongjiang Province, China. The viral genome was used to establish a reverse genetics system based on a fosmid library of the PRV-HL-2021 genome. This system facilitated the creation of recombinant PRV, including one expressing EGFP and another with deletions in the US9, gI, and gE genes. PRV-HL-2021 was found to be highly lethal to mice in vivo. The recombinant PRV strains, such as rPRV-US9-EGFP and rPRV-delgI/gE/US9, exhibited growth characteristics similar to the parental PRV-HL-2021 strain. The isolation and characterization of PRV-HL-2021 contribute to a better understanding of the genetic diversity of PRV strains. The developed reverse genetics system provides valuable tools for investigating viral functions, creating genetically modified PRV strains, and advancing the development of safer vaccines. These findings will enhance strategies for controlling PRV outbreaks and mitigating its impact on both animal and public health.