Epidemiology and Pathogenicity Analysis Based on Partial Recombinant PRRSV Strains in China

Area of Science:

• Veterinary Virology
• Molecular Epidemiology
• Viral Evolution

Background:

• Multiple recombinant variants of porcine reproductive and respiratory syndrome virus (PRRSV) are circulating in China.
• These variants exhibit varying pathogenicity, necessitating a comprehensive understanding of their current status and recombination patterns.

Purpose of the Study:

• To analyze the evolutionary and recombination patterns of PRRSV strains in China from 2019 to 2023.
• To investigate the genetic variations and pathogenicity of specific PRRSV recombinant strains.

Main Methods:

• Evolutionary analysis of 677 PRRSV strains, with 673 from mainland China.
• Identification and analysis of recombination patterns and hotspots in PRRSV-2 strains.
• Phylogenetic analysis and animal experiments for selected PRRSV strains.

Main Results:

• NADC30-like PRRSV strains have replaced highly pathogenic PRRSV (HP-PRRSV) strains as the dominant type in China.
• Recombination hotspots differ between NADC30-like and HP-PRRSV-derived strains, with specific regions showing higher or lower recombination frequencies.
• Selected PRRSV strains (ZJ-2021-1, JS-2020-1) showed distinct pathogenicity in animal experiments, correlating with their parental strains.

Conclusions:

• PRRSV strains in China are highly complex and evolving, with NADC30-like variants being dominant.
• Understanding recombination patterns is crucial for characterizing PRRSV epidemiology and pathogenicity.
• The pathogenicity of recombinant PRRSV strains is influenced by their genetic backbone.