The evolution and diversity of porcine reproductive and respiratory syndrome virus in China

The porcine reproductive and respiratory syndrome virus (PRRSV) has emerged as a significant pathogen in the global pork industry since the late 1980s, causing substantial economic losses due to its high contagiousness and genetic variability. China, with its complex epidemiological landscape, has witnessed the emergence of four distinct lineages of PRRSV-2 (Lineages 1, 3, 5, and 8) and occasional occurrences of PRRSV-1. This review summarizes the historical context and epidemiological trends that have led to the diversification of PRRSV in China, discusses the evolutionary dynamics behind the establishment of diverse genetic variants, as well as the impact of recombination and modified live vaccines (MLVs) on the virus's rapid evolution. The implications for disease management, including strategies to reduce the complexity of PRRSV epidemics and improve prevention and control measures, are also suggested. Understanding the evolutionary pattern and factors contributing to PRRSV diversity is crucial for enhancing our knowledge, control capabilities, and prevention strategies, which could be integrated into swine health management practices.