"Characteristics and Variability of Porcine Reproductive and Respiratory Syndrome Virus Strains: Implications for Virulence and Control - A Scoping Review"

Background: Porcine reproductive and respiratory syndrome virus (PRRSV) is the responsible agent of one of the most important diseases in the pig industry and is distributed worldwide. There are two main classifications of the virus, PRRSV 1 and PRRSV 2, the first common in Europe and the second in the United States and China. The major challenge in controlling the agent is the significant variation in the strains, which limits the efficiency of vaccines and control measures. We examined peer-reviewed literature to investigate the characteristics and distinctions among various strains and identify the attributes enabling the virus to thrive within pig herds. We searched the PubMed, Scopus, and Web of Science databases between July and August 2022. We identified 2,847 articles published between 2012 and 2022 and evaluated their eligibility based on the Preferred Reporting Items for Systematic Reviews and Meta-Analyses Extension for Scoping Reviews (PRISMA-ScR) guidelines. Thirty-one articles were finally selected, analysed, and compared to extract and systematise as many factors that account for PRRSV virulence as possible. Results: /conclusions The selected studies focused on experimental models of PRRSV infection that compared the virulence and pathogenic characteristics of different strains in different age groups. These studies aimed to identify differences in disease development, transmission, and host susceptibility between breeding-age and young pigs. By comparing different parameters, we provided insights into the varying virulence of PRRSV strains. Future research aims to monitor markers that can help understand the complex interactions between the host, pathogen, and environment, improve animal health, and effectively control the consequences of PRRSV infection.