Epidemiological and genetic characteristics of porcine reproductive and respiratory syndrome virus circulating in central and South China in 2016.

Abstract

Porcine reproductive and respiratory syndrome virus (PRRSV) is a leading cause of reproductive failure in sows and respiratory disorders in all ages of pigs; PRRSV is one of the most serious threats to the global pig industry. Continuously monitoring the epidemiological and genetic characteristics of PRRSV epidemic strains is beneficial for PRRSV prevention and control. In this study, we detected PRRSV from different types of porcine samples collected from 257 pig farms in Central (Henan Province) and South China (Fujian, Guangdong, and Guangxi Provinces) in 2016. Of the 1047 samples collected, 530 (50.62%) were positive for PRRSV by RT-PCR. The positive rates of virus detection for each of the geographical regions were higher than 44.25%. These findings suggest that the prevalence of PRRSV continues to be a major problem for the pig industry in China. Phylogenetic analysis showed that PRRSV2 was still the prevalent species in Central and South China, and highly pathogenic PRRSV (HP-PRRSV) was the predominate PRRSV type. However, the emergence and circulation of novel PRRSV strains such as the GM2-like strains and NADC30-like strains is worrisome and should receive more attention. In terms of different geographical regions, HP-PRRSV strains were the predominate PRRSV strains circulating in South China, while both HP-PRRSV strains and NADC30-like strains appeared to be the predominate PRRSV strains in Central China (Henan Province). These findings demonstrate that PRRSV types circulating in different regions in China are some different. In addition, a number of amino acid mutation types including amino acid changes and deletions were observed in both the GP5 and Nsp2 proteins. Our study provides important information on the epidemiological and genetic characteristics of PRRSV strains currently circulating in China.