The Genomic and Pathogenic Characteristics of the Highly Pathogenic Porcine Reproductive and Respiratory Syndrome Virus Isolate WUH2

To fully understand the extent of genetic diversity and pathogenesis of the highly pathogenic PRRSV found in China, we determined the genomic sequence of PRRSV WUH2; the pathogenicity of WUH2 was compared to the classical PRRSV isolate CH-1a. Our results showed that the WUH2 genome had a discontinuous deletion of 30 aa in Nsp2, a 1 nucleotide deletion located in both the 5′ and 3′ UTRs, and point mutations within GP5. Experimental infection demonstrated that PRRSV WUH2 reproduced the phenotype and symptoms of porcine high fever syndrome. Importantly, we found that there were differences in viral burden in the serum and tissues when comparing infections of the pathogenic isolate WUH2 to those of the classical isolate CH-1a. These data provide insight into the genomic diversity and altered pathogenicity of Chinese PRRSV isolates and help elucidate the evolution and potential pathogenic mechanisms of PRRSV.