Complete Genomic Characterization of Porcine Reproductive and Respiratory Syndrome Virus Strain HB-XL

Porcine reproductive and respiratory syndrome virus (PRRSV) is the causal agent of a serious disease of swine. Here, we report the genome sequence of PRRSV strain HB-XL isolated from a pig farm with a clinical outbreak of porcine reproductive and respiratory syndrome. The genome is 15,323 bp long and has nine open reading frames (GenBank: KP162169). Comparative and phylogenetic analysis showed that HB-XL belongs to the highly pathogenic PRRSV (HP-PRRSV) subfamily in the family PRRSV. The viral nonstructural protein 2 (Nsp2) of the HB-XL strain contained 30 discontinuous amino acid (AA) deletions relative to that of the Nsp2 of the VR2332 strain. The AA substitutions R13 and R151 suggested high virulence of the HB-XL strain. The unique mutations in glycoprotein 5 (GP5) and Nsp2 revealed that HB-XL might be a novel variant PRRSV strain recombined with vaccine strains. However, the low morbidity and mortality in the pig herd from which HB-XL was isolated indicate that the virulence of the virus was weak, so it has potential as a future vaccine strain.