Genomic analysis of a recombinant NADC30-like porcine reproductive and respiratory syndrome virus in china.

Recently, NADC30-like porcine reproductive and respiratory syndrome viruses (PRRSVs), which are genetically similar to the NADC30 strain isolated in the United States of America in 2008, have become prevalent in China. Here, a novel variant PRRSV strain named HNhx was successfully isolated on porcine alveolar macrophages from Henan province and the full-length genome sequence was determined. Phylogenetic analysis indicated that HNhx strain was classified into the NADC30-like PRRSV subgroup, in which all the strains had the unique discontinuous 131-amino acid deletion relative to that of the nonstructural protein 2 (Nsp2) of the VR2332 strain. Genetically, HNhx shared 92.9% nucleotide similarity to NADC30. Furthermore, HNhx strain contained extensive amino acid mutations in GP5. In particular, the S32H, N33D, D34N, and S36G variations resulted in that HNhx lost all the putative N-linked glycosylation sites at amino acid positions 30, 32, 33, 34, and 35. Recombination analysis revealed that HNhx was the result of recombination between the NADC30 strain and the highly pathogenic PRRSV vaccine strain circulating in China in Nsp4 (nt 5261) to Nsp9 (nt 7911). The novel genome data of HNhx will be helpful for understanding the evolution and epidemiology of PRRSV in China.