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Emergence of novel recombination lineage 3 of porcine reproductive and respiratory syndrome viruses in Southern China
Author(s) -
Sun YanKuo,
Li Qi,
Yu ZhiQing,
Han XiaoLiang,
Wei YingFang,
Ji ChiHai,
Lu Gang,
Ma ChunQuan,
Zhang GuiHong,
Wang Heng
Publication year - 2019
Publication title -
transboundary and emerging diseases
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.392
H-Index - 63
eISSN - 1865-1682
pISSN - 1865-1674
DOI - 10.1111/tbed.13067
Subject(s) - lineage (genetic) , biology , virulence , phylogenetic tree , virology , genome , phylogenetics , porcine reproductive and respiratory syndrome virus , gene , genetics , zoology
Lineage 3 of porcine reproductive and respiratory syndrome viruses, which belong to North America type 2, has a long epidemic history in China. The novel lineage 3 viruses constantly emerging in recent years are characterized by a high detection rate and significant pathogenicity. In this study, we investigated the prevalence of lineage 3 in southern China and selected two isolated strains for genome and virulence analyses. A cross‐sectional epidemiology investigation indicated that the prevalence of lineage 3 antigens was 35.68% (95% CI : 27.6–44.3%) among 227 samples collected from over 100 infected farms from January 2016 to July 2017 in southern China. Two novel isolates of lineage 3 were selected. After 20 passages, Marc‐145 cells were not susceptible to those viruses. Full‐length genome analysis indicated that the two strains share 95.2% homology with each other and 95.7%–96.2% with highly pathogenic porcine reproductive and respiratory syndrome viruses ( HP ‐ PRRSV s; JXA 1‐like strain, lineage 8.7). Phylogenetic and molecular evolutionary results showed that for the two isolates, HP ‐ PRRSV provides most of the ORF1 gene. Animal experiment revealed discrepancies in virulence between the strains. Although challenge resulted in 100% morbidity, the isolate carrying most of the HP ‐ PRRSV ORF 1 caused severe clinical symptoms and 40% mortality, whereas the other isolate containing part of the ORF 1 gene caused no mortality. Overall, these findings suggest that lineage 3 viruses might be commonly circulating in most of southern China. Frequent recombination events within HP ‐ PRRSV s of this lineage with changing virulence could represent potential threats to the pig industry.