Characteristic Features Of Porcine Endogenous Retroviruses In Vietnamese Native Pigs

We aimed to clarify the genomic characteristics of porcine endogenous retroviruses (PERVs) in Vietnamese native pig (VnP) breeds. First, we investigated genetic polymorphisms in beta- and gamma-like PERVs, and we then measured the copy numbers of infectious gamma-like PERVs (PERV-A, B, and C). We purified genomic DNA from 15 VnP breeds from 12 regions all over the country and three Western pig breeds as controls, and investigated genetic polymorphisms in all known PERVs, including the beta (beta)1-4 and gamma (gamma)1-5 groups. PERVs of beta 1, beta 2, beta 3, and gamma 4 were highly polymorphic with VnP-specific haplotypes. We did not identify genetic polymorphisms in beta 4, gamma 1, or gamma 2 PERVs. We then applied a real-time polymerase chain reaction-based method to estimate copy numbers of the gag, pol, and env genes of gamma 1 PERVs (defined as A, B, and C). VnP breeds showed significantly lower copy number of the PERV genes compared with the Western pig breeds (on average, 16.2 and 35.7 copies, respectively, p < .05). Two VnP breeds showed significantly higher copy number compared with the other VnPs (p < .05). Our results elucidated that VnPs have specific haplotypes and a low copy number of PERV genes.