Characterization of three porcine reproductive and respiratory syndrome virus isolates from a single swine farm bearing strong homology to a vaccine strain

Emergence of mosaic recombinant strains potentially associated with vaccine JXA1-R and predominant circulating strains of porcine reproductive and respiratory syndrome virus in different provinces of China

“…2, there were 44 JXA1-R-like strains, which included the 10 potential JXA1-R-like strains in this study and seven reported strains in China (NT1, NT2, NT3, 11NZ-GD, 11XX-GD, 11SH1-GD, and 11SH-GD) [23, 27]. These 27 Chinese strains were deposited in the GenBank database because they shared the highest nucleotide identities with JXA1-R strains (>99%) (Additional file 3: Table S3) and contained 6–11 amino acids unique to JXA1-R (Additional file 4: Figure S1).…”

“…In order to determine the original of these isolates, we compared 28 sequences identified in this study with all available genomic sequences ( n  = 623) of type 2 PRRSV in the GenBank database. The sublineage 10.7 include up to 65 field samples with a wide geographical range, in which the intralineage diversity was the lowest (0.8%), and found nine JXA1-R-like isolates out of the 28 isolates based one the three criteria reported previously [23]. Of course, it was possible that these recombinants might be also derived from other HP-PPRSV vaccine strains, such as HuN4-F112, TJM-F92, and GDr180, because those vaccine strains are derived from HP-PRRSV and there is no published complete sequences of those vaccine strains.…”

“…The virulence reversion of the vaccine strain JXA1-R has been described [23, 27], but no recombination of this strain has yet been reported. Recombination analyses showed that 10 strains, which included nine strains from the present study and one isolate retrieved from the GenBank database, evolved through complicated recombination events between vaccine JXA1-R-like strains and predominant circulating strains in China.…”

“…Only the strains that fit all of the following three criteria, as modified from a previous report [23], were recognized as JXA1-R (JXA1 P80)-like strains: (1) nested in the phylogenetic tree within the same cluster as the vaccine strain JXA1-R, (2) sharing the highest sequence identity with the JXA1-R strain (>99%), and (3) presenting amino acids (aa) unique to JXA1-R strain derivatives.…”

A highly pathogenic porcine reproductive and respiratory syndrome virus candidate vaccine based on Japanese encephalitis virus replicon system

“…Although MLVs perform well against homologous infection (Jeong et al, 2016; Linhares et al, 2012), MLVs show poor protection to heterologous strains and cannot prevent PRRSV to disseminate through the placenta (Kimman et al, 2009). Furthermore, China and Denmark each have related reports that MLVs might revert to the high virulence strain (Botner et al, 1997; Jiang et al, 2015; Opriessnig et al, 2002). Inactivated virus vaccines are safer than MLVs, but the inactivated virus vaccines provide limited protective immunity against PRRSV infection (Renukaradhya et al, 2015; Scortti et al, 2007).…”