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

Abstract

BackgroundPorcine reproductive and respiratory syndrome virus (PRRSV) has caused several outbreaks in China since 2006. However, the genetic diversity of PRRSV in China has greatly increased by rapid evolution or recombination events. Modified live-attenuated vaccines are widely used to control this disease worldwide. Although the risk and inefficacy of the vaccine has been reported, the genetic diversity between epidemic field strains and vaccine strains in China has not been completely elucidated.MethodsA total of 293 clinical samples were collected from 72 pig farms in 16 provinces of China in 2015 for PRRSV detection. A total of 28 infected samples collected from 24 pig farms in nine provinces were further selected for immunohistochemical analysis and whole genome sequencing of PRRSV. Phylogenetic analysis and recombination screening were performed with the full genome sequences of the 28 strains and other 623 reference sequences of PRRSV.ResultsOf 293 clinical samples, 117 (39.93%) were positive for PRRSV by RT-PCR. Phylogenetic results showed that the 28 strains were nested into sublineage 10.5 (classic highly pathogenic [HP]-PRRSV), sublineage 10.6 (HP-PRRSV-like strains and related recombinants), sublineage 10.7 (potential vaccine JXA1-R-like strains), and lineage 9 (NADC30-like strains and recombinants of NADC30-like strains), respectively, suggesting that multiple subgenotypes of PRRSV currently circulate in China. Recombination analyses showed that nine of 28 isolates and one isolate from other laboratory were potential complicated recombinants between the vaccine JXA1-R-like strains and predominant circulating strains.ConclusionsThese results indicated an increase in recombination rates of PRRSV under current vaccination pressure and a more pressing situation for PRRSV eradication and control in China.Electronic supplementary materialThe online version of this article (doi:10.1186/s12985-017-0735-3) contains supplementary material, which is available to authorized users.

A recombination between two Type 1 Porcine Reproductive and Respiratory Syndrome Virus (PRRSV‐1) vaccine strains has caused severe outbreaks in Danish pigs

“…Recombination between PRRSV field strains has been extensively described for PRRSV-2 (Dong et al, 2017;Li et al, 2009;Wenhui et al, 2012;Zhao et al, 2017) and less frequently for PRRSV-1 (Dortmans, Buter, Dijkman, Houben, & Duinhof, 2019;Martin-Valls et al, 2014). More rarely, recombination between PRRSV-1 field strains and strains of PRRSV-1 MLV vaccine strains has been reported (Chen et al, 2017;Frossard et al, 2013;Marton et al, 2019).…”

Complete Genome Sequence of a Novel Subgenotype of Porcine Reproductive and Respiratory Syndrome Virus Strain JX/CH/2016, Isolated in Jiangxi, China

“…In addition, genovariations of PRRSVs have been frequently observed. Recently, several provinces in China reported outbreaks of NADC30-like PRRSVs with genovariations existing in the open reading frame 5 (ORF5) region of the genome of PRRSVs ( 2 , 3 , 7 – 11 ). Herein, we report the full-length genome sequence and molecular characteristics of a novel subgenotype of the PRRSV strain JX/CH/2016 isolated in Jiangxi, China.…”

Genetic Characterization and Pathogenicity of a Novel Recombined Porcine Reproductive and Respiratory Syndrome Virus 2 among Nadc30-Like, Jxa1-Like, and Mlv-Like Strains

“…Recently, QYYZ-like PRRSV strains were discovered to recombine with JXA1-like strains (GDsg and GD1404) [ 15 , 16 ]. Additionally, NADC30-like strains were found to recombine with JXA1-like strains (HENAN-HEB, JL580, FJ1402, TJnh1501, 15HEN1, HNhx, and SCnj16) [ 17 , 18 , 19 , 20 , 21 , 22 , 23 ] or VR-2332-like strains (Chsx1401, HENAN-XINX, and HNyc15) [ 14 , 20 , 24 ]. Moreover, several complex recombinants among the three lineages of PRRSV-2 strains (SDhz1512, SD17-38, SCcd16, SCcd17, and SCya17) have also been observed in China [ 25 , 26 , 27 , 28 ].…”

“…Previous studies have revealed that natural recombination can occur between PRRSV field strains as well as between field and modified live virus (MLV) vaccine strains [ 22 , 29 , 30 ]. Since the highly pathogenic PRRS (HP-PRRS) outbreaks in China in 2006 [ 31 ], imported and domestic commercial MLV vaccines, such as CH-1R (parental strain CH-1a), Ingelvac PRRS MLV/RespPRRS MLV (VR-2332), JXA1-P80 (JXA1), TJM-F92 (TJ), HuN4-F112 (HuN4), R98 (R98), and GDr180 (GD), have been used to safeguard against PRRSV-2 throughout the country.…”