Pathogenicity comparison between highly pathogenic and NADC30-like porcine reproductive and respiratory syndrome virus

Porcine reproductive and respiratory syndrome virus (PRRSV) is a major economically significant pathogen that has adversely affected China's swine industry. Currently, a novel type 2 PRRSV, called the NADC30-like strain, is epidemic in numerous provinces of China, and commercial vaccines provide limited protection for infected animals. The extensive recombination phenomenon among NADC30-like PRRSVs is identified as a unique molecular characteristic of the virus. However, our understanding of how recombination influences NADC30-like PRRSVs is largely inadequate. In this study, we analysed the genetic characteristics of a recombinant NADC30-like PRRSV (SC-d) and examined its pathogenicity compared with a non-recombinant NADC30-like PRRSV (SD-A19) and a highly pathogenic PRRSV (HuN4). SC-d has three discontinuous deletions in nsp2, consistent with NADC30 isolated from the United States in 2008. Furthermore, we identified four recombination breakpoints in the SC-d genome, which separated the SC-d genome into four regions (regions A, B, C and D). Regions A and C are closely related to the JXA1-like strain, one of the earliest Chinese HP-PRRSV strains, and regions B and D are closely related to the NADC30 strain. Moreover, SC-d inoculated piglets exhibited a persistent fever, moderate weight loss, mild thymus atrophy and obvious microscopic lung lesions. In summary, the recombinant NADC30-like PRRSV SC-d strain displayed a higher pathogenicity than the non-recombinant NADC30-like PRRSV SD-A19 strain; however, the pathogenicity of the NADC30-like PRRSV SC-d was lower compared with the HP-PRRSV HuN4 strain in piglets. Our findings demonstrate that recombination is responsible for the enormous genetic diversity and pathogenicity variance of the NADC30-like PRRSV in China. This study provides a theoretical basis for developing a more reasonable PRRSV control and prevention strategy.

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

A natural recombinant PRRSV between HP-PRRSV JXA1-like and NADC30-like strains

Wang

Liu

Tang

et al. 2018

“…Several pathogenicity studies showed that NADC30‐like viruses isolated in recent years, such as HNjz15, CHsx1401, FJ1402 and HN201605, caused fever and respiratory symptoms, but no death (Sun et al., ; Zhang et al., ; Zhou et al., ; Zhang et al., ). The triple recombinant virus SDhz1512 has even lower virulence (60% morbidity and 0% mortality) than the NADC30‐like strains (Liu et al., ).…”

Section: Discussionmentioning

confidence: 99%

Emergence of a novel highly pathogenic recombinant virus from three lineages of porcine reproductive and respiratory syndrome virus 2 in China 2017

Chen

et al. 2018

Self Cite

A novel porcine reproductive and respiratory syndrome virus 2 (PRRSV2) was isolated from diseased piglets in Shandong, China in 2017 and denominated as SD17-38. ORF5 sequencing showed that SD17-38 contains a unique serine/asparagine deletion at position 33 and an asparagine insertion at position 60 of GP5, which has never been described. The SD17-38 complete genome was then determined, and genome-based phylogenetic analysis showed that SD17-38 is clustered with NADC30-like isolates. Sequence alignment and recombination analyses by RDP4 and SimPlot all indicated that SD17-38 is a recombinant virus from NADC30 (lineage 1), BJ-4 (lineage 5) and TJ (lineage 8) isolates. Animal challenge study in 4-week piglets showed that SD17-38 causes high fever (≥41°C), 100% morbidity and 40% mortality. In addition, significantly lower weight gain and severe histopathological lung lesions could be observed in SD17-38-infected pigs. In particular, the unique deletion and insertion in GP5 were stable during the challenge study. This study provides direct evidence for the natural occurrence of recombination events among three lineages of PRRSV2 in Chinese swine herds, resulting in the emergence of novel PRRSV variant with unique genetic property and high pathogenicity.

“…All PRRSV strains used in this study were stored in our laboratories including PRRSV1: BJEU06‐1 and HLJB1 strains (Chen et al, ; Chen, Liu, et al, ), CA‐PRRSV2: R98 and CH‐1R strains (Chen et al, ), HP‐PRRSV2: JXA1‐R and SHH strains (Chen et al, ; Tian et al, ), and NL‐PRRSV2: HNjz15 and SD17‐38 strains (Chen et al, ; Sun et al, ). The other viral pathogens including classical swine fever virus (CSFV) JS1805‐2 strain, porcine epidemic diarrhoea virus (PEDV) XM1‐2 strain, pseudorabies virus (PRV) XJ03 strain, porcine parvovirus (PPV) NADL‐2 strain, porcine circovirus (PCV) type 2 TJ08‐1 strain and type 3 SD17‐36 strain were used in the specificity tests of the assays (Chen, Li, et al, , ; Tian et al, ).…”

Section: Methodsmentioning

confidence: 99%

“…The infection of different PRRSV isolates causes similar clinical signs at the early stage of infection, but they have distinct virulence (Ming et al, ; Tian et al, ; Zhao et al, ). HP‐PRRSV2 isolates generally have the highest virulence followed by the NL‐PRRSV2 and CA‐PRRSV2 isolates (Li et al, ; Sun et al, ; Tian et al, ), while current Chinese PRRSV1 isolates are low virulent (Chen et al, ; Ming et al, ). In addition, commercial PRRSV vaccines provide limited cross‐protection against different genotypes/subtypes of PRRSV infection (Bai et al, ; Zhou et al, ).…”

Section: Introductionmentioning

confidence: 99%

Development of universal and quadruplex real‐time RT‐PCR assays for simultaneous detection and differentiation of porcine reproductive and respiratory syndrome viruses

Chen

Xiao

et al. 2019

Self Cite

Porcine reproductive and respiratory syndrome virus 1 (PRRSV1) and 2 (PRRSV2) (including 3 major subtypes: classical (CA‐PRRSV2), highly pathogenic (HP‐PRRSV2) and NADC30‐like (NL‐PRRSV2)) are currently coexisting in Chinese swine herds but with distinct virulence. Reliable detection and differentiation assays are crucial to monitor the prevalence of PRRSV and to adopt effective control strategies. However, current diagnostic methods cannot simultaneously differentiate the four major groups of PRRSV in China. In this study, universal and quadruplex real‐time RT‐PCR assays using TaqMan‐MGB probes were developed for simultaneous detection and differentiation of Chinese PRRSV isolates. The newly developed real‐time RT‐PCR assays exhibited good specificity, sensitivity, repeatability and reproducibility. In addition, the newly developed real‐time RT‐PCR assays were further validated by comparing with a universal PRRSV conventional RT‐PCR assay on the detection of 664 clinical samples collected from 2016 to 2019 in China. Based on the clinical performance, the agreements between the universal and quadruplex real‐time RT‐PCR assays and the conventional RT‐PCR assay were 99.55% and 99.40%, respectively. Totally 90 samples were detected as PRRSV‐positive, including 2 samples that were determined to be co‐infected with NL‐PRRSV2 and HP‐PRRSV2 isolates by the quadruplex real‐time RT‐PCR assay. ORF5 sequencing confirmed the real‐time RT‐PCR results that 2, 6, 27 and 57 of the 92 sequences were PRRSV1, CA‐PRRSV2, NL‐PRRSV2 and HP‐PRRSV2, respectively. This study provides promising alternative tools for simultaneous detection and differentiation of PRRSV circulating in Chinese swine herds.