Porcine reproductive and respiratory disease virus: Evolution and recombination yields distinct ORF5 RFLP 1-7-4 viruses with individual pathogenicity

Abstract

Recent cases of porcine reproductive and respiratory syndrome virus (PRRSV) infection in United States swine-herds have been associated with high mortality in piglets and severe morbidity in sows. Analysis of the ORF5 gene from such clinical cases revealed a unique restriction fragment polymorphism (RFLP) of 1-7-4. The genome diversity of seventeen of these viruses (81.4% to 99.8% identical; collected 2013-2015) and the pathogenicity of 4 representative viruses were compared to that of SDSU73, a known moderately virulent strain. Recombination analyses revealed genomic breakpoints in structural and nonstructural regions of the genomes with evidence for recombination events between lineages. Pathogenicity varied between the isolates and the patterns were not consistent. IA/2014/NADC34, IA/2013/ISU-1 and IN/2014/ISU-5 caused more severe disease, and IA/2014/ISU-2 did not cause pyrexia and had little effect on pig growth. ORF5 RFLP genotyping was ineffectual in providing insight into isolate pathogenicity and that other parameters of virulence remain to be identified.

Detection of porcine reproductive and respiratory syndrome virus ( PRRSV ) 1‐7‐4‐type strains in Peru

“…While differences in virulence were reported for US PRRSV 1‐7‐4 strains under experimental conditions, field reports consistently describe a large number of abortions and pyrexia in affected farms (van Geelen et al., ). A similar clinical presentation was overserved in Peru during the outbreaks investigated here.…”

“…Prediction of the RFLP cut pattern for each sample included here was performed. ORF5 RFLP typing revealed that 15 samples (75%) belong to the PRRSV 1‐7‐4 type, which have been circulating in the US since 2013–2014 (Geelen et al., ). Additionally, two samples contained 1‐7‐3 PRRSV strains, two samples contained 1‐7‐2 PRRSV strains and one PRRSV sample was typed as 1‐4‐4 (Table ).…”

Pathogenicity of porcine reproductive and respiratory syndrome virus (ORF5 RFLP 1-7-4 viruses) in China

“…To determine the pathogenicity of PRRSV, the use of RFLP typing is not deterministic to conclude disease severity, and so far, no single domain is found to be associated with the pathogenic strain (van Geelen et al, 2018). Therefore, our approach to evaluating strain pathogenicity involved the isolation of the NADC34‐like strain in China and conducting in vivo experiments using the pig model.…”

“…Fifteen three‐week‐old pigs that were free from PRRSV, porcine circovirus type 2 (PCV2) and pseudorabies virus (PRV) infections were randomly divided into three groups, with five pigs in each group, and we first performed serological and RT‐PCR tests on pregnant sows and selected negative pregnant sows. After the piglets were produced, we performed serological and RT‐PCR tests on the piglets and selected negative piglets for pathogenicity testing (van Geelen et al, 2018; Jestin, Foulon, Pertuiset, Blanchard, & Labourdet, 1990; Pogranichnyy et al, 2000; Sui et al, 2018). The experimental pigs were maintained in its respective individual biosafety rooms under the following conditions: (a) PRRSV‐ZDXYL‐China‐2018‐1‐inoculated group ( n = 5); (b) LQ‐JXA1‐like‐inoculated group ( n = 5) and (c) phosphate‐buffered saline (PBS) as a negative control ( n = 5).…”

The infectious cDNA clone of commercial HP‐PRRS JXA1‐R‐attenuated vaccine can be a potential effective live vaccine vector

“…Since 2013, NADC30‐like PRRSV2 (lineage 1) variants have been prevalent in China (Brockmeier et al., 2012; Zhao et al., 2015; Zhou, Wang, et al., 2015). Since 2017, NADC34‐like PRRSV2 (lineage 1) has been detected and has the potential to be an endemic strain in China (van Geelen et al., 2018; Xu et al., 2020; Zhang et al., 2018). In addition, PRRSV1 isolates were also sporadically detected in China in recent years (Chen et al., 2011, 2017; Liu et al., 2017; Zhou, Liu, et al., 2015).…”