Genetic Diversity of the ORF5 Gene of Porcine Reproductive and Respiratory Syndrome Virus Isolates in Southwest China from 2007 to 2009

Abstract

To gain insight into the molecular epidemiology and possible mechanisms of genetic variation of porcine reproductive and respiratory syndrome (PRRS) in Yunnan Province of China, the ORF5 gene of 32 PRRSV isolates from clinical samples collected from 2007 to 2009 were sequenced and analyzed. Nucleotide and amino acid analyses were carried out on 32 isolates and representative strains of the North American genotype, European genotype and two representative Chinese isolates. Results revealed that these isolates share 86.9–99.0% nucleotide and 87.5–98.0% amino acid identity with VR-2332 the prototypical North American PRRSV, 61.7–62.9% and 54.3–57.8% with Lelystad virus (LV) the representative strain of European genotype, 91.2–95.4% and 90.0–94.5% with CH-1a that was isolated in mainland China in 1996, 88.1–99.3% and 85.5–99.0% with JX-A1 the representative strain of High pathogenic PRRSV in China, and 86.2–99.8% and 85.5–100.0% between isolated strains of different years, respectively. Phylogenetic analysis revealed that all 32 PRRSV isolates belonged to the North American genotype and were further divided into two different subgenotypes. Subgenotype 1 comprised twenty two Yunnan isolates which divided into two branches. Subgenotype 2 comprised ten isolates which closely related to the RespPRRS vaccine and its parent strain VR-2332. The functional domains of GP5 such as the signal peptide, ectodomain, transmembrane regions and endodomain were identified and some motifs in GP5 with known functions, such as primary neutralizing epitope (PNE) and decoy epitope were also further analyzed. Our study shown the great genetic diversity of PRRSV in southwest China, rendering the guide for control and prevention of this disease.

Effects of ribavirin on the replication and genetic stability of porcine reproductive and respiratory syndrome virus

“…Because PRRSV evolves very quickly [9,10], there is a great deal of genetic variability among PRRSV strains. In general, PRRSV strains are grouped into European (type 1) and North American (type 2) genotypes [11][12][13], but high levels of genetic variability still exist among viruses, even within the same genotype [10,14,15], which results in suboptimal cross-protection between different PRRSV strains and becomes a significant impediment to the development of effective vaccines. Modified live virus (MLV) vaccines have been most commonly used to control PRRSV because they confer better protection against homologous virus strains compared to inactivated or recombinant vaccines [16].…”

Analysis of molecular variation in porcine reproductive and respiratory syndrome virus in China between 2007 and 2012

“…Other representative amino acid mutations of the PNE (S37→P37, H38→Q38/Y38, L41→S41, Y43→C43, and G52→V52) were also found in these 89 isolates. It has been reported that ORF5 codon positions 13 and 151 played a key role in denaturing VR2332 to MLV RespPRRSV (Yin G, et al, 2009). In this study, Q13 was observed in 7 of 89 isolates (7.87%), while R13 was observed in the remaining 82 isolates (92.13%) (Supplementary Table 2).…”

“…GP5 is one of the structural proteins with the highest variability in PRRSV . As the main candidate protein for the development of vaccine subunits, also as a result of its immunological significance and polymorphic nature, GP5 has been the target for analysis of the genetic diversity of PRRSV (Yin G, et al, 2009). The results in this study showed that the length of deduced amino acids of 89 complete ORF5 of PRRSV ranged from 199 aa to 201 aa (Supplementary Table 1).…”

“…It comprises 2-4 glycosylation sites, a 31-aa signal peptide, and 6 antigenic determinants that induce neutralizing antibodies (Yin G, et al, 2009;Mu C, et al, 2013). GP5 is one of the structural proteins with the highest variability in PRRSV .…”

Phylogeography, phylodynamics and the recent outbreak of lineage 3 porcine reproductive and respiratory syndrome viruses in China

“…5 lineage viruses were identified in China – lineage 8.7 (Chinese HP‐PRRSV), lineage 5.1 (VR2332‐like), lineage 1 (NADC30‐like), lineage 9 (JX014356.1_XJNJ‐12‐1) and lineage 3 (GM2‐like; Gao et al, ; Shi, Lam, Hon, Murtaugh, et al, ). Epidemiological studies reported that lineage 3 viruses are endemic in China from some time (Cao et al, ; Wang et al, ; Xie et al, ; Yin et al, ). Recent evidence states that novel lineage 3 viruses with increased virulence emerged in south China (Dong et al, ; Zhang et al, ).…”