The emergence of a highly pathogenic porcine reproductive and respiratory syndrome virus with additional 120aa deletion in Nsp2 region in Jiangxi, China

Abstract

Highly pathogenic porcine reproductive and respiratory syndrome (HP-PRRS), which emerged in China in 2006, was characterized by high fever, high morbidity and high mortality. The causative agent of the disease was a highly pathogenic variant of porcine reproductive and respiratory syndrome virus (also called HP-PRRSV), which has a discontinuous deletion of 1 + 29 amino acids (aa) in the Nsp2 coding region, compared to classical PRRSV. In 2014, fattened pigs on a pig farm in Jiangxi Province suffered from clinical symptoms of high fever, dyspnoea and death. A PRRSV, termed JX2014T2, was isolated from samples of the dead pigs. Genomic analysis of the isolated PRRSV indicated that the genome of the virus was 14,960 bp in length and belonged to the North American genotype. In the Nsp2-coding region, there was a discontinuous deletion of 1 + 29 aa, similar to HP-PRRSV; however, an additional continuous deletion of 120 amino acids between aa 628 and 747 was found. Further analysis of the pathogenicity of PRRSV JX2014T2 was performed in piglets, and the results indicated that all infected piglets suffered from typical clinical symptoms of PRRS, such as high fever, cough, mental depression, anorexia, dyspnoea and palpebral swelling and died within 15 days postinfection (dpi). This demonstrated that the newly isolated PRRSV JX2014T2 strain containing an additional deletion of 120 aa is highly pathogenic to piglets, suggesting that a highly pathogenic variant with new genetic features is circulating in China.

Chimeric HP-PRRSV2 containing an ORF2-6 consensus sequence induces antibodies with broadly neutralizing activity and confers cross protection against virulent NADC30-like isolate

“…In addition, MLV-derived field isolates and recombinants from MLV and wild-type strains have been isolated [ 26 , 62 ]. Moreover, some MLV-like isolates (NT1, JX2014T2 and XJ17-5) are highly virulent viruses determined by animal challenge studies [ 24 , 63 , 64 ]. Therefore, more attention should be paid to PRRS vaccine safety.…”

Identification of Two Porcine Reproductive and Respiratory Syndrome Virus Variants Sharing High Genomic Homology but with Distinct Virulence

“…Whether these highly homologous HP-PRRSV variants with novel deletion in nsp2 have distinct virulence becomes an interesting question. Notably, a recent study identified that a new isolate JX2014T2, which contains the same 150-amino-acid deletion in nsp2 , is highly pathogenic to piglets [24]. However, the similarity between the JX2014T2 and our isolates was unable to be determined because the JX2014T2 sequence is not available.…”

“…Marc-145 cells were infected with 200 median tissue culture infectious doses (TCID 50 ) of XJ17-5 and JSTZ1712-12, respectively. The infected Marc-145 cells were fixed at 24 h post infection and evaluated by IFA according to the standard procedure [24]. Porcine reproductive and respiratory syndrome virus (PRRSV)-specific murine mAb 15A1 (1:500 dilution) against the N protein was used as the primary antibody, while the Dylight 594 (Goat anti-mouse IgG, 1:1000, Invitrogen) was used as the secondary antibody.…”

Reappraisal of PRRS Control Strategies: The Way forward

“…These were observed e.g. in virulent Chinese PRRSV strains [108]. Interestingly, some nsp2 deletions were shown to reduce the expression of IL-1 beta [99].…”