Emergence of novel recombinant type 2 porcine reproductive and respiratory syndrome viruses with high pathogenicity for piglets in China

Several studies in this journal reported genetic diversity of African swine fever virus (ASFV) genomes and suggested ASFV was a potential threat to unaffected countries in Asia. 1 Ye C. Wu X.P. Chen T.T. Huang Q.Y. Fang R.D. An T.Q. The updated analysis of African swine fever virus genomes: two novel genotypes are identified. J Infect. 2020; 80: 232-254https://doi.org/10.1016/j.jinf.2019.10.013 Abstract Full Text Full Text PDF PubMed Scopus (3) Google Scholar , 2 Li X.B. Xiao K.P. Zhang Z.P. Yang J.J. Wang R.C. Shen X.J. et al. The recombination hot spots and genetic diversity of the genomes of African swine fever viruses. J Infect. 2020; 80: 121-142https://doi.org/10.1016/j.jinf.2019.08.007 Abstract Full Text Full Text PDF PubMed Scopus (11) Google Scholar , 3 Lu G. Pan J.L. Zhang G.H. African swine fever virus in Asia: its rapid spread and potential threat to unaffected countries. J Infect. 2020; 80: 350-371https://doi.org/10.1016/j.jinf.2019.11.011 Abstract Full Text Full Text PDF Scopus (16) Google Scholar Porcine reproductive and respiratory syndrome (PRRS), caused by porcine reproductive and respiratory syndrome virus (PRRSV), is another swine viral disease causing huge economic losses to the global swine industry. 4 Eric J.N. James B.K. Colin D.J. John W.M. Eric J.B. Ann H.S. et al. Assessment of the economic impact of porcine reproductive and respiratory syndrome on swine production in the United States. J Am Vet Med Assoc. 2005; 227: 385-392https://doi.org/10.2460/javma.2005.227.385 Crossref PubMed Scopus (750) Google Scholar PRRSV is an enveloped, positive-strand RNA virus under the family Arteriviridae. This virus is divided into major types, the North American type 2 and the European type 1, with VR-2332 and Lelystad as prototypical strains, respectively. 5 Lunney J.K. Fang Y. Ladinig A. Chen N. Li Y. Rowland R.R. et al. Porcine reproductive and respiratory syndrome virus (PRRSV): pathogenesis and interaction with the immune system. Annu Rev Anim Biosci. 2016; 4: 129-154https://doi.org/10.1146/annurev-animal-022114-111025 Crossref PubMed Scopus (312) Google Scholar Emergence of novel PRRSV strains have caused many outbreaks of severe PRRS. 6 Tian K. Yu X. Zhao T. Feng Y. Cao Z. Wang C. et al. Emergence of fatal PRRSV variants: unparalleled outbreaks of a typical PRRS in China and molecular dissection of the unique hallmark. PLoS ONE. 2007; 2: e526https://doi.org/10.1371/journal.pone.0000526 Crossref PubMed Scopus (739) Google Scholar Since 2013, several PRRSV NADC30-like strains, sharing a unique discontinuous deletion of 131 aa in non-structural protein 2 (nsp2), have emerged in China and caused outbreaks. 7 Zhou L. Wang Z.C. Ding Y.P. Ge X.N. Guo X. Yang H.C. NADC30-like strain of porcine reproductive and respiratory syndrome virus, China. Emerg Infect Dis. 2015; 21: 2256-2257https://doi.org/10.3201/eid2112.150360 Crossref PubMed Scopus (126) Google Scholar In 2020, a novel PRRSV variant, with a 142aa deletion in nsp2, emerged in north China. Via this letter we report the unique genetic characteristics of this novel PRRSV variant and its pathogenicity for piglets.