Porcine Reproductive and Respiratory Syndrome Virus Comparison: Divergent Evolution on Two Continents

Abstract

Porcine reproductive and respiratory syndrome virus (PRRSV) is a recently described arterivirus responsible for disease in swine worldwide. Comparative sequence analysis of 3′-terminal structural genes of the single-stranded RNA viral genome revealed the presence of two genotypic classes of PRRSV, represented by the prototype North American and European strains, VR-2332 and Lelystad virus (LV), respectively. To better understand the evolution and pathogenicity of PRRSV, we obtained the 12,066-base 5′-terminal nucleotide sequence of VR-2332, encoding the viral replication activities, and compared it to those of LV and other arteriviruses. VR-2332 and LV differ markedly in the 5′ leader and sections of the open reading frame (ORF) 1a region. The ORF 1b sequence was nearly colinear but varied in similarity of proteins encoded in identified regions. Furthermore, molecular and biochemical analysis of subgenomic mRNA (sgmRNA) processing revealed extensive variation in the number of sgmRNAs which may be generated during infection and in the lengths of noncoding sequence between leader-body junctions and the translation-initiating codon AUG. In addition, VR-2332 and LV select different leader-body junction sites from a pool of similar candidate sites to produce sgmRNA 7, encoding the viral nucleocapsid protein. The presence of substantial variations across the entire genome and in sgmRNA processing indicates that PRRSV has evolved independently on separate continents. The near-simultaneous global emergence of a new swine disease caused by divergently evolved viruses suggests that changes in swine husbandry and management may have contributed to the emergence of PRRS.

Highly pathogenic porcine reproductive and respiratory syndrome virus infection results in acute lung injury of the infected pigs

“…Different pathogenic PRRSV strains in the field induced totally different consequences of infected pigs because of genetically extensive variation (Li et al, 2007;Meng, 2000;Nelsen et al, 1999). Our previous studies have shown that the low pathogenic PRRSV (LP-PRRSV) infection resulted in highly pathogenic porcine reproductive and respiratory syndrome virus (HP-PRRSV) infection pigs lung acute lung injury (ALI)…”

Effect of porcine circovirus type 2a or 2b on infection kinetics and pathogenicity of two genetically divergent strains of porcine reproductive and respiratory syndrome virus in the conventional pig model

“…Porcine reproductive and respiratory syndrome virus (PRRSV), a single-stranded, positive-sense RNA virus, is characterized by a high mutation rate with the potential of genetically diverse strains evolving over time (Forsberg et al, 2001;Hanada et al, 2005;Pirzadeh et al, 1998;Rowland et al, 1999). In the past, PRRSV isolates have emerged within the swine population with varying degrees of virulence (Fang et al, 2007;Han et al, 2006;Nelsen et al, 1999) possibly due to a high degree of mutation and recombination (Yuan et al, 1999(Yuan et al, , 2000(Yuan et al, , 2001(Yuan et al, , 2004. More recently, attention has focused on the occurrence of high mortality in Chinese swine herds which Veterinary Microbiology 158 (2012) To determine differences in infection kinetics of two temporally and genetically different type 2 porcine reproductive and respiratory syndrome virus (PRRSV) isolates in vivo with and without concurrent porcine circovirus (PCV) type 2a or 2b infection, 62 pigs were randomly assigned to one of seven groups: negative controls (n = 8); pigs coinfected with a 1992 PRRSV strain (VR-2385) and PCV2a (CoI-92-2a; n = 9), pigs coinfected with VR-2385 and PCV2b (CoI-92-2b; n = 9), pigs coinfected with a 2006 PRRSV strain (NC16845b) and PCV2a (CoI-06-2a; n = 9), pigs coinfected with NC16845b and PCV2b (CoI-06-2b; n = 9), pigs infected with VR-2385 (n = 9), and pigs infected with NC16845b (n = 9).…”

A method to provide improved dose–response estimates for airborne pathogens in animals: An example using porcine reproductive and respiratory syndrome virus

“…Isolate ATCC VR-2332 (American Type Culture Collection, Manassas, VA, USA; GenBank accession number PRU87392; Nelsen et al, 1999) was propagated in MARC-145 cells, as described in Hermann et al (2007). To prepare one lot of high-titered PRRSV sufficient to conduct all the replicates, the propagated virus was pooled and concentrated using a Prep/Scale spiral wound ultrafiltration module (Model CDUF 001 LH, Millipore, Billerica, MA, USA) such that approximately 2 l of supernatant was reduced to approximately 200 ml of virus stock.…”