TY - JOUR
T1 - Porcine reproductive and respiratory syndrome virus
T2 - Genetic diversity of recent British isolates
AU - Frossard, Jean Pierre
AU - Hughes, Gareth J.
AU - Westcott, David G.
AU - Naidu, Brindha
AU - Williamson, Susanna
AU - Woodger, Nicholas G.A.
AU - Steinbach, Falko
AU - Drew, Trevor W.
PY - 2013/3/23
Y1 - 2013/3/23
N2 - Porcine reproductive and respiratory syndrome (PRRS) continues to be a significant problem for European pig producers, contributing to porcine respiratory disease complex, neonatal piglet mortality, infertility and occasional abortion storms. PRRS virus (PRRSV), a member of the arterivirus family with two defined major genotypes, has been shown to be quite genetically diverse. In the present study, genetic analysis of multiple gene regions of over 100 viruses isolated in Britain between 2003 and 2007 revealed that the diversity of British strains is now far greater than during the early 1990s. All isolates belong to genotype 1 (European). While some recent isolates are still very similar to early isolates, a wide range of more diverse viruses is now also circulating. Interestingly, some isolates were found to be very similar to a modified-live vaccine strain, and it is suggested that use of the vaccine has affected the evolution pattern of PRRS virus strains in Britain. Evidence of deletions in one viral gene, ORF3, and of genome recombination was also seen. A molecular clock model using the ORF7 sequences estimates the rate of substitution as 3.8×10-3 per site per year, thereby dating the most recent common ancestor of all British viruses to 1991, coincident with the first outbreak of disease. Our findings therefore have implications for both the diagnostic and prophylactic methods currently being used, which are discussed.
AB - Porcine reproductive and respiratory syndrome (PRRS) continues to be a significant problem for European pig producers, contributing to porcine respiratory disease complex, neonatal piglet mortality, infertility and occasional abortion storms. PRRS virus (PRRSV), a member of the arterivirus family with two defined major genotypes, has been shown to be quite genetically diverse. In the present study, genetic analysis of multiple gene regions of over 100 viruses isolated in Britain between 2003 and 2007 revealed that the diversity of British strains is now far greater than during the early 1990s. All isolates belong to genotype 1 (European). While some recent isolates are still very similar to early isolates, a wide range of more diverse viruses is now also circulating. Interestingly, some isolates were found to be very similar to a modified-live vaccine strain, and it is suggested that use of the vaccine has affected the evolution pattern of PRRS virus strains in Britain. Evidence of deletions in one viral gene, ORF3, and of genome recombination was also seen. A molecular clock model using the ORF7 sequences estimates the rate of substitution as 3.8×10-3 per site per year, thereby dating the most recent common ancestor of all British viruses to 1991, coincident with the first outbreak of disease. Our findings therefore have implications for both the diagnostic and prophylactic methods currently being used, which are discussed.
KW - Genetic variation
KW - Molecular epidemiology
KW - Molecular evolution
KW - Molecular sequence data
KW - Phylogeny
KW - Porcine respiratory and reproductive syndrome virus
KW - Viral/genetics RNA
UR - http://www.scopus.com/inward/record.url?scp=84872493003&partnerID=8YFLogxK
U2 - 10.1016/j.vetmic.2012.11.011
DO - 10.1016/j.vetmic.2012.11.011
M3 - Article
C2 - 23218831
AN - SCOPUS:84872493003
SN - 0378-1135
VL - 162
SP - 507
EP - 518
JO - Veterinary Microbiology
JF - Veterinary Microbiology
IS - 2-4
ER -
