The emergence of porcine circovirus 2b genotype (PCV-2b) in swine in Canada.
Since late 2004, the swine industry in the province of Quebec has experienced a significant increase in death rate related to postweaning multisystemic wasting syndrome (PMWS). To explain this phenomenon, 2 hypotheses were formulated: 1) the presence of a 2nd pathogen could be exacerbating the porcine circovirus 2 (PCV-2) infection, or 2) a new and more virulent PCV-2 strain could be infecting swine. In 2005, 13 PMWS cases were submitted to the Quebec provincial diagnostic laboratory and PCV-2 was the only virus that could be found consistently by PCR in all 13 samples. The PCR detection results obtained for other viruses revealed the following: 61.5% were positive for porcine reproductive and respiratory syndrome virus, 30.8% for swine influenza virus, 15.4% for porcine parvovirus, 69.2% for swine torque teno virus (swTTV), 38.5% for swine hepatitis E virus (swHEV) and 84.6% for Mycoplasma hyorhinis; transmissible gastroenteritis virus and porcine respiratory coronavirus (TGEV/PRCV) was not detected. Sequences of the entire genome revealed that these PCV-2 strains belonged to a genotype (named PCV-2b) that has never been reported in Canada. Further sequence analyses on 83 other Canadian PCV-2 positive cases submitted to the provincial diagnostic laboratory during years 2005 and 2006 showed that 79.5% of the viral sequences obtained clustered in the PCV-2b genotype. The appearance of the PCV-2b genotype in Canada may explain the death rate increase related to PMWS, but this relationship has to be confirmed.
Gagnon
Carl A
CA
Service de diagnostic, Université de Montréal, St-Hyacinthe, Québec. carl.a.gagnon@umontreal.ca
Tremblay
Donald
D
Tijssen
Peter
P
Venne
Marie-Hélène
MH
Houde
Alain
A
Elahi
Seyyed Mehdy
SM
D000818:Animals; D002170:Canada / Q000453:epidemiology; D017925:Circovirus / Q000145:classification / Q000302:isolation & purification / Q000472:pathogenicity*; D004279:DNA, Viral / Q000235:genetics*; D004196:Disease Outbreaks / Q000662:veterinary*; D005260:Female; D005838:Genotype; D008297:Male; D010802:Phylogeny; D016133:Polymerase Chain Reaction / Q000662:veterinary; D053570:Porcine Postweaning Multisystemic Wasting Syndrome / Q000453:epidemiology* / Q000401:mortality / Q000821:virology; D013552:Swine; D014774:Virulence