PMID- 12951261
OWN - NLM
STAT- MEDLINE
DCOM- 20040220
LR  - 20220408
IS  - 0168-1702 (Print)
IS  - 0168-1702 (Linking)
VI  - 96
IP  - 1-2
DP  - 2003 Oct
TI  - Molecular epidemiology of porcine reproductive and respiratory syndrome virus 
      (PRRSV) in Quebec.
PG  - 3-14
AB  - Porcine reproductive and respiratory syndrome virus (PRRSV) strains identified in 
      samples from 226 field cases originating from Quebec herds and submitted over a 
      4-year period (March 1998-July 2002) were studied. Sequencing of PRRSV strains 
      was performed on the ORF5 gene amplified product and restriction fragment length 
      polymorphism (RFLP) patterns for enzymes MluI, HincII and SacII were determined 
      on these sequences. Twenty-four other PRRSV isolates including three vaccine 
      strains were also included for comparison purposes and the total of 250 PRRSV 
      strains were used in a phylogenetic analysis. Clinical and epidemiological data 
      were collected through a questionnaire for each of the submitted field cases. 
      About 75% of the cases were submitted during autumn and winter. Over 60% of the 
      cases were submitted for reproductive problems, 33% for respiratory problems and 
      6% for increased PRRSV serological titers in the herd in absence of clinical 
      signs. In 69% of the cases there was a PRRS vaccination program for the herd. 
      However, only 26% of the animals from which samples were obtained had been 
      vaccinated themselves. The genomic analysis of this large number of strains 
      revealed a great variability of PRRSV ORF5 with 59% of amino acid positions being 
      polymorphic. A total of 29 RFLP patterns were obtained. The main RFLP patterns 
      obtained were 1-8-4 (28%), 1-4-4 (16%), 1-2-4 (9%) and 1-11-4 (9%). The global 
      findings derived from the molecular analysis of 226 PRRSV strains suggest that 
      PRRSV circulating in Quebec represent a different sub-population of strains. 
      Vaccine-like strains were identified in 10% of the cases. A phylogenetic tree 
      enabled the identification of 44 groupings comprising two to 23 strains each. Of 
      the 250 sequences analyzed, 183 (73%) could be included in one of these 
      groupings. The data collected from the questionnaires were used to establish 
      epidemiological links between strains within groupings. The main relationships 
      between strains within a grouping were the introduction of infected animals (19%) 
      and area spread (33%). In 40% of the cases from which an area spread was 
      suspected, herds were located within 3 km from another. Aerosol transmission was 
      suspected in several cases, more than half of which belonged to different owners. 
      In 41 herds, more than one strain (2-8) were identified over a period varying 
      from 3 months to 4 years. Data indicated that a PRRSV strain can persist in a 
      herd up to 3.5 years displaying as little as 2% variation in ORF5 during this 
      time. In 78% of the herds with multiple submissions genetically different strains 
      were identified; often within 1 year of the original identification. These 
      genetically distinct strains were often associated with a recrudescence of 
      moderate to severe clinical signs. Coexistence on the same farm of different 
      PRRSV strains was also observed.
FAU - Larochelle, Renee
AU  - Larochelle R
AD  - Laboratoire d'hygiene veterinaire et alimentaire, Agence canadienne d'inspection 
      des aliments, 3400 Casavant ouest, St-Hyacinthe, Quebec, Canada J2S 8E3. 
      larocheller@videotron.ca
FAU - D'Allaire, Sylvie
AU  - D'Allaire S
FAU - Magar, Ronald
AU  - Magar R
LA  - eng
PT  - Journal Article
PT  - Research Support, Non-U.S. Gov't
PL  - Netherlands
TA  - Virus Res
JT  - Virus research
JID - 8410979
RN  - 0 (DNA, Viral)
SB  - IM
MH  - Animals
MH  - DNA, Viral/chemistry/genetics/isolation & purification
MH  - Open Reading Frames
MH  - Phylogeny
MH  - Polymerase Chain Reaction/veterinary
MH  - Polymorphism, Restriction Fragment Length
MH  - Porcine Reproductive and Respiratory Syndrome/*epidemiology
MH  - Porcine respiratory and reproductive syndrome 
      virus/classification/*genetics/isolation & purification/pathogenicity
MH  - Quebec
MH  - Swine
MH  - Swine Diseases/*epidemiology
EDAT- 2003/09/03 05:00
MHDA- 2004/02/21 05:00
CRDT- 2003/09/03 05:00
PHST- 2003/09/03 05:00 [pubmed]
PHST- 2004/02/21 05:00 [medline]
PHST- 2003/09/03 05:00 [entrez]
AID - S0168170203001680 [pii]
AID - 10.1016/s0168-1702(03)00168-0 [doi]
PST - ppublish
SO  - Virus Res. 2003 Oct;96(1-2):3-14. doi: 10.1016/s0168-1702(03)00168-0.