title: Nested polymerase chain reaction detection and duration of porcine circovirus type 2 in semen with sperm morphological analysis from naturally infected boars.
abstract: A nested polymerase chain reaction (nPCR) protocol was applied to porcine semen to demonstrate the porcine circovirus type 2 (PCV2) shedding patterns and duration in naturally infected boars. Sperm morphology analysis was performed on a subset of samples to determine if the presence of PCV2 DNA in semen was associated with reduced semen quality. Semen was collected serially from 43 boars representing 6 breeds, aged 33.9 to 149.3 weeks. Of the 903 semen samples collected, 30 samples (3.3%) were positive for PCV2 DNA by nPCR from 13 boars. Boars shedding PCV2 DNA in semen ranged between 35.9 and 71.0 weeks of age, and shedding occurred during a period of up to 27.3 weeks. A semen nPCR test was 2.6 times more likely to be positive when collected from pigs that were < or =52 weeks of age, and 3.0 times more likely to be positive when collected from pigs that were < or =26 weeks from time of entry into the stud main unit (generalized estimating equations: P = 0.02; 95% confidence interval [CI] of the odds ratio 1.2 to 5.5, and P = 0.01; 95% CI of the odds ratio 1.3 to 6.9, respectively). These results demonstrate a sporadic and long-term shedding pattern of PCV2 DNA in semen from naturally infected boars. PCV2 DNA in semen does not appear to have detrimental effects on sperm morphology; however, boar age and, possibly, breed may contribute to the persistence of PCV2-shedding in semen.
authors.affiliation: Department of Veterinary Microbiology, Western College of Veterinary Medicine, University of Saskatchewan, Saskatoon, Saskatchewan S7N 5B4, Canada.
authors.forename: Kathleen A
authors.initials: KA
authors.lastname: McIntosh
authors.forename: John C S
authors.initials: JC
authors.lastname: Harding
authors.forename: Sarah
authors.initials: S
authors.lastname: Parker
authors.forename: John A
authors.initials: JA
authors.lastname: Ellis
authors.forename: Greg D
authors.initials: GD
authors.lastname: Appleyard
mesh_terms: D000818:Animals; D017925:Circovirus / Q000235:genetics* / Q000302:isolation & purification*; D004279:DNA, Viral / Q000032:analysis / Q000235:genetics; D008297:Male; D016133:Polymerase Chain Reaction / Q000379:methods / Q000662:veterinary*; D012661:Semen / Q000821:virology*; D013094:Spermatozoa / Q000166:cytology* / Q000821:virology; D013552:Swine / Q000821:virology*
chemical_list: D004279:DNA, Viral