title: Effects of the timing of the administration of Mycoplasma hyopneumoniae bacterin on the development of lesions associated with porcine circovirus type 2.
abstract: To determine whether there is an effect of the timing of vaccination on porcine circovirus type 2 (PCV-2) replication and PCV-2-associated lesions, 78 pigs were randomly assigned to eight groups: group 1 (10 pigs) was vaccinated with a commercial Mycoplasma hyopneumoniae vaccine at two and four weeks of age, group 2 (nine pigs) was vaccinated at four and six weeks of age, group 3 (10 pigs) at six and eight weeks of age and group 4 (10 pigs) at eight and 10 weeks of age; group 5 (nine pigs) was vaccinated once with a double dose at four weeks of age, and group 6 (10 pigs) was vaccinated once with a double dose at eight weeks of age. Groups 7 and 8, both of 10 pigs, were not vaccinated. At eight weeks of age, the pigs in groups 1 to 7 were inoculated with PCV-2. Fourteen days after they had been inoculated, the pigs in groups 1, 4 and 5 had significantly (P<0.05) more copies of the PCV-2 genome in their serum than the unvaccinated pigs. Microscopically, 14 of the 68 inoculated pigs had normal lymphoid tissues, 40 had mild PCV-2-associated lymphoid lesions and 14 had moderate lesions. The mean overall lymphoid lesions (lymphoid depletion, granulomatous inflammation, and quantity of PCV-2 antigen in spleen, tonsil, and five lymph nodes) were significantly (P<0.05) more severe in groups 4 and 5 than in groups 2, 3, 7 and 8.
authors.affiliation: Department of Veterinary Diagnostic and Production Animal Medicine, College of Veterinary Medicine, Iowa State University, Ames, IA 50011, USA.
authors.forename: T
authors.initials: T
authors.lastname: Opriessnig
authors.forename: P G
authors.initials: PG
authors.lastname: Halbur
authors.forename: S
authors.initials: S
authors.lastname: Yu
authors.forename: E L
authors.initials: EL
authors.lastname: Thacker
authors.forename: M
authors.initials: M
authors.lastname: Fenaux
authors.forename: X J
authors.initials: XJ
authors.lastname: Meng
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D000914:Antibodies, Viral / Q000097:blood; D000956:Antigens, Viral / Q000378:metabolism; D001428:Bacterial Vaccines / Q000008:administration & dosage / Q000276:immunology*; D018173:Circoviridae Infections / Q000276:immunology / Q000473:pathology / Q000662:veterinary* / Q000821:virology; D017925:Circovirus / Q000235:genetics / Q000276:immunology* / Q000502:physiology; D004279:DNA, Viral / Q000235:genetics / Q000276:immunology; D007150:Immunohistochemistry; D045705:Mycoplasma hyopneumoniae / Q000276:immunology*; D011897:Random Allocation; D013552:Swine; D013553:Swine Diseases / Q000276:immunology* / Q000473:pathology / Q000821:virology; D013997:Time Factors; D014611:Vaccination / Q000379:methods / Q000592:standards / Q000662:veterinary*; D014779:Virus Replication / Q000276:immunology; D019282:Wasting Syndrome / Q000276:immunology / Q000473:pathology / Q000662:veterinary / Q000821:virology
chemical_list: D000914:Antibodies, Viral; D000956:Antigens, Viral; D001428:Bacterial Vaccines; D004279:DNA, Viral