title: Efficacy of a reformulated inactivated chimeric PCV1-2 vaccine based on clinical, virological, pathological and immunological examination under field conditions.
abstract: Inactivated chimeric porcine circovirus (PCV) 1-2 vaccine was initially taken off the market due to concerns that the vaccine virus was not killed and thus further replicated and spread in the pig population. In August 2011, a reformulated inactivated chimeric PCV1-2 vaccine re-entered the market. The efficacy of the reformulated inactivated chimeric PCV1-2 vaccine was evaluated under field conditions for registration as recommended by the Republic of Korea's Animal, Plant & Fisheries Quarantine & Inspection Agency. Three farms were selected based on their history of postweaning multisystemic wasting syndrome (PMWS). On each farm, a total of 50 3-week-old pigs were randomly allocated to one of two treatment groups: (i) vaccinated at 3 weeks of age and (ii) non-vaccinated. Clinical examination indicated that vaccinated animals displayed an improved average daily weight gain (672.2g/day vs. 625g/day; difference of +47.3g/day; P<0.05) and a reduced time to market (177 days vs. 183 days; difference of -6 days; P<0.05). Virological examination indicated that vaccinated animals displayed a reduced PCV2 load in the blood and nasal swabs compared to non-vaccinated animals. Pathological examination indicated that vaccination of pigs against PCV2 effectively reduced the number of PMWS-associated microscopic lesions and the PCV2 load in lymphoid tissues compared to non-vaccinated animals in the 3 herds. Immunological examination indicated that vaccinated animals induced PCV2-specific neutralizing antibodies (NA) and interferon-γ-secreting cells (IFN-γ-SCs). A reduction in the PCV2 load in the blood coincided with the appearance of both PCV2-specific NA and IFN-γ-SCs in the vaccinated animals. The number of CD4(+) cells was decreased in non-vaccinated animals compared to vaccinated animals. The reformulated inactivated chimeric PCV1-2 vaccine seems to be very effective in controlling PCV2 infection based on clinical, virological, pathological, and immunological evaluations under field conditions.
authors.affiliation: Department of Veterinary Pathology, College of Veterinary Medicine, Seoul National University, 599 Gwanak-ro, Gwanak-gu, Seoul 151-742, Republic of Korea.
authors.forename: Hwi Won
authors.initials: HW
authors.lastname: Seo
authors.forename: Kiwon
authors.initials: K
authors.lastname: Han
authors.forename: Yeonsu
authors.initials: Y
authors.lastname: Oh
authors.forename: Changhoon
authors.initials: C
authors.lastname: Park
authors.forename: Chanhee
authors.initials: C
authors.lastname: Chae
mesh_terms: D000818:Animals; D057134:Antibodies, Neutralizing / Q000097:blood; D000914:Antibodies, Viral / Q000097:blood; D000956:Antigens, Viral / Q000276:immunology; D018173:Circoviridae Infections / Q000276:immunology / Q000517:prevention & control / Q000662:veterinary*; D017925:Circovirus / Q000276:immunology; D004279:DNA, Viral / Q000097:blood; D007111:Immunity, Cellular; D056724:Immunity, Humoral; D007371:Interferon-gamma / Q000276:immunology; D016131:Lymphocyte Subsets / Q000276:immunology; D053570:Porcine Postweaning Multisystemic Wasting Syndrome / Q000276:immunology / Q000517:prevention & control* / Q000821:virology; D056910:Republic of Korea; D013552:Swine; D014611:Vaccination / Q000662:veterinary; D015164:Vaccines, Inactivated / Q000276:immunology; D014765:Viral Vaccines / Q000276:immunology*
chemical_list: D057134:Antibodies, Neutralizing; D000914:Antibodies, Viral; D000956:Antigens, Viral; D004279:DNA, Viral; D015164:Vaccines, Inactivated; D014765:Viral Vaccines; D007371:Interferon-gamma