title: A commercial vaccine based on PCV2a and an experimental vaccine based on a variant mPCV2b are both effective in protecting pigs against challenge with a 2013 U.S. variant mPCV2b strain.
abstract: During 2012 and 2013, an apparent increase in porcine circovirus associated disease occurred in the USA. A variant PCV2b strain designated mPCV2b was recovered from many of these cases. This raised concerns of a decrease in efficacy of commercially available PCV2 vaccines. The objective of this study was to compare the ability of a commercial PCV2a-based vaccine and an experimental mPCV2b-based vaccine to control mPCV2b-associated disease, lesions, and viremia in a challenge model. Twenty-six caesarian-derived, colostrum-deprived pigs were randomly assigned to one of four groups: (1) vaccinated with a commercial PCV2a-based vaccine and challenged (PCV2a-VAC; n=7), (2) vaccinated with an experimental mPCV2b-based vaccine and challenged (mPCV2b; n=7), (3) sham-vaccinated with saline and challenged (positive controls; n=7), and (4) sham-vaccinated with saline without challenge (negative controls; n=5). Vaccination was done on D0 and D14, challenge was done on D28 using a tissue homogenate containing PRRSV and mPCV2b and the experiment was terminated on D49. Among the challenged pigs, 47.6% (10/21) developed severe clinical disease and either died or had to be humanely euthanized between D39 and D48 (11-20 days after challenge). PCV2 viremia was almost completely absent in the vaccinated groups regardless of vaccine type except for two PCV2a-vaccinated pigs which had detectable PCV2 DNA levels on individual days after challenge. Microscopic lesions typical of PCV2 infection were limited to the positive control group which developed mild-to-severe lesions associated with low-to-abundant PCV2 antigen. Under the conditions of this study, PCV2 vaccines regardless of PCV2 type were effective against mPCV2b challenge.
authors.affiliation: Department of Veterinary Diagnostic and Production Animal Medicine, College of Veterinary Medicine, Iowa State University, Ames, Iowa, USA; The Roslin Institute and The Royal (Dick) School of Veterinary Studies, University of Edinburgh, Midlothian, United Kingdom. Electronic address: Tanja.Opriessnig@roslin.ed.ac.uk.
authors.forename: Tanja
authors.initials: T
authors.lastname: Opriessnig
authors.affiliation: Department of Veterinary Diagnostic and Production Animal Medicine, College of Veterinary Medicine, Iowa State University, Ames, Iowa, USA; Laboratório de Pesquisa em Virologia Animal, Departamento de Medicina Veterinária Preventiva, Escola de Veterinária, Universidade Federal de Minas Gerais, Brazil.
authors.forename: Priscilla F
authors.initials: PF
authors.lastname: Gerber
authors.affiliation: Department of Veterinary Diagnostic and Production Animal Medicine, College of Veterinary Medicine, Iowa State University, Ames, Iowa, USA.
authors.forename: Chao-Ting
authors.initials: CT
authors.lastname: Xiao
authors.affiliation: Harrisvaccines, Inc, Ames, Iowa, USA.
authors.forename: Mark
authors.initials: M
authors.lastname: Mogler
authors.affiliation: Department of Veterinary Diagnostic and Production Animal Medicine, College of Veterinary Medicine, Iowa State University, Ames, Iowa, USA.
authors.forename: Patrick G
authors.initials: PG
authors.lastname: Halbur
mesh_terms: D000818:Animals; D000914:Antibodies, Viral / Q000097:blood; D018173:Circoviridae Infections / Q000517:prevention & control / Q000662:veterinary*; D017925:Circovirus / Q000145:classification* / Q000276:immunology; D056738:Cross Protection; D010865:Pilot Projects; D011897:Random Allocation; D034421:Sus scrofa; D013552:Swine; D013553:Swine Diseases / Q000517:prevention & control* / Q000821:virology; D014765:Viral Vaccines / Q000276:immunology*
chemical_list: D000914:Antibodies, Viral; D014765:Viral Vaccines
keywords: Experimental model; PCV2a; Porcine circovirus type 2 (PCV2); Vaccination; Vaccine; mPCV2b