title: A commercial PCV2a-based vaccine is effective in protection from experimental challenge of PCV2 mutant with two amino acids elongation in capsid protein.
abstract: Current commercial PCV2 vaccines are almost based on PCV2a and have been shown to be effective in reducing PCV2a and PCV2b viremia and PCV2-associated lesions and diseases. The recent emergence of novel mutant PCV2 (mPCV2) strains and linkage of mPCV2 with cases of porcine circovirus associated disease (PCVAD) in pig herds have raised concerns over emergence of vaccine-escape mutants and reduced efficacy of PCV2a-based vaccines. The aim of this study was to determine the ability of a commercial PCV2a-based vaccine developed by our laboratory to protect conventional pigs against experimental challenge with mPCV2 at 9 weeks of age. Twenty 4-week-old pigs free of PCV2 infection were randomly divided into four treatment groups with 5 pigs each. Two groups were unvaccinated as positive and negative controls. Another two groups were vaccinated with the commercial PCV2a-based vaccine (PCV2-LG strain, China) at 4 weeks of age and identical booster immunization was conducted 3 weeks post primary immunization. At 9 weeks of age, all pigs except the negative control were challenged with a mutant PCV2b/YJ (mPCV2b/YJ) with two amino acids elongation in capsid protein. The experiment was terminated 28 days after challenge. Under the conditions of this study, vaccinated pigs were protected against PCV2 viremia and lesions whereas unvaccinated pigs were not. Moreover, mPCV2b/YJ infection was demonstrated in positive control and almost all had macroscopic or microscopic lesions consistent with PCVAD while negative control did not develop PCVAD. This study indicates that mPCV2b/YJ infection alone can trigger PCVAD development and that the commercial vaccine (PCV2-LG) is still effective in protecting conventional pigs against the emerging mPCV2b/YJ strain in China.
authors.affiliation: Swine Infectious Diseases, State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute of the Chinese Academy of Agricultural Sciences, 427 Maduan Street, Nangang Region, Harbin 150001, PR China.
authors.forename: Long-Jun
authors.initials: LJ
authors.lastname: Guo
authors.affiliation: Swine Infectious Diseases, State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute of the Chinese Academy of Agricultural Sciences, 427 Maduan Street, Nangang Region, Harbin 150001, PR China; Shenyang Institute of Technology, No. 1, East Binhe Road, Development Zone, Fushun 113122, Liaoning, PR China.
authors.forename: Yu-Jie
authors.initials: YJ
authors.lastname: Fu
authors.affiliation: Swine Infectious Diseases, State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute of the Chinese Academy of Agricultural Sciences, 427 Maduan Street, Nangang Region, Harbin 150001, PR China.
authors.forename: Li-Ping
authors.initials: LP
authors.lastname: Huang
authors.affiliation: Swine Infectious Diseases, State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute of the Chinese Academy of Agricultural Sciences, 427 Maduan Street, Nangang Region, Harbin 150001, PR China.
authors.forename: Yi-Ping
authors.initials: YP
authors.lastname: Wang
authors.affiliation: Swine Infectious Diseases, State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute of the Chinese Academy of Agricultural Sciences, 427 Maduan Street, Nangang Region, Harbin 150001, PR China.
authors.forename: Yan-Wu
authors.initials: YW
authors.lastname: Wei
authors.affiliation: Swine Infectious Diseases, State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute of the Chinese Academy of Agricultural Sciences, 427 Maduan Street, Nangang Region, Harbin 150001, PR China.
authors.forename: Hong-Li
authors.initials: HL
authors.lastname: Wu
authors.affiliation: Swine Infectious Diseases, State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute of the Chinese Academy of Agricultural Sciences, 427 Maduan Street, Nangang Region, Harbin 150001, PR China. Electronic address: lcm@hvri.ac.cn.
authors.forename: Chang-Ming
authors.initials: CM
authors.lastname: Liu
mesh_terms: D000818:Animals; D036022:Capsid Proteins / Q000235:genetics / Q000276:immunology*; D002681:China; D018173:Circoviridae Infections / Q000517:prevention & control / Q000662:veterinary* / Q000821:virology; D017925:Circovirus / Q000235:genetics / Q000276:immunology*; D016254:Mutagenesis, Insertional; D050505:Mutant Proteins / Q000235:genetics / Q000276:immunology*; D011897:Random Allocation; D013552:Swine; D013553:Swine Diseases / Q000517:prevention & control* / Q000821:virology*; D016896:Treatment Outcome; D014611:Vaccination / Q000379:methods; D014765:Viral Vaccines / Q000008:administration & dosage / Q000276:immunology* / Q000302:isolation & purification
chemical_list: D036022:Capsid Proteins; D050505:Mutant Proteins; D014765:Viral Vaccines
keywords: Mutant PCV2; PCV2a; PCV2b; Porcine circovirus type 2 (PCV2); Vaccine