Chimeric porcine circovirus type 2 (PCV2) vaccines

Generation and Testing of Chimeric Vaccines

[0080]In one embodiment, shuffled PCV2 capsid genes were first cloned into the backbone of PCV2a. A total of four chimeric viruses were found viable in vitro and subsequently used to infect pigs to assess their ability to induce cross-neutralizing antibodies against different PCV2 subtypes. One chimeric virus (PCV2-3cl.14) induced higher neutralizing antibody titers against different PCV2 subtypes. A candidate vaccine (PCV1-3cl.14) was produced by cloning the shuffled 3cl.14 capsid gene into the genomic backbone of the non-pathogenic PCV1.

[0081]A vaccine efficacy study conducted in thirty two (32) pigs revealed that the chimeric virus PCV1-3cl.14 induces protective immunity against challenge with PCV2b or PCV2d. Pigs vaccinated with PCV1-3cl.14 and subsequently challenged with either PCV2b or PCV2d had significantly decreased microscopic lesions and lower viral DNA loads in serum and lymphoid tissues compared to mock-vaccinated pigs. The chime

Chimeric Virus Derivatives

[0123]Derivatives of the chimeric PCV capsid polypeptides disclosed herein are included within the scope of this disclosure. The amino acid sequences of epitopes that are included in the chimeric PCV capsid polypeptides disclosed herein may be altered somewhat and still be suitable for use as therapeutic immunogens. For example, certain conservative amino acid substitutions may be made in epitope domains as well as other non-epitope domains of the capsid polypeptides without having a deleterious effect on the immunogenicity of included epitopes. Those of skill in the art recognize the nature of conservative substitutions, for example, substitution of a positively charged amino acid for another positively charged amino acid; substitution of a negatively charged amino acid for another negatively charged amino acid; substitution of a hydrophobic amino acid for another hydrophobic amino acid; etc. All such substitutions or alterations of the chimeric PCV capsid po

Chimeric Vaccine Compositions

[0127]Whether as a live virus vaccine, a modified live virus vaccine, inactivated virus vaccine, attenuated vaccine, plasmid DNA vaccine or a subunit polypeptide vaccine, an immunologically effective amount is administered. The “immunogenically effective” amount is sufficient to stimulate an immune response, i.e., to stimulate the production of humoral antibodies and / or to stimulate a cell-mediated response. The vaccine composition may include suitable adjuvants as well as one or more wetting or dispersing agents. Such wetting agents include non-ionic surfactants such as polyoxyethylene / polyoxypropylene block copolymers, i.e. those marketed under the mark PLURONIC® and available from BASF Corp. (Mt. Olive, N.J.). Other useful nonionic surfactants include polyoxyethylene esters such as polyoxyethylene sorbitan monooleate (polysorbate 80), available under the trademark TWEEN 80®.

[0128]Examples of suitable adjuvants include, without limitation, immunostimu