Porcine Circovirus Strain 2 (PCV2) Vaccines and Diagnostic (RFT-468)
Scientists at NDSU have mapped the putative protective and non-protective regions of the PCV2 capsid protein. The key concept for this disclosure is that eliminating or altering the non-protective regions resulted in rational antigen redesign that is expected to improve vaccine efficacy against both PCV2a and b subtypes and reduce viral shedding, when compared to existing vaccines that target only the PCV2a subtype. Immunization of pigs with the modified vaccines, followed by challenge with a virulent field strain showed that the efficacy of the vaccine was comparable to a commercial vaccine. However, performance of the animals was improved, based on findings that the average weight gain was higher than the commercial vaccine (See Figure below). This invention also enabled creation of negative selection markers for the development of the DIVA immunoassay, which enables identification of whether any specific animal received the vaccine.
To develop a rationally designed, improved PCV2 vaccine with the ability to differentiate vaccinated and infected animals (DIVA), positive and negative DIVA markers were introduced in the vaccine constructs. In addition, decoy B cell epitopes which can divert the protective antibody responses towards non-protective regions of the vaccine antigen were modified by site directed mutagenesis to avoid possible subversion of the host immunity and achieve a rationalized vaccine design. An appropriate response to the positive and negative DIVA tags was detected. Therefore, the strategy used in this study is the first to enable1) an epitope-based approach to target improved immunogenicity against both PCV2a and PCV2b subtypes, and 2) a DIVA capable vaccine and accompanying immuno-assay.
- Expected to provide efficacy against both PCV2a and PCV2b subtypes
- Average weight gain substantially increased
- Improved vaccine activity compared to commercial vaccine
- DIVA capable vaccine and accompanying immuno-assa
- Reduces the liklihood of pssible subversion of the host immunity
- First mover advantage of vaccine that differentiates infected and vaccinated animals (DIVA)
Porcine circovirus type 2 (PCV2) belongs to Circoviridae family and is an important pathogen for swine industry as the cause of porcine circovirus associated diseases (PCVAD). While several effective commercial vaccines against PCV2 are available, none of them are capable of differentiating infected and vaccinated animals (DIVA). Moreover, all of them target the PCV2a strain which has been replaced by PCV2b in the U.S since 2007.
A provisional patent application was filed April 11, 2016. The technology is available for licensing/partnering opportunities.
Henry Nowak, Technology Manager
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