SBIR-STTR Award

Poultry companies use ELISA to determine if their flocks have been adequately vaccinated against specific poultry pathogens. These assays are a valuable tool in the control of avian diseases. Herpes virus of turkeys (HVT) has been used as a vector to create recombinant vaccines (rHVT) that protect against Marek's disease virus (MDV) and other poultry diseases. These rHVT vaccines are widely used in modern poultry operations yet no ELISA kit has been developed to differentiate between MDV infected and HVT vectored vaccinated birds. Such an ELISA would address research priority 3 improving animal health and well-being by allowing producers to determine if a flock has been successfully vaccinated leading to better disease management and control. The cross reactivity between HVT and pathogenic (MDV-1) and vaccine strains (MDV-2) presents a challenge. We propose to approach this problem by using individual purified protein antigens from HVT. We will target the glycoproteins from HVT since these surface proteins have the most sequence diversity between HVT and MDV. Glycoprotein genes will be cloned separately into a vector containing the maltose binding protein (MBP) gene to facilitate purification. The MBP fusion proteins will be expressed in the baculovirus system and then affinity purified. Purified antigens will be checked for their utility as antigens in the ELISA with monospecific HVT antisera. Those that produce sufficient signals with HVT antisera will then be retested using monospecific MDV-1 and MDV-2 antisera. The ideal antigen candidate will be the MBP-glycoprotein that gives a strong signal with only the HVT antisera.

Poultry companies use ELISA to determine if their flocks have been adequately vaccinated against poultry pathogens. Herpesvirus of turkeys (HVT) has been used as a vector to create recombinant vaccines (rHVT) that protect against Marek's disease virus (MDV) and other poultry diseases. These rHVT vectored vaccines are widely used in poultry operations yet no ELISA kit has been developed to differentiate between MDV infected and HVT vectored vaccinated birds. Such an ELISA would address research priority 3 improving animal health and well-being by allowing poultry producers to determine if a flock has been successfully vaccinated leading to better disease management and control. In our Phase I project we demonstrated that the glycoprotein B (gB) from HVT could be used as an antigen in the ELISA to differentiate antibodies to HVT from antibodies to MDV-1 and MDV-2 serotypes. In this Phase II project we are proposing to develop a commercially viable ELISA kit by improving our signal to background ratio. This will be accomplished by improving the differentiating quality of our HVT gB antigen and optimizing the ELISA procedure. We will focus on increasing the signal of our HVT ELISA by cloning and expressing fragments of the gB gene that are the least similar sequence-wise with the MDV-1 and MDV-2 gB proteins. The ELISA protocol will also be optimized by testing a variety of test parameters to create a workable product ready for submission to the USDA for licensure via a strategic diagnostic industry partner.