Poultry companies use elisa to determine if their flocks have been adequately vaccinated against specific poultry pathogens

This Project Grant from the Department of Agriculture's National Institute of Food and Agriculture, under the Small Business Innovation Research (SBIR) Program/Small Business Technology Transfer (STTR) Program (CFDA 10.212), provides $135,484 to Larad Inc. to develop an enzyme-linked immunosorbent assay (ELISA) kit. The kit aims to differentiate between Marek's disease virus infected and herpesvirus of turkeys vectored vaccinated poultry flocks. Larad will purify individual glycoprotein antigens from herpesvirus of turkeys, which show sequence diversity from Marek's disease virus, for use in the ELISA. The antigens will be tested for specificity with monospecific antisera to identify candidates that reliably indicate herpesvirus of turkeys vaccination status. The funding period is from July 1, 2022 to February 28, 2023. The ELISA kit, once developed, will support improved disease management and control in the poultry industry by enabling producers to determine vaccination effectiveness.

These assays are a valuable tool in the control of avian diseases. 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 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.