Location: Animal Disease Research
Project Number: 2090-32000-032-00-D
Project Type: In-House Appropriated
Start Date: Oct 1, 2011
End Date: Sep 30, 2016
Objective 1: Develop a recombinant herpesvirus expressing OvHV-2 proteins that stimulate a neutralizing antibody response. Subobjective 1.A. Develop an infectious AlHV-2 BAC clone. Subobjective 1.B. Construct infectious recombinant AlHV-2 BACs containing OvHV-2 genes encoding proteins that can stimulate a neutralizing antibody response. Subobjective 1.C. Determine neutralizing activity of hyper immune sera against individual OvHV-2 proteins expressed by recombinant AlHV-2. Objective 2: Develop an efficacious vaccine for protection of clinically-susceptible species from sheep-associated MCF. Subobjective 2.A. Vaccinate bison with recombinant AlHV-2 containing OvHV-2 genes to stimulate a neutralizing antibody response against OvHV-2. Subobjective 2.B. Determine the MCF protection rates of bison vaccinated with recombinant AlHV-2 upon challenge with a lethal dose of OvHV-2. Subobjective 2.C. Determine if vaccination prevents bison from developing MCF when exposed to OvHV-2 infected sheep.
The proposed research will develop a recombinant herpesvirus expressing OvHV-2 proteins by utilizing AlHV-2, a non-pathogenic MCFV carried by African antelopes (hartebeest and topi) that can grow in cell culture, as a vaccine. AlHV-2 has been isolated from clinically normal topi antelope and hartebeest in Africa and the U.S. (61, 79, 84). There has been no report of AlHV-2-induced MCF in cattle under natural transmission conditions, although an MCF case in red deer reported from the San Diego Wildlife Park was associated with an AlHV-2-like virus from Jackson Hartebeest (36). Experimental inoculation of cattle with cell-free AlHV-2 isolates can result in infection, but does not induce clinical disease. Moreover, inoculation of cattle with AlHV-2 does not elicit antibodies protective against subsequent AlHV-1 challenge (66). We will use recombination-mediated genetic engineering to generate recombinant AlHV-2 (rAlHV-2) containing relevant OvHV-2 genes (rAlHV-2OvHV-2g). The rAlHV-2OvHV-2g will be tested as a vaccine to stimulate local immune responses in the respiratory tract to protect clinically susceptible hosts from SA-MCF. Our main hypothesis is: immunization with rAlHV-2OvHV-2g will stimulate neutralizing antibodies at the viral entry site in bison, which will correlate with reduced viral load and protection against lethal OvHV-2 challenge. The hypothesis will be tested through the previous two objectives.