Recombinant Bovine Adenovirus-3 Co-Expressing Bovine Respiratory Syncytial Virus Glycoprotein G and Truncated Glycoprotein gD of Bovine Herpesvirus-1 Induce Immune Responses in Cotton Rats

One of the impediments in the development of safe and cost effective vaccines for veterinary use has been the availability of appropriate delivery vehicle. We have chosen to develop and use bovine adenovirus (BAdV)-3 as vaccine delivery vector in cattle. Here, we describe the construction of recombinant E3 deleted BAdV-3 vectors expressing single vaccine antigen (BAV360; bovine respiratory syncytial virus G) or two vaccine antigens (BAV851; bovine herpesvirus-1gDt and bovine respiratory syncytial virus G). Recombinant proteins expressed by BAV360 or BAV851 were recognized by protein-specific monoclonal antibodies. Moreover, intranasal immunization of cotton rats with BAV360 (expressing a single vaccine antigen) or BAV851 (expressing two vaccine antigens) induced strong antigen-specific immune responses. These results suggest that single replication-competent BAdV-3 expressing vaccine antigens of two economically important respiratory pathogens of calves has potential to act as a feasible approach in the development of economically effective veterinary vaccines for cattle.