Increasingly effective vaccination strategies are needed to counteract the high incidence of contagious diseases associated with intensive swine breeding. Recombinant viral vaccines are a promising new avenue in this direction. Key features of viral vectors suitable for immunoprophylaxis are safety, ease of manipulation and the ability to replicate in a variety of hosts. Most of the above requirements are met by bovine herpesvirus 4 (BoHV-4), a non-pathogenic dsDNA virus capable of infecting a broad range of cell types in vitro. Here we report the results of an exploratory study using an engineered BoHV-4 virus (eBoHV-4) expressing two unrelated glycoprotein antigens from bovine viral diarrhea virus (BVDV) and bovine herpesvirus 1 (BoHV-1), to assess the potential of recombinant BoHV-4 as a self-adjuvanted immunogen in pigs. Free eBoHV-4 virions and virions preloaded into homologous swine adipose-derived stromal cells (SADSC) were tested. Neither virus formulation elicited neutralizing anti-BoHV-4 antibodies, nor any disease symptom, yet both induced specific immune responses against the heterologous antigens. However, a much earlier (18 vs 28 days post-infection) and more robust neutralizing response against BVDV and BoHV-1 viruses was elicited by eBoHV-4-preinfected SADSCs compared to free virions. The data validate BoHV-4 as a safe and effective heterologous antigen carrier/producer and identify SADSCs as helpful tools for the formulation of increasingly efficacious recombinant immunogens for pig vaccination.
Animals Antibodies, Neutralizing