The control and prevention of bovine viral diarrhea virus (BVDV) infections has provided substantial challenges. Viral genetic variation, persistent infections, and viral tropism for immune cells have complicated disease control strategies. Vaccination has, however, provided an effective tool to prevent acute systemic infections and increase reproductive efficiency through fetal protection. There has been substantial controversy about the safety and efficacy of BVDV vaccines, especially when comparing killed versus modified-live viral (MLV) vaccines. Furthermore, numerous vaccination protocols have been proposed to protect the fetus and ensure maternal antibody transfer to the calf. These issues have been further complicated by reports of immune suppression during natural infections and following vaccination. While killed BVDV vaccines provide the greatest safety, their limited immunogenicity makes multiple vaccinations necessary. In contrast, MLV BVDV vaccines induce a broader range of immune responses with a longer duration of immunity, but require strategic vaccination to minimize potential risks. Vaccination strategies for breeding females and young calves, in the face of maternal antibody, are discussed. With intranasal vaccination of young calves it is possible to avoid maternal antibody interference and induce immune memory that persists for 6–8 months. Thus, with an integrated vaccination protocol for both breeding cows and calves it is possible to maximize disease protection while minimizing vaccine risks.

Several years have elapsed since the publication by Johnson et al. (1989) of the cloning of a recombinant antigen from the cestode parasite Taenia ovis which stimulated high levels of protective immunity in sheep. A great deal of subsequent research and development was necessary to bring the fledgling vaccine to the point of being a registered commercial product. The results of these subsequent studies are dealt with briefly in this paper, including the results of field trials. The T. ovis vaccine was registered by the New Zealand Animal Remedies Board in February 1994. Where then is the commercial product ? This paper gives a background to market problems which have emerged through the politics (and realities) of the NZ T. ovis control campaign. It serves as notice that the best science dedicated to producing vaccines or products for parasitic, or other, diseases often faces significant hurdles in the real world of commerce and politics.