Infestation of the skin with Psoroptes Ovis (sheep scab mite) represents a major animal welfare and economic burden on the sheep industry. A prototype sheep scab vaccine is effective at controlling sheep scab with an efficacy of over 80% (lesion size reduction). However, the development of a vaccine was considered a ‘market failure.’ The ever-decreasing amount of treatment options means sustainable control approaches are becoming more attractive.

Bovine Respiratory Disease (BRD) in cattle remains a significant problem in the beef and dairy industries. BRD is caused by a variety of infectious agents. Most outbreaks start with viral infection. The key viruses involved in the disease are respiratory syncytial virus (BRSV), parainfluenza 3 virus (PI3V), bovine herpesvirus 1 (BHV-1) and bovine viral diarrhoea virus (BVDV). BRD is still a significant problem despite several vaccines and medications being commercially available. This suggests these options are not sufficiently effective.

BVDV eradication in Scotland has progressed well and is no longer an issue. Vaccines for the other viruses are moderately protective against disease but ineffective in controlling the spread of disease. Modified live vaccines induce broader, more complete immune responses. However, viral proteins have evolved to significantly interfere with the immune response. Further, modified live virus vaccine strains of BHV-1 can appear in vaccinated animals and, when reactivated reduce the immune response. Similar latency and reversion issues appear for virulence bovine respiratory syncytial virus.

In sum, there are several key challenges related to:

• Overcoming the limitations of the current chemotherapeutics; reduced efficacy and antibiotic resistance; and the effects of residues on the environment, operator, and food safety.
• Providing increased productivity and efficiency in livestock production with the economic, food security and environmental benefits which accrue from that.