Efficient vaccines against orbivirus diseases
Bluetongue virus (BTV), African horse sickness virus (AHSV) and epizootic haemorrhagic disease virus (EHDV) are sources of significant animal suffering and deaths in Europe. These viruses are transmitted by biting midges from animal to animal, inducing high morbidity and mortality. Existing commercially available vaccines generate an antibody response to all of the viral proteins, thereby making it impossible to distinguish vaccinated from infected animals. In addition, there is a great need for immune responses that protect against all different virus serotypes. The scope of the EU-funded 'Development of vaccines for bTV, EHDV and AHSV' (ORBIVAC) project was to address these issues and generate multivalent vaccines that offer a broad protective immune response. To achieve this, the ORBIVAC consortium included under its umbrella major industrial companies currently manufacturing vaccines in Europe. A series of novel vaccines were designed and successfully developed. For BTV, the generated multivalent vaccines conferred complete protection against all virus serotypes in sheep and cattle. Similar efficacy was achieved with protein-based AHSV vaccines that elicited strong neutralising antibodies for all nine virus serotypes. For EHDV, researchers employed a virus-like particles strategy to express four different antigens during immunisation. Subsequent evaluation in a small animal model demonstrated sufficient immunogenicity. In addition to these innovative vaccine strategies, the consortium devoted considerable effort to the development of novel diagnostic reagents for use in specially adapted methods that can differentiate between infected and vaccinated animals (DIVA). These include microarrays, real time polymerase chain reaction assays and new enzyme-linked immunosorbent assay tests for serotyping. Overall, the compliance of the ORBIVAC vaccines to DIVA regulations, coupled with their cross-protection capacity against multiple strains of virus, offers a new and promising approach to vaccination. Given the socioeconomic impact of orbivirus diseases, implementation of these vaccines is expected to benefit animal farming and boost Europe's agriculture economy.
Keywords
Vaccines, orbivirus diseases, BTV, AHSV, EHDV, DIVA regulations
