The Vaccine Group (TVG) has demonstrated outstanding results in a cattle challenge trial conducted by the UK government’s Animal and Plant Health Agency using a novel BRSV vaccine candidate. BRSV (bovine respiratory syncytial virus) is a highly contagious and economically damaging disease in both beef and dairy herds. The Pirbright Institute quotes the annual cost to British farmers at £54 million*, while the global figure could be as much as £5.6 billion**. It is a leading cause of bovine respiratory disease.
The results represent an important validation of the Company’s bovine herpesvirus-4 vaccine platform technology. They demonstrate for the first time that the vaccine platform can safely prevent a global livestock disease. For the trial, 3-6 week-old calves immunised intramuscularly with TVG’s vaccines were challenged with BRSV and the results compared to a control group of infected, but unvaccinated, calves. The vaccinated calves demonstrated immunity to the disease when measured by:
- Clinical disease: the vaccines prevented clinical disease, with vaccinated calves showing no significant signs including elevated temperatures compared to the control group
- Virus shedding: the primary route of BRSV transmission for infected animals is via nasal discharge; vaccinated animals had no detectable BRSV in nasal swabs post-challenge
- Lung pathology: lungs in the unvaccinated calves suffered significant lesions, while those in the vaccinated group had minimal changes.
TVG’s technology offers a further advantage to current commercial vaccines. These vaccines use the live or inactivated whole virus of BRSV to stimulate an immune response. Many young calves of the target age for vaccination against BRSV will have maternal antibody from their mothers, which will interfere with the immune response to these conventional vaccines given parenterally. This means that farmers have to wait for the impact of the maternally derived antibodies to diminish over time before administering whole viral BRSV vaccines. There is a window of opportunity for calves to become infected as the maternal antibody protection wains but still prevents immunisation – and a major reason why current vaccines prove ineffective in young calves.
TVG’s BRSV vaccine can be administered to very young animals, even in the presence of maternal antibodies because the BoHV-4 vector is not affected by maternal immunity. TVG’s vaccine candidate represents an opportunity to provide complete protection against a major livestock disease with important benefits that cannot be replicated by the current market offerings.
Following the success of the trials, TVG is seeking to engage strategic partners for further development of the vaccine.
Jeremy Salt, TVG CEO commented: “These results are a fantastic endorsement of the platform that we use for vaccine development. A novel BRSV vaccine that induces sterilising immunity in maternal antibody positive calves without adding to the circulating BRSV strain pool is a market leading product.”
*The UK figure is from The Pirbright Institute based on pages 1, and 32 to 34 of the ADAS publication Economic Impact of Health and Welfare Issues in Beef Cattle and Sheep in England (Microsoft Word – Economic Impact of Disease report Final 170413.doc).
**The global figure is conservatively based on assumptions that the total cattle population is 1.5 billion; that there are 450 million bovine respiratory cases each year, of which BRSV is responsible for 25 per cent at an average cost of £50 per cow.