Researchers awarded funding to develop improved Q fever vaccines for livestock

Researchers from the Moredun Research Institute (MRI) together with partners from Wageningen University and Research (WUR), the Netherlands, and the University of Copenhagen, Denmark, have received a major funding award of over £1 million from BBSRC and the Department of Health to develop improved vaccines to control Q fever in livestock.

Q fever is an important and highly contagious disease of worldwide importance affecting both livestock and humans caused by the intracellular Gram-negative bacterium, Coxiella burnetii. Infection of humans occurs following exposure to as few as 1-10 bacteria and can result in both acute and chronic forms of disease. Infections can result in death, especially in the elderly or immunocompromised. Livestock, in particular sheep and goats, are the major source of human infections where infection can cause abortion, stillbirth and delivery of weak offspring. The loss of lambs and kids can result in devastating economic losses to the livelihoods of farmers in Europe as well as low to middle income countries, particularly during abortion storms where up to 35% losses can occur.

Vaccines are currently considered the most effective way to control Q fever, and vaccines based on inactivated C. burnetii organisms are commercially available for use in both ruminants and humans. However, the safety of these vaccines is a major issue considering that severe local and systemic reactions occur post-vaccination in humans previously exposed to the bacteria and vaccination of ruminants is associated with significant production losses. Furthermore, manufacture of these vaccines involves growth of the organisms in culture or hens eggs, which has both cost and safety issues. These issues have resulted in limited use of these vaccines; for example, human vaccines are only licenced for use in Australia. There is therefore an urgent need to develop safe, effective and easily manufactured vaccines to control Q fever in both humans and livestock species.

Attempts have been made to develop subunit vaccines targeting key C. burnetii proteins which would be safer to manufacture and could be engineered to induce fewer side effects following vaccination. However, current approaches to subunit vaccine development have been severely hampered by a lack of knowledge of the appropriate bacterial proteins to target.

In the currently funded project (CoxiMap), the researchers will use a novel peptide chip array technology developed at the University of Copenhagen to identify the key C. burnetii proteins recognised by antibodies from sheep and goats vaccinated with the current protective, but unsafe commercial vaccine in a high throughput and detailed manner. These antibody responses will be compared with those generated by a non-protective C. burnetii vaccine which is based on a different (non-virulent) form of the bacteria. By comparing antibody responses from protected and non-protective vaccines, bacterial proteins which are specifically targeted by the protective vaccine will be identified. Synthetic versions of these proteins will then be generated and subunit vaccines based on pools of these proteins will be tested in a sheep challenge model. This will provide preliminary safety and efficacy data to inform future Q fever vaccine development programmes.

Dr Tom McNeilly, principle investigator of the project, said “Q fever is a significant issue for both livestock and human health, and while current vaccines are available, their manufacture is both problematic and the side effects of vaccines have limited their use. By teaming up with Wageningen, leading experts in Q fever in livestock, and deploying cutting edge peptide chip technologies developed at the University of Copenhagen, we hope to use Moredun’s expertise in livestock vaccines to develop new prototype vaccines which are both cheap to manufacture and safe to use. Furthermore, by characterising antibody responses in both vaccinated and C. burnetii challenged animals, diagnostic tests capable of differentiating vaccinated from infected animals may also be developed.”

For further information, please contact Dr Tom McNeilly (Tom [dot] McNeilly [at] moredun [dot] ac [dot] uk).