COUNTERMEASURES TO PREVENT AND CONTROL TUBERCULOSIS IN CATTLE AND WILDLIFE RESERVOIRS
Location: Infectious Bacterial Diseases Research Unit
Title: Update on Veterinary Tuberculosis Vaccines
Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: April 29, 2009
Publication Date: April 29, 2009
Citation: Waters, W.R. 2009. Update on Veterinary Tuberculosis Vaccines [abstract].
At the conclusion of this presentation, the participant will know the current status of veterinary tuberculosis vaccine research and development, and understand the challenges which remain for the future introduction of tuberculosis vaccines intended for wildlife and livestock.
Bovine tuberculosis (bTB), caused by Mycobacterium bovis, accounts for up to 10% of human TB cases in developing countries and is increasing in cattle in the US and UK. Control of bTB is hindered by the presence of numerous wildlife reservoirs such as white-tailed deer, European badgers, and brush-tailed possums. While the mainstay of control has been abattoir inspection and targeted testing, vaccines are now being considered as an additional tool, both in cattle and wildlife. However, significant obstacles exist for development of bTB vaccines including product cost constraints, safety concerns (for the animal and potential meat consumer), formidable obstacles with field efficacy trials, and the need for co-development of diagnostic techniques to differentiate infected from vaccinated animals. Currently, M. bovis BCG is the only bTB vaccine available. As with humans, BCG efficacy in cattle is variable and responses to BCG may interfere with standard ante-mortem bTB tests. With experimental trials, other bTB vaccine platforms have been evaluated including DNA, subunit, live-vectored, attenuated M. bovis strains, auxotrophic mutants, and killed mycobacterial preparations. Of these, BCG prime and subunit boost strategies have shown improved efficacy over BCG alone. Also, recent studies indicate that vaccine-elicited central memory immune responses to specified antigens (e.g., Ag85A) prior to challenge correlate with reduced pathology and mycobacterial colonization upon experimental M. bovis infection, indicating the potential for screening of vaccine candidates without costly challenge procedures. In contrast, infection-elicited antibody and effector recall IFN-gamma responses positively correlate with pathology. Together, these findings demonstrate significant advances in experimental approaches to development of bTB vaccines; however, translation of these advances to large-scale field studies is yet to be realized.
1. Waters W.R., M.V. Palmer, B.J. Nonnecke, T.C. Thacker, C.F. Capinos Scherer, D.M. Estes, R.G. Hewinson, H.M. Vordermeier, S.W. Barnes, G.C. Federe, J.R. Walker, R.J. Glynne, T. Hsu, B. Weinrick, K. Biermann, M.H. Larsen and W.R. Jacobs. 2009. Efficacy and immunogenicity of Mycobacterium bovis DeltaRD1 against aerosol M. bovis infection in neonatal calves. Vaccine, 27(8):1201-1209.