|Capinos Scherer, Charles|
|De Aguiar, Juliana|
Submitted to: Transboundary and Emerging Diseases
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/30/2008
Publication Date: 8/1/2009
Citation: Capinos Scherer, C.F., Endsley, J.J., De Aguiar, J.B., Jacobs, W.R., Larsen, M., Palmer, M.V., Nonnecke, B.J., Waters, W.R., Estes, D.M. 2009. Evaluation of Granulysin and Perforin as Candidate Biomarkers for Protection Following Vaccination with Mycobacterium bovis BCG or M. bovis DeltaRD1. Transboundary and Emerging Diseases. 56(6-7):228-239.
Interpretive Summary: Despite highly successful eradication efforts in several countries, tuberculosis of cattle remains a serious health concern worldwide. In addition, recent outbreaks of tuberculosis in Michigan, California, Texas, Minnesota, and New Mexico demonstrate that the disease is far from eliminated from the United States. Improved strategies are needed for the control of tuberculosis in cattle. To develop these strategies, it is beneficial to first understand the immune response to infection. In this study, specific host responses of cattle to tuberculosis were determined. Specifically, a potential correlate to protective immunity is described. Knowledge obtained from this study will assist in the development of new diagnostic tests and vaccines for the control of tuberculosis of cattle.
Technical Abstract: Tuberculosis remains a major health problem worldwide. Cell mediated immunity based on a Th1 response plays an important role in the outcome of the disease. Measurements of immune responsiveness after TB vaccination include the standard skin test, IFN gamma-based diagnostic assays and T cell proliferation assays. These methods frequently fail to correlate with a protective host response. In addition to the search for vaccines which exceed the protective capacity of BCG is the need to develop better correlates of protection. Our group has cloned and characterized a bovine homologue of the antimicrobial protein granulysin (Bo-lysin), a potential biomarker molecule for TB vaccination. In the present study we examined the kinetics of Bo-lysin, compared to perforin, IFN gamma and Fas-L in vitro, after an antigen specific stimulation with M. bovis purified protein derivative (BoPPD). Gene expression profiles of BCG vaccinated animals following antigen specific recall showed significant increases in transcripts for bo-lysin and IFN gamma in both CD4+ and CD8+ T cells, as compared to non-vaccinated subjects. When IFN gamma and perforin were examined by flow cytometric staining, BCG vaccinated animals had 1-2% more boPPD specific cells than non-vaccinated animals. The bovine granulysin 15 KDa preprotein examined by immunoblot was present in both BCG- and non-vaccinated animals, but only the 9KDa form was observed following response to specific antigen in BCG vaccinated animals. Granulysin was significantly increased in 2 vaccine groups as compared to controls in a vaccine trial performed in bovine neonates. Both perforin and IFN gamma genes were significantly increased during the different time points after vaccination and challenge, but only perforin was increased after the challenge. Secreted IFN gamma was higher in the control, non-protected group as compared to both vaccine groups, BCG and Delta RD1, demonstrating no correlation with protection upon vaccination. Analysis of lung and lymph nodes from tissues of BCG- and non-vaccinated animals also showed evidence that granulysin might be a good correlate of protection. In summary, results shown here provide evidence that granulysin together with perforin are prospective candidates as biomarkers of protection after vaccination against TB.