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MHM-2 Sept 2008. Michael Welsh - IFNg bTB Field testing Jim McNair – bTB Infection models. AFBI Bacteriology Branch Veterinary Sciences Division Belfast, Northern Ireland United Kingdom. R = 0.94. 12. 8. ODI MBSE Ab. 4. 0. 0. 10. 20. 30. 40. 50. PM Score.
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MHM-2 Sept 2008 Michael Welsh - IFNg bTB Field testing Jim McNair – bTB Infection models AFBI Bacteriology Branch Veterinary Sciences Division Belfast, Northern Ireland United Kingdom
R = 0.94 12 8 ODI MBSE Ab 4 0 0 10 20 30 40 50 PM Score Experimental & Field Investigations of bTB in Northern Ireland • What we know • IFNg testing 2004-08. >50k animals, >460 bTB infected herds (Parallel testing:- skin test / IFNg tested animals). Skin test missing 41% of animals with confirmed disease. • IFNg+ve / skin test –ve animals >>> risk of subsequently being identified as diseased • IgG1 antibody responses correlate with pathology and pathology relates to the frequency of nasal shedding of M. bovis bacilli • Molecular bTB strain typing:- evidence of infected animals negative in multiple tuberculin skin tests (latency or anergy?)
Difference PPD-B- PPD-A Problems and Logistics of delivering large scale CMI based bovine TB testing • Test must be cheap, practical to deliver and accurate • AFBI filed a patent application UK0722128.6 that improves the logistical ability to deliver CMI based diagnostic tests.
What do we need to consider for the future in managing bTB infection in farmed species • How early do we need to detect infection to reduce risk of transmission? • What is the risk associated with failure to detect heavily diseased anergic animals and can we identify an immunological profile of latency? • Can we continue with low frequency testing with imperfect antigens mainly targeting CD4 T-cell responses (multiplexing / proteomic fingerprinting)? • How do the genetics of M. bovis strain types affect virulence & diagnostics? • Animal genetics:- is there a quantitative heritability / risk of disease? • Does our experimentalist outlook match the epidemiological picture within the diseased population? Are all animals susceptible to infection & capable of transmitting infection? • What about other infections? BVD virus – leukopenia / suppression of normal immune responses / Parasites.