الفهرس 
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Abstract
Mycobacterium bovis (M. bovis), the cause of bovine tuberculosis (BTB) in cattle, still has a great importance as a zoonotic and economically problem all over the world. Many diagnostic tools are essential for M. bovis eradication program. This study aimed to apply different serological tests for detection of BTB antibody and use bovine γ-IFN assay with multiplex PCR for rapid identification of M. bovis isolates. 4250 cattle were tested from 38 dairy farms in several Egyptian governorates, by using single intradermal cervical comparative tuberculin test (SICCT), only 90 (2.1%) cattle reacted positively. The postmortem (PM) examination of positive reactors revealed 65 (72.2%) out of 90 slaughtered cattle showed visible lesions (VL) while the other 25 (27.8%) reactors with non-visible lesions (NVL). The VL detected in head were 10 (15.4%), 32 (49.2%) in respiratory system, 5 (7.7%) in the digestive system, 11 (16.9%) in mixed tuberculosis, and 7(10.8%) in generalized tuberculosis.
The bacteriological isolation of processed samples from the 90 slaughtered cattle revealed 55 M. bovis isolates (61.1%); 51 (78.5%) were from 65 VL and 4 (16.0%) were from 25 NVL.
Enzyme Linked Immuno-Sorbent Assay (ELISA) was used for sera of the tuberculin positive animals, only 38 (42.2%) out of the 90 tuberculin positive animals were positive ELISA, 36 (55.4%) out of 65 cattle with VL and 2 (8%) out of 25 cattle with NVL, at the same time by using lateral flow test (LFT); Rapid Bovine TB Ab kit, only detected 33 (36.7%) out of the 90 tuberculin positive animals, 32 (49.2%) out of 65 cattle with VL and 1 (4%) out of 25 cattle with NVL).
Gamma Interferon (γ-IFN) Assay was applied for detection of BTB, 150 blood samples (87 tuberculin reactors, and 63 tuberculin negative) from 10 tuberculosis-affected farms, revealed 80 (53.3%) out of 150 animals were positive γ-IFN assay. The sensitivity of γ-IFN assay and SICCT were 93.8% and 86.2% respectively, while the specificity were 82.9% and 92.1% respectively.
Finally mPCR was used for rapid identification of different Mycobacteria isolates. Two sets of primers were used, the first set gave 123bp DNA PCR product expressing IS6110 insertion element for Mycobacterium tuberculosis complex (MTBC). The second set gave 500bp from RvD1Rv2031c genomic sequence which is species-specific for M. bovis. The m-PCR findings were in a concordance with results of conventional culturing and identification tests with high sensitivity and specificity (100%).
Conclusion
It is concluded that, the tuberculin skin test is still the gold standard screening test in the field, to avoid the false negative reactions in anergic cattle, a complementary immunodiagnostic test as γ-IFN assay is needed. ELISA using B-PPD could detect latent infection and helpful in anergic cattle (False negative). LFT could be used as a screening test as complementary to the skin test. Culturing is time consuming, requires several weeks but remains the gold standard technique, mPCR could be used as a rapid screening and a complementary to culturing, as it reduces the time for diagnosis to 2 days.