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- Author or Editor: Charles O. Thoen x
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Objective—To monitor by use of 5-color flow cytometry the antigen-specific responses of subsets of peripheral T cells in cattle inoculated with a killed Mycobacterium avium subsp paratuberculosis (MAP) vaccine and to compare results with those for 2 established cell-mediated immunity assays.
Animals—45 female Holstein cattle with negative results for MAP in skin tests conducted at time of inoculation with MAP.
Procedures—Cattle were allocated to 4 groups. Cattle of group 1 (n = 12) were 0 to 3 months old and inoculated with a killed MAP vaccine. The 10 cattle of group 2 were the same age as those in group 1 but were not inoculated with MAP vaccine. The 11 cattle of group 3 were 9 to 12 months old and inoculated with killed MAP vaccine. The 12 cattle of group 4 were the same age as those in group 3 but were not inoculated with MAP vaccine.
Results—Flow cytometry identified T-cell subsets that responded specifically to the recall antigen. Results of assays for CD25 expression and wholeblood interferon-γ had the strongest correlation with results for skin tests as well as results with each other. Intracellular expression of interferon-γ was not correlated as well with results for the other tests.
Conclusions and Clinical Relevance—Flow cytometry can be useful for characterizing the immune response after administration of MAP vaccine and should be evaluated with regard to its sensitivity and specificity when used in detecting cattle naturally infected with MAP.
Objective—To determine whether cats exposed at a residence were infected with Mycobacterium bovis, whether the tuberculin skin test can identify cats infected with M bovis, and whether an ELISA could identify tuberculosis-infected cats.
Animals—20 domestic cats exposed to a cat with laboratory-confirmed disseminated M bovis infection.
Procedure—Cats were administered a tuberculin skin test and monitored for 72 hours. Blood and fecal samples were collected. Cats were then euthanatized, and postmortem examinations were performed. Tissues were examined grossly and histologically for signs of mycobacteriosis. Pooled tissue samples and fecal samples were submitted for mycobacterial culture. Blood samples were examined for evidence of tuberculosis by use of a comparative ELISA.
Results—4 cats had positive responses for the ELISA, and 2 cats had suspicious responses. All tuberculin skin tests yielded negative results. No gross or histologic lesions of tuberculosis were detected in any tissues, and mycobacteria were not isolated from tissues or feces obtained from the 20 cats.
Conclusions and Clinical Relevance—All cats that had positive or suspicious responses for the ELISA were offspring of the cat with tuberculosis. Evidence of tuberculosis was not seen in other cats at the residence, the owner, or the attending veterinarian. The most likely source of tuberculosis for the infected cat was through the consumption of M bovis-infected wildlife carcasses or offal. Because M bovis is endemic in wildlife in northeastern Michigan, there is a risk of exposure to tuberculosis in companion animals, their owners, and attending veterinarians. (Am J Vet Res 2002;63:1507–1511)