Detection of antibodies to Mycobacterium johnei by counterimmunoelectrophoresis

Counterimmunoelectrophoresis (CIE) was applied in the detection of antibodies to Mycobacterium johnei in 110 sheep, 11 goat and 31 cattle sera and compared to immunodiffusion (ID) test. One per cent Noble agar, 7 ml per slide of 5 cm x 10 cm; barbitone-tris buffer, mu = 0.03, pH 8.6; a constant current of 5 mA per slide and M johnei protoplasmic antigen at 4 mg per ml were found to impart high sensitivity to CIE and give rapid results. CIE detected 97 sheep, 11 goat and 31 cattle positive sera, a total of 139, as compared to 44, 11, 28 and 83 respectively, detected by ID. Strongly positive sera could be demonstrated within 30 minutes by CIE and the test was run for only 90 minutes while earliest reactions were not observed before 18 hours and some reactions took 144 hours to develop in ID test.