RAMLAN M., YEOH N.N., NORLINDAWATI A.P. AND SURAYANI A.R.
Several enzyme-linked immunosorbent assays (ELISAs) have been developed for the detection of antibodies against Corynebacterium pseudotuberculosis, the causative agent of caseous lymphadenitis (CLA). However, none is commercially available. The ELISA using sonicated C. pseudotuberculosis to detect total antibody or IgG class antibody in serum was developed in Veterinary Research Institute, Ipoh (VRI). Our objective was to estimate the sensitivity and specificity of the developed ELISA and the agar gel immunodiffusion test (AGID) which is the diagnostic test for the detection of CLA. AGID test takes three days and ELISA only takes six to eight hours for testing. Using ELISA test, more samples can be tested in a shorter time. A total number of 500 sheep and goat sera were collected for the AGID and ELISA testing. The correlation between the two serological tests was analyzed. The estimated specificity was 95.1% for the AGID; 93.0% for the ELISA using an optical density measured cutoff point of 0.30; 90.0% using a cutoff of 0.25. The estimated sensitivities were 83.6% for the AGID; 88.0% and 93.0% for the ELISA using the cutoff of 0.30 and 0.25 respectively. Using the cutoff of 0.30 OD, the specificity is higher, 93.0% compared to 89.9% for the cutoff of
0.25 OD. The correlation between both serologic tests was 91.6%. The AGID and ELISA were specific but lack sensitivity and consistently identified the infected animals with moderate overlap between the positive test samples.