Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 6/1/2008
Publication Date: 6/1/2008
Citation: Jagadeesan, B., Raizman, E., Nanduri, V., Bannantine, J.P., Bhunia, A.K. 2008. Rapid Label Free Sero-diagnosis of Johne's Disease Using Surface Plasmon Resonance Biosensor [abstract]. American Society for Microbiology. p. 247. Interpretive Summary:
Technical Abstract: Johne’s disease (JD) is a chronic and progressive intestinal disease occurring mainly in dairy cows caused by Mycobacterium paratuberculosis (Map). Individual fecal culture is the most definitive method of diagnosis since it can detect Map during both subclinical and clinical stages of JD with an estimated specificity of 100% and sensitivity of 40-80%. The test, however, requires up to 16 weeks of incubation. Hence, the most common diagnostic test for Map is serum ELISA. The sensitivity of ELISA test, however, is low (15%) in subclinically infected cows, thus, any significant progress in the control of JD depends upon the development of a diagnostic test with high sensitivity and relatively short turnaround time. Thus, in this study, we tested the use of surface plasmon resonance (SPR) biosensor for the sero diagnosis of Johne’s disease. SPR sensor can sensitively measure the binding events between two molecules, occurring on the gold surface. Recombinant Mycobacterium paratuberculosis antigen (Map 0900 - cell envelope antigen) (5 µg) was immobilized by physical adsorption (30 min) onto the gold surface of the Spreeta**TM SPR biosensor. Control antigen (5 µg of MBP-LacZ) was immobilized in the control channel. After a PBS wash, the surface was blocked with bovine serum albumin (BSA) (1 mg/ml). The sensor was tested with Johne's disease- positive and -negative serum samples collected from dairy farms in Indiana and each sample was previously tested for anti-Map antibody by ELISA. Different dilutions of fetal calf serum (FCS) were used to determine the non specific interaction between the antigens and the serum proteins. Based on the FCS binding results, we used 1:1000 or higher dilutions of the serum and SPR data strongly correlated with the ELISA data for tested serum samples. Moreover, a concentration dependent increase in SPR signal was observed for positive serum samples. Thus, this study demonstrated the potential use of SPR sensor for sero diagnosis of Johne’s disease. Further studies are underway to determine the detection threshold of anti-Map antibodies in serum samples from cows with clinical or sub clinical infection.