Possibilities for standardisation of the ELISA for detection of Salmonellaantibodies in sera and meat juices of pigs

Programmes for controlling salmonella infections in German piggeries are ba sed on the meat-juice-ELISA conducted in various investigation centres by u sing different test-kits. A usual procedure for harmonisation (standardisat ion) of results is the calculation of the percentage of antibody-concentrat ion from field samples in relation to the extinctions of a set of control-s era with known antibody concentrations. Whether this system is still accept able in case of using different test-kits seems to be questionable. In prin ciple, difficulties arise by calculating field results from the regression curve of control-sera because the calculated percentages of antibodies do n ot represent the antibody concentration but, instead, the percentages of th e extinctions measured, and secondly, because control-sera presently in use are directed against different salmonella serovars. In regard to the number of laboratories involved and because of a variety o f test-kits used it seems to be more adequate to include only one anti-Salm onella Typhimurium standard-serum at a given antibody concentration which i s to be tested repeatedly on every test-plate. Simultaneously, further cont rols should include another anti-Salmonella Typhimurium and one anti-Salmon ella Choleraesuis serum which should provide results similar to the Danish system which is regarded as a standard. As well, a negative serum must be i ncluded in the test and a minimum difference in extinctions between this ne gative serum and the standard positive control-serum should be reached to p rove the Validity of results from the test plate.