Elisa Systems for Rabies Antibody Detection

J. Esterhuysen1 andJ. Barrat2 The reference method to determine the antibody level of a serum sample is seroneutralisation. The principle of this technique is to incubate a constant known amount of rabies virus with a constant volume of the serum to be tested. The virus that has not been neutralised by the antibodies is quantified using an inoculation test either in vivo or in vitro. This method is sensitive but time-consuming. Results are obtained within 1 to 5 days (with cells) and up to 14 days with mice. Contaminated or putrefied serum samples are most often impossible to titrate because the bacteria (or their toxins) kill the mice or cells. The immunocapture phenomenon used in ELISA tests is not susceptible to the contamination risk or to the toxin hazard as the techniques using a "living" final step. A second important point is that ELISA tests give their answer more rapidly than the classical seroneutralisation. The antibody level may be determined in two different ways with ELISA techniques: antibodies are directly quantified using microplates coated with the corresponding antigen antibodies first react with a known amount of antigen. The remaining antigen is then quantified using a plate coated with the corresponding antibody. One example of each procedure will be detailed here for rabies antibody titration using the ELISA technique.