Determination of serum neutralization antibodies to rabies virus by a modified counterimmunoelectrophoresis test

A modified counterimmunoelectrophoresis (CIE/SN) technique was developed as a diagnostic procedure for the detection of serum-neutralizing antibodies to rabies virus. CIE/SN test results with sera from individuals undergoing postexposure rabies immunization compared favorably with those obtained by the standard mouse neutralization test procedure. Fractionation of selected sera by Sephadex G-200 column chromatography demonstrated that serological activity involved in both procedures was present in the immunoglobulin G-containing fractions of the sera. The mean advantage of the CIE/SN over the standard mouse neutralization test consists in considerably reducing the time required for results, a factor which can be of clinical importance in evaluating antibody levels to rabies virus. In addition, the CIE/SN method is simple to perform and inexpensive.