[Titration of serum and antirabies immunoglobulins by the radial immunodiffusion method].

Titration on mice of sera and immunoglobulin rabies anibodies is expensive, tedious and long. We are proposing a cheap, easy and rapid method which could be useful during the preparation of immunoglobulin or for the final titration. The antigen is a purified inactivated vaccine cultured on human diploid cells and purified by dextran sulfate and ultracentrifugation; it is included in agar on a glass slide. The reference serum was given us by Dr Atanasiu from Pasteur Institute; its titre was compared with international reference on mice test and was given a titre of 65 IU per ml. Five specific rabies immunoglobulin and 3 sera were received from two producers for titration. For IDR test, immunoglobulin and reference serum dilutions are diposed in wells of the same agar slide and then incubated at ambiant room temperature during 48 hours. Migration of each Ig and serum dilution is measured after coloration reported on a graph and compared. Each of the samples was checked 4 times by radial immunodiffusion test and twice by seroneutralization test on mice. Statistical analysis of the results by Student's test demonstrates that both methods are comparable.