The reverse single radial immunodiffusion technique for detecting antibodies to Dermatophilus congolensis.

The reverse single radial immunodiffusion technique was used to detect Dermatophilus congolensis antibody in sera collected from animals previously infected to varying levels with D congolensis. Ammonium sulphate and trichloroacetic acid extracts of five different strains of D congolensis obtained from different geographical locations were used as antigens. All the extracts showed variations in their sensitivities in detecting D congolensis antibody in the various serum samples. Multiple antibodies were detected by some extracts while some showed negative antibody reaction to all extracts. Two extracts also showed cross-reactions with the serum from an animal that was infected by Nocardia species. Trichloroacetic acid extracts of all the strains were found to be more active serologically, detecting antibody in more sera and giving sharper and clearer reactions than ammonium sulphate extracts.