Antiserum against Propionibacterium acnes (type. reference sera) may be easily produced in rabbits by immunization with phenol-killed whole bacterial cells of reference type strains. However, this reference serum is not specific and it would not allow to identify various type strains by routine bacterial agglutination test and even by sensitive passive haemagglutination test. Preparation of type specific reference sera by absorption with heterologous serotype is not possible either since the type specific antigens is generally lacking on the surface of cell wall of P. acnes.
In this study, type specificity of bacterial antigen and TCA extracts of cell- wall against reference type sera was analysed by bacterial agglutination, double diffusion, immunoeletrophoresis (IE), two-dimensional (TDIE) and tandem crossed-IE(TCIE).
Using the reference sera, both bacterial agglutination test and double diffusion test showed high cross-reaction. Neverthless, using the reference sera the TCA extracted antigens from type I and type II showed type specificity by IE, TDIE and TCIE. By means of TCIE, distinct type specific antigens wtih electrophoretic mobilities of 1. 0 in type I and 1.2 in type. II (relative to bovine serum albumin) were demonstrated. The distinct electrophoretic mobilities of type specific antigens were also developed,, against heterologous antiserum.
This result indicated that the TCA extracted antigens of two types are isomorphic in the structure of the antigen but highly specific for the type of P. acnes..
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