IMMUNOGENIC PROPERTIES OF THE MYCOBACTERIUM-LEPRAE RECOMBINANT 18-KDAANTIGEN PURIFIED FROM SACCHAROMYCES-CEREVISIAE - ENHANCEMENT OF DELAYED-TYPE HYPERSENSITIVITY AFTER GAMMA-IRRADIATION

In this paper we report the purification and study of the immunogenic properties of the Mycobacterium leprae 18-kDa protein antigen produced and secreted by the yeast Saccharomyces cerevisiae, using an expressi on system we recently described [Biotech. Lett. 16 (1994) 1241-1246]. The 18-kDa protein was purified from the yeast culture media by precip itation, ion exchange chromatography (MonoQ) and exclusion size chroma tography (Sephacryl S-100). The biological properties of the recombina nt protein, previously irradiated with gamma rays, were assayed by imm unization of mice. Humoral and cellular responses, monitored by antibo dy production and delayed-type hypersensitivity, respectively, were ob tained. Furthermore, gamma-irradiation of the recombinant protein prio r to the administration was shown to significantly potentiate the T-ce ll response. The data suggest that this irradiated recombinant antigen could be used in a more sensitive standardized skin test to monitor M . leprae infection.