title: Immunogenic "subunit" of the ICRC antileprosy vaccine.
abstract: The administration of a vaccine containing ICRC bacilli, which is currently undergoing clinical trials in India, induces persistent lepromin conversion in lepromatous leprosy (LL) patients and lepromin-negative healthy subjects, with "upgrading" of tissue response in the former. A sonicate of ICRC bacilli, when subjected to gel-filtration chromatography using high-pressure liquid chromatography (HPLC), yields a high molecular weight glycolipoprotein (PP-I) with an apparent molecular weight of 10(6) daltons. PP-I, which brings about lepromin conversion in lepromin-negative healthy subjects, is a major immunogen of the organism, and carries epitopes for both B and T cells. A similar high molecular weight glycolipoprotein (PP-I Mycobacterium leprae) has been isolated from the sonicate of M. leprae. The two PP-I fractions exhibit a close antigenic relatedness at both B- and T-cell levels. However, they differ in their chemical composition and carry different charges. PP-I of ICRC is not only a good immunogen. Its high lipid content provides the necessary built-in adjuvant that would make it a good candidate for a "subunit" antileprosy vaccine. Also, since it carries epitopes for both B and T cells, PP-I ICRC could be used for "molecular engineering" to obtain molecules which selectively stimulate T-cell immunity which is the dominant host defense against M. leprae.
mesh_terms: D000328:Adult; D000596:Amino Acids / Q000032:analysis; D001426:Bacterial Proteins / Q000032:analysis / Q000276:immunology*; D001428:Bacterial Vaccines / Q000032:analysis / Q000276:immunology*; D002241:Carbohydrates / Q000032:analysis; D002851:Chromatography, High Pressure Liquid; D003429:Cross Reactions; D004797:Enzyme-Linked Immunosorbent Assay; D006001:Glycoconjugates / Q000032:analysis / Q000276:immunology*; D006801:Humans; D005779:Immunodiffusion; D007525:Isoelectric Focusing; D007916:Lepromin; D008055:Lipids / Q000032:analysis; D008297:Male; D009162:Mycobacterium avium / Q000276:immunology*; D009166:Mycobacterium leprae / Q000276:immunology*; D012882:Skin Tests
chemical_list: D000596:Amino Acids; D001426:Bacterial Proteins; D001428:Bacterial Vaccines; D002241:Carbohydrates; D006001:Glycoconjugates; D008055:Lipids; D007916:Lepromin