Biological, chemical, immunological and staining properties of bacteria isolated from tissues of leprosy patients

Abstract

Two kinds of microorganisms are found in tissue of leprosy patients: Mycobacterium leprae (ML) and leprosy derived corynebacteria (LDC). ML from untreated patients has an alcohol-acid-fastness, which is lost upon treatment with antibiotics and immune response (tuberculoid leprosy). Vulnerable ML thus produced can be reversibly de-stained by organic solvent: in tissue sections from tuberculoid and treated patients, more bacteria are, thus, revealed by the Wade-Fite than by the Ziehl-Neelsen procedure. Organisms of genera Corynebacterium, Mycobacterium and Nocardia (CMN group), have DNA with %GC contents of 50-70, 69-72, and 68-70 respectively. GC values of DNA from ML and LDC are close to 56%. DNA from different LDC strains display high homology among them and low homology with reference corynebacteria. CMN cell wall consists of interconnected peptidoglycan and polysaccharide-mycolate complex. Peptidoglycan of LDC (and known CMN) has the polysaccharide backbone linked to a tetrapeptide of L-Ala, D-Glu, m-DAP (meso-diaminopimelate), D-Ala. In ML, L-Ala is replaced by glycine. Mycobacterial wall polysaccharides (that of ML is unknown) are branched arabinogalactans with end arabinoses linked to C70 to C90 mycolates. LDC peripheral polysaccharides are arabinogalactomannans with arabinose and mannose lateral strands. Mycolic acids of LDC are of corynomycolic type (C32, C34 and C36 with 1-4 double bonds) and those of ML are of mycobacterial type. Components of CMN wall and cytoplasm are immunologically active as antigens (polysaccharides, proteins), haptens (lipids) and adjuvants (peptidoglycans). Strong intrageneric and weak intergenera crossreactions are observed among CMN bacteria: LDC preparations, however, crossreact strongly with ML and mycobacteria, and weakly with reference corynebacteria. LDC in leprosy tissues can, thus, be revealed as well by fluorescent anti-LDC antisera as by anti-ML antisera. The main crossreacting component is antigen M1 of LDC, which corresponds to antigens Ag 7 of ML and Ag60 of BCG, the active components of lepromin and tuberculin (known reagents for cutaneous tests). Antigen M1 has a polysaccharide moiety crossreacting with the wall polysaccharide of LDC.(ABSTRACT TRUNCATED AT 400 WORDS)