Detection of Surface-exposed Epitopes on Chlamydia trachomatis by Immune Electron Microscopy

Abstract

The cell surfaces of two Chlamydia trachomatis serovars were explored by immune electron microscopy with monoclonal anti bodies that recognize a number of chlamydial outermembrane components. Species, subspecies and serovar-reactive epitopes on the major outermembrane protein (MOMP) of a lymphogranuloma venereum biovar strain, L2/434/Bu, and a trachoma biovar strain, F/UW-6/Cx, were exposed on the surfaces of both elementary bodies (EBs) and reticulate bodies (RBs). Three epitopes on MOMP were inaccessible on EBs and RBs of both strains. These included a genus-reactive, species-reactive, and a subspecies-reactive epitope. In contrast, genus-specific epitopes on lipopolysaccharide (LPS) were not detected on the EB surface, but were clearly expressed on RBs of both L2/434/Bu and F/UW-6/Cx chlamydiae. Antibodies specific for the 60 kDa and 12 kDa 'cysteine-rich' outer-membrane proteins did not react with surface epitopes on either EBs or RBs. These data provide evidence that MOMP is a major surface antigen of both morphological forms, whereas some portions of the LPS molecule are exposed on the RB surface but become inaccessible to antibody after conversion to the infectious EB form.

Partial protection against genital reinfection by immunization of guinea-pigs with isolated outer-membrane proteins of the chlamydial agent of guinea-pig inclusion conjunctivitis

“…The same patterns held for the SDS-61 kDa immunogen. The analogue of the latter protein has been shown not to be surface exposed in C. trachomatis strains (Collett et al, 1989), even though it frequently induces a prominent humoral response in genital infection in humans (Newhall et al, 1982) and guinea-pigs (Batteiger & Rank, 1987). In contrast, the OGP-MOMP elicited strong antibody responses both in immunoblot and in EIA, and elicited marginally more vigorous blastogenic responses.…”

Alteration of chlamydia trachomatis biologic behavior in synovial membranes suppression of surface antigen production in reactive arthritis and reiter's syndrome

“…Since outer membrane components and surface antigen expression of C trachomatis change during the development cycle (23)(24)(25)(26)(27)(28), panels of primary antibodies against the L2 strain were used to detect chlamydial particles by IEM. These antibodies were 1) murine monoclonal antibody to chlamydial LPS (LPSMAb), 2) goat polyclonal antibody to chlamydial MOMP (MOMP-PAb) (both of these antibodies were provided by Dr. Whittum-Hudson), and 3) purified goat antibodies to all EB antigens of C trachomatis (EB-Ab; Biodesign International, Kennebunk, ME).…”

Immunoelectron Microscopy of Chlamydia psittaci with Monoclonal Antibodies

“…Birkelund et al (2) showed that anti-LPS MAbs bound strongly on the surface of formalin-fixed EB and that LPS readily dissociated from the surface of unfixed EBs. In contrast, Collett et al (9) did not detect the LPS antigen on the surfaces of C. trachomatis EB particles using anti-LPS MAbs and suggested that the LPS moiety was not exposed on the EB surface. This confusion, as to the localization of the LPS moiety on the EB surface, might be due to different MAbs used.…”

“…Immunofluorescent assay, peroxidase-and ferritinlabeled immunoelectron microscopy have been used for this purpose (8,17,19). In recent years, the immunogold-labeling method for electron microscopy has been applied to antigenic analysis of the surface of C. trachomatis as well as to that of other micro-organisms (2,9,12). Kuo and Chi (12) and Collett et al (9) examined the surface distribution of epitopes in C. trachomatis using several MAbs, and Birkelund et al (2) examined lipopolysaccharide (LPS) distribution on the C. trachomatis EB surface.…”

“…In recent years, the immunogold-labeling method for electron microscopy has been applied to antigenic analysis of the surface of C. trachomatis as well as to that of other micro-organisms (2,9,12). Kuo and Chi (12) and Collett et al (9) examined the surface distribution of epitopes in C. trachomatis using several MAbs, and Birkelund et al (2) examined lipopolysaccharide (LPS) distribution on the C. trachomatis EB surface. These studies were performed mainly on LPS, major outer membrane protein (MOMP) and other cysteine-rich proteins, and it was suggested that the surface-exposed MOMP might be responsible for the neutralization of C. trachomatis infection.…”