Pathogenesis Of Gonorrhea Research Articles

The Long and Winding Road (Apologies to the Beatles).

The Long and Winding Road (Apologies to the Beatles).

Gonorrhea

Gonorrhea is a common bacterial infection caused by Neisseria gonorrhoeae, a Gram-negative diplococcus that is transmitted almost exclusively by sexual contact or perinatally. It primarily affects the mucous membranes of the lower genital tract and less frequently those of the rectum, oropharynx, and conjunctivae. Ascending genital infection in women leads to the predominant complication, acute salpingitis, one of the most common causes of female infertility in the world. Since the 1990s, a remarkable surge of information ensued regarding the pathogenesis of gonorrhea and its agent. Gonorrhea has proven difficult to control in most populations and remains a prime example of the influence that social, behavioral, and demographic factors can have on the epidemiology of an infectious disease. The management of gonorrhea and other sexually transmitted infections requires both treatment of the patient as an individual and of his or her sexual partner(s) as a public health measure to interrupt the onward spread of infection and prevent long-term complications.

Differential recognition of members of the carcinoembryonic antigen family by Opa variants of Neisseria gonorrhoeae.

Opacity (Opa) protein variation in Neisseria gonorrhoeae is implicated in the pathogenesis of gonorrhea, possibly by mediating adherence and entry of the bacteria into human tissues. One particular Opa protein mediates adherence to epithelial cells through cell surface proteoglycans. Recently, two other eukaryotic cell receptors for Opa proteins have been reported. These receptors are members of a subgroup of the carcinoembryonic (CEA) gene family that express CD66 antigens. CEA family members vary in their distribution in human tissues. In order to understand whether interactions between Opa and CEA-like molecules play any role in pathogenesis, we must investigate which CEA family members are able to serve as Opa receptors and which Opa proteins recognize CEA-like molecules. We therefore studied HeLa cells that were stably transfected with five different members of the CEA family, i.e., CEA, CEA gene family member 1a (CGM1a), CGM6, nonspecific cross-reacting antigen (NCA), and biliary glycoprotein a (BGPa). We infected these transfectants with all possible 11 Opa variants of gonococcal strain MS11 and determined the numbers of bacteria that were bound and internalized. To account for proteoglycan-mediated adherence, infection assays were also performed in the presence of heparin. Our results show that of the 11 Opa variants of MS11, the same 4 recognized CGM1a and NCA. CGM6, however, was not recognized by any Opa variant of MS11. CEA was recognized by at least 9 of 11 Opa variants, and the BGP transfectants specifically bound and internalized 10 of 11 Opa variants and also bound Opa-negative gonococci. Immunofluorescence experiments showed that clustering of CEA-like molecules occurred upon infection of HeLa transfectants with those Opa variants that interacted specifically with the CEA family member. Together these data show that CEA family members are differentially recognized by gonococcal Opa variants, suggesting that this phenomenon may contribute to cell tropism displayed by gonococci.

Gonococcal infections.

Gonorrhea may be the most extensively studied infection of the past 20 years. The gonorrhea epidemic in the United States began in the early 1960s and peaked in 1975. Ironically, since 1976 the declining overall incidence has been offset by the advent of plasmid-mediated beta-lactamase production by Neisseria gonorrhoeae and by a growing problem with outbreaks due to strains with chromosomally mediated penicillin and tetracycline resistance. This new antimicrobial resistance, coupled with the frequency of concurrent chlamydial infection in developed countries and concurrent syphilis in some developing countries, has created a need for new approaches to gonorrhea therapy. With the introduction of certain new antimicrobial agents, highly effective forms of therapy are again available. New approaches to rapid diagnosis are also becoming available, but require critical appraisal. Unfortunately, in most of the world's population, gonorrhea remains epidemic, diagnosis of gonorrhea in women is extremely difficult, and highly effective antimicrobial agents are no longer affordable. Thus, vaccine development remains an extremely important goal. Although no candidate gonococcal vaccine currently holds high promise, the increasing understanding of the biology of the gonococcus and the pathogenesis of gonorrhea will serve to focus future research on vaccine development.

Fractionation of guinea pig serum for an inducer of gonococcal resistance to killing by human serum: active fractions containing glucopeptides similar to those from human red blood cells.

The resistance of gonococci to complement-mediated killing by serum is important in the pathogenesis of gonorrhoea. Most urethal strains lose this resistance on subculture. The host product(s) which induces the resistance in vivo is therefore fundamental to pathogenesis. Human genital secretions and some sera induced gonococci to serum resistance in vitro. Guinea pig serum was more active than human serum and low molecular weight fractions from it conferred resistance to gonococci in 3 h at 37 degrees C. Similar active fractions were obtained from human sera. Now guinea pig serum has been further fractionated for the low molecular weight inducer by membrane filtration, gel filtration on Sephadex G25, high performance liquid chromatography (HPLC) with a Spherisorb ODS reverse phase column, chromatography on Sephadex LH20 and HPLC with a Partisil SCX cation exchange column. The small yield (less than 1 mg from 400 ml serum) of highly active material was contaminated with breakdown products from the Partisil SCX column and a mixture of compounds. However, analysis indicated the presence of one or more small glucopeptides containing cysteine, glutamic acid, aspartic acid, threonine, serine, glycine, alanine, valine and lysine. Similar glucopeptides are liberated from fresh human red blood cells in slightly hypertonic saline and samples of them induced gonococci to serum resistance.

Analyses of gonococcal lipopolysaccharide in whole-cell lysates by sodium dodecyl sulfate-polyacrylamide gel electrophoresis: stable association of lipopolysaccharide with the major outer membrane protein (protein I) of Neisseria gonorrhoeae.

The lipopolysaccharide (LPS) of Neisseria gonorrhoeae whole-cell lysates and proteinase K-digested lysates was examined and compared with purified homologous LPS by a method which preferentially stains LPS in polyacrylamide gels. The silver-stained profile of gonococcal LPS in the proteinase K-digested lysate was similar to that of homologous purified LPS; however, the LPS profile in whole-cell lysates was much smaller than that of digested lysates or purified LPS. Conditions of solubilization did not affect these differences. Since it is known that LPS migrates in a unique fashion in second-dimension electrophoresis, the location of LPS in the whole-cell lysates was probed by second-dimension sodium dodecyl sulfate-polyacrylamide gel electrophoresis with a variety of stains and radiolabels. Results from these experiments indicated a stable and reproducible association of LPS with proteins ranging between 23,000 to 36,000 in Mr, in particular major outer membrane protein I. In addition to staining with the silver method, which preferentially stains LPS, the putative LPS was resistant to digestion by proteinase K, did not stain with Coomassie brilliant blue, and was not labeled extrinsically with 125I (Iodogen method) or intrinsically with [35S]methionine. Analysis of two-dimensional gels by immunoblotting with rabbit antisera prepared from protein I bands removed from a polyacrylamide gel revealed the presence of antigens in the same area of the gel (below proteins that were 23,000 to 36,000 in Mr). Antibodies to constituents which migrated below the diagonal were essentially removed by adsorption of antisera with purified LPS, as were antibodies to homologous LPS and LPS in proteinase K-digested whole-cell lysates. Immunoblotting with a monoclonal antibody specific for LPS demonstrated reactivity of the antibody with LPS and with the protein I band. On the basis of these data, we conclude that protein I and perhaps other proteins in the whole-cell lysate are stably associated with LPS; this complex is resistant to dissociation in sodium dodecyl sulfate at high temperature (approximately 100 degrees C) but does, for unknown reasons, dissociate with electrophoresis in the second dimension. The association of LPS with protein antigens in sodium dodecyl sulfate-polyacrylamide gels adds another dimension of complexity to analysis of these antigens by immunoelectroblotting. Furthermore, the tight association of LPS with the major outer membrane protein I may alter the nature of the immune response generated by "purified" protein I vaccine antigens. The possible role of protein-LPS complexes in the pathogenesis of gonorrhea is discussed.

Gonococcal adherence: selected topics.

Gonococcal adherence to human host epithelial surfaces appears to be an important feature in pathogenesis of gonorrhea. Attaining and maintaining close association with epithelial cells may involve interactions of both gonococcus to epithelial cell and gonococcus to gonococcus; it is suggested that two distinct gonococcal surface components--pili and outer membrane protein II--play complementary roles in promoting these close associations with mucosal cells. Both pili and outer membrane protein II occur in several different molecular forms among gonococci of a given strain, and expression of a particular form of each changes at high frequency in vitro. If analogous changes occur in vivo, gonococci may have a sizeable repertoire of surface facades to cope with changing or different cellular and humoral components of the host.

Serology of Neisseria gonorrhoeae: W-antigen serogrouping by coagglutination and protein I serotyping by enzyme-linked immunosorbent assay both detect protein I antigens.

A total of 224 strains were serogrouped by coagglutination (COA) and serotyped by protein I enzyme-linked immunosorbent assay (ELISA). Of these strains, 61 were from patients with disseminated gonococcal infection, 21 were from patients with pelvic inflammatory disease, and 115 were from patients with uncomplicated gonococcal infection in Singapore, the Philippines, and Denmark. Twenty-seven were laboratory reference strains. Of the patient strains, 102 belonged to COA serogroup WI, and all of the 100 strains that typed with protein I serotypes 1, 2, or 3 were in this group. Most of the strains of gonococci from the 61 patients with disseminated gonococcal infection were within this group (COA WI, 53 or 87%; protein I serotypes 1, 2, or 3, 51 or 84%). All 46 strains that were protein I serotypes 4 through 7 were also COA serogroup WII. Protein I serotypes 8 and 9 accounted for 49 (25%) of the 197 patient strains. Twenty-eight of these strains typed as COA serogroup WII, 20 typed as serogroup WIII, and 1 typed as serogroups WII and WIII. COA W serogrouping and protein I ELISA both appeared to detect antigens on the protein I molecule of the outer membrane of Neisseria gonorrhoeae. Protein I serotyping, which uses unboiled organisms, may generally recognize more variable and surface-exposed antigenic determinants. In contrast, COA W serogrouping, which uses boiled organisms, may recognize less exposed shared antigenic determinants in addition to variable protein I antigenic determinants. Both methods may prove useful for further studies of the epidemiology and pathogenesis of gonorrhea.

The Influence of Surface Charge on the Attachment of Neisseria gonorrhoeae to Human Cells

Isoelectric focusing showed that Neisseria gonorrhoeae has an overall negative surface charge. Chemical modification of protein amino or carboxyl groups changed the surface charge and thereby altered the ability of the organisms to attach to human amnion cells grown in tissue culture. Attachment of modified and unmodified N. gonorrhoeae was increased by the presence of pili only when the bacteria bore a negative surface charge. Thus an important factor in the pathogenesis of gonorrhoea may be the ability of pili to facilitate attachment of N. gonorrhoeae by overcoming the initial electrostatic repulsive barrier which exists between it and the host cell.