In situ expression and localization of Neisseria gonorrhoeae opacity proteins in infected epithelial cells: apparent role of Opa proteins in cellular invasion.

Abstract

SummaryDuring natural infection, gonococcal opacity proteins (Opa) undergo rapid phase variation, but how this phenomenon contributes to the virulence of the bacteria is not well understood. In the present immunomorphological study we examined the actual Opa status ofindividual gonococci during various stages ofgonococcal infection of Chang epithelial cells, by probing ultrathin sections of infected specimens with Opa-specific monoclonal antibodies. Our results demonstrate a heterogeneous Opa expression during the initial interaction of the bacteria, but an almost 100% expression of one of the probed Opas during their secondary attachment and entry into the host cells, suggesting a role for distinct Opas in cellular penetration . The association between Opa expression, tight attachment, and bacterial invasion into the host cells could be confirmed with isogenic variants that expressed different Opa proteins. Once inside the epithelial cells, both morphologically intact, Opa positive and morphologically disintegrated, Opa negative bacteria were observed. The loss ofOpa immiinoreactivity in intracellular gonococci could not be related to the presence of a particular Opa protein, but could be mimicked by incubating the organisms with extracts of sonicated uninfected epithelial cells, suggesting that it was caused by host cell proteolytic activity. Taken together, our data suggest that Opa phase transitions confer a functional adaptation of the bacteria enabling host cell penetration .

Antibodies to opacity proteins (Opa) correlate with a reduced risk of gonococcal salpingitis.

“…Different Opa appear to mediate adherence to different cell types. The recent work by Weel et al (36) indicated that only one of the initially many Opa types was expressed by intracellular organisms. The authors hypothesized that perhaps only certain Opa types can mediate the attachment or induce the endocytosis required for cellular penetration.…”

Virulent strain associated outer membrane proteins of Borrelia burgdorferi.

“…The second category, lipoproteins, have a lipid moiety anchored to the inner leaflet of the OM and a periplasmic protein moiety. It is the outer membrane spanning proteins of many pathogenic bacteria, which are known to mediate essential steps in pathogenesis, such as adhesion (46,47), invasion (48)(49)(50)(51)(52), and serum resistance (53)(54)(55)(56). In contrast, most studies on pathogenesis and immunity in Lyme disease have focused on B. burgdorferi lipoproteins, such as OspA (5)(6)(7)(8)(9)(10)14), whose principle cellular location appears to be subsurface (12).…”

Digital confocal microscopy allows measurement and three-dimensional multiple spectral reconstruction of Neisseria gonorrhoeae/epithelial cell interactions in the human fallopian tube organ culture model.

“…Existing data indicate that gonococcal Opa proteins mediate attachment in the Fallopian tube (11) and, in some cell lines, invasion (6,7,12,13). Certain Opas also mediate intergonococcal adherence via interactions with lipo-oligosaccharide (39).…”

“…These two events may be mediated by single or multiple microbial factors (1). Attempts to sort out the role of putative attachment and invasion factors of Neisreriagonorrhoerze (GC) have utilized a variety of cell types and models, many of which use resistance to killing by extracellular agents, such as gentamicin, to distinguish extracellular from intracellular bacteria (2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13). Results of these investigations have not been uniform with different cell types (6,12,13), so extrapolation of these data to infections of natural target tissues is difficult.…”