Porphyromonas gingivalis virulence in mice: induction of immunity to bacterial components

Abstract

Selected cell envelope components of Porphyromonas gingivalis were tested in a BALB/c mouse model in an attempt to elucidate further the outer membrane components of this putative oral pathogen that might be considered as virulence factors in host tissue destruction. Lipopolysaccharide (LPS), outer membrane, and outer membrane vesicles of P. gingivalis W50, ATCC 53977, and ATCC 33277 were selected to examine an immunological approach for interference with progressing tissue destruction. Mice were actively immunized with heat-killed (H-K) or Formalin-killed (F-K) whole cells or with the outer membrane fraction, LPS, or outer membrane vesicles of the invasive strain P. gingivalis W50. The induction of invasive spreading lesions with tissue destruction and lethality were compared among different immunization groups in normal, dexamethasone-treated (dexamethasone alters neutrophil function at the inflammatory site), and galactosamine-sensitized (galactosamine sensitization increases endotoxin sensitivity) mice after challenge infection with the homologous strain (W50) and heterologous strains (ATCC 53977 and ATCC 33277). Enzyme-linked immunosorbent assay analyses revealed significantly elevated immunoglobulin G and M antibody responses after immunization with H-K or F-K cells or the outer membrane fraction compared with those of nonimmunized mice. The killed whole-cell vaccines provided significantly greater protection against challenge infection in normal mice (decreased lesion size and death) than did either the outer membrane fraction or LPS immunization. The lesion development observed in dexamethasone-pretreated mice was significantly enhanced compared with that of normal mice after challenge with P. gingivalis. Immunization with P. gingivalis W50 provided less protection against heterologous challenge infection with P. gingivalis ATCC 53977; however, some species-specific antigens were recognized and induced protective immunity. Only viable P. gingivalis induced a spreading lesion in normal, dexamethasone-treated, or galactosamine-sensitized mice; F-K or H-K bacteria did not induce lesions. The F-K and outer membrane vesicle immunization offered greater protection from lesion induction than did the H-K immunogen after challenge infection simultaneous with galactosamine sensitization. The H-K cell challenge with galactosamine sensitization produced 100% mortality without lesion induction, suggesting that LPS or LPS-associated outer membrane molecules were functioning like endotoxin. Likewise, P. gingivalis W50 LPS (1 ,ug per animal) administered intravenously produced 80%o mortality in galactosamine-sensitized mice. In contrast to the effects of immunization on lesion development, immunization with H-K or F-K cells or LPS provided no protection against intravenous challenge with LPS; 100% of the mice died from acute endotoxin toxicity. These findings suggest that the murine model will be useful in examining the tissuedestructive components of P. gingivalis.

Porphyromonas gingivalisinfection-induced tissue and bone transcriptional profiles

“…Microorganisms and mouse infection P. gingivalis FDC 381 was cultured and maintained for the animal infections, which were initiated within 15-30 min of bacterial preparation, as described previously (Kesavalu et al, 1992) in studies showing that P. gingivalis induces an inflammatory infiltrate, osteoclast activation, and increased messenger RNA (mRNA) expression of proinflammatory cytokines in calvarial tissues (Zubery et al, 1998;Kesavalu et al, 2002). P. gingivalis was injected at 1.5 · 10 9 cells (n = 10) into the soft tissues overlying the calvaria of the mice.…”

Inflammatory response to chlorhexidine, minocycline HCl and doxycycline HCl in an in vivo mouse model

“…The bacteria were washed three times with PBS and then heat killed at 801C for 10 min. (Kesavalu et al 1992). Using a spectrophotometer, the bacterial concentrations were standardized to an optical density of 0.1 at 650 nm, which corresponds to 10 10 CFU/ml (Baker et al 1994).…”

Mouse model of experimental periodontitis induced by Porphyromonas gingivalis/Fusobacterium nucleatum infection: bone loss and host response

“…Many investigations have been designed to study the virulence of several oral pathogens and their role in the aetiology of periodontal disease. Most of them involved mono-infection animal models (Kesavalu et al 1992, Genco et al 1998, Baker et al 2000. Several studies have shown that co-infection with different pathogens modulates the immune response and affects the clinical outcome of the infection in various diseases (Vitovec et al 2001, Stoicov et al 2004).…”