CELL-ENVELOPE AND CELL-WALL IMMUNIZATION OF MACACA-FASCICULARIS - EFFECT ON THE PROGRESSION OF LIGATURE-INDUCED PERIODONTITIS

The nonhuman primate, Macaca fascicularis, was used to study the role of immunization with selected members of the periodontopathic microbio ta in the longitudinal progression of ligature-induced periodontitis. Animals were immunized with cell envelope antigens prepared from Porph yromonas gingivalis and Prevotella intermedia, and a mixture prepared from Fusobacterium nucleatum, Campylobacter rectus, and Actinomyces vi scosus. Serum immunoglobulin G-(IgG), IgM and IgA isotype antibodies i ncreased significantly in all immunization groups and were specific fo r each of the immunogens. P. gingivalis and P. intermedia immunization resulted in a stabilization of the proportions of these species throu ghout most of the experiment. The high P. gingivalis antibody titer re sulted in low P. gingivalis numbers being recovered. P. gingivalis imm unization, while lowering recoverable viable P. gingivalis, resulted i n significantly increased levels of Prevotella la loescheii, Prevotell a buccae, Bacteroides macacae and Prevotella melaninogenica compared w ith preligation and preimmunization levels. Actinobacillus actinomycet emcomitans, Capnocytophaga spp. and Eikenella spp. remained at preliga tion levels postimmunization. Campylobacter spp. increased significant ly during the course of the experiment in all groups, whereas the leve ls of Fusobacterium spp. decreased. Plaque indices and bleeding on pro bing showed significant increases in all groups following ligation, wi th the placebo group showing the greatest increase. Pocket depth measu rements revealed that, whereas the placebo animals showed an approxima te 5% increase, the P. gingivalis- and P. intermedia-immunized groups showed nearly a 20% increase in pocket depth. Attachment level measure ments showed significantly greater attachment loss in the P. gingivali s- and P. intermedia-immunized groups, and the F. nucleatum + C rectus + A. viscosus immunization appeared to prevent significant changes in pocket depth/ attachment level loss. Radiographic measurement of bone loss by computer-assisted densitometric image analysis revealed that the placebo group lost bone throughout the experiment. P. gingivalis- and P. intermedia-immunized groups showed an exacerbated loss of bone density and the group immunized with F. nucleatum + C. rectus + A. vis cosus exhibited significantly lower amounts of bone loss when analyzed by computer-assisted densitometric image analysis, compared with the other immunized groups. Although immunization with P. gingivalis and P . intermedia cell envelope antigens had an effect on their emergence i n the complex microbiota of the developing periodontal pocket, this im munization also resulted in greater bone loss than immunization with F . nucleatum + C. rectus + A. viscosus, suggesting that, whereas select ed members of the putative periodontopathic microbiota may play a dire ct role in periodontal tissue destruction, the complexity of the subgi ngival microbiota dictates that considerable scrutiny is required to s elect useful immunogens that can elicit functional protection from per iodontal tissue destruction induced by oral microorganisms that alread y colonize or infect the host.