Virulence of major periodontal pathogens and lack of humoral immune protection in a rat model of periodontal disease.
OBJECTIVE
This study was designed to test the hypothesis that periodontal pathogens Tannerella forsythia and Porphyromonas gingivalis are synergistic in terms of virulence potential using a model of mixed-microbial infection in rats.


METHODS
Three groups of rats were infected orally with either T. forsythia or P. gingivalis in mono-bacterial infections or as mixed-microbial infections for 12 weeks and a sham-infected group were used as a control. This study examined bacterial infection, inflammation, immunity, and alveolar bone loss changes with disease progression.


RESULTS
Tannerella forsythia and P. gingivalis genomic DNA was detected in microbial samples from infected rats by PCR indicating their colonization in the rat oral cavity. Primary infection induced significantly high IgG, IgG2b, IgG1, and IgG2a antibody levels indicating activation of mixed Th1 and Th2 immune responses. Rats infected with the mixed-microbial consortium exhibited significantly increased palatal horizontal and interproximal alveolar bone loss. Histological examinations indicated significant hyperplasia of the gingival epithelium with moderate inflammatory infiltration and apical migration of junctional epithelium. The results observed differ compared to uninfected controls.


CONCLUSIONS
Our results indicated that T. forsythia and P. gingivalis exhibit virulence, but not virulence synergy, resulting in the immuno-inflammatory responses and lack of humoral immune protection during periodontitis in rats.
Verma
R K
RK
Department of Periodontology, Collegeof Dentistry, University of Florida, Gainesville, FL 32610, USA.
Bhattacharyya
I
I
Sevilla
A
A
Lieberman
I
I
Pola
S
S
Nair
M
M
Wallet
S M
SM
Aukhil
I
I
Kesavalu
L
L
D016301:Alveolar Bone Loss / Q000276:immunology / Q000382:microbiology / Q000473:pathology; D000818:Animals; D000907:Antibodies, Bacterial / Q000032:analysis; D000942:Antigens, Bacterial / Q000032:analysis; D001426:Bacterial Proteins / Q000032:analysis; D016866:Bacteroidaceae Infections / Q000276:immunology; D001439:Bacteroides / Q000276:immunology / Q000472:pathogenicity*; D001442:Bacteroides Infections / Q000276:immunology; D004195:Disease Models, Animal; D018450:Disease Progression; D004846:Epithelial Attachment / Q000276:immunology / Q000382:microbiology; D004848:Epithelium / Q000276:immunology / Q000382:microbiology; D005260:Female; D005885:Gingival Hyperplasia / Q000276:immunology / Q000382:microbiology; D056724:Immunity, Humoral / Q000276:immunology*; D007074:Immunoglobulin G / Q000032:analysis; D008565:Membrane Proteins / Q000032:analysis; D010518:Periodontitis / Q000276:immunology / Q000382:microbiology* / Q000473:pathology; D016966:Porphyromonas gingivalis / Q000276:immunology / Q000472:pathogenicity*; D011897:Random Allocation; D051381:Rats; D018417:Th1 Cells / Q000276:immunology; D018418:Th2 Cells / Q000276:immunology; D013997:Time Factors; D014774:Virulence
D000907:Antibodies, Bacterial; D000942:Antigens, Bacterial; D001426:Bacterial Proteins; C116104:BspA protein, Bacteroides; C105995:BspA protein, bacteria; D007074:Immunoglobulin G; D008565:Membrane Proteins