Aj. Vanwinkelhoff et al., K-ANTIGENS IN PORPHYROMONAS-GINGIVALIS ARE ASSOCIATED WITH VIRULENCE, Oral microbiology and immunology, 8(5), 1993, pp. 259-265
We investigated antigens in spreading and non-spreading Porphyromonas
gingivalis strains. On the basis of differences in virulence in the mo
use model, 8 strains were selected for antiserum production in rabbits
. Hyperimmune sera were tested by double immunoprecipitation and immun
oelectrophoresis. Besides a common antigen, differences in antigenic c
omposition were observed in the thermolabile antigens between all stra
ins tested. Two different heat-stable antigens were found after heatin
g at 120-degrees-C. One such antigen was detected after sonication of
the pellet fraction of autoclaved P. gingivalis cells. This antigen cr
oss-reacted with 6 of the 8 immune sera. This somatic antigen was almo
st neutrally charged and sensitive to sodium periodate treatment, sugg
estive of lipopolysaccharide. A second heat-stable antigen was detecte
d in the supernatant of autoclaved strains of W 83, W 50, HG 184 and A
7A1-28. These non-somatic antigens were strain-specific, i.e., no cros
s-reactivity was found with heterologous hyperimmune sera. An exceptio
n was strain W 50, which had a non-somatic heat-stable antigen which w
as recognized by W 83 antiserum. These antigens were resistant to DNAs
e, RNAse and proteinase-K treatment but were degraded by sodium period
ate. In immunoelectrophoresis, these antigens appeared to be negativel
y charged. These properties are characteristics of a K-antigen, which
likely represent a thermostable carbohydrate capsule. The presence of
K-antigen correlates very well with the serum resistance, the low chem
iluminescence, the resistance to phagocytosis and the need for opsoniz
ation with specific antibodies for complement-mediated killing of viru
lent P gingivalis strains. We propose to designate these antigens in P
gingivalis W 83 and W 50 as K1, in HG 184 as K2 and in A7A1-28 as K3.