1% of divergence between P. gingivalis strains [30]. Although they used the same arrays and also used some identical strains the differences between our data sets were substantial. We detect a much higher number of aberrant genes probably because of higher resolution due to the use of three arrays per strain. We also excluded AG-881 a set of 55 genes before the analyses (see above) which further elevated the percentages
found in this study. Table 4 Aberrant and absent CDSs of P. gingivali s strains Strain Aberrant CDSs % aberrant Absent CDSs % absent HG184 213 11,4 133 7,8 HG1025 214 11,4 135 7,8 ATCC49417 153 8,2 88 4,7 HG1690 187 10,0 107 5,7 HG1691 227 12,1 158 8,5 34-4 207 11,0 126 6,8 FDC381 256 13,7 195 10,5 Proteases P. gingivalis is known to have a vast arsenal of proteases. The main function of these enzymes is to provide peptides for growth. These peptides can be derived from host-proteins, involved in defence against pathogens, thereby potentially disrupting the host immune response. Other proteases degrade collagen, thereby weakening the tooth-supporting tissues. Proteases have PRIMA-1MET cost therefore been regarded as important virulence factors. A selection of 64 proteases/peptidases was made by text searches in the P. gingivalis
W83 genome annotation combined with peptidases found in the MEROPS P. gingivalis peptidase database [50] (http://merops.sanger.ac.uk/index.shtml). This selection was learn more analyzed for presence in the test strains. From the analysis it was clear that most proteases, 58 in total, belong to the core gene set of P. gingivalis. From the 6 non-core protease genes (Table 5) tpr Pregnenolone was already mentioned earlier. The gene prtC, a collagenase, was found to be aberrant only in three strains with medium/low virulence in a subcutaneous mouse model. Interestingly, in early studies on P. gingivalis
virulence one of the discriminatory factors between virulent and avirulent strains was described to be collagenase activity, which was found to be low in avirulent strains [51]. Another non-core protease gene is the well-described rgpA, an arg-gingipain which has regularly been described as one of the most important virulence factors of P. gingivalis [52, 53]. RgpA is aberrant in the highly virulent strain ATCC53977. This finding is however in line with a murine periodontitis model study in which rgpA was found to be not important in virulence using P. gingivalis knockouts [34]. From the present study, however, no hard conclusion should be drawn as no functional changes have been explored. Table 5 Non-core protease genes of P.