IgG Serum Levels against Porphyromonas gingivalis recombinant HmuY protein

Porphyromonas gingivalis, an anaerobic Gram- negative bacterium associated to periodontitis, uses outer membrane receptors, gingipains and lipoproteins to obtain iron/heme, necessary for its growth. HmuY is a putative heme-binding lipoprotein associated with the outer membrane. Objectives: This study was undertaken to evaluate Immunoglobulin G serum levels against Porphyromonas gingivalis HmuY recombinant protein. Methods: Were included 93 patients divided in four groups: 29 chronic periodontitis (CP),12 aggressive periodontitis (AP), 22 gingivitis patients(GP), and 30 healthy controls (HC). Recombinant HmuY protein was constructed, overexpressed and purified from Escherichia coli cells. Humoral response was assayed by ELISA whose quality control was determined using the coordinate points of the ROC curve, establishing cut off, sensitivity and specificity. Clinical periodontal examination was considered as the gold standard to compare the ELISA results. The non-parametric Kruskal-Wallis test was used for comparisons among groups. Differences in serum antibody levels between paired groups were assessed by Mann-Whitney U test and the alpha values were corrected by the Bonferroni pos-hoc test. Results: The cut off value determined was 0.324, establishing 79.3% sensitivity and 76.7% specificity. CP group had higher levels of IgG than AP, GP and HC groups (p<0,001). There was no statistically significant diference between AP, GP and HC. Conclusion: HmuY is a important immunogenic protein from Porphyromonas gingivalis related to chronic periodontitis.