Reconstruction of outer glycolipid synthesis pathways from Porphyromonas gingivalis in Escherichia coli for production of a vaccine candidate.

Background: Porphyromonas gingivalis is a major human oral opportunistic pathogen and a key etiological agent of periodontal disease, contributing to inflammation and bone loss in the oral cavity. Periodontitis is not limited to oral health complications; it has also been associated with a range of systemic conditions, including coronary heart disease (CAD), respiratory disease, rheumatoid arthritis, chronic kidney disease (CKD), and certain types of cancer.

Objectives: Immunization-based prevention of periodontitis appears to be a promising strategy; however, no vaccine is currently available for commercial use. In the present study, a novel vaccine candidate against P. gingivalis was proposed, consisting of a P. gingivalis protein, gingipain, glycosylated with the carbohydrate moiety of P. gingivalis lipopolysaccharide (LPS).

Material and methods: Glycosylation of gingipain was achieved in Escherichia coli by introducing the Campylobacter jejuni N-glycosylation system, the P. gingivalis LPS biosynthetic pathway and the gingipain gene.

Results: The neoglycoprotein was purified using column chromatography to a purity exceeding 99%, yielding a soluble antigen. The modified protein was recognized by commercial antibodies targeting the protein backbone, the carbohydrate moiety, and a custom monoclonal antibody specific to the purified LPS of P. gingivalis American Type Culture Collection (ATCC) 33277. The glycoprotein was used to immunize mice, and the resulting sera were analyzed for their ability to opsonize bacterial cells. The absence of detectable opsonization suggests that the elicited antibodies are more likely directed against the protein component of the vaccine rather than the glycan surface antigen.

Conclusions: The final product was most likely assembled correctly, as it was recognized by LPS-specific antibodies. Further evaluation in an animal model of induced periodontitis is necessary to determine whether the elicited antibodies can effectively inhibit gingipain released by the pathogen. If this vaccine candidate demonstrates protective efficacy, the approach could accelerate and enhance the safety of vaccine design against a wide range of other pathogens.