Evaluation of humoral and cellular immunity of recombinant autolysin protein Staphylococcus aureus in mouse model

Staphylococcal aureus is a gram positive cocci and opportunistic pathogen. Due to the spread of this bacterium to antibiotics resistance, one of the most important ways of prevention is the use of vaccines. In this respect, autolysin protein as one of the adhesion molecule of bacteria plays an important role for binding bacteria to the host cells and cell division. Herein, the role of autolysin protein was evaluated as a vaccine candidate.

Following preparation of recombinant autolysin, Balb/c mice were injected subcutaneously with 20µg of r-autolysin formulated in Montanide ISA-266 and Alum adjuvants three times with two week intervals with proper control group. Total, specific isotype antibodies, IFN-γ and IL-4 cytokine were evaluated on sera by ELISA. Experimental mice were challenged with a sub-lethal dose of staphylococcus strains (1.5 ×108 CFU) and following that, the number of bacteria from internal organs were determined. Survival rate was recorded for 30 days.

Significant increase of antibody with high level of IgG1 and IgG2a isotypes was demonstrated in vaccinated mice versus the control group. Also, IFN-γ and IL-4 cytokines showed significant differences in all of the experimental vaccine groups compared to control group. The bacterial load in the internal organs from immunized mice was 1000 times less than control groups. Finally, the life span of immunized mice after bacterial challenge was extended versus control mice.

These results may indicate the capacity of autolysin as candidate vaccine to control the staphylococcus infections.