Selenium Nanoparticles as a Co-adjuvant with Autolysin Recombinant Protein in the Development of a Vaccine Candidate Against Methicillin-Resistant Staphylococcus Aureus

Methicillin-resistant Staphylococcus aureus (MRSA) causes various infections in susceptible individuals who are resistant to antibiotics, resulting in high morbidity and mortality rates. This study aimed to investigate the adjuvant effect of selenium Nanoparticles (SeNPs) for the purpose of developing an effective vaccine to prevent and reduce the complications of MRSA.

Autolysin recombinant protein, expressed by IPGD and purified by Ni-NTA chromatography was used to develop the vaccine. Together with alum adjuvant, SeNPs produced in two synthetic and biogenic forms were used as a co-adjuvant to increase the vaccine’s efficacy. Four groups of BALB/c mice were subcutaneously injected with three doses of different vaccine combinations. In order to evaluate humoral immunity, the ELISA test was used to measure total IgG, IgG1, and IgG2a levels. The 30-day survival rate of experimental mice was recorded after they were exposed to a bacterial challenge test of MRSA (1.5 ×108 CFU).

In both groups receiving autolysin recombinant protein with synthetic SeNPs and with biogenic SeNPs, total IgG were higher than the control group. Compared to the control group, IgG1 and IgG2a increased more in the two previously mentioned groups. After the bacterial challenge test, the survival rate of vaccinated mice was higher than that of the control group.

The results showed that, as a co-adjuvant, synthetic and biogenic SeNPs in combination with autolysin recombinant protein could improve the humoral immune system against MRSA.