Ribosomal protein RPSA is a promising target for the prevention of Streptococcus suis serotype 2

Streptococcus suis serotype 2 is a significant zoonotic pathogen that poses a serious threat to the health of humans and various animals. Ribosomal protein S1 (RPSA), acting as a key virulence factor, mediates SS2 adhesion to host cells and facilitates its penetration of the blood-brain barrier. In this study, we expressed the SS2 RPSA recombinant protein and used it to immunize BALB/c mice. Through screening, we obtained a high-affinity hybridoma clone and produced a specific anti-RPSA monoclonal antibody (designated mAb-RPSA-5E2). We found that mAb-RPSA-5E2 exhibited potent antibacterial activity, significantly inhibiting the proliferation of SS2 in vitro. In SS2-challenged mice, treatment with mAb-RPSA-5E2 significantly reduced mortality and alleviated pathological damage in the lung and brain tissues. Furthermore, evaluating the immunoprotective effect of the SS2-RPSA protein as a subunit vaccine revealed that this vaccine provided good protection against SS2 infection. These findings indicate that RPSA is a promising candidate target for developing SS2 subunit vaccines and targeted therapeutic biologics. KEY POINTS: • The SS2 RPSA monoclonal antibody can inhibit the proliferation of SS2 in vitro. • The SS2 RPSA monoclonal antibody can reduce the mortality rates of mice. • The SS2-RPSA subunit vaccine provides significant immunoprotective effects in mice.