Protective effect of vaccination with recombinant proteins from Streptococcus equi subspecies equi in a strangles model in the mouse.

The research conducted experiments on mice to estimate the protective impact of vaccination with specific proteins derived from Streptococcus equi subspecies equi, a bacteria causing an equine disease known as strangles. The outcomes showed that vaccination with certain proteins resulted in the production of protective antibodies while others did not, and combining certain proteins in the vaccine enhanced the protective immune response.

Background of the Study

• The research focused on the disease ‘strangles’ caused by the bacterium Streptococcus equi subspecies equi (S. equi subsp. equi), which is a problematic disease for horses.
• The scientists used a mouse model for their study, which simulated the infection pattern in horses.

Procedure and Findings

• The procedure involved vaccinating the mice with chosen recombinant proteins from S. equi subsp. equi and then exposing them to the bacterium.
• After the challenge, the progress of the infection was tracked through weight loss of the mice and nasal colonisation by the bacterium.
• The results demonstrated that vaccination with a collagen-binding protein (CNE) and a collagen-like protein (SclC) stimulated the generation of protective antibodies. In contrast, a novel fibronectin-binding protein (FNEB) did not produce protective antibodies.
• The most critical finding was that a combination of CNE with EAG, a protein group with low immunogenicity (alpha2-macroglobulin-, albumin-, and immunoglobulin G-binding protein), enhanced the protective immune response. This points to a synergistic effect when these proteins are co-administered in vaccination.

Implications of the Study

• The study’s findings contribute to better understanding of the bacterial mechanisms at play during strangles infection and point towards new directions in vaccine development against this disease.
• The results demonstrate that not all proteins derived from the bacterium generate a protective immune response. Still, certain combinations can initiate a robust immune defense, potentially improving the vaccine’s effectiveness.
• The research paves the way for further investigations about the applicability of these findings in horses, which are naturally affected by the disease.