Development of a sub-unit vaccine to protect swine against the infections caused by Streptococcus suis

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Streptococcus suis is one of the most important causes of bacterial disease in post-weaned piglets. Affected animals suffer from meningitis (affected brain), endocarditis (affected heart), arthritis (affected joints) and septicemia (general infection). There are 35 serotypes of S. suis (same bacteria but different antigens). Some of these serotypes (such as serotype 2) can also affect humans (transmission from pigs), causing serious disease. Usually, veterinarians use antibiotics to treat and even protect animals. However, the large use of antibiotic induces the increase of antibiotic-resistance and there are now many S. suis bacterial strains that are resistant. Unfortunately, there are no effective vaccines in the market to protect against this infection. We have identified a protein called "Sao" that protects pigs against a bacterial strain of S. suis serotype 2. It is not known if it protects against other strains and other serotypes that cause disease in pigs. Production of Sao protein should also be improved to obtain acceptable yields to have enough material to be tested in a large vaccine trial. In addition, this protein should be mixed with a very good pharmacological agent that increase or aid the immune response of animals (called "adjuvant"). A good adjuvant for Sao protein that is allowed to be commercially used in pigs needs to be found. The general objective of this project is to obtain a reliable Sao-adjuvant prototype vaccine that will protect pigs against most serotypes of S. suis. In addition, and to complete the vaccine, other proteins already identified by our laboratory will be tested and incorporated into the vaccine. At the end of the project we will have a vaccine prototype composed by Sao combined with other protein(s) with an appropriate adjuvant.