Group A Streptococcus Adsorbed Vaccine: Repeated Intramuscular Dose Toxicity Test in Minipigs.

Streptococcus pyogenes infection continues to be a worldwide public health problem causing various diseases in humans and plays an important role in the pathogenesis of rheumatic fever and rheumatic heart disease. We developed a vaccine candidate to prevent S. pyogenes infections, identified as StreptInCor, that presented promising results in mouse models. A certified and independent laboratory conducted two repeated intramuscular dose toxicity tests (28 days, four weekly injections). The first test, composed of four experimental groups treated with 0 (vehicle), 50, 100 or 200 µg/500 µL StreptInCor, did not show significant alterations in clinical, hematological, biochemical or anatomopathological parameters related to the administration of StreptInCor. In addition to the parameters mentioned above, we evaluated the cardiac function and valves of animals by echocardiography before and after administration of 200 µg/500 µL StreptInCor versus placebo. We did not observe any changes related to StreptInCor administration, including changes in cardiac function and valves in animals, after receiving the highest dose of this vaccine candidate. The results obtained in the two repeated intramuscular dose toxicity tests showed that this vaccine formulation did not induce harmful effects to the tissues and organs studied, indicating that the candidate vaccine is well tolerated in minipigs.