Streptococcus pyogenes, also known as Group A Streptococcus (GAS), is a human pathogen that causes mild infections, such as pharyngitis, and life-threatening conditions like streptococcal toxic shock syndrome. Moreover, prolonged exposure to GAS infections can lead to post-streptococcal autoimmune sequalae, resulting in more than 500,000 deaths annually. Despite the public health burden, there are currently no licensed vaccines against GAS infections.
Most bacteria release extracellular vesicles (EVs), which are promising vaccine candidates since these display multiple antigens in their native conformation. In this study, we isolated and characterized naturally released EVs from S. pyogenes. Human monocytic cells were treated with GAS-derived EVs to test their cytotoxicity and immunostimulatory properties. Furthermore, mice were immunized with GAS-derived EVs and the serum antibody response against bacteria was measured by ELISA. Our current efforts focus on identifying antigens that elicit antibody production in immunized mice. We demonstrate that GAS-derived EVs possess immunostimulatory properties in vitro and induce production of bacteria-specific antibodies in immunized mice, serving as a potential antigen presenting platform that can aid in the discovery of novel vaccine candidates.