Vaccine that harnesses antifungal immunity protects mice from staph infection

S. aureusis one of the most common bacterial infections worldwide, and antibiotic-resistant strains such as methicillin-resistantS. aureus(MRSA) are a major threat and burden to public health. MRSA not only infects immunocompromised patients but also healthy individuals, and has rapidly spread from the healthcare setting to the outside community. Vaccines aimed at targetingS. aureushave failed in clinical trials, and the reason for this lack of success remains unclear. As this pathogen continues to rapidly spread on a global scale, it is vital that new approaches toS. aureusvaccination are developed. Immunocompromised individuals such as patients with HIV are highly susceptible toS. aureusinfections, and they are also at increased risk of developing fungal infections. Based on this evidence, Underhill and colleagues tested whether stimulation of antifungal immunity would promote the type of immune responses needed for effective host defense againstS. aureus.

The researchers developed a new vaccine called 4X-SA-GP, which consists of fungal ?-glucan particles loaded with fourS. aureusproteins. Mice were vaccinated once a week for three weeks with 4X-SA-GP, and then injected withS. aureuseither four or eight weeks later. Vaccination induced protective T cell and antibody responses, and the T cell responses in particular were essential for vaccine-induced protection fromS. aureusinfection. Moreover, the mice had detectable antibody levels and reducedS. aureuslevels in the spleen and kidneys eight weeks after immunization. According to the authors, this work potentially broadens the use of the ?-glucan particle vaccine system for a much-needed vaccine targetingS. aureus.

The authors conclude, "We need some creative new approaches to explore towards developing aS. aureusvaccine, and we are excited to share our recent experiences with antigen-loaded fungal particles."