Immune evasion by staphylococci
Staphylococci are a common cause of hospital-acquired infections and are increasingly linked to community-acquired infections. There are two primary human pathogens in the genus; Staphylococcus aureus and Staphylococcus epidermidis. The latter is generally non-pathogenic, although it can cause disease in immunocompromised individuals. In contrast, S. aureus infection is often much more serious and can, in some cases, be life-threatening. S. aureus possesses a variety of virulence factors that enable it to evade the host immune system, the majority of which are not found in S. epidermidis. S. aureus produces a variety of proteins that perform various functions in evasion of the immune system, but also has certain structural features that enable it to thwart the host immune response. Understanding the pathogenesis of this organism is critical to developing effective and sustainable treatments for S. aureus infections. By elucidating the mechanisms by which the organism causes disease, it may be possible to identify new drug targets either for preventative or curative treatments. In addition, there has been interest in exploiting this knowledge for use in the treatment of autoimmune disorders. Autoimmune disorders are characterised by an excessive or unwanted immune response, which is harmful to the patient rather than protective. Therefore, the proteins produced by S. aureus, which have the effect of interfering with or inhibiting the immune response, may have use as therapeutic products for these types of illnesses. This review will focus on the evasion of the innate immune response in humans by S. aureus, namely evasion of the complement system, phagocytes and antimicrobial peptides, as well as briefly outlining some of the promising applications of this research in the treatment of S. aureus infection and auto-immune disorders.