Evasion mechanisms of pathogenic Neisseriae

The outcome of the early stages of a neisserial infection is determined by receptor-mediated events that culminate in the attachment and invasion of human mucosal tissues. The factors participating in this process, including pili, opacity proteins (Opa), and perhaps lipopolysaccharide (LPS), undergo phase and antigenic variation allowing the pathogens to evade the human immune response. In addition antigenic variation is essential in the modulating pathogen host cell interactions. Likewise the production of distinct Opa proteins allows the bacteria to enter epithelial cells and thereby to escape the humoral host responses. Other mechanisms including antigenic mimicry by capsular polysaccharides and antigenic masquerade by immunoglobulin fragments confer additional resistance to the extracellular life style of these organisms. Finally alpha-protein, a putative hormone-like factor produced by pathogenic Neisseriae, may contribute to the complex evasion-program of these species.