Innate Immunity

Two major forms of immune defense are activated once a virus has breached a natural barrier to entry, innate and adaptive immunity. This chapter deals with the innate immune response, a mechanism that operates immediately to limit tissue injury and prevent the spread of virus to adjacent, healthy cells, the so-called “bystander” effect. Innate immunity is of broad specificity, modulated largely by the secretion of an extensive array of signaling molecules that collectively form local inflammatory responses. Almost all viruses have developed elaborate strategies to circumvent host innate immunity. Some viruses use the host innate response as a vital part of the replication cycle, for example by taking advantage of innate responses the number of cell surface viral receptors may increase or use of an expanded endoplasmic reticulum for virus assembly.