Immunomodulation in Viral Infections: Virus or Infection-Induced?

Symptoms of immunomodulation are a common feature of many infections, regardless of whether the infecting agents are bacteria, fungi, protozoa, multicellular parasites, or viruses. An essential question is whether and to what extent they are nonspecific consequences of infectious processes per se (the nature and the properties of the aggressor being important only in that they influence infection characteristics and severity as well as host reactions) or represent the result of direct, specific interactions between the infecting agent (or its products) and IC. In the case of viral infections the question is particularly relevant because 1) viruses are especially equipped to interact with, to invade, and to modify the behavior of cells, 2) various classes of IC have been shown to bind, to internalize and to replicate viruses possessing widely different biological and pathogenetic properties, and 3) the mechanism(s) whereby immunomodulation is generated may have important bearings on the ways acute and chronic viral infections evolve, on the pathogenesis of viral diseases and on the choice of rational therapy.