Abstract
Different virus families are characterized by various immune evasion strategies. These viruses have co-evolved with an increasingly sophisticated mammalian immune system which has continually placed pressure on their continued survival. This paper proposes that exposure to directly antiviral cytokines, namely TNF and members of the IFN family, during inflammatory and early immune responses, exerted particularly strong selective pressures on viruses, and has had a critical influence on the development of viral immune evasion strategies and pathogenesis. In the context of antiviral cytokine activity, this report concentrates on two DNA virus families with contrasting pathogenic and immune evasion strategies, namely poxviruses and HSV.