Taking advantage of viral immune evasion: virus-derived proteins represent novel biopharmaceuticals.

In healthy individuals, natural and adaptive immune responses are able to control virus entry into the host. In particular, CD8(+)-mediated cytotoxicity, sustained by the intervention of CD4+ cells, represents the major key event leading to virus eradication. On the other hand, viruses are able to evade from host immune response via several mechanisms, and special emphasis will be placed on hepatitis C virus and chronic Epstein-Barr infections also in view of personal data. Virokines, viroreceptors, and serpins greatly contribute to viral immune escape, and, among virokines, interleukin (IL)-10 has been object of intensive studies. Finally, all these products have been used as biopharmaceuticals, and, for instance, viral IL-10, chemokine-binding proteins, and serpins exhibit in animal models immunosuppressive, anti-inflammatory, and antiatherogenic activities. As far as their use in human trials is concernded, many cautions are required in order to avoid deleterious side effects and, in particular, the purity of the product, its route and frequency of administration, as well as the immune status of the patient should be taken into serious account.