An evolutionary view of viral regulatory genes

It is my great honor to dedicate this article to Professor Ludwig C. Yen at the occasion of the Annual Meeting of the Chinese Society of Microbiology, commemorating his 101st Birthday. I have had the privilege of being one of the earliest students of Professor Yen, and as a staff member working for 16 years under him, I have been benefited enormously from his teachings. I am most grateful to Dr. Czausiung Yang and the executive board members of the Chinese Society of Microbiology for giving me this opportunity to present some of my research activities which would be relevant to Professor Yen's teachings. Introduction to the evolutionary view of host-parasite relationship was one of the many contributions Professor Yen made to enlighten students and colleagues as early as in 1940. As promulgated by Professor Yen, natural history of infectious diseases has witnessed the reality of Theobald Smith's premise, "pathogenicity of microorganisms is an accident in the evolutionary processes of host-parasite relationship, and the outcome of evolutionary forces is a modus vivendi (a feasible compromise) according to which the parasite and the host reach some sort of equilibrium which permits the survival of both"(1). These evolutionary concept has since become a common knowledge for modern students of infectious diseases. The natural history of recently discovered human retroviruses such as HTLVs (human T-lymphotropic viruses) and HIVs (human immunodeficiency viruses) has amply demonstrated the truth of the premise. I shall review some results of our research which would be of relevance to the evolution of viral quasispecies and variants, viral oncogenes, and the cellular as well as viral regulatory genes. I shall focus on the roles played by these genes in the delicate and complex balance of host-virus relationships, and on their association with cellular differentiation and oncogenesis.