Modulation of cell surface protein expression by infection with HIV-1

The examples discussed above show the profound influence of HIV infection on expression pattern of cell surface proteins and the functional relevance thereof. Altered cell surface pattern is involved in all aspects of HIV-induced pathogenesis such as viral spreading viral adhesion and cellular apoptosis and is an important parameter for therapeutical approaches. The regulatory mechanism is not homogenous for all proteins but includes divergent effects like modulation of gene transcription and proteolytic cleavage. Modulation by viral infection might be either a direct or an indirect effect. Various viral proteins have been implicated in direct modulation like the regulatory proteins Tat, Nef and Vpu, but also the envelope proteins gp 120 and gp41. In addition, infection by HIV-1 has been shown to modulate expression of various cytokines including IL-10 and IFN-gamma. The altered expression of various surface proteins might be an indirect effect of cytokines acting on B cells, T cells and monocytic cells. By virus capture assays the presence of further proteins on viral surface was demonstrated indicating a possible function for viral life cycle. To study the modulation of expression of those additional important surface molecules by HIV and its biological function for the pathogenesis will be the aim of further studies in our laboratory.