HIV AND COMPLEMENT - ROLE OF THE COMPLEMENT-SYSTEM IN HIV-INFECTION

HIV, in contrast to animal retroviruses, is not lysed by human serum b ut nevertheless the virus as well as virus-infected cells activate the complement system efficiently. HIV activates the classical pathway by binding Clq to the transmembrane protein gp41. On the surface of HIV- infected cells, both the alternative and the classical pathway are act ivated. Complement-treated HIV has an enhanced ability to infect cells carrying receptors for C3 fragments. By this mechanism complement can target the virus to certain cells, e.g. follicular dendritic cells. H IV-infected complement-coated cells can interact with complement recep tor carrying cells and thereby spread the infection or cause the destr uction of the infected cells. Due to direct or indirect effects of HIV the complement system is in an activated state and the cellular expre ssion of complement receptors as well as regulatory molecules is modif ied in the blood of HIV-infected patients.