Tracing complement-retroviral interactions from mucosal surfaces to the lymphatic tissue

During (nearly) all steps in retroviral pathogenesis, viruses are confronted with complement and complement receptor (CR)-positive cells. As all of the retroviruses tested so far activate the complement system, members of this virus family have adapted different protection mechanisms to keep complement activation under the threshold necessary to avoid complement-mediated lysis. As a consequence of complement activation, retroviruses are covered with complement proteins and thus provide additional ligands to interact with CR-expressing cells. This review discusses the complex complement-retroviral interactions and follows the fate of the virus on its way to the lymphatic tissue.