Purpose of review: New evidence is provided that the complement system is not only an effective component of the innate immunity, but is also involved in bridging innate and adaptive immune response to control retroviral infections.
Recent findings: The complement contributes to the control of retroviral replication by various strategies, such as complement-mediated lysis, triggering of B-cell responses by trapping the virus on follicular dendritic cells in the germinal center or enhancing of antigen presentation and thus the induction of virus-specific cytotoxic T lymphocytes. HIV has evolved mechanisms to escape from complement-meditated neutralization and counteracts these immune responses by escaping from lysis, using follicular dendritic cells as anchor to generate a latent viral reservoir and enhancing the infection of antigen-presenting cells.
Summary: This review will discuss the complex interactions of complement and complement receptors with retroviruses and review the escape mechanisms, which protect this virus family from complement-mediated destruction.