Antiviral antibodies constitute an important component of the host immune response against viral infections and serve to neutralize and reduce infectivity of the virus. However, these antibodies, intended to protect the host, may sometimes prove beneficial to the virus, by facilitating viral entry and replication in the target cell. This phenomenon, known as antibody-dependent enhancement (ADE) of infection, is a result of interaction of virus–antibody immune complexes with Fcγ and/or complement receptors on certain types of host cells and promotes viral entry into the host cells. The internalized immune complexes then modulate host immune response so as to enhance viral replication and aggravate disease severity. The possibility of induction of ADE remains a concern in the development and implementation of viral vaccines and immunotherapeutics.