Figure 1.

Strategies of virus entry. To gain access to the cytoplasm of host cells, viruses can employ two main strategies, i.e., either (A) through endocytosis and escape from endosomal vesicles in a process referred as receptor-mediated endocytosis or (B) by direct penetration from the plasma membrane, referred as endocytosis-independent receptor-mediated entry. Enveloped viruses are shown; however non-enveloped viruses have evolved similar strategies. These are just generalizations and there are exemptions from these rules. Black arrows represent the sequence of events and dashed-red arrows the potential induced signaling.