Figure 4.

Schematic of different pathways of viral entry. (A) Viral-cell membrane fusion of pH-independent viruses could occur at the plasma membrane under neutral pH after binding to receptor. (B) A viral particle could enter the cell through an endocytic pathway after receptor binding. Viral-cell membrane fusion could then occur in an intracellular compartment. Low pH may or may not be required for membrane fusion to occur. (C) viruses could enter cells through macropinocytosis, where the viral particle is engulfed by the cell after receptor binding. Fusion between the viral and cellular membranes would then take place at an intracellular compartment.