What process might a virus use for entry into a host cell?

A virus commonly utilizes receptor-mediated endocytosis to gain entry into a host cell. This process involves the virus binding to specific receptors on the surface of the cell. Once attached, the cell undergoes conformational changes that result in the internalization of the virus, typically forming a vesicle around it.

Receptor-mediated endocytosis is particularly effective for viruses because they often have proteins on their surface that specifically interact with host cell receptors, ensuring their uptake. This targeted approach allows viruses to efficiently infect cells and initiate replication.

Phagocytosis, while a form of endocytosis, is generally used by the immune system to engulf larger particles like bacteria and debris, rather than for viral entry. Exocytosis is the process by which substances are expelled from a cell, not entered, and active transport typically involves moving substances across membranes against their concentration gradient, which is not how viruses gain entry. Thus, receptor-mediated endocytosis is the most relevant and effective mechanism for viral cell entry.