What structure do viruses use to attach to host cells?

Viruses use glycoproteins to attach to host cells, which are proteins with carbohydrate (sugar) molecules attached to them. These glycoproteins typically exist on the surface of the virus and are critical for the virus's ability to recognize and bind to specific receptors on the surfaces of host cells. This binding is an essential first step in viral infection because it allows the virus to enter the host cell and begin its replication cycle.

The specificity of glycoproteins in the attachment process determines the host range of the virus — meaning which types of cells or organisms the virus can infect. Different viruses have distinct glycoproteins that facilitate attachment to their respective host cells, contributing to their virulence and the diseases they may cause.

In contrast, the capsid, which is the protein shell that encases the viral genetic material, plays a role in protecting the virus and assisting in the delivery of its genome into host cells but does not directly engage in the attachment process itself. The nucleus is a structure found within eukaryotic cells and is not relevant to viral structure or function. The cell wall is a rigid structure found in many bacteria and plants, providing structural support, but it is not a feature of viruses. Thus, glycop