In humans, unique molecules are present on cell surfaces and are used for everyday cellular processes and communication. To cause disease, microbes can recognize many of these molecules, and use them to attach to the cells they want to invade or colonize.
The above video depicts microorganisms attaching to a cell surface. As the immune system functions, Y-shaped antibodies may also attach to the microbial receptors, targeting them for destruction by immune cells.Edit Summary
"To initiate replication in a host cell, most viruses must first adhere to the plasma membrane, an interaction mediated by binding to a specific receptor, a cell surface molecule." (Flint et al. 2004:127)