Peplomer

A peplomer is a glycoprotein spike on a viral capsid. These protrusions will only bind to certain receptors on the host cell: they are essential for both host specificity and viral infectivity. Host receptors can include cell-surface proteins such as flagella, pili, and lipopolysaccharides. The tail fibers of some bacteriophages, especially the T4-like phages, are modified peplomers.