Most recently two drugs for preventing influenza infection have entered the market. They inhibit the neuraminidase, an enzyme which serves as a viral entry protein by cleaving the neuraminic acid in the viral receptor. Viruses often replicate upon entry to the host, in tissues not associated with the site of major pathology. Rabies, while advancing to the brain via dorsal neurons causes no symptoms in the peripheral tissue where the bite occurred and symptoms only arise when virus reaches the brain. All viruses spread by cell to cell transmission.
Viremia can also occur with no spread to lymphnodes.