Virus attacks mucous membranes of upper respiratory tract, sometimes lungs. Most serious problems due to bacteria that invade while defences are weak. Death may occur in infants, elderly. DNA synthesis occurs in nucleus. Proteins synthesized in cytoplasm, travel back to nucleus for assembly.
Virus buds out of nucleus, travels to cell membrane and is released.
Initial infection produces blisters around mouth. Virus then migrates to trigeminal cranial nerve ganglion, remains in latent state. Each blister episode lasts a week or so. Special problem for dental workers, who can get infections of hands. Transmitted sexually, produces blisters in genital tract.