Electron microscopy of vesicle fluid - rapid result but cannot distinguish between HSV and VZV
Immunofluorescence of skin scrappings - can distinguish between HSV and VZV
PCR - now used routinely for the diagnosis of herpes simple encephalitis
HSV-1 and HSV-2 are among the easiest viruses to cultivate. It usually takes only 1 - 5 days for a result to be available.
Not that useful in the acute phase because it takes 1-2 weeks for before antibodies appear after infection. Used to document to recent infection.