These results were confirmed in the electron microscopic
study. The virus sample was prepared from extracellular
fluids which have been shown to contain enveloped HSV
only if the multiplicity of infection and time of preparation
are carefully controlled (11). The intact envelope of herpesviruses
presents an amorphic sphere with little detail except
for spikes visible around the edges. Once the integrity of the
envelope is disrupted, the negative stain can penetrate and
reveal details of the internal capsid and individual capsomeres
(11). The envelope of herpesviruses can be preserved
intact during banding in the heavy-salt gradients by fixation
in formaldehyde or paraformaldehyde (9, 10). Therefore,
damage to the envelope of these viruses prior to fixation in
this study was most probably a function of the preincubation
of the virus with the anthraquinone and not an artifact of
sample preparation.