Cytomegalovirus and Varicella–zoster Virus Vaccines
long-term clinical trial. In seropositive but
immunocompromised individuals, such
as candidates for transplantation
immunosuppression, inactivated varicella
virus or recombinant protein subunit vac-
cines may be safer alternatives even though
they are generally less effective in stimu-
lating cytotoxic T cells.
Virion Structure and Composition
All of the members of the human her-
pesvirus family have a common structure
for the virus particle, or virion, as shown
in Fig. 1. From the inside to the out-
side, there are four structures: an inner
core containing the viral genetic informa-
tion (DNA genome) associated with viral
protein, a protein shell with icosahedral
symmetry known as an icosahedral cap-
sid, an amorphous layer containing viral
proteins known as the tegument or ma-
trix, and a surface envelope composed
of a cell-derived lipid bilayer and mul-
tiple species of viral glycoprotein. The
single-letter alphabetical nomenclature for
individual envelope glycoproteins is based
upon homology to envelope glycoproteins
of herpes simplex virus-1 (HSV-1). The
envelope is the most fragile component
of the virion, and removal or destruction
of the envelope with detergents or or-
ganic solvents such as ether or chloroform
renders the virion noninfectious. The cor-
responding capsid, tegument/matrix, and
envelope glycoproteins of CMV and VZV
serve similar functions in virus attachment
to cells, intracellular replication, and virus
assembly and egress. However, the corre-
sponding CMV and VZV proteins have
distinct amino acid sequences and can
be distinguished by reactivity with VZV-
speci±c versus CMV-speci±c antibody.
Viral DNA Genomes and Specifc Gene
Sequences For Recombinant Vaccines
The viral genome for all herpesviruses
is a linear molecule of double-stranded
DNA. This genome encodes all these
virion-associated structural proteins as
proteins that may function as intracellular
enzymes and regulatory proteins. The
230 kb DNA genome of CMV is among
Lipid bilayer (envelope)
Major glycoproteins:
CMV gB, gH/gL/gO
VZV gE/gI, gB, gH/gL/gO
Tegument/matrix proteins:
CMV pp65, pp150
VZV IE62, IE63
Icosahedral capsid
linear, double-stranded DNA
200 nm
±ig. 1
Structure and composition of CMV and VZV virions.
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