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J. Virol., Jun 1996, 3461-3469, Vol 70, No. 6
BC Herold, SI Gerber, BJ Belval, AM Siston and N Shulman
Although heparan sulfate (HS) serves as an initial receptor for the binding
of both herpes simplex virus type 1 (HSV-1) and HSV-2 to cell surfaces, the
two serotypes differ in epidemiology, cell tropism, and ability to compete
for viral receptors in vitro. These observations are not necessarily
contradictory and can be explained if the two serotypes recognize different
structural features of HS. To compare the specific features of HS important
for the binding and infection of HSV-1 and HSV- 2, we took advantage of
structural similarities between heparin and cell surface HS and compared
the abilities of chemically modified heparin compounds to inhibit plaque
formation. We found that the antiviral activity of heparin for both
serotypes was independent of anticoagulant activity. Moreover, specific
negatively charged regions of the polysaccharide, including N sulfations
and the carboxyl groups, are key structural features for interactions of
both HSV-1 and HSV-2 with cell surfaces since N desulfation or carboxyl
reduction abolished heparin's antiviral activity. In contrast, 6-O
sulfations and 2-,3-O sulfations are important determinants primarily for
HSV- 1 infection. The O-desulfated heparins had little or no inhibitory
effect on HSV-1 infection but inhibited HSV-2 infection. Using a series of
intertypic recombinant mutant viruses, we found that susceptibility to O-
desulfated heparins can be transferred to HSV-1 by the gene for
glycoprotein C of HSV-2 (gC-2). This supports the notion that the envelope
glycoproteins of HSV-1 and HSV-2 interact with different affinities for
different structural features of heparin. To determine if the modified
heparin compounds inhibited plaque formation by competing with cell surface
HS for viral attachment, binding studies were also performed. As
anticipated, most compounds inhibited binding and plaque formation in
parallel. However, several compounds inhibited the binding of HSV-1 to
cells during the initial attachment period at 4 degrees C; this inhibitory
effect was reversed when the cells and inoculum were shifted to 37 degrees
C. This temperature-dependent differential response to modified heparin
compounds was evident primarily when glycoprotein C of HSV-1 (gC-1) was
present in the virion envelope. Minimal temperature-dependent differences
were seen for HSV-1 with gC-1 deleted and for HSV-2. These results suggest
differences in the interactions of HSV-1 and HSV-2 with cell surface HS
that may influence cell tropism.
Copyright © 1996, American Society for Microbiology
Differences in the susceptibility of herpes simplex virus types 1 and 2 to modified heparin compounds suggest serotype differences in viral entry
Section of Pediatric Infectious Diseases and Committee on Virology, University of Chicago, Illinois 60637-1470, USA.
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