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J Virol, July 1998, p. 6092-6103, Vol. 72, No. 7
School of Dental
Medicine,1
Center for Oral Health
Research,2
School of
Medicine,4 and
School of Veterinary
Medicine,5 University of Pennsylvania,
Philadelphia, Pennsylvania 19104, and
Microbiology-Immunology Department, Northwestern University
Medical School, Chicago, Illinois 606113
Received 10 March 1998/Accepted 14 April 1998
The herpes simplex virus (HSV) gH-gL complex is essential for virus
infectivity and is a major antigen for the host immune system. The
association of gH with gL is required for correct folding, cell surface
trafficking, and membrane presentation of the complex. Previously, a
mammalian cell line was constructed which produces a secreted form of
gHt-gL complex lacking the transmembrane and cytoplasmic tail regions
of gH. gHt-gL retains a conformation similar to that of its full-length
counterpart in HSV-infected cells. Here, we examined the structural and
antigenic properties of gHt-gL. We first determined its stoichiometry
and carbohydrate composition. We found that the complex consists of one
molecule each of gH and gL. The N-linked carbohydrate (N-CHO) site on
gL and most of the N-CHO sites on gH are utilized, and both proteins also contain O-linked carbohydrate and sialic acid. These results suggest that the complex is processed to the mature form via the Golgi
network prior to secretion. To determine the antigenically active sites
of gH and gL, we mapped the epitopes of a panel of gH and gL monoclonal
antibodies (MAbs), using a series of gH and gL C-terminal truncation
variant proteins produced in transiently transfected mammalian cells.
Sixteen gH MAbs (including H6 and 37S) reacted with the N-terminal
portion of gH between amino acids 19 and 276. One of the gH MAbs, H12,
reacted with the middle portion of gH (residues 476 to 678). Nine gL
MAbs (including 8H4 and VIII 62) reacted with continuous epitopes
within the C-terminal portion of gL, and this region was further mapped
within amino acids 168 to 178 with overlapping synthetic peptides.
Finally, plasmids expressing the gH and gL truncations were employed in
cotransfection assays to define the minimal regions of both gH and gL
required for complex formation and secretion. The first 323 amino acids of gH and the first 161 amino acids of gL can form a stable secreted hetero-oligomer with gL and gH792, respectively, while gH323-gL168 is
the smallest secreted hetero-oligomer. The first 648 amino acids of gH
are required for reactivity with MAbs LP11 and 53S, indicating that a
complex of gH648-gL oligomerizes into the correct conformation. The
data suggest that both antigenic activity and oligomeric structure
require the amino-terminal portions of gH and gL.
0022-538X/98/$04.00+0
Copyright © 1998, American Society for Microbiology. All rights reserved.
Structural and Antigenic Analysis of a Truncated
Form of the Herpes Simplex Virus Glycoprotein gH-gL Complex


*
Corresponding author. Mailing address: Microbiology
Department, School of Dental Medicine, University of Pennsylvania, 4010 Locust St., Levy Bldg., Rm. 215, Philadelphia, PA 19104-6002. Phone:
(215) 898-6553. Fax: (215) 898-8385. E-mail:
tpeng{at}biochem.dental.upenn.edu.
Present address: Nephrology Section, Dept. of Medicine, University
of Chicago, Chicago, IL 60637.
Present address: SmithKline Beecham Biologicals, Rue de
l'Institute 89, B-1330, Rixensart, Belgium.
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