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Journal of Virology, July 1999, p. 5520-5526, Vol. 73, No. 7
Laboratory of Molecular Virology and
Epidemiology, AIDS Research Center, National Institute of Infectious
Diseases, Shinjuku, Tokyo 162-8640, Japan
Received 6 October 1998/Accepted 17 March 1999
To assess the role of naturally occurring basic amino acid
substitutions in the V3 loop of human immunodeficiency virus type 1 (HIV-1) subtype E on viral coreceptor usage and cell tropism, we have
constructed a panel of chimeric viruses with mutant V3 loops of HIV-1
subtype E in the genetic background of HIV-1LAI. The
arginine substitutions naturally occurring at positions 8, 11, and 18 of the V3 loop in an HIV-1 subtype E X4 strain were systematically
introduced into that of an R5 strain to generate a series of V3 loop
mutant chimera. These chimeric viruses were employed in virus
infectivity assays using HOS-CD4 cells expressing either CCR5 or CXCR4,
peripheral blood mononuclear cells, T-cell lines, or macrophages. The
arginine substitution at position 11 of the V3 loop uniformly caused
the loss of infectivity in HOS-CD4-CCR5 cells, indicating that position
11 is critical for utilization of CCR5. CXCR4 usage was conferred by a
minimum of two arginine substitutions, regardless of combination,
whereas arginine substitutions at position 8 and 11 were required for
T-cell line tropism. Nonetheless, macrophage tropism was not conferred
by the V3 loop of subtype E R5 strain per se. We found that the
specific combinations of amino acid changes in HIV-1 subtype E env V3
loop are critical for determining viral coreceptor usage and cell
tropism. However, the ability to infect HOS-CD4 cells through either
CXCR4 or CCR5 is not necessarily correlated with T-cell or macrophage
tropism, suggesting that cellular tropism is not dictated solely by
viral coreceptor utilization.
0022-538X/99/$04.00+0
Copyright © 1999, American Society for Microbiology. All rights reserved.
Role of Naturally Occurring Basic Amino Acid
Substitutions in the Human Immunodeficiency Virus Type 1 Subtype E
Envelope V3 Loop on Viral Coreceptor Usage and Cell Tropism
*
Corresponding author. Mailing address: Laboratory of
Molecular Virology and Epidemiology, AIDS Research Center, National
Institute of Infectious Diseases, Toyama 1-23-1, Shinjuku, Tokyo
162-8640, Japan. Phone: (81) 3-5285-1111. Fax: (81) 3-5285-1129. E-mail: takebe{at}nih.go.jp.
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