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J Virol, April 1998, p. 3394-3400, Vol. 72, No. 4
Laboratory of Immunoregulation, National
Institute of Allergy and Infectious Diseases, National Institutes
of Health, Bethesda, Maryland 20892
Received 10 October 1997/Accepted 24 December 1997
Monocytes/macrophages (M/M) and CD4+ T cells are two
important targets of human immunodeficiency virus (HIV) infection.
Different strains of HIV-1 vary markedly in their abilities to infect
cells belonging to the M/M lineage. Macrophagetropic (M-tropic) HIV-1 strains replicate well in primary lymphocytes as well as in primary macrophages; however, they generally infect T-cell lines poorly, if at
all. Although promonocytic cell lines such as U937 have been used as in
vitro models of HIV-1 infection of M/M, these cell lines are
susceptible to certain T-cell-tropic (T-tropic) HIV-1 strains but are
resistant to M-tropic HIV-1. In this study, we demonstrate that (i)
certain U937 clones ("plus" clones), which are susceptible only to
T-tropic HIV-1, become highly susceptible to M-tropic HIV-1 upon
differentiation with retinoic acid (RA); (ii) other U937 clones
("minus" clones), which are resistant to both T- and M-tropic
HIV-1, remain resistant to both viruses; and (iii) RA treatment induces
expression of CCR5, a fusion/entry cofactor for M-tropic HIV-1 in both
types of U937 clones, and yet enhances the fusogenicity of the plus
clones, but not the minus clones, with M-tropic Env's. These results
indicate that the major restriction of M-tropic HIV-1 infection in
promonocytic cells occurs at the fusion/entry level, that
differentiation into macrophage-like phenotypes renders some of these
cells highly susceptible to infection with M-tropic HIV-1, and that CD4
and CCR5 may not be the only determinants of fusion/entry of M-tropic HIV-1 in these cells.
0022-538X/98/$04.00+0
Copyright © 1998, American Society for Microbiology. All rights reserved.
Differentiation of Promonocytic U937 Subclones into
Macrophagelike Phenotypes Regulates a Cellular Factor(s) Which
Modulates Fusion/Entry of Macrophagetropic Human
Immunodeficiency Virus Type 1
*
Corresponding author. Mailing address: Laboratory of
Immunoregulation, National Institute of Allergy and Infectious
Diseases, National Institutes of Health, Building 10, Room 6A11,
Bethesda, MD 20892. Phone: (301) 402-2617. Fax: (301) 402-4122. E-mail: hmoriuchi{at}atlas.niaid.nih.gov.
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