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J Virol. 2015 Nov;89(22):11294-311. doi: 10.1128/JVI.00946-15. Epub 2015 Sep 2.

Phenotypic Correlates of HIV-1 Macrophage Tropism.

Author information

1
Department of Microbiology and Immunology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA.
2
Department of Surgery, Duke University Medical Center, Durham, North Carolina, USA.
3
Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA.
4
AbbVie Inc., North Chicago, Illinois, USA.
5
Malawi-Liverpool-Wellcome Trust Clinical Research Program, University of Malawi College of Medicine, Blantyre, Malawi Department of Paediatrics and Child Health, University of Malawi College of Medicine, Blantyre, Malawi.
6
Malawi-Liverpool-Wellcome Trust Clinical Research Program, University of Malawi College of Medicine, Blantyre, Malawi.
7
Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA.
8
Division of Infectious Diseases, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA UNC Center for AIDS Research, University of North Carolina at Chapel Hill School of Medicine, Chapel Hill, North Carolina, USA.
9
Department of Neurology, Yale University School of Medicine, New Haven, Connecticut, USA.
10
Department of Neurology, University of California San Francisco, San Francisco, California, USA.
11
Department of Microbiology and Immunology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA UNC Center for AIDS Research, University of North Carolina at Chapel Hill School of Medicine, Chapel Hill, North Carolina, USA Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA risunc@med.unc.edu.

Abstract

HIV-1 is typically CCR5 using (R5) and T cell tropic (T-tropic), targeting memory CD4(+) T cells throughout acute and chronic infections. However, viruses can expand into alternative cells types. Macrophage-tropic (M-tropic) HIV-1 variants have evolved to infect macrophages, which have only low levels of surface CD4. Most M-tropic variants have been isolated from the central nervous system during late-stage chronic infection. We used the HIV-1 env genes of well-defined, subject-matched M-tropic and T-tropic viruses to characterize the phenotypic features of the M-tropic Env protein. We found that, compared to T-tropic viruses, M-tropic viruses infect monocyte-derived macrophages (MDMs) on average 28-fold more efficiently, use low-density CD4 more efficiently, have increased sensitivity to soluble CD4 (sCD4), and show trends toward sensitivity to some CD4 binding site antibodies but no difference in sensitivity to antibodies targeting the CD4-bound conformation. M-tropic viruses also displayed a trend toward resistance to neutralization by monoclonal antibodies targeting the V1/V2 region of Env, suggesting subtle changes in Env protein conformation. The paired M- and T-tropic viruses did not differ in autologous serum neutralization, temperature sensitivity, entry kinetics, intrinsic infectivity, or Env protein incorporation. We also examined viruses with modestly increased CD4 usage. These variants have significant sensitivity to sCD4 and may represent evolutionary intermediates. CD4 usage is strongly correlated with infectivity of MDMs over a wide range of CD4 entry phenotypes. These data suggest that emergence of M-tropic HIV-1 includes multiple steps in which a phenotype of increased sensitivity to sCD4 and enhanced CD4 usage accompany subtle changes in Env conformation.

IMPORTANCE:

HIV-1 typically replicates in CD4(+) T cells. However, HIV-1 can evolve to infect macrophages, especially within the brain. Understanding how CCR5-using macrophage-tropic viruses evolve and differ from CCR5-using T cell-tropic viruses may provide insights into viral evolution and pathogenesis within the central nervous system. We characterized the HIV-1 env viral entry gene from subject-matched macrophage-tropic and T cell-tropic viruses to identify entry features of macrophage-tropic viruses. We observed several differences between T cell-tropic and macrophage-tropic Env proteins, including functional differences with host CD4 receptor engagement and possible changes in the CD4 binding site and V1/V2 region. We also identified viruses with phenotypes between that of "true" macrophage-tropic and T cell-tropic viruses, which may represent evolutionary intermediates in a multistep process to macrophage tropism.

PMID:
26339058
PMCID:
PMC4645658
DOI:
10.1128/JVI.00946-15
[Indexed for MEDLINE]
Free PMC Article

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