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J. Virol., 12 1995, 8164-8168, Vol 69, No. 12
A Pelchen-Matthews, P Clapham and M Marsh
We have analyzed the role of CD4 endocytosis in human immunodeficiency
virus (HIV) entry by measuring the infection of HeLa cells expressing
various CD4 constructs with endocytosis rates of between 0.2 and 30%/min in
a quantitative infectious focus assay. For a number of laboratory-adapted
HIV-1 and HIV-2 strains, the highest levels of infection were found on
cells with very limited CD4 endocytosis, while cells with efficient CD4
uptake were only poorly infectable, suggesting that CD4 internalization is
not required for HIV entry. This was confirmed in a modified assay
involving prebinding of HIV-1LAI to HeLa- CD4 cells at 4 degrees C,
synchronized virus entry during warming to 37 degrees C, and neutralization
of virions remaining at the cell surface with anti-V3 loop antibodies.
Warming cells in hypertonic medium inhibited CD4 endocytosis but did not
affect the rate or the extent of infection. These studies confirm that HIV
infection does not require endocytosis and that laboratory-adapted virus
strains can enter HeLa- CD4 cells by fusion at the plasma membrane.
Copyright © 1995, American Society for Microbiology
Role of CD4 endocytosis in human immunodeficiency virus infection
Medical Research Council Laboratory for Molecular Cell Biology, University College London, United Kingdom.
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