4th International AIDS Conference Stockholm, Sweden. — June 12-16, 1988

Int Conf AIDS. 1988 Jun 12-16;4:1.118 (abstract no. 1023)

David Pauza¹, Jose Galindo¹, Todd Price^2
1The Salk Institute, San Diego, CA and ²Department of Biology, University of California, San Diego

OBJECTIVE: Discern the infectious route of HIV particle entry into susceptible cells.

METHODS: 32P-labelled HIV was added to growing cultures of the lymphoid line CEM; the radioactive label was contained primarily in viral RNA. We observed the entry of these particles by determining the rate at which the label first became resistant to trypsin treatment, indicative of particle internalization, and then susceptible to RNase digestion in cell extracts; the latter characteristic reflects virus uncoating. Electron microscopy provided a visual parallel to the biochemical data.

RESULTS AND CONCLUSIONS: At short times subsequent to adding radiolabelled virus to CEM cells, a fraction of the counts were observed to be trypsin resistant and RNase resistant, thus indicating that intact viral particles had been internalized. At longer intervals, this fraction of the virus particles became trypsin resistant and RNase sensitive, revealing that viral uncoating occurred at an internal cellular location. Electron microscopy confirmed the conclusion that intact HIV particles penetrated the T-cells and micrographs of viral:endosomal membrane fusion events were obtained. Accordingly, evidence is presented that infectious entry of HIV into susceptible T-cells proceeds via receptor-mediated endocytosis. In addition, more than 5,000 cell-surface bound virus particles were examined; no evidence was obtained to support the notion that HIV penetration occurs by direct fusion with the plasma membrane.

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1023

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