Assembling HIV

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Science  22 Aug 2003:
Vol. 301, Issue 5636, pp. 1019
DOI: 10.1126/science.301.5636.1019b

Most enveloped animal viruses produce their surface spike proteins via the host secretory pathway; these meet up with the cytoplasmically generated capsid at the cell surface before budding infectious virions directly into the external milieu. Pelchen-Matthews et al. examined the budding process of the AIDS virus, HIV-1, in human monocyte-derived macrophages. Cryoelectron microscopy revealed virions budding into an intracellular space that displayed the immunological hallmarks of late endosomes—a compartment involved in the endocytosis and recycling of material from the cell surface. Consistent with the idea that these intracellular compartments are the bona fide source of secreted viruses, it was possible to precipitate virions from the extracellular medium with antibodies against endosomal markers, but not with those recognizing cell surface markers. Thus, in macrophages, which are a major reservoir of HIV, most infectious HIV appears to bud into an intracellular compartment, where it is likely to be protected from immunological attack during assembly, and which may facilitate cell-to-cell transmission. — SMH

J. CellBiol. 162, 443 (2003).

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