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Glycosylphosphatidylinositol-anchor deficiency attenuates the production of infectious HIV-1 and renders virions sensitive to complement attack.

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Amet T, Lan J, Shepherd N, Yang K, Byrd D, Xing Y, Yu Q,


Amet T, Lan J, Shepherd N, Yang K, Byrd D, Xing Y, Yu Q, (click to view)

Amet T, Lan J, Shepherd N, Yang K, Byrd D, Xing Y, Yu Q,

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AIDS research and human retroviruses 2016 5 26()

Abstract

HIV-1 escapes complement-mediated lysis (CML) by incorporating host regulators of complement activation (RCA) into its envelope. CD59, a key member of RCA, is incorporated into HIV-1 virions at levels that protect against CML. Since CD59 is a glycosylphosphatidylinositol-anchored protein (GPI-AP), we used GPI-anchor deficient Jurkat cells (Jurkat-7) that express intracellular CD59, but not surface CD59, to study the molecular mechanisms underlying CD59 incorporation into HIV-1 virions and the role of host proteins in virus replication. Compared to Jurkat cells, Jurkat-7 cells were less supportive to HIV-1 replication and more sensitive to CML. Jurkat-7 cells exhibited similar capacities of HIV-1 binding and entry to Jurkat cells, but were less supportive to viral RNA and DNA biosynthesis, as infected Jurkat-7 cells produced reduced amounts of HIV-1 RNA and DNA. HIV-1 virions produced from Jurkat-7 cells were CD59-negative, suggesting that viral particles acquire CD59, and probably other host proteins, from the cell membrane rather than intracellular compartments. As a result, CD59-negative virions were sensitive to CML. Strikingly, these virions exhibited reduced activity of virus binding and were less infectious, implicating that GPI-APs may be also important in ensuring the integrity of HIV-1 particles. Transient expression of the PIG-A gene restored CD59 expression on the surface of Jurkat-7 cells. After HIV-1 infection, the restored CD59 was colocalized with viral envelope glycoprotein gp120/gp41 within lipid rafts, which is identical to that on infected Jurkat cells. Thus, HIV-1 virions acquire RCA from the cell surface, likely lipid rafts, to escape CML and to ensure viral infectivity.

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