Virion-associated cholesterol is critical for the maintenance of HIV-1 structure and infectivity.
OBJECTIVE
HIV-1 particles are enriched with cholesterol; however, the significance of this cholesterol enrichment is unknown. This study examines the structural and functional roles of cholesterol in HIV-1 replication.


METHODS
Using methyl-beta-cyclodextrin (CD) to remove cholesterol from the HIV-1 envelope, buoyant density and infectivity of the cholesterol-deficient HIV-1 particles were compared with the untreated control. The specificity and requirement of cholesterol as an HIV-1-associated lipid were investigated by replenishing cholesterol-deficient HIV-1 with cholesterol, cholestenone (a cholesterol structural analogue) or sphingomyelin (a structurally unrelated yet virion-associated lipid).


RESULTS
CD-mediated removal of virion cholesterol increased the buoyant density of virion particles and reduced HIV-1 infectivity. Trans-supplementation of exogenous cholesterol rescued the defects associated with CD-induced cholesterol depletion in HIV-1. However, the restoration of viral infectivity could not be achieved by trans-supplementation of either cholestenone or sphingomyelin.


CONCLUSIONS
This study provides the first direct evidence that HIV-1-associated cholesterol is important for the maintenance of virion structure and infectivity. While the buoyant density of cholesterol-defective HIV-1 can be restored by a cholesterol structural analogue, cholestenone, the requirement for cholesterol is essential for HIV-1 infectivity.
Campbell
Shahan M
SM
AIDS Pathogenesis Research Unit, Macfarlane Burnet Institute for Medical Research and Public Health, Prahran, Victoria, Australia.
Crowe
Suzanne M
SM
Mak
Johnson
J
D002460:Cell Line; D002783:Cholestenones / Q000494:pharmacology; D002784:Cholesterol / Q000494:pharmacology / Q000502:physiology*; D003505:Cyclodextrins / Q000494:pharmacology; D015497:HIV-1 / Q000737:chemistry / Q000187:drug effects / Q000472:pathogenicity* / Q000502:physiology; D006801:Humans; D013109:Sphingomyelins / Q000494:pharmacology; D014759:Viral Envelope Proteins / Q000187:drug effects; D014771:Virion / Q000737:chemistry*; D014779:Virus Replication / Q000187:drug effects / Q000502:physiology; D047392:beta-Cyclodextrins
D002783:Cholestenones; D003505:Cyclodextrins; D013109:Sphingomyelins; D014759:Viral Envelope Proteins; D047392:beta-Cyclodextrins; C108732:methyl-beta-cyclodextrin; D002784:Cholesterol