A novel soluble mimic of the glycolipid, globotriaosyl ceramide inhibits HIV infection.
OBJECTIVE
To determine the effect of a gp120 binding, non-cytotoxic soluble analogue of the glycosphingolipid (GSL), globotriaosyl ceramide (Gb3) on HIV infection in vitro.


METHODS
HIV-1(IIIB) (X4 virus) infection in Jurkat and phytohaemagglutinin (PHA)/interleukin-2 (IL2) activated, peripheral blood mononuclear cells (PBMC), and HIV-1(Ba-L) (R5 virus) infection of PHA activated PBMC in vitro were assessed. We monitored cell surface markers, cell viability, and viral/host cell morphology to eliminate pleiotropic effects. Viral-host cell fusion was measured to further address any inhibitory mechanism.


METHODS
HIV infection was monitored by p24(gag) ELISA. CD4, CCR5, CXCR4 and apoptosis were determined by fluorescent antibody cell sorting. A model fusion system comprising a cell line transfected with either CD4 and CXCR4 or CCR5, cocultured with a cell line expressing gp120 from either X4-, R5-tropic HIV-1 or HIV-2 virions, was used. PHA/IL2 activated PBMC GSL synthesis was monitored by metabolic radiolabelling.


RESULTS
AdamantylGb3 blocked X4 and R5 virus infection with a 50% inhibitory concentration of approximately 150 microM. A reverse transcriptase and a protease-resistant X4 HIV-1 strain retained adamantylGb3 sensitivity. AdamantylGb3 had minimal effect on cell viability. Treated Jurkat cells showed a small increase in CCR5/CXCR4 expression and a slight, transient CD4 down-regulation, which was probably not related to the mechanism of inhibition. Electron microscopy showed normal viral and host cell morphology following adamantylGb3 treatment, and viral entry was blocked. AdamantylGb3 was able to prevent virus-host cell fusion irrespective of HIV strain or chemokine receptor preference.


CONCLUSIONS
These results suggest that adamantylGb3 may provide a new basis for blocking HIV infections, irrespective of HIV envelope/chemokine co-receptor preference or resistance to other therapeutics.
Lund
Nicole
N
Department of Laboratory Medicine and Pathobiology, University of Toronto, Ontario, Canada.
Branch
Donald R
DR
Mylvaganam
Murugespillai
M
Chark
Davin
D
Ma
Xue-Zhong
XZ
Sakac
Darinka
D
Binnington
Beth
B
Fantini
Jacques
J
Puri
Anu
A
Blumenthal
Robert
R
Lingwood
Clifford A
CA
D000218:Adamantane / Q000031:analogs & derivatives / Q000627:therapeutic use; D000998:Antiviral Agents / Q000627:therapeutic use*; D004797:Enzyme-Linked Immunosorbent Assay; D005434:Flow Cytometry; D006017:Glycolipids / Q000627:therapeutic use*; D015658:HIV Infections / Q000188:drug therapy*; D015497:HIV-1; D006801:Humans; D020128:Inhibitory Concentration 50; D019169:Jurkat Cells; D007963:Leukocytes, Mononuclear / Q000821:virology; D008854:Microscopy, Electron; D014281:Trihexosylceramides / Q000627:therapeutic use*
D000998:Antiviral Agents; D006017:Glycolipids; D014281:Trihexosylceramides; C514155:adamantyl-globotriaosyl ceramide; C018549:globotriaosylceramide; D000218:Adamantane