AEGiS-07IAC: Kinetics of HIV-1 fusion with liposomes and erythrocyte ghosts.

7th International AIDS Conference

Florence, Italy — June 16-21, 1991

Kinetics of HIV-1 fusion with liposomes and erythrocyte ghosts.

Int Conf AIDS 1991 Jun 16-21; 7:97 (abstract no. M.A.1022)
Larsen CE, Nir S, Alford DR, Jennings M, Lee KD, Duzgunes N; University of California, San Francisco, CA, USA

OBJECTIVE: We investigated the kinetics and extent of membrane fusion between HIV-1 and phospholipid vesicles and erythrocyte ghost membranes and studied the effects of pH, divalent cation, target membrane composition, temperature and viral trypsinization on this process.

METHODS: Purified HIV-1 was labeled with octadecyl rhodamine B chloride (R18); fusion was monitored continuously as the dilution of probe into target membranes. Ultrastructural analysis of the virus and reaction products by transmission electron microscopy was also utilized to confirm the results of the R18 assay.

RESULTS: HIV-1 fusion is strongly dependent upon target membrane lipid composition. The virus fuses with anionic liposomes dramatically faster than with erythrocyte ghost membranes or pure dioleoylphosphatidylcholine (DOPC) liposomes at neutral pH. Reduction of pH from 7.5 enhances the rate and extent of HIV-1 fusion with vesicles containing anionic lipids. Physiologically relevant concentrations of calcium stimulate HIV-1 fusion with several liposome compositions and with erythrocyte ghost membranes. Compared to intact virions, the fusion products show a striking reduction in the fusion rate with liposomes. Infection of CD4-expressing cells was reduced when the fusion products of HIV with CL liposomes were applied instead of the intact virions. HIV-1 fusion with CL vesicles is temperature dependent and, in the presence of calcium, is greatly reduced following virus trypsinization.

CONCLUSIONS: HIV-1 fuses with model and biological membranes lacking the known viral receptor, CD4. Like Influenza and Sendai, HIV-1 fusion with membranes containing its own envelope protein(s) is strongly inhibited. Unlike these viruses, HIV-1 fusion is promoted by calcium and appears to be more sensitive to envelope protein surface density. HIV-1 fusion with liposomes is similar to SIVmac fusion (Larsen et al. (1990) J. gen Virol. 71, 1947-1955).

Keywords: AEGIS, Liposomes, Erythrocyte Membrane, Kinetics, Membrane Fusion, Membrane Lipids, Phosphatidylcholines, HIV-1, Hydrogen-Ion Concentration, Virion, Cell Membrane, Antigens, CD4, Rhodamines, Cations, Divalent, 1,2-oleoylphosphatidylcholine, octadecyl Rhodamine B chloride, pharmacokinetics, ICA7
910616
MA1022