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The Non-peptidic Carbohydrate-binding Pradimycin Antibiotics Inhibit HIV Infection, Viral Capture by DC-SIGN, and Viral Transmission and thus May Qualify as Potential Microbicide Candidate Drugs
J Balzarini1, K Francois1, D Huskens1, J Auwerx1, K Van Laethem1, Y Igarashi2, T Oki3, and Dominique Schols*1
1Rega Inst for Med Res, KULeuven, Belgium; 2Biotech Res Ctr, Toyama Prefectural Univ, Japan; and 3Keck Sch of Med, Univ of Southern California, Los Angeles, US
Background: Pradimycin
A (PRM-A) is a naphtaquinocene derivative (molecular weight <1000) that was
shown to inhibit HIV entry due to its specific α(1,2)-mannose binding
properties. PRM-A may therefore qualify as a potential microbicide lead
compound. Due to its lipophilic properties, PRM-A has a limited
water-solubility. However, a novel sulfated derivative, designated PRM-S, has a
much higher solubility, which may be advantageous from a therapeutic viewpoint.
Methods: Virus
replication was analyzed in T cell lines and peripheral blood mononuclear cells
(PBMC) by cytopathicity, MTS, or viral p-24 antigen enzyme-linked immunosorbent
assay (ELISA). Various HIV-1 clades (A, B, C, D, A/E, F, G, and group O), HIV-2,
and simian immunodeficiency (SIV) strains were evaluated for their sensitivity in
PBMC by p24/p27 antigen ELISA. Captured HIV-1 in DC-SIGN+ cells was
assessed by p-24 antigen ELISA. HIV-1 transmission was analyzed by p-24 antigen
ELISA and by syncytia formation. The cytotoxicity, cellular activation and
anti-proliferative potential were evaluated in PBMC by various fluorometric
methods. Cytokine production profile was determined by the Bio-Plex human
cytokine 27 Plex suspension array system.
Results: PRM-A
and PRM-S were equally and consistently inhibitory to a variety of laboratory
and clinical HIV-1 clade isolates in T cell lines and PBMC cultures. The
antibiotic also effectively inhibits various HIV-2 and SIV strains.
The 50% effective concentrations were in the lower micromolar range. PRM-A and
PRM-S, in contrast with cyanovirin, were not stimulatory or mitogenic and they
did not induce any of the analyzed 27 cytokines/chemokines. Both PRM-S and
PRM-A were also inhibitory against syncytium formation between HIV-1-infected
and uninfected T cells, and efficiently inhibited DC-SIGN-directed capture of
HIV-1 particles and subsequent transmission to CD4+ T lymphocytes.
When HIV-1-infected CEM T cell cultures were exposed to PRM-S-escalating drug
concentrations, several deletions in the glycan shield of the viral gp120
envelope occurred, predominantly targeting the high-mannose type N-glycans.
Conclusions:
In conclusion, PRM-S can be an interesting microbicide drug candidate
for further preclinical research.
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