Inhibition of endoplasmic reticulum glucosidases is required for in vitro and in vivo dengue antiviral activity by the iminosugar UV-4

Abstract

The antiviral activity of UV-4 was previously demonstrated against dengue virus serotype 2 (DENV2) in multiple mouse models. Herein, step-wise minimal effective dose and therapeutic window of efficacy studies of UV-4B (UV-4 hydrochloride salt) were conducted in an antibody-dependent enhancement (ADE) mouse model of severe DENV2 infection in AG129 mice lacking types I and II interferon receptors. Significant survival benefit was demonstrated with 10–20 mg/kg of UV-4B administered thrice daily (TID) for seven days with initiation of treatment up to 48 h after infection. UV-4B also reduced infectious virus production in in vitro antiviral activity assays against all four DENV serotypes, including clinical isolates. A set of purified enzyme, in vitro, and in vivo studies demonstrated that inhibition of endoplasmic reticulum (ER) α-glucosidases and not the glycosphingolipid pathway appears to be responsible for the antiviral activity of UV-4B against DENV. Along with a comprehensive safety package, these and previously published data provided support for an Investigational New Drug (IND) filing and Phases 1 and 2 clinical trials for UV-4B with an indication of acute dengue disease.

Minimal In Vivo Efficacy of Iminosugars in a Lethal Ebola Virus Guinea Pig Model

“…Both drugs were able to inhibit ER α-glucosidase II in vivo , although only N B-DNJ inhibited α-glucosidase I. This effect is probably due to the 15x higher dose of N B-DNJ that was administered, and given that M O N-DNJ is only 3–4 fold more potent than N B-DNJ against α-glucosidase I and α-glucosidase II in vitro ([36, 47, 49]), this may explain why N B-DNJ showed some effect yet M O N-DNJ did not. This also could imply that inhibition of ER α-glucosidase I is needed to achieve an antiviral effect against EBOV.…”

“…As EVD is an acute disease, to which acquired immunity eventually develops, extended courses of treatment may not be necessary, making side effects easier to tolerate and manage. In addition, new iminosugars have been developed over the last two decades to provide greater potency against the target enzymes with fewer off-target effects [34–36]. …”

Mechanisms of Antiviral Activity of Iminosugars Against Dengue Virus

“…MON-DNJ was developed to be a more potent yet similarly non-toxic derivative of N-butyl-DNJ (NB-DNJ) through alkyl chain elongation and oxygenation [44,45] and has demonstrated more potent in vivo antiviral effects than NB-DNJ against dengue virus. MON-DNJ has antiviral activity against a range of viruses in vitro, and in vivo efficacy in animal models against dengue [51,89] and influenza virus [74,88]. A Phase I single-ascending dose clinical trial of MON-DNJ in humans (NCT02061358) has recently been completed, in which 64 volunteers received a single oral dose ranging from 3-1000 mg, with no serious adverse events reported.…”

“…Experiments published in 2015 have clarified that treatment of DENV-infected cells with a range of iminosugars results in reduced secretion of DENV, rather than a reduction in virion infectivity [68,89]. Iminosugars have demonstrated antiviral activity against all four serotypes of DENV [92] (Table 20.1) with IC 50 values falling within a tenfold range across the four serotypes [51].…”

“…Thus, the presence of each species of FOS can be correlated with successful inhibition of the respective cellular α-glucosidase. Addition of 100 μM NB-DNJ, NN-DNJ, MON-DNJ or celgosivir to macrophages led to the generation of both mono-and tri-glucosylated FOS species, demonstrating inhibition of both α-glucosidases [68,89]. When the degree of inhibition of just GluII (ie.…”