Study of the Mechanism of Antiviral Action of Iminosugar Derivatives against Bovine Viral Diarrhea Virus

Abstract

The glucose-derived iminosugar derivatives N-butyl-and N-nonyl-deoxynojirimycin (DNJ) have an antiviral effect against a broad spectrum of viruses including Bovine viral diarrhea virus (BVDV). For BVDV, this effect has been attributed to the reduction of viral secretion due to an impairment of viral morphogenesis caused by the ability of DNJ-based iminosugar derivatives to inhibit ER ␣-glucosidases (N. Zitzmann, A. S. Mehta, S. Carrouée, T. D. Butters, F. M. Platt, J. McCauley, B. S. Blumberg, R. A. Dwek, and T. M. Block, Proc. Natl. Acad. Sci. USA 96:11878-11882, 1999). Here we present the antiviral features of newly designed DNJ derivatives and report for the first time the antiviral activity of long-alkyl-chain derivatives of deoxygalactonojirimycin (DGJ), a class of iminosugars derived from galactose which does not inhibit endoplasmic reticulum (ER) ␣-glucosidases. We demonstrate the lack of correlation between the ability of long-alkyl-chain DNJ derivatives to inhibit ER ␣-glucosidases and their antiviral effect, ruling out ER ␣-glucosidase inhibition as the sole mechanism responsible. Using short-and long-alkyl-chain DNJ and DGJ derivatives, we investigated the mechanisms of action of these drugs. First, we excluded their potential action at the level of the replication, protein synthesis, and protein processing. Second, we demonstrated that DNJ derivatives cause both a reduction in viral secretion and a reduction in the infectivity of newly released viral particles. Long-alkyl-chain DGJ derivatives exert their antiviral effect solely via the production of viral particles with reduced infectivity. We demonstrate that long-alkyl-chain DNJ and DGJ derivatives induce an increase in the quantity of E2-E2 dimers accumulated within the ER. The subsequent enrichment of these homodimers in secreted virus particles correlates with their reduced infectivity.Iminosugar derivatives containing the glucose analogue deoxynojirimycin (DNJ) exert antiviral effects against viruses of different families, including Human immunodeficiency virus (HIV) (9-12, 16), Hepatitis B virus (HBV) (3,18,19), Woodchuck hepatitis virus (4), Bovine viral diarrhea virus (BVDV) (29), and Dengue virus (8). The antiviral effects were either proven (10, 11) or assumed to be associated with the inhibitory action of DNJ-containing iminosugar derivatives on enzymes in the endoplasmic reticulum (ER), ␣-glucosidases I and II. DNJ, a ring-nitrogen-containing and unmetabolizable glucose analogue, competitively binds to these enzymes and prevents them from performing the stepwise removal of three glucose residues attached to the N-linked glycans carried by newly synthesized polypeptides. This in turn prevents these polypeptides from interacting with the ER chaperones calnexin and calreticulin, which bind to monoglucosylated glycoproteins (14). Interaction with these ER chaperones is crucial for the correct folding of some but not all glycoproteins (13,17,22). Potentially all viruses which encode glycoproteins that depend on calnexin interaction for prope...

The hepatitis C virus p7 protein forms an ion channel that is inhibited by long-alkyl-chain iminosugar derivatives

“…Previous experiments have shown that the antiviral effect of the longalkyl-chain derivative N-nonyl-DNJ (NN-DNJ) is more pronounced than that of the short-alkyl-chain derivative N-butyl-DNJ (NB-DNJ), although the latter achieves a more effective ER ␣-glucosidase inhibition in cellulo. In addition, long-alkylchain DGJ derivatives that are not recognized by and do not inhibit ER ␣-glucosidases also show potent antiviral activity (3). Therefore, ER ␣-glucosidase inhibition does not correlate directly with the observed antiviral effect and is ruled out as the sole antiviral mechanism.…”

“…The predominant antiviral mechanism is proposed to be mediated directly or indirectly by an effect of the long-alkyl side chains on the membrane and͞or membrane proteins, because treatment with long-alkyl-chain iminosugars affects the dimerization of viral membrane glycoproteins and alters the membrane glycoprotein composition of secreted BVDV virions but does not influence either viral RNA replication or protein synthesis (3).…”

“…However, infective viral particles can be generated by complementing p7 in trans (9), which suggests that the pestivirus p7 is essential for the production of infective progeny virus. Interestingly, noninfective BVDV particles also are created by treatment with long-alkyl-chain iminosugar derivatives (3).…”

“…In the absence of both a suitable small animal model and a reliable in vitro infectivity assay for HCV, potential antiviral drugs initially have been tested by using a related pestivirus, bovine viral diarrhea virus (BVDV) (2). BVDV in vitro infectivity assays were used to demonstrate that long-alkyl-chain iminosugar derivatives containing either the glucose analogue deoxynojirimycin (DNJ) or the galactose analogue deoxygalactonojirimycin (DGJ) are potent antiviral inhibitors (3).…”

Synthesis of Iminosugar‐Containing KRN7000 Analogues

“…[21][22][23] Iminosugar-based compounds are promising medicine candidates against various diseases such as tumor metastasis, diabetes, viral infection, and lysosomal storage disorders. [23][24][25] Our group discovered that certain iminosugar derivatives possess immunosuppressive activities while minor structure changes lead to immunostimulating activities, showing the potential as the lead compounds with various biological activities. [26][27][28] Two castanospermine (an iminosugar) analogues also showed up-regulation of the Th1/Th2 cytokine ratio, with apparent bias towards Th1 cytokines.…”