Inhibition of arenavirus infection by thiuram and aromatic disulfides

CLAUDIA S. SEPÚLVEDA; C. C. GARCÍA; JESICA M. LEVINGSTON MACLEOD; NORA LÓPEZ; E. B. DAMONTE

Richmond, Virginia, USA

Simposio; 10th Annual Symposium on Antiviral Drug Resistance: targets and mechanisms; 2009

Arenaviruses are enveloped viruses containing a bipartite, single-stranded RNA genome, with ambisense coding strategy. Five arenaviruses are known to cause severe hemorrhagic fevers in humans, but at present no reliable drug therapy is available. The presence in arenaviruses of the Z protein, containing a highly conserved RING finger motif, prompted us to initiate studies about this protein as a possible target for a new antiviral strategy. We have previously shown that antiretroviral compounds with diverse chemical structures, provided by the National Cancer Institute (USA), which target to the Zn-finger motifs in the HIV nucleocapsid protein NCp7, display antiviral and virucidal activity against arenaviruses. Here, the in vitro inhibitory activity of a selected group of disulfides is reported. The thiuram disulfide NSC14560 and the aromatic disulfide NSC4492 were, respectively, the more potent antiviral and virucidal agents against the pathogenic arenavirus Junín, with values of antiviral effective concentration 50% (EC50) of 8.5 µM for NSC14560, as determined by virus yield inhibition, and inactivating concentration 50% (IC50) of 0.2 µM for NSC4492. NSC14560 showed a wide spectrum of inhibitory effect against different arenaviruses in monkey and human cells. Mechanistic studies demonstrated that cell pretreatment did not affect infection. Virus adsorption and internalization were not affected. Time of addition experiments indicated that the inhibitory activity of NSC14560 appears to target two steps of viral infection: an early step before 5 h of infection and a late stage of the cycle. NSC4492 inactivated diverse arenaviruses, with a linear kinetics of reaction up to 45 minutes. Western blot analysis of virus-like particles released into the supernatants from cells expressing an HA-tagged version of Junin virus Z protein in presence of NSC4492, showed an alteration in the electrophoretic profile of Z oligomers, suggesting that the compound might induce conformational change in Z protein.