A771726, the active metabolite of leflunomide, as inhibitor of Junín virus replication

SEPÚLVEDA, C.S.; GARCÍA, C. C.; DAMONTE, E.B.

Congreso; 28th International Conference on Antiviral Research; 2015

The active metabolite of the immunomodulatory drug leflunomide A771726, also known as teriflunomide, inhibits mitochondrial enzyme dihydroorotate dehydrogenase (DHODH), which catalyzes the dihydroorotic acid conversion to orotic acid, leading to pyrimidine depletion. This drug is usually used for the treatment of multiple sclerosis and has demonstrated antiviral activity against DNA and RNA viruses (HSV-1, CMV, BKV, HIV-1, and RSV).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, including Junín virus (JUNV) agent of Argentine hemorrhagic fever (AHF), but at present no reliable drug therapy is available.In the present study, the antiviral effects of A771726 were assayed against JUNV determining the effective concentration 50% (EC50) and cytotoxic concentration 50% (CC50). The effectiveness of A771726 to inhibit JUNV multiplication was not importantly affected by the initial virus inoculum, with similar dose response curves in virus yield inhibition assays performed in Vero cells in the range of 0.01-20 plaque forming units (PFU)/cell. Mechanistic studies demonstrated that addition of A771726 to infected cells between 1-4 h after virus adsorption caused a strong inhibition of virus production whereas drug treatment at later times resulted in a time-dependent decrease of the antiviral effect. Furthermore, A771726 failed to inactivate virus before cell pre-treatment. Viral infectitivity of JUNV can be restored in the presence of excess orotic acid, which is the product of DHODH in de novo pryrimidine biosynthesis pathway.These results allow to consider this cellular enzyme as a promising target for hemorrhagic fever arenavirus inhibition.