nitd008 and Enterovirus-Infections

Flavivirus and enterovirus can emerge unexpectedly in human populations and cause a spectrum of potentially severe diseases or even death. Since effective vaccine is currently unavailable against most of these deadly viruses, antiviral chemical drugs remain in urgent need. To meet this unmet demand, we developed a series of 10,10'-bis(trifluoromethyl) marinopyrrole A derivates bearing various substituents at C5'-positions, which exhibited impressive in vitro activities against flaviviruses (ZIKV, DENV, YFV, JEV) and enteroviruses (EV71, CA6, CA16). The lead compound 10,10'-bis(trifluoromethyl) marinopyrrole A 3 was highly effective against enteroviruses EV71 and CA16 in cultured cells, but with low inhibitory activities against flavivirus. Elaborately modified from compound 3, compounds 32 and 33 with sulfhydryl aliphatic chains were found as promising ZIKV and DENV inhibitor; pyrazine-containing compound 19 is a potent broad-spectrum flavivirus inhibitor; thiophene compound 15 exhibited prominent selective inhibitory effect against JEV-SA14, YFV-17D, in addition to broad-spectrum enterovirus inhibitory effect. These results thus suggest that the 5'-sulfhydryl derivates of 10,10'-bis(trifluoromethyl) marinopyrrole A may be promising lead compounds for the development of novel anti-flavivirus and anti-enterovirus drugs.

Topics: Antiviral Agents; Enterovirus; Enterovirus Infections; Flavivirus; Humans; Pyrroles; Zika Virus; Zika Virus Infection

A series of phosphoamidate derivatives of nucleoside 2'-acetylene-7-deaza-adenosine (NITD008) were synthesized and evaluated for their in vitro antiviral activities against the enteroviruses EV71 and EV-D68. The phosphoamidate (15f) containing a hexyl ester of l-alanine exhibited the most promising activity against EV71 (IC

Topics: Adenosine; Antiviral Agents; Dose-Response Relationship, Drug; Drug Design; Enterovirus; Enterovirus Infections; Humans; Microbial Sensitivity Tests; Molecular Structure; Structure-Activity Relationship

Enterovirus 71 (EV71) is a major viral pathogen in China and Southeast Asia. There is no clinically approved vaccine or antiviral therapy for EV71 infection. NITD008, an adenosine analog, is an inhibitor of flavivirus that blocks viral RNA synthesis. Here we report that NITD008 has potent antiviral activity against EV71. In cell culture, the compound inhibits EV71 at a 50% effective concentration of 0.67 μM and a 50% cytotoxic concentration of 119.97 μM. When administered at 5 mg/kg in an EV71 mouse model, the compound reduced viral loads in various organs and completely prevented clinical symptoms and death. To study the antiviral mechanism and drug resistance, we selected escape mutant viruses by culturing EV71 with increasing concentrations of NITD008. Resistance mutations were reproducibly mapped to the viral 3A and 3D polymerase regions. Resistance analysis with recombinant viruses demonstrated that either a 3A or a 3D mutation alone could lead to resistance to NITD008. A combination of both 3A and 3D mutations conferred higher resistance, suggesting a collaborative interplay between the 3A and 3D proteins during viral replication. The resistance results underline the importance of combination therapy required for EV71 treatment. Importance: Human enterovirus 71 (EV71) has emerged as a major cause of viral encephalitis in children worldwide, especially in the Asia-Pacific region. Vaccines and antivirals are urgently needed to prevent and treat EV71 infections. In this study, we report the in vitro and in vivo efficacy of NITD008 (an adenosine analog) as an inhibitor of EV71. The efficacy results validated the potential of nucleoside analogs as antiviral drugs for EV71 infections. Mechanistically, we showed that mutations in the viral 3A and 3D polymerases alone or in combination could confer resistance to NITD008. The resistance results suggest an intrinsic interaction between viral proteins 3A and 3D during replication, as well as the importance of combination therapy for the treatment of EV71 infections.

Topics: Adenosine; Animals; Antiviral Agents; Chlorocebus aethiops; Drug Resistance, Viral; Enterovirus A, Human; Enterovirus Infections; Mice; Mutation; Vero Cells; Viral Load; Viral Plaque Assay; Virus Replication