Avaliação dos efeitos do lapachol no ciclo replicativo do zika vírus

Abstract

Since its re-emergence in 2015, Orthoflavivirus zikaense (Zika virus - ZIKV) has been a cause of public health concern due to its propensity to cause widespread epidemics and its sudden association with serious complications such as Guillain-Barré and Congenital Zika Syndrome (CSZ), despite the efforts made there still is a lack of effective treatments against it, making imperative the need to develop antiviral therapies. Lapachol, a 1,4-naphthoquinone compound, seems to be a promising candidate as an antiviral agent since its activity against other RNA viruses as well as other human pathogens has been previously reported. Here we demonstrated the activity of lapachol in inhibiting ZIKV replication in vitro. Vero E6 cells were treated with lapachol at concentrations ranging from 0.78 µM to 100 µM in the presence or absence of infection with ZIKVPE243. Time-of-addition assays were used to identify the steps of ZIKV life cycle that lapachol was able to inhibit. Immunofluorescence assays were employed to assess virus titers by quantifying focus formation units (FFU). Its mechanism of action was studied through protein-based substrate digestion assays and target-specific molecular docking analysis. The formation of intracellular reactive oxygen species (ROS) was also assessed. The results demonstrate that lapachol acts as a strong inhibitor of viral replication with a strong selectivity index of 50.7 and an EC50 = 3.0 μM, exhibiting its greater effect after virus entry to the cell. Further assays suggest that its mechanism of action may be through the blockage of the catalytic site of NS2B-NS3 protease and NS5 polymerase. A protective effect over the cells was also evidenced when treated before infection, as well as the capacity of lapachol to induce ROS formation in vitro, suggesting further mechanisms may be contributing to its antiviral activity, such as triggering an oxidative stress response that damages the viral particles. These findings shed light on the potential of lapachol to be employed for the development of ZIKV inhibitors.