Melatonin inhibits Zika virus replication in Vero epithelial cells and SK-N-SH human neuroblastoma cells

Zika virus (ZIKV) is an emerging flavivirus that is causing significant public health concerns worldwide because of its association with severe neurological disorders in both newborns and adults. At present, the search for effective antiviral drugs for ZIKV infection is intense. Melatonin is a molecule that influences a wide variety of physiological processes. Melatonin is a direct free radical scavenger, an indirect antioxidant due to its stimulation of antioxidant enzymes and an anti-inflammatory and immunoregulatory molecule; recent studies also have shown melatonin to have anti-viral activity. Here, we are the first to show that melatonin inhibits ZIKV replication in both Vero cells and SK-N-SH cells. The suppressive actions of melatonin pretreatment on ZIKV infection was found to be time- and dose-dependent. The inhibitory effect of melatonin was more pronounced in human SK-N-SH neural cells than in Vero cells. Molecular docking experiments showed that melatonin exhibited high binding affinity to ZIKV nonstructural 3 (NS3) protein, the possible underlying inhibitory mechanism of melatonin on ZIKV replication. The results suggest that melatonin may have potential prophylactic and treatment effects against ZIKV infection.