Abstract
Viruses are dependent on cellular energy metabolism for their replication, and the drug nitazoxanide (Alinia) was shown to interfere with both processes. Nitazoxanide is an uncoupler of mitochondrial oxidative phosphorylation (OXPHOS). Our hypothesis was that mitochondrial uncoupling underlies the antiviral effects of nitazoxanide. Tizoxanide (the active metabolite of nitazoxanide), its derivative RM4848 and the uncoupler CCCP were applied to a virus-releasing cell line to obtain the same increasing levels of mitochondrial uncoupling, hence identical impact on OXPHOS. A decrease in infectious viral particle release was observed and reflected the intensity of impact on OXPHOS, irrespective of the nature of the drug. The antiviral effect was significant although the impact on OXPHOS was modest (≤ 25%), and disappeared when a high concentration (25 mM) of glucose was used to enhance glycolytic generation of ATP. Accordingly, the most likely explanation is that moderate interference with mitochondrial OXPHOS induced rearrangement of ATP use and acquisition of infective properties of the viral particles be highly sensitive to this rearrangement. The antiviral effect of nitazoxanide has been supported by clinical trials, and nitazoxanide is considered a safe drug. However, serious adverse effects of the uncoupler dinitrophenol occurred when used to increase significantly metabolic rate with the purpose of weight loss. Taken together, while impairment of mitochondrial bioenergetics is an unwanted drug effect, moderate interference should be considered as a basis for therapeutic efficacy.