Since 2015, Zika Virus (ZIKV) has caused several outbreaks, with more than one million estimated cases occurring in North and South America. Pregnant women infected with ZIKV can transmit it to their unborn child, which can lead to miscarriage and microcephaly, a condition in which the baby’s head is much smaller than expected standard size. Currently, there are no approved treatments available to address the public health impact of this disease. Previous studies have shown that favipiravir and ribavirin can inhibit ZIKV replication in vitro and provide protection against disease in some animal models. In particular, favipiravir has been shown to be effective against several RNA viruses in different animal models of infection. In this study, researchers conducted a study to assess the effectiveness of favipiravir and ribavirin in a mouse model of ZIKV infection.
When comparing favipiravir, ribarvirin, and a combination of the two to protect mice against lethal ZIKV challenge, researchers discovered that only favipiravir was effective against ZIKV infection. Protection from lethality with favipiravir was significantly different between male and female mice, with survival rates at 25% and 87%, respectively. These findings suggest that sex may be a variable in the efficacy of favipiravir against ZIKV and underscores the importance of using animal models of both sexes in preclinical models for medical countermeasures. Further studies are required to define the underlying mechanisms of the sex differences associated with favipiravir treatment, as well as if it is a viable option as an intervention for other similar viral infections.
Reference: Matz et al. Favipiravir (T-705) Protects IFNAR−/− Mice against Lethal Zika Virus Infection in a Sex-Dependent Manner, Microorganisms, 9(6), 1178.