Mechanism of action of methotrexate against Zika virus

Abstract

Zika virus (ZIKV), which is associated with microcephaly in infants and Guillain-Barré 18 syndrome, reemerged as a serious public health threat in Latin America in recent years. Previous 19 high-throughput screening (HTS) campaigns have revealed several potential hit molecules against 20 ZIKV, including methotrexate (MTX), which is clinically used as an anti-cancer chemotherapy and 21 anti-rheumatoid agent. We studied the mechanism of action of MTX against ZIKV in relation to its 22 inhibition of dihydrofolate reductase (DHFR) in vitro using Vero and human neural stem cells 23 (hNSCs). As expected, an antiviral effect for MTX against ZIKV was observed, showing up to ten-24 fold decrease in virus titer during MTX treatment. We also observed that addition of leucovorin (a 25 downstream metabolite of DHFR pathway) rescued the ZIKV replication impaired by MTX 26 treatment in ZIKV-infected cells, explaining the antiviral effect of MTX through inhibition of DHFR. 27We also found that addition of adenosine to ZIKV-infected cells was able to rescue ZIKV replication 28 inhibited by MTX, suggesting that restriction of de novo synthesis adenosine triphosphate (ATP) 29 pools suppresses viral replication. These results confirm that the DFHR pathway can be targeted to 30 inhibit replication of ZIKV, similar to other published results showing this effect in related 31 flaviviruses.32

Methotrexate inhibits SARS‐CoV‐2 virus replication “in vitro”

“…Its dose‐dependent antiviral activity is extremely potent. Consistent with data reported for Zika Virus infection 16 and the established mechanism of action of MTX, 13 these pieces of data indicate that the cellular purine biosynthetic pathway is a reliable target to inhibit SARS‐CoV‐2 replication. Accordingly, MTX should be most effective in patients at the earliest appearance of symptoms to prevent the synthesis of new viral RNA and, therefore, the formation of virus particles able to extend the infection to contiguous lung alveolar epithelium and extrapulmonary sites 10 and to spread the infection to other people through virus‐containing droplet emission.…”

The anti-viral facet of anti-rheumatic drugs: Lessons from COVID-19

“…In vitro findings reported an anti-viral effect for MTX against ZKV through inhibition of DHFR pathway with mechanisms similar to other published results in related Flaviviruses [184].…”

The folate antagonist methotrexate diminishes replication of the coronavirus SARS-CoV-2 and enhances the antiviral efficacy of remdesivir in cell culture models

“…Especially the lack of purine nucleotides can be expected to diminish the synthesis of virus RNA. Folate antagonists have not been broadly evaluated as antivirals, with the exception of some flaviviruses ( 1 , 2 ). In contrast, sulfonamides and trimethoprim are routinely used for treating bacterial infections, and their mechanism of action is to prevent the synthesis of folic acid in bacteria ( 3 ).…”