Small interfering RNAs are highly effective inhibitors regarding Crimean-Congo hemorrhagic fever virus replication in vitro

Crimean-Congo hemorrhagic fever virus (CCHFV) is one of the prioritized diseases of the World Health Organization, considering its potential to create a public health emergency and more importantly, the absence of efficacious drugs and/or vaccines regarding treatment. The highly lethal nature characteristic to CCHFV restricts research to BSL-4 laboratories, which complicates effective research and developmental strategies. In consideration of antiviral therapies, RNA interference can be used to suppress viral replication by targeting viral genes. RNA interference uses small interfering RNAs (siRNAs) to silence genes. The aim of our study was to design siRNAs that inhibit CCHFV replication and can serve as a basis for further antiviral therapies. A549 cells were infected with CCHFV after transfection with the siRNAs. Following 72 hours, nucleic acid from the supernatant was extracted for Droplet Digital PCR analysis. Among the investigated siRNAs we identified four effective candidates against all three segments of CCHF genome: one for the S and M segments, whilst two for the L segment. Consequently, blocking any segment of CCHFV leads to changes in the virus copy number that indicates an antiviral effect of the siRNAs in vitro. The most active siRNAs were demonstrated a specific inhibitory effect against CCHFV in a dose-dependent manner. In summary, we demonstrated the ability of specific siRNAs to inhibit CCHFV replication in vitro. This promising result can be used in future anti-CCHFV therapy developments.