Replication of the Chikungunya virus genome requires cellular chloride channels

Chikungunya virus (CHIKV) causes fever and debilitating joint pain, with frequent long-term health implications and cumulating fatalities worldwide. There are no specific antivirals and vaccines, therefore understanding CHIKV replication is essential to establish treatments and preventative measures. Cellular ion channels are druggable targets and are known to facilitate replication of RNA viruses. To determine if the activities of cellular chloride channels (Cl--channels) are required during CHIKV replication, we applied broad-ranging inhibitors and siRNA to mammalian and invertebrate cells. The Cl--channel inhibitors DIDS, 9-ACA and NPPB significantly reduced the titre of released CHIKV progeny at 12 h post-infection in a dose-dependent manner suggesting that Cl--channels are pro-viral factors. Analysis of viral protein expression and time-of-inhibitor-addition studies indicated that CHIKV requires Cl--channels at post-entry and pre-egress stages. Replication of a sub-genomic replicon was restricted and genome copy numbers reduced by Cl--channel inhibition, implying that Cl--channels are involved in genome replication. siRNA knock-down identified the chloride intracellular channels (CLIC) 1 and 4 to be required for the CHIKV infectious cycle with CLIC1 interacting with the viral protein nsP3. We hypothesise that the channels play a role in formation or maintenance of the membranous, viral replication-complexes and that this important role is conservt amongst the mammalian and invertebrate hosts. These findings advance our understanding of CHIKV replication in the two host environments and help to identify drugs/druggable targets for treatment and prevention of CHIKV disease.