Chikungunya virus recruits the ESCRT trafficking machinery at multiple steps during the intracellular life cycle

Chikungunya virus (CHIKV) causes a re-emerging zoonotic disease characterized by fever and joint pain. Since there are no available vaccines nor medicine for CHIKV infection, better understanding of molecular mechanisms underlying CHIKV infection is demanded to develop new treatments. To date, few studies exist describing host factors necessary for intracellular trafficking of CHIKV; thus, the aim of this study is to identify trafficking genes regulating CHIKV infection and to investigate their roles.

We conducted imaging-based siRNA screen targeting 73 trafficking genes, examined the interaction with CHIKV proteins by co-immunoprecipitation and confocal analyses, and then investigated which infection steps of CHIKV were affected by the identified gene(s).

The siRNA screen showed that endosomal sorting complexes required for transport (ESCRT) proteins were involved in CHIKV infection. Co-immunoprecipitation analyses between ESCRT proteins and CHIKV proteins revealed that both structural and non-structural proteins of CHIKV interacted with HGS, a component of ESCRT-0 complex. Confocal analyses demonstrated colocalization of HGS with CHIKV E2 and dsRNA, a marker for the replicated CHIKV genome. Gene knockdown analyses using CHIKV replicon and CHIKV-like particle system demonstrated that HGS facilitated both genome replication and post-translational steps of CHIKV infection, as well as other ESCRT factors.

Here, we propose for the first time that CHIKV requires ESCRT factors at multiple steps during its intracellular life cycle.