A replication-defective Chikungunya Virus platform for high-throughput drug screening and diagnostics

Chikungunya virus (CHIKV) is a mosquito-borne alphavirus that poses a significant global health threat. Although vaccines have recently been approved, the requirement for Biosafety Level 3 (BSL-3) containment substantially impedes therapeutic and diagnostic development for CHIKV. Here, we engineered an RNA replication-defective CHIKV (CHIKV-ΔnsP4) via trans-complementation, wherein the deleted nsP4 gene product is supplied in trans. CHIKV-ΔnsP4 replicates exclusively in nsP4-expressing cells, completing a full infectious cycle, while exhibiting no detectable replication in naïve cells. Consistent with this, CHIKV-ΔnsP4 demonstrated high attenuation in animal models. Building upon this platform, we generated an mCherry-expressing RNA replication-defective reporter virus, which enabled high-content antiviral screening and serological diagnostics. Collectively, this study establishes the RNA replication-defective strategy as a safe and effective platform for CHIKV research.