A dual-pronged host-directed therapeutic targeting cyclophilin A and pathogenic interferon response abrogates virus-triggered pregnancy pathologies

Pathogenic viruses threaten fetal development by achieving vertical transmission and instigating placental immunopathology, while the pathobiological mechanisms and effective therapeutics remain critical gaps. Here, we reveal cyclophilin A (CypA) as a crucial host factor necessary for Zika virus (ZIKV) replication in human placental trophoblasts, acting independently of its canonical functions. ZIKV infection recruits CypA into the viral replication organelle and reconfigures its interactome, thereby subverting host RNA decay machinery and stress granule-mediated antiviral surveillance. Both genetic ablation of CypA and its pharmacological inhibition with clinically approved drug ciclosporin A (CsA) restrict ZIKV transplacental transmission and corresponding placental and fetal pathologies. Beyond its anti-ZIKV potency, CsA concurrently counteracts pathological type I interferon signaling by targeting the JAK1-STAT1/2 pathway, broadly ameliorating pregnancy-specific interferonopathies driven by viral infection or endogenous double-stranded RNA stress. Our findings elucidate CypA-governed ZIKV pathogenesis and license CsA as a promising dual-action therapeutic to counteract congenital viral infections. Vertical transmission of Zika virus (ZIKV) poses significant risks to fetal development. Here the authors show that cyclophilin A (CypA) is essential for ZIKV replication in placental cells, and demonstrate that ciclosporin A is protective by inhibiting CypA-driven ZIKV infection and the pathogenic interferon response in trophoblasts.