Cord blood natural killer cell-derived extracellular vesicles inhibit Zika virus infectivity through ITGB2/perforin-mediated envelope disruption in vitro and in vivo.

Zika virus (ZIKV) can traverse the placental barrier, leading to fetal microcephaly and congenital zika syndrome (CZS). The viral E protein mediates host-cell interactions and infection. Here, we demonstrated that cord blood natural killer cell-derived extracellular vesicles (CBNK-EVs) potently inhibit ZIKV infection in vitro without compromising cellular viability. Mechanistically, CBNK-EVs engage ZIKV through ITGB2, a surface-enriched integrin that interacts with the viral E protein, facilitating nanoparticle-virion contact or membrane fusion. This interaction triggers antiviral activity via perforins within extracellular vesicles (EVs), resulting in diminished viral infectivity. Notably, CBNK-EVs not only effectively crossed the placental barrier to protect fetuses from ZIKV-induced pathologies, but also reduced the ZIKV burden in IFN-deficient murine models and decreased CZS incidence and mortality. Additionally, either blockade of ITGB2 with a monoclonal antibody or chelation of Ca(2+) with EGTA impaired the anti-ZIKV activity of CBNK-EVs. Collectively, our findings identified CBNK-EVs as natural antiviral nanoparticles that play a pivotal role in curbing ZIKV infection and vertical transmission, offering a promising therapeutic strategy against congenital ZIKV-related complications.