Developing Zika virus-transduced hACE2 expression models for severe acute respiratory syndrome coronavirus 2 infection in vitro and in vivo

To address the human ACE2 dependence for SARS-CoV-2 infection, this study presents a novel strategy for generating ZIKV-hACE2 single-round infectious particles (SRIPs) by incorporating the hACE2 gene into a Zika virus (ZIKV) mini-replicon. SARS-CoV-2 SRIP infection was significantly enhanced in HEK293T cells pre-infected with ZIKV-hACE2, as evidenced by increased cytopathic effects and elevated mRNA and protein levels of the SARS-CoV-2 nucleocapsid (N) protein. A mouse model was also developed with this approach to investigate SARS-CoV-2 infection. Immunohistochemical and real-time RT-PCR analyses confirmed the presence of the SARS-CoV-2 N protein in the lungs of mice injected with ZIKV-hACE2 SRIPs, indicating successful infection. The mouse model displayed COVID-19-like pathological changes, including increased macrophages in BALF, severe lung damage, and elevated pro-inflammatory cytokines (IL-6 and IL-1β). These features mimic severe COVID-19 cases in humans. Additionally, treatment with nirmatrelvir resulted in a 6.2-fold reduction in viral load and a marked decrease in N protein levels. Overall, this ZIKV mini-replicon-mediated hACE2 expression model, both in vitro and in vivo, is a valuable tool for studying SARS-CoV-2 infection and evaluating therapeutic interventions. The mouse model's pathological features further underscore its relevance for in vivo research on SARS-CoV-2.