An in vivo NanoBiT-based pseudoviral biosensor for real-time monitoring of SARS-CoV-2 spike/hACE2 interactions and therapeutic screening

Abstract

Severe acute respiratory syndrome coronavirus 2 infects host cells through its trimeric surface spike protein, which binds to the human angiotensin-converting enzyme 2 (hACE2) receptor. The spike/hACE2 interaction is a critical target for therapeutic intervention against COVID-19. Although existing hACE2 transgenic mouse (TG) models facilitate studies of viral pathogenesis, they lack the capacity for real-time, non-invasive monitoring of viral entry events in vivo. To address this limitation, we developed a novel in vivo NanoLuc Binary Technology-based pseudoviral biosensor optimized for dynamic visualization of spike-hACE2 binding in live animals. Genetically engineered LgBiT-fused hACE2 (LgBiT-hACE2) mice and a pseudovirus tagged with SmBiT-fused spike protein were developed. Upon spike-hACE2 binding, Nanoluciferase reconstitution generated quantifiable bioluminescent signals detectable within 6 h post-infection. Quantitative bioluminescence imaging using an in vivo imaging system enabled the visualization of virus infection in the LgBiT-hACE2 mouse model. Furthermore, baicalein and baicalin, two active flavonoid compounds derived from Scutellaria baicalensis, were identified as potent inhibitors for the viral spike and the hACE2 protein, respectively. Combined treatment yielded up to 90 % inhibition of spike/hACE2 interaction in vivo. This study presents an innovative in vivo biosensing model to non-invasively quantify virus-host interactions and evaluate the efficacy of spike-targeted antiviral agents under physiologically relevant conditions.

Keywords: Angiotensin-converting enzyme type II; Baicalein; Baicalin; Nanoluciferase binary technology; Severe acute respiratory syndrome coronavirus 2; Spike protein.