Preventing SARS-CoV-2 Infection Using Anti-spike Nanobody-IFN-[beta] Conjugated Exosomes

Purpose To inhibit the transmission of SARS-CoV-2, we developed engineered exosomes that were conjugated with anti-spike nanobodies and type I interferon [beta] (IFN-[beta]). We evaluated the efficacy and potency of nanobody-IFN-[beta] conjugated exosomes to treatment of SARS-CoV-2 infection. Methods Milk fat globule epidermal growth factor 8 (MFG-E8) is a glycoprotein that binds to phosphatidylserine (PS) exposed on the exosomes. We generated nanobody-IFN-[beta] conjugated exosomes by fusing an anti-spike nanobody and IFN-[beta] with MFG-E8. We used the SARS-CoV-2 pseudovirus with the spike of the D614G mutant that encodes ZsGreen to mimic the infection process of the SARS-CoV-2. The SARS-CoV-2 pseudovirus was infected with angiotensin-converting enzyme-2 (ACE2) expressing adenocarcinomic human alveolar basal epithelial cells (A549) or ACE2 expressing HEK-blue IFN[alpha]/[beta] cells in the presence of nanobody-IFN-[beta] conjugated exosomes. By assessing the expression of ZsGreen in target cells and the upregulation of interferon-stimulated genes (ISGs) in infected cells, we evaluated the anti-viral effects of nanobody-IFN-[beta] conjugated exosomes. Results We confirmed the anti-spike nanobody and IFN-[beta] expressions on the exosomes. Exosomes conjugated with nanobody-hIFN-[beta] inhibited the interaction between the spike protein and ACE2, thereby inhibiting the infection of host cells with SARS-CoV-2 pseudovirus. At the same time, IFN-[beta] was selectively delivered to SARS-CoV-2 infected cells, resulting in the upregulation of ISGs expression. Conclusion Exosomes conjugated with nanobody-IFN-[beta] may provide potential benefits in the treatment of COVID-19 because of the cooperative anti-viral effects of the anti-spike nanobody and the IFN-[beta].