Preventing SARS-CoV-2 Infection Using Anti-spike Nanobody-IFN-β Conjugated Exosomes

To inhibit the transmission of SARS-CoV-2, we developed engineered exosomes that were conjugated with anti-spike nanobodies and type I interferon β (IFN-β). We evaluated the efficacy and potency of nanobody-IFN-β conjugated exosomes to treatment of SARS-CoV-2 infection.

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-β conjugated exosomes by fusing an anti-spike nanobody and IFN-β 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 IFNα/β cells in the presence of nanobody-IFN-β 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-β conjugated exosomes.

We confirmed the anti-spike nanobody and IFN-β expressions on the exosomes. Exosomes conjugated with nanobody-hIFN-β 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-β was selectively delivered to SARS-CoV-2 infected cells, resulting in the upregulation of ISGs expression.

Exosomes conjugated with nanobody-IFN-β 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-β.