Safety and Tolerability of the Adeno-Associated Virus Vector, AAV6.2FF, Expressing a Monoclonal Antibody in Murine and Ovine Animal Models.

Adeno-associated virus (AAV) vector mediated expression of therapeutic monoclonal antibodies is an alternative strategy to traditional vaccination to generate immunity in immunosuppressed or immunosenescent individuals. In this study, we vectorized a human monoclonal antibody (31C2) directed against the spike protein of SARS-CoV-2 and determined the safety profile of this AAV vector in mice and sheep as a large animal model. In both studies, plasma biochemical parameters and hematology were comparable to untreated controls. Except for mild myositis at the site of injection, none of the major organs revealed any signs of toxicity. AAV-mediated human IgG expression increased steadily throughout the 28-day study in sheep, resulting in peak concentrations of 21.4-46.7 µg/ mL, demonstrating practical scale up from rodent to large animal models. This alternative approach to immunity is worth further exploration after this demonstration of safety, tolerability, and scalability in a large animal model.

A novel mouse AAV6 hACE2 transduction model of wild-type SARS-CoV-2 infection studied using synDNA immunogens.

More than 100 million people have been infected with severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2). Common laboratory mice are not susceptible to wild-type SARS-CoV-2 infection, challenging the development and testing of effective interventions. Here, we describe the development and testing of a mouse model for SARS-CoV-2 infection based on transduction of the respiratory tract of laboratory mice with an adeno-associated virus vector (AAV6) expressing human ACE-2 (AAV6.2FF-hACE2). We validated this model using a previously described synthetic DNA vaccine plasmid, INO-4800 (pS). Intranasal instillation of AAV6.2FF-hACE2 resulted in robust hACE2 expression in the respiratory tract. pS induced robust cellular and humoral responses. Vaccinated animals were challenged with 105 TCID50 SARS-CoV-2 (hCoV-19/Canada/ON-VIDO-01/2020) and euthanized four days post-challenge to assess viral load. One immunization resulted in 50% protection and two immunizations were completely protective. Overall, the AAV6.2FF-hACE2 mouse transduction model represents an easily accessible, genetically diverse mouse model for wild-type SARS-CoV-2 infection and preclinical evaluation of potential interventions.