AAV-Vectored Immunoprophylaxis for the Prevention and Treatment of Infectious Diseases

Rghei, Amira
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University of Guelph

Vectored monoclonal antibody (mAb) expression mediated by adeno-associated virus (AAV) vectors can generate sustained concentrations of therapeutic mAbs and protect against a range of infectious diseases. Our rationally engineered AAV6 triple mutant capsid, AAV6.2FF, facilitates rapid and robust mAb expression following intramuscular (IM) administration. Here we engineered AAV6.2FF to produce human (h)IgG1 mAbs isolated from human survivors of natural infection for protection against various infections. While AAV vectored immunoprophylaxis for human immunodeficiency virus (HIV) has been highly successful in preclinical models, translation to nonhuman primates and humans has been hampered by the formation of anti-drug antibodies (ADAs) and the clearance of vector transduced cells. We hypothesized that AAV6.2FF vectors expressing mAbs isolated from human survivors of acute viral infections, which are thought to be less immunogenic than broadly neutralizing HIV mAbs, would be safe and tolerable in a large animal model, allowing for sustained mAb expression. AAV6.2FF production in cell stacks was optimized for production of high-titer, high-quality vectors. AAV-mAb expression of a hIgG in mice at variable doses, and in sheep at 5x1012 vg/kg was well tolerated, with no evidence of changes in serum biochemistry, hematology, or tissue pathology. AAV-mediated expression of Marburgvirus (MARV)-specific mAbs, MR78 and MR191 were protective against mouse adapted MARV, with MR191 conferring 100% protection at low serum concentrations of MR191. No sex-based differences in serum hIgG expression were observed; however, administering the same dose over multiple injections significantly increase serum hIgG. AAV6.2FF-MR191 administered to sheep at 5x1012 vg/kg resulted in serum hIgG over 470 days, with low levels of anti-capsid and ADA responses. Finally, we demonstrated that AAV-mediated expression of RSV-specific mAbs prevented virus replication in the lungs of mice administered 1x1011 vg of AAV IM. Female mice administered AAV-mAbs passively transferred mAbs to their offspring, which when challenged with RSV six weeks post-partum were fully protected from virus replication. We also demonstrated maternal transfer of AAV-mAbs in an ovine model, with detectable serum hIgG in sheep progeny up to nine weeks post-partum. AAV-mAb expression is a promising therapeutic option, and poses as an alternative strategy for immunocompromised populations or in rapid response circumstances.

Adeno-associated virus (AAV), Infectious Diseases, AAV-Vectored Immunoprophylaxis, Prevention, Treatment
Rghei, A.D., van Lieshout, L.P., Santry, L.A., Guilleman, M.M., Thomas, S.P., Susta, L., Karimi, K., Bridle, B.W.; Wootton, S.K. AAV Vectored Immunoprophylaxis for Filovirus Infections. Trop. Med. Infect. Dis. 2020, 5, 169. https://doi.org/10.3390/tropicalmed5040169
Rghei AD, Stevens BAY, Thomas SP, Yates JGE, McLeod BM, Karimi K, Susta L, Bridle BW, Wootton SK. Production of Adeno-Associated Virus Vectors in Cell Stacks for Preclinical Studies in Large Animal Models. J Vis Exp. 2021 Jun 30;(172). doi: 10.3791/62727.
Rghei, A.D., van Lieshout, L.P., McLeod, B.M., Pei, Y., Lopes, J.A., Zielinska, N., Baracuhy, E.M., Stevens, B.A.Y., Thomas, S.P., Yates, J.G.E., Warner, B.M., Kobasa, D., Fausther-Bovendo, H., Kobinger, G.P., Karimi, K., Thompson, B., Bridle, B.W., Susta, L., Wootton, S.K. Safety and Tolerability of the Adeno-Associated Virus Vector, AAV6.2FF, Expressing a Monoclonal Antibody in Murine and Ovine Animal Models. Biomedicines 2021, 9, 1186. https://doi.org/10.3390/biomedicines9091186