Influenza causes serious and sometimes fatal disease in individuals at risk due to advanced age or immunodeficiencies. Despite progress in the development of seasonal influenza vaccines, vaccine efficacy in elderly and immunocompromised individuals remains low. We recently developed a passive immunization strategy using an adeno-associated virus (AAV) vector to deliver a neutralizing anti-influenza antibody at the site of infection, the nasal airways. Here we show that young, old, and immunodeficient (severe combined immunodeficient [SCID]) mice that were treated intranasally with AAV9 vector expressing a modified version of the broadly neutralizing anti-influenza antibody FI6 were protected and exhibited no signs of disease following an intranasal challenge with the mouse-adapted H1N1 influenza strain A/Puerto Rico/8/1934(H1N1) (PR8) (Mt. Sinai strain). Nonvaccinated mice succumbed to the PR8 challenge due to severe weight loss. We propose that airway-directed AAV9 passive immunization against airborne infectious agents may be beneficial in elderly and immunocompromised patients, for whom there still exists an unmet need for effective vaccination against influenza.
Intramuscular (IM) administration of adeno-associated viral (AAV) vectors has entered the early stages of clinical development with some success, including the first approved gene therapy product in the West called Glybera. In preparation for broader clinical development of IM AAV vector gene therapy, we conducted detailed pre-clinical studies in mice and macaques evaluating aspects of delivery that could affect performance. We found that following IM administration of AAV8 vectors in mice, a portion of the vector reached the liver and hepatic gene expression contributed significantly to total expression of secreted transgenes. The contribution from liver could be controlled by altering injection volume and by the use of traditional (promoter) and non-traditional (tissue-specific microRNA target sites) expression control elements. Hepatic distribution of vector following IM injection was also noted in rhesus macaques. These pre-clinical data on AAV delivery should inform safe and efficient development of future AAV products.
Effective control of HIV-1 infection in humans is achieved using combinations of antiretroviral therapy (ART) drugs. In humanized mice (hu-mice), control of viremia can be achieved using either ART or by immunotherapy using combinations of broadly neutralizing antibodies (bNAbs). Here we show that treatment of HIV-1-infected hu-mice with a combination of three highly potent bNAbs not only resulted in complete viremic control but also led to a reduction in cell-associated HIV-1 DNA. Moreover, lowering the initial viral load by coadministration of ART and immunotherapy enabled prolonged viremic control by a single bNAb after ART was withdrawn. Similarly, a single injection of adeno-associated virus directing expression of one bNAb produced durable viremic control after ART was terminated. We conclude that immunotherapy reduces plasma viral load and cell-associated HIV-1 DNA and that decreasing the initial viral load enables single bNAbs to control viremia in hu-mice.
The emergence of a new influenza pandemic remains a threat that could result in a substantial loss of life and economic disruption worldwide. Advances in human antibody isolation have led to the discovery of monoclonal antibodies (mAbs) that have broad neutralizing activity against various influenza strains, although their direct use for prophylaxis is impractical. To overcome this limitation, our approach is to deliver antibody via adeno-associated virus (AAV) vectors to the site of initial infection, which, for respiratory viruses such as influenza, is the nasopharyngeal mucosa. AAV vectors based on serotype 9 were engineered to express a modified version of the previously isolated broadly neutralizing mAb to influenza A, FI6. We demonstrate that intranasal delivery of AAV9.FI6 into mice afforded complete protection and log reductions in viral load to 100 LD?? (median lethal dose) of three clinical isolates of H5N1 and two clinical isolates of H1N1, all of which have been associated with historic human pandemics (including H1N1 1918). Similarly, complete protection was achieved in ferrets challenged with lethal doses of H5N1 and H1N1. This approach serves as a platform for the prevention of natural or deliberate respiratory diseases for which a protective antibody is available.
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