BACKGROUND To understand the features of a replicating vaccine that might drive potent and durable immune responses to transgene-encoded antigens, we tested a replication-competent adenovirus type 4 encoding influenza virus H5 HA (Ad4-H5-Vtn) administered as an oral capsule or via tonsillar swab or nasal spray.METHODS Viral shedding from the nose, mouth, and rectum was measured by PCR and culturing. H5-specific IgG and IgA antibodies were measured by bead array binding assays. Serum antibodies were measured by a pseudovirus entry inhibition, microneutralization, and HA inhibition assays.RESULTS Ad4-H5-Vtn DNA was shed from most upper respiratory tract–immunized (URT-immunized) volunteers for 2 to 4 weeks, but cultured from only 60% of participants, with a median duration of 1 day. Ad4-H5-Vtn vaccination induced increases in H5-specific CD4+ and CD8+ T cells in the peripheral blood as well as increases in IgG and IgA in nasal, cervical, and rectal secretions. URT immunizations induced high levels of serum neutralizing antibodies (NAbs) against H5 that remained stable out to week 26. The duration of viral shedding correlated with the magnitude of the NAb response at week 26. Adverse events (AEs) were mild, and peak NAb titers were associated with overall AE frequency and duration. Serum NAb titers could be boosted to very high levels 2 to 5 years after Ad4-H5-Vtn vaccination with recombinant H5 or inactivated split H5N1 vaccine.CONCLUSION Replicating Ad4 delivered to the URT caused prolonged exposure to antigen, drove durable systemic and mucosal immunity, and proved to be a promising platform for the induction of immunity against viral surface glycoprotein targets.TRIAL REGISTRATION ClinicalTrials.gov NCT01443936 and NCT01806909.FUNDING Intramural and Extramural Research Programs of the NIAID, NIH (U19 AI109946) and the Centers of Excellence for Influenza Research and Surveillance (CEIRS), NIAID, NIH (contract HHSN272201400008C).
Kenta Matsuda, Stephen A. Migueles, Jinghe Huang, Lyuba Bolkhovitinov, Sarah Stuccio, Trevor Griesman, Alyssa A. Pullano, Byong H. Kang, Elise Ishida, Matthew Zimmerman, Neena Kashyap, Kelly M. Martins, Daniel Stadlbauer, Jessica Pederson, Andy Patamawenu, Nathaniel Wright, Tulley Shofner, Sean Evans, C. Jason Liang, Julián Candia, Angelique Biancotto, Giovanna Fantoni, April Poole, Jon Smith, Jeff Alexander, Marc Gurwith, Florian Krammer, Mark Connors