Nausin Tasnim, University of Manitoba

Tasnim, N., Zhu, W., V3P consortium, Pelka, P.

Discovering & Evolving

Viral vector vaccine platforms have emerged as rapid and adaptable tools to address emerging infectious threats, as demonstrated during the SARS-CoV-2 pandemic. Adenovirus-based vectors are particularly promising due to their robust immunogenicity, scalable production, and ability to express diverse antigens. In this study, we engineered a replication-defective human adenovirus type 4 (Ad4) vector as a candidate vaccine against highly pathogenic avian influenza A (H5N1). The Ad4 E1 and E3 regions were deleted to eliminate viral replication and provide genomic space for heterologous antigens. These regions were replaced with the H5N1 hemagglutinin (HA) and nucleoprotein (NP) genes to elicit both humoral and cellular immune responses. However, existing manufacturing cell substrates such as HEK293 and PER.C6 optimized for Ad5 and other adenoviruses do not efficiently complement Ad4 due to the genetic incompatibility of early region proteins. To overcome this limitation, we developed a novel complementing A549-derived cell line stably expressing Ad4 E1A and E1B genes, enabling high-titer production of the replication-deficient vector. This system supports efficient viral rescue and propagation while enhancing biosafety by minimizing the risk of replication-competent adenovirus (RCA) generation and restricting viral growth to complementing cells. The combination of a tailored viral vector and a specialized production cell line highlights a flexible platform that can be rapidly adapted to future pandemic threats, supporting global vaccine preparedness.