New Pre‐pandemic Influenza Vaccines: An Egg‐ and Adjuvant‐independent Human Adenoviral Vector Strategy Induces Long‐lasting Protective Immune Responses in Mice

Highly pathogenic avian H5N1 influenza viruses that are currently circulating in southeast Asia may acquire the potential to cause the next influenza pandemic. A number of alternate approaches are being pursued to generate cross‐protective, dose‐sparing, safe, and effective vaccines, as traditional vaccine approaches, i.e ., embryonated egg‐grown, are not immunogenic. We developed a replication‐incompetent adenoviral vector‐based, adjuvant‐ and egg‐independent pandemic influenza vaccine strategy as a potential alternative to conventional egg‐derived vaccines. In this paper, we address suboptimal dose and longevity of vaccine‐induced protective immunity and demonstrate that a vaccine dose as little as 1 × 10 6 plaque‐forming unit (PFU) is sufficient to induce protective immune responses against a highly pathogenic H5N1 virus. Furthermore, the vaccine‐induced humoral and cellular immune responses and protective immunity persisted at least for a year. Clinical Pharmacology & Therapeutics (2007) 82 , 665–671. doi: 10.1038/sj.clpt.6100418 ; published online 24 October 2007