The rapid transmission of the pandemic 2009 H1N1 influenza virus (pH1N1) among humans has raised the concern of a potential emergence of reassortment between pH1N1 and highly pathogenic influenza strains, especially the avian H5N1 influenza. Here, we report that the cold-adapted pH1N1 live attenuated vaccine (CApH1N1) elicits cross-reactive immunity against seasonal and H5 influenza A viruses in the mouse model. Immunization with CApH1N1 induced both systemic and mucosal antibodies with broad reactivity to seasonal and H5 strains including HAPI H5N1 and the avian H5N2 virus, providing a complete protection against heterologous and hetero-subtypic lethal challenges. Our results not only accentuate the merit of using live attenuated influenza vaccines in view of cross-reactivity, but also represent the potential of CApH1N1 live vaccine for mitigating the clinical severity that arises from reassortant viruses between pH1N1 and highly pathogenic H5 subtype viruses.
Interesting…maybe because the live attenuated vaccine elicits both humoral and cell-medidated immunity, and to more than just envelope glycoproteins?