Cross-protective immunity to influenza A viruses

Abstract

Antigenic changes in influenza virus occur gradually, owing to mutations (antigenic drift), and abruptly, owing to reassortment among subtypes (antigenic shift). Availability of strain-matched vaccines often lags behind these changes, resulting in a shortfall in public health. In animal models, cross-protection by vaccines based on conserved antigens does not completely prevent infection, but greatly reduces morbidity, mortality, virus replication and, thus, viral shedding and spread. Such immunity is especially effective and long-lasting with mucosal administration. Cross-protective immunity in humans is controversial, but is suggested by some epidemiological findings. ‘Universal’ vaccines protective against all influenza A viruses might substantially reduce severity of infection and limit spread of disease during outbreaks. These vaccines could be used ‘off the shelf’ early in an outbreak or pandemic, before strain-matched vaccines are available.

Keywords::

• animal models
• conserved antigens
• cross-protection
• heterosubtypic immunity
• human
• influenza
• pandemic
• subtypes
• universal vaccine
• vaccine

Acknowledgments

The authors would like to thank Maryna Eichelberger, Andrew Byrnes, Mary Quirion, Chia-Yun Lo and Mark Soboleski for critical review of the manuscript.

Disclaimer

The opinions and information in this article are those of the authors, and do not represent the views and/or policies of the US FDA.

Financial & competing interests disclosure

Funding of research in Suzanne Epstein’s laboratory is provided by the Center for Biologics Evaluation and Research/US FDA Division of Cellular and Gene Therapies. Grants have been received from the Center for Biologics Evaluation and Research Pandemic Influenza Initiative, the National Vaccine Program, the DHHS Office of Public Health Medical Emergency Counter-Measures, the NIAID Trans-NIH/FDA Intramural Biodefense Program and the FDA Chief Scientist’s Challenge Grant program. The authors have no other relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript apart from those disclosed.

No funding for writing assistance was utilized in the production of this manuscript.