Detection of Extensive Cross-Neutralization between Pandemic and Seasonal A/H1N1 Influenza Viruses Using a Pseudotype Neutralization Assay

• Published in: PloS one Vol. 5; no. 6; p. e11036
• Main Authors: Labrosse, Béatrice, Tourdjman, Mathieu, Porcher, Raphaël, LeGoff, Jérôme, de Lamballerie, Xavier, Simon, François, Molina, Jean-Michel, Clavel, François
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 09.06.2010; Public Library of Science (PLoS)
• Subjects: Age; Assaying; Health aspects; HIV; HIV-1 - immunology; Human immunodeficiency virus; Humans; Immunity; Immunoglobulins; Infection; Infections; Influenza; Influenza A Virus, H1N1 Subtype - immunology; Influenza vaccines; Middle Aged; Neutralization; Neutralization Tests; Neutralizing; Pandemics; Public health; Sensitivity and Specificity; Swine flu; Vaccination; Vaccines; Virology/Emerging Viral Diseases; Virology/Host Antiviral Responses; Virology/Host Invasion and Cell Entry; Viruses; United States > US
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0011036

Cross-immunity between seasonal and pandemic A/H1N1 influenza viruses remains uncertain. In particular, the extent that previous infection or vaccination by seasonal A/H1N1 viruses can elicit protective immunity against pandemic A/H1N1 is unclear. Neutralizing titers against seasonal A/H1N1 (A/Brisbane/59/2007) and against pandemic A/H1N1 (A/California/04/2009) were measured using an HIV-1-based pseudovirus neutralization assay. Using this highly sensitive assay, we found that a large fraction of subjects who had never been exposed to pandemic A/H1N1 express high levels of pandemic A/H1N1 neutralizing titers. A significant correlation was seen between neutralization of pandemic A/H1N1 and neutralization of a standard seasonal A/H1N1 strain. Significantly higher pandemic A/H1N1 neutralizing titers were measured in subjects who had received vaccination against seasonal influenza in 2008-2009. Higher pandemic neutralizing titers were also measured in subjects over 60 years of age. Our findings reveal that the extent of protective cross-immunity between seasonal and pandemic A/H1N1 influenza viruses may be more important than previously estimated. This cross-immunity could provide a possible explanation of the relatively mild profile of the recent influenza pandemic.