Pseudoparticle neutralization is a reliable assay to measure immunity and cross-reactivity to H5N1 influenza viruses.
The standard serological methods present limitations for the measurement of immunity against H5N1 influenza strains. The hemagglutination inhibition (HI) assay lacks sensitivity and requires standardization, while the viral micro-neutralization (MN) assay needs handling of live virus. We produced pseudoparticles expressing hemagglutinin from clades 1 or 2 H5N1 in order to measure neutralizing antibodies in human sera after prime-boost vaccination with plain or MF59-adjuvanted H5N1 clade 1 subunit vaccines. Titers measured by pseudoparticle neutralization (PPN) assay significantly correlated with those measured by HI, single radial haemolysis or MN, with a PPN titer of 1:357 corresponding to an MN titer of 1:80. Notably, results from the PPN assay, confirm that MF59-H5N1 vaccine induces potent and long-lasting neutralizing antibody responses not only against the vaccine strain, but also against several heterologous clade 2 strains. Overall, the PPN assay represents a valid alternative to conventional serological methods for the evaluation of H5N1 vaccine immunogenicity.
Alberini
Isabella
I
Novartis Vaccines, Siena, Italy.
Del Tordello
Elena
E
Fasolo
Alba
A
Temperton
Nigel J
NJ
Galli
Grazia
G
Gentile
Chiara
C
Montomoli
Emanuele
E
Hilbert
Anne K
AK
Banzhoff
Angelika
A
Del Giudice
Giuseppe
G
Donnelly
John J
JJ
Rappuoli
Rino
R
Capecchi
Barbara
B
D000328:Adult; D000914:Antibodies, Viral / Q000097:blood*; D003429:Cross Reactions; D006385:Hemagglutination Inhibition Tests; D019267:Hemagglutinin Glycoproteins, Influenza Virus / Q000276:immunology*; D006801:Humans; D053124:Influenza A Virus, H5N1 Subtype / Q000276:immunology*; D007252:Influenza Vaccines / Q000276:immunology*; D007251:Influenza, Human / Q000276:immunology / Q000517:prevention & control*; D009500:Neutralization Tests
D000914:Antibodies, Viral; D019267:Hemagglutinin Glycoproteins, Influenza Virus; D007252:Influenza Vaccines