Aged and fresh nanoparticles induce hemagglutinin-inhibiting responses.

<p>Log of hemagglutination inhibition titer from mice post-boost immunization. Dotted line represents an HAI titer of 40, defined by the FDA to provide protective antibody responses[<a href="" target="_blank">14</a>]. * represents significantly different average titers from a titer of 40. Each data point represents a serum titer from one mouse. Limit of detection = 1:20 dilution.</p>