Properly Folded Bacterially Expressed H1N1 Hemagglutinin Globular Head and Ectodomain Vaccines Protect Ferrets against H1N1 Pandemic Influenza Virus
Figure 2
Development of neutralizing and anti-HA binding antibodies following wt H1N1 (A/California/7/2009) infection in ferrets & post-H1N1 vaccination (inactivated vaccine) in humans.
(A) Microneutralization of H1N1 A/California/2009 virus with post-H1N1-infected ferret samples. End-point titers (mean of three replicates) using post-infection sera from multiple ferrets at each time point in a microneutralization assay performed with A/California/07/2009 (X-179A). For day 21, sera of ten animals were pooled. Each dot in other time-points represents an individual H1N1 infected ferret. (B–D) Antibody kinetics following H1N1 challenge in ferrets. Steady-state equilibrium analysis of post-H1N1 infected ferret sera or pre- & post-H1N1 vaccinated human sera to mammalian H1N1 HA0 (Immune Technologies, NY) and properly folded bacterially expressed H1N1 HA1 (1–330) or H1N1 HA (1–480) fragment were measured using SPR. Ten-fold diluted individual post-infection sera from each time point, were injected simultaneously onto recombinant mammalian H1N1 HA0 in (B) and properly folded bacterially expressed H1N1 HA1 (1–330) in (C) or H1N1 HA (1–480) in (D), immobilized on a sensor chip through the free amine group, and onto a blank flow cell, free of peptide. SPR binding of pre-vaccine and post-H1N1 vaccination sera from two individuals with different neutralizing antibody titers (in parenthesis) is shown with recombinant mammalian H1N1 HA0 in (E) and properly folded bacterially expressed H1N1 HA1 (1–330) in (F) or H1N1 HA (1–480) in (G). Binding was recorded using ProteOn system surface plasmon resonance biosensor instrument (BioRad Labs, Hercules, CA).