title: Design of Escherichia coli-expressed stalk domain immunogens of H1N1 hemagglutinin that protect mice from lethal challenge.
abstract: The hemagglutinin protein (HA) on the surface of influenza virus is essential for viral entry into the host cells. The HA1 subunit of HA is also the primary target for neutralizing antibodies. The HA2 subunit is less exposed on the virion surface and more conserved than HA1. We have previously designed an HA2-based immunogen derived from the sequence of the H3N2 A/HK/68 virus. In the present study, we report the design of an HA2-based immunogen from the H1N1 subtype (PR/8/34). This immunogen (H1HA0HA6) and its circular permutant (H1HA6) were well folded and provided complete protection against homologous viral challenge. Antisera of immunized mice showed cross-reactivity with HA proteins of different strains and subtypes. Although no neutralization was observable in a conventional neutralization assay, sera of immunized guinea pigs competed with a broadly neutralizing antibody, CR6261, for binding to recombinant Viet/04 HA protein, suggesting that CR6261-like antibodies were elicited by the immunogens. Stem domain immunogens from a seasonal H1N1 strain (A/NC/20/99) and a recent pandemic strain (A/Cal/07/09) provided cross-protection against A/PR/8/34 viral challenge. HA2-containing stem domain immunogens therefore have the potential to provide subtype-specific protection.
authors.affiliation: Molecular Biophysics Unit, Indian Institute of Science, Bangalore, India.
authors.forename: Gayathri
authors.initials: G
authors.lastname: Bommakanti
authors.forename: Xianghan
authors.initials: X
authors.lastname: Lu
authors.forename: Michael P
authors.initials: MP
authors.lastname: Citron
authors.forename: Tariq Ahmad
authors.initials: TA
authors.lastname: Najar
authors.forename: Gwendolyn J
authors.initials: GJ
authors.lastname: Heidecker
authors.forename: Jan
authors.initials: J
authors.lastname: ter Meulen
authors.forename: Raghavan
authors.initials: R
authors.lastname: Varadarajan
authors.forename: Xiaoping
authors.initials: X
authors.lastname: Liang
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002942:Circular Dichroism; D003429:Cross Reactions; D004797:Enzyme-Linked Immunosorbent Assay; D004926:Escherichia coli / Q000235:genetics*; D005260:Female; D006168:Guinea Pigs; D019267:Hemagglutinin Glycoproteins, Influenza Virus / Q000737:chemistry / Q000276:immunology*; D007106:Immune Sera; D053118:Influenza A Virus, H1N1 Subtype / Q000276:immunology*; D051379:Mice; D008807:Mice, Inbred BALB C; D008969:Molecular Sequence Data; D009500:Neutralization Tests; D013050:Spectrometry, Fluorescence; D020349:Surface Plasmon Resonance
chemical_list: D019267:Hemagglutinin Glycoproteins, Influenza Virus; D007106:Immune Sera