Design of an HA2-based Escherichia coli expressed influenza immunogen that protects mice from pathogenic challenge

Bommakanti, Gayathri and Citron, Michael P and Hepler, Robert W and Callahan, Cheryl and Heidecker, Gwendolyn J and Najar, Tariq Ahmad and Lu, Xianghan and Joyce, Joseph G and Shiver, John W and Casimiro, Danilo R and ter Meulen, Jan and Liang, Xiaoping and Varadarajan, Raghavan (2010) Design of an HA2-based Escherichia coli expressed influenza immunogen that protects mice from pathogenic challenge. In: Proc Natl Acad Sci Unit States Am, 107 (31). pp. 13701-13706.

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Abstract

Influenza HA is the primary target of neutralizing antibodies during infection, and its sequence undergoes genetic drift and shift in response to immune pressure. The receptor binding HA1 subunit of HA shows much higher sequence variability relative to the metastable, fusion-active HA2 subunit, presumably because neutralizing antibodies are primarily targeted against the former in natural infection. We have designed an HA2-based immunogen using a protein minimization approach that incorporates designed mutations to destabilize the low pH conformation of HA2. The resulting construct (HA6) was expressed in Escherichia coli and refolded from inclusion bodies. Biophysical studies and mutational analysis of the protein indicate that it is folded into the desired neutral pH conformation competent to bind the broadly neutralizing HA2 directed monoclonal 12D1, not the low pH conformation observed in previous studies. HA6 was highly immunogenic in mice and the mice were protected against lethal challenge by the homologous A/HK/68 mouse-adapted virus. An HA6-like construct from another H3 strain (A/Phil/2/82) also protected mice against A/HK/68 challenge. Regions included in HA6 are highly conserved within a subtype and are fairly well conserved within a clade. Targeting the highly conserved HA2 subunit with a bacterially produced immunogen is a vaccine strategy that may aid in pandemic preparedness.

Item Type:	Journal Article
Publication:	Proc Natl Acad Sci Unit States Am
Publisher:	National Academy of Sciences
Additional Information:	Copyright of this article belongs to National Academy of Sciences.
Keywords:	Hemagglutinin; protein design; bacterial expression.
Department/Centre:	Division of Biological Sciences > Molecular Biophysics Unit
Date Deposited:	15 Sep 2010 09:24
Last Modified:	19 Sep 2010 06:16
URI:	http://eprints.iisc.ac.in/id/eprint/32118

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