Current flu vaccines primarily elicit an immune response against the head region of hemagglutinin, a portion of the influenza virus that changes rapidly. Thus, new vaccines must be developed each year, and unanticipated mutations in the virus may lead to the outbreak of an influenza pandemic. Now, thanks to the work of Ekiert and others on broadly neutralizing antibodies, it may be possible for vaccines to target a region of hemagglutinin that does not change. Thus, one vaccine could protect against most types of flu over a much longer term.
The work focused on two antibodies that neutralize many strains of influenza. Ekiert used x-rays from the General Medicine and Cancer Institutes Collaborative Access Team (GM/CA-CAT) facility at APS Sector 23 to determine the structure of these antibodies in complex with their target antigen, hemagglutinin. The structural data pinpointed the region on the virus that is targeted by the antibody. Further studies showed that the structure of this region is unchanged, or conserved, across many strains of influenza. One of the antibodies tested is now in initial clinical trials in humans for use as a treatment for acute influenza infection.
Ekiert also collaborated with a group led by David Baker (Univ. of Washington) that developed a computational method for designing novel protein-protein interactions. The method was used to design several proteins to target the conserved region of hemagglutinin, and Ekiert solved the structure of one of these proteins when complexed with hemagglutinin from the 1918 pandemic influenza virus.
According to Ekiert, there were some challenges due to the size, flexibility, and heterogeneity of the sample. Hemagglutinin is heavily glycosylated, which can make crystallization challenging, and large regions of the antibodies were disordered in some of the structures. “Tools developed at GM/CA-CAT were crucial for the collection of high-quality diffraction data,” Ekiert said. “Several of the structures would have been difficult or perhaps impossible to obtain at many other beamlines.” Critical to the work were the minibeam (an x-ray beam with a 5-20-μm spot size) and a rastering function developed at GM/CA-CAT. “Together, these tools allowed us to find and center on crystals we were unable to visualize in the mounting loop, collect diffraction data from very small crystals, and to zero in on small, high-quality sections of otherwise unusable crystals,” Ekiert said.
The X-ray structural studies formed the basis of Ekiert’s dissertation work in Ian Wilson’s group at the Scripps Research Institute. The antibody project as a whole was a collaboration between Scripps and the biopharmaceutical company Crucell, of the Netherlands.
Ekiert is now a post-doctoral fellow at the University of California, San Francisco, in the laboratory of Jeffery Cox, where he is working on host-pathogen interactions in M. tuberculosis.
D.C. Ekiert, R. H. E. Friesen, G. Bhabha, T. Kwaks, M. Jongeneelen, W. Yu, C. Ophorst, F. Cox, H.J.W.M. Korse, B. Brandenburg, R. Vogels, J.P.J. Brakenhoff, R. Kompier, M.H. Koldijk, L.A.H.M. Cornelissen, L.L.M. Poon, M. Peiris, W. Koudstaal, I.A. Wilson, J. Goudsmit. “A highly conserved neutralizing epitope on Group 2 influenza A viruses,” Science, 333, 843 (2011). DOI: 10.1126/science.1204839
S.J. Fleishman*, T.A Whitehead*, D.C. Ekiert*, C. Dreyfus, J.E. Corn, E.M. Strauch, I.A. Wilson, D. Baker. "Computational design of proteins targeting the conserved stem region of influenza hemagglutinin." Science, 332, 816 (2011).
R. Xu*, D.C. Ekiert*, J.C. Krause, R. Hai, J.E. Crowe, Jr., I.A. Wilson. “Structural basis of preexisting immunity to the 2009 H1N1 pandemic influenza virus,” Science, 328, 357 (2010). DOI: 10.1126/science.1186430
D.C. Ekiert, G. Bhabha, M.A. Elsliger, R.H. Friesen, M. Jongeneelen, M. Throsby, J. Goudsmit, I.A. Wilson. “Antibody recognition of a highly conserved influenza virus epitope.” Science, 324, 246 (2009). DOI: 10.1126/science.1171491
The APS and the APSUO established the Rosalind Franklin Young Investigator Award to recognize an important technical or scientific accomplishment by a young investigator that depended on, or is beneficial to, the APS. The award is open to senior graduate students and those whose Ph.D. was awarded no more than two years prior to nomination. The award is presented every other year at the annual APS Users Meeting, where the recipient of the award is asked to present 20-minute talk on his or her research.
About Rosalind Franklin
The brilliant but short-lived chemist Rosalind Franklin played a critical but largely unacknowledged role in the discovery of the structure of DNA. While working as a research associate for John Randall at King's College in 1951, Franklin was assigned to study the unwieldy DNA molecule with x-ray crystallography, a technique only just beginning to be used for biological molecules. Her results revealed the position of the sugar-phosphate backbone and the basic helical structure of the molecule; when her x-ray photographs filtered unofficially to John Watson at Cambridge, he immediately saw their implications. Franklin went on to work on the tobacco mosaic virus and the polio virus, but her career came to an untimely end when she died of cancer in 1958 at age 37.More information on Franklin is at
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