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Preferential Recognition of Avian-Like Receptors in Human Influenza A H7N9 Viruses
Rui Xu, Robert P. de Vries, Xueyong Zhu, Corwin M. Nycholat, Ryan McBride, Wenli Yu, James C. Paulson, and Ian A. Wilson
Science 6 December 2013: 342 (6163), 1230-1235. [DOI:10.1126/science.1243761]
News Release
Scripps Research Institute Scientists: Emerging Bird Flu Strain Is Still Poorly Adapted for Infecting Humans
LA JOLLA, CA?December 5, 2013
...
Answering Critical Questions
Paulson?s and Wilson?s laboratories, long experienced in flu virus and immunity research, were among the many that mobilized to try to answer the crucial question of H7N9?s transmissibility among humans. They quickly decided to collaborate. Paulson?s laboratory evaluated H7N9?s ability to bind the sialylated sugar receptors to which flu viruses normally attach on host cells. Wilson?s laboratory used X-ray crystallography to determine the atomic structures of the H7N9 hemagglutinin protein bound to these sialic acid receptor molecules.
Paulson?s team?including postdoctoral fellows Robert P. de Vries and Corwin M. Nycholat and Research Assistant Ryan McBride?tested the ability of the virus?s hemagglutinin (HA) protein, to bind to different human and avian receptor variants. These tests showed clearly that the isolate tested (A/Shanghai/2/2013 or ?Sh2?) still has a strong preference for avian-type receptors and binds human-type receptor variants only weakly.
In Wilson?s laboratory, postdoctoral fellow Rui Xu, the study?s first author, along with Staff Scientist Xueyong Zhu and Research Assistant Wenli Yu, performed X-ray crystallography studies of the Sh2 HA protein bound to several avian- and human-type receptors. The latter, provided by Paulson?s laboratory, were more accurate versions of these receptors than any that had been used in previous H7N9 structural analyses.
The new data highlighted the looseness of the contacts that Sh2 HA makes with human-type receptors, in contrast to the snug couplings it makes with certain avian-type receptors.
Thus, despite hints that it had begun to adapt to human hosts rather than its natural bird hosts, H7N9 does not appear to pose an imminent threat of a human pandemic. ?These results suggest that we should continue to observe H7N9 and see if it undergoes any changes that make it more likely to spread in the human population,? said Wilson. Paulson added, ?If it does evolve a true human-type receptor specificity, it could potentially spread among humans much better than it does now.?..
Scripps Research Institute Scientists: Emerging Bird Flu Strain Is Still Poorly Adapted for Infecting Humans
LA JOLLA, CA?December 5, 2013
...
Answering Critical Questions
Paulson?s and Wilson?s laboratories, long experienced in flu virus and immunity research, were among the many that mobilized to try to answer the crucial question of H7N9?s transmissibility among humans. They quickly decided to collaborate. Paulson?s laboratory evaluated H7N9?s ability to bind the sialylated sugar receptors to which flu viruses normally attach on host cells. Wilson?s laboratory used X-ray crystallography to determine the atomic structures of the H7N9 hemagglutinin protein bound to these sialic acid receptor molecules.
Paulson?s team?including postdoctoral fellows Robert P. de Vries and Corwin M. Nycholat and Research Assistant Ryan McBride?tested the ability of the virus?s hemagglutinin (HA) protein, to bind to different human and avian receptor variants. These tests showed clearly that the isolate tested (A/Shanghai/2/2013 or ?Sh2?) still has a strong preference for avian-type receptors and binds human-type receptor variants only weakly.
In Wilson?s laboratory, postdoctoral fellow Rui Xu, the study?s first author, along with Staff Scientist Xueyong Zhu and Research Assistant Wenli Yu, performed X-ray crystallography studies of the Sh2 HA protein bound to several avian- and human-type receptors. The latter, provided by Paulson?s laboratory, were more accurate versions of these receptors than any that had been used in previous H7N9 structural analyses.
The new data highlighted the looseness of the contacts that Sh2 HA makes with human-type receptors, in contrast to the snug couplings it makes with certain avian-type receptors.
Thus, despite hints that it had begun to adapt to human hosts rather than its natural bird hosts, H7N9 does not appear to pose an imminent threat of a human pandemic. ?These results suggest that we should continue to observe H7N9 and see if it undergoes any changes that make it more likely to spread in the human population,? said Wilson. Paulson added, ?If it does evolve a true human-type receptor specificity, it could potentially spread among humans much better than it does now.?..
Rui Xu, Robert P. de Vries, Xueyong Zhu, Corwin M. Nycholat, Ryan McBride, Wenli Yu, James C. Paulson, and Ian A. Wilson
Science 6 December 2013: 342 (6163), 1230-1235. [DOI:10.1126/science.1243761]