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PLoS Pathog. 2016 Jan 27;12(1):e1005411. doi: 10.1371/journal.ppat.1005411. eCollection 2016 Jan.

An Open Receptor-Binding Cavity of Hemagglutinin-Esterase-Fusion Glycoprotein from Newly-Identified Influenza D Virus: Basis for Its Broad Cell Tropism.

Song H1,2, Qi J1, Khedri Z3, Diaz S3, Yu H4, Chen X4, Varki A3, Shi Y1,2,5, Gao GF1,2,5.

Author information

1
CAS Key Laboratory of Pathogenic Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China.
2
University of Chinese Academy of Sciences, Beijing, China.
3
University of California, San Diego, La Jolla, California, United States of America.
4
University of California, Davis, Davis, California, United States of America.
5
Research Network of Immunity and Health (RNIH), Beijing Institutes of Life Science, Chinese Academy of Sciences, Beijing, China.

Abstract

Influenza viruses cause seasonal flu each year and pandemics or epidemic sporadically, posing a major threat to public health. Recently, a new influenza D virus (IDV) was isolated from pigs and cattle. Here, we reveal that the IDV utilizes 9-O-acetylated sialic acids as its receptor for virus entry. Then, we determined the crystal structures of hemagglutinin-esterase-fusion glycoprotein (HEF) of IDV both in its free form and in complex with the receptor and enzymatic substrate analogs. The IDV HEF shows an extremely similar structural fold as the human-infecting influenza C virus (ICV) HEF. However, IDV HEF has an open receptor-binding cavity to accommodate diverse extended glycan moieties. This structural difference provides an explanation for the phenomenon that the IDV has a broad cell tropism. As IDV HEF is structurally and functionally similar to ICV HEF, our findings highlight the potential threat of the virus to public health.

PMID:
26816272
PMCID:
PMC4729479
DOI:
10.1371/journal.ppat.1005411
[Indexed for MEDLINE]
Free PMC Article

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