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Literature detail

Identification of Stabilizing Mutations in an H5 Hemagglutinin Influenza Virus Protein.

Anthony Hanson1 Masaki Imai1 Masato Hatta1 Ryan McBride2 Hirotaka Imai1 Andrew Taft1 Gongxun Zhong1 Tokiko Watanabe3 Yasuo Suzuki4 Gabriele Neumann1 James C Paulson5 Yoshihiro Kawaoka6
Affiliations 6 institutions
  1. Department of Pathobiological Sciences, School of Veterinary Medicine, University of Wisconsin-Madison, Madison, Wisconsin, USA.
  2. Departments of Cell and Molecular Biology and Chemical Physiology, The Scripps Research Institute, La Jolla, California, USA.
  3. ERATO Infection-Induced Host Responses Project, Saitama, Japan.
  4. College of Life and Health Sciences, Chubu University, Aichi, Japan.
  5. Departments of Cell and Molecular Biology and Chemical Physiology, The Scripps Research Institute, La Jolla, California, USA Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, California, USA.
  6. Department of Pathobiological Sciences, School of Veterinary Medicine, University of Wisconsin-Madison, Madison, Wisconsin, USA ERATO Infection-Induced Host Responses Project, Saitama, Japan Department of Special Pathogens, International Research Center for Infectious Diseases, Institute of Medical Science, University of Tokyo, Tokyo, Japan Division of Virology, Department of Microbiology and Immunology, Institute of Medical Science, University of Tokyo, Tokyo, Japan [email protected].
PMID 26719265 2015 J Virol eng epublish
PubMed DOI Browse context

Article

Publication summary

Highly pathogenic avian influenza viruses of the H5N1 subtype continue to circulate in poultry in Asia, Africa, and the Middle East. Recently, outbreaks of novel reassortant H5 viruses have also occurred in North America. Although the number of human infections with highly pathogenic H5N1 influenza viruses continues to rise, these viruses remain unable to efficiently transmit between humans. However, we and others have identified H5 viruses capable of respiratory droplet transmission in ferrets. Two experimentally introduced mutations in the viral hemagglutinin (HA) receptor-binding domain conferred binding to human-type receptors but reduced HA stability. Compensatory mutations in HA (acquired during virus replication in ferrets) were essential to restore HA stability. These stabilizing mutations in HA also affected the pH at which HA undergoes an irreversible switch to its fusogenic form in host endosomes, a crucial step for virus infectivity. To identify additional stabilizing mutations in an H5 HA, we subjected a virus library possessing random mutations in the ectodomain of an H5 HA (altered to bind human-type receptors) to three rounds of treatment at 50°C. We isolated several mutants that maintained their human-type receptor-binding preference but acquired an appreciable increase in heat stability and underwent membrane fusion at a lower pH; collectively, these properties may aid H5 virus respiratory droplet transmission in mammals. We have identified mutations in HA that increase its heat stability and affect the pH that triggers an irreversible conformational change (a prerequisite for virus infectivity). These mutations were identified in the genetic background of an H5 HA protein that was mutated to bind to human cells. The ability to bind to human-type receptors, together with physical stability and an altered pH threshold for HA conformational change, may facilitate avian influenza virus transmission via respiratory droplets in mammals.

Adaptation, Biological Mutation, Missense Virus Attachment Hemagglutinin Glycoproteins, Influenza Virus Humans Hydrogen-Ion Concentration Influenza A Virus, H5N1 Subtype Mutant Proteins Protein Stability Receptors, Virus Temperature Virus Internalization hemagglutinin, avian influenza A virus

Structured evidence records

Evidence records

4 total
Host Range Experiment 2 records
Host Range Experiment Extraction confidence 0.90
Key finding

H5N1 influenza virus mutants with experimentally altered HA showed binding to human-type receptors and required compensatory mutations for stability during replication in ferrets, indicating modified host-range traits supporting mammalian transmission.

Virus
IAV H5N1
Location
Not specified
Supporting text

Two experimentally introduced mutations in the viral hemagglutinin (HA) receptor-binding domain conferred binding to human-type receptors but reduced HA stability. Compensatory mutations in HA (acquired during virus replication in ferrets) were essential to restore HA stability. These stabilizing mutations in HA also affected the pH at which HA undergoes an irreversible switch to its fusogenic form... These properties may aid H5 virus respiratory droplet transmission in mammals.

Method
experimental mutation; virus replication
Experimental system
in vivo animal experiment
Host Range Experiment Extraction confidence 0.90
Key finding

An H5 hemagglutinin mutant library selected under heat stress retained human-type receptor binding and gained increased thermal stability and altered fusion pH, properties linked to enhanced infectivity in mammalian hosts.

Virus
IAV
Location
Not specified
Supporting text

We subjected a virus library possessing random mutations in the ectodomain of an H5 HA (altered to bind human-type receptors) to three rounds of treatment at 50°C. We isolated several mutants that maintained their human-type receptor-binding preference but acquired an appreciable increase in heat stability and underwent membrane fusion at a lower pH.

Method
mutant virus library screening; receptor-binding assay; fusion assay
Experimental system
in vitro cell culture
Molecular Adaptation 1 records
Molecular Adaptation Extraction confidence 0.98
Key finding

Mutations in the H5N1 hemagglutinin conferred human-type receptor binding and altered HA stability and pH-dependent fusion, representing molecular adaptation linked to mammalian transmissibility.

Virus
IAV H5N1
Host
Not specified
Location
Not specified
Supporting text

Two experimentally introduced mutations in the viral hemagglutinin (HA) receptor-binding domain conferred binding to human-type receptors but reduced HA stability. Compensatory mutations in HA (acquired during virus replication in ferrets) were essential to restore HA stability. These stabilizing mutations in HA also affected the pH at which HA undergoes an irreversible switch to its fusogenic form in host endosomes, a crucial step for virus infectivity.

Genes or proteins
hemagglutinin; HA
Receptors
human-type receptors
Mechanism types
receptor_binding; protein_stability; fusion_pH_dependence; transmission_fitness
Receptor Usage 1 records
Receptor Usage Extraction confidence 0.95
Key finding

Mutations in the H5 hemagglutinin receptor-binding domain of avian influenza virus conferred binding to human-type receptors and stabilizing mutations allowed retention of this receptor-binding preference with improved HA stability.

Virus
IAV
Location
Not specified
Supporting text

Two experimentally introduced mutations in the viral hemagglutinin (HA) receptor-binding domain conferred binding to human-type receptors but reduced HA stability. Additional stabilizing mutations maintained human-type receptor-binding preference while increasing heat stability.

Receptors
human-type receptors