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    Discovery provides potential target for vaccines, treatments  
    Scientists have solved the structure of a protein that helps a    common respiratory virus evade the immune system. The    researchers have identified critical parts of the protein that    could be targeted with drugs or vaccines, opening up the    possibility of preventing or treating an infection that sickens    thousands of babies and elderly people every year.  
    By age 2, most children have been infected with respiratory    syncytial virus (RSV), which usually causes only mild cold    symptoms. But people with weakened immune systems, such as    infants and the elderly, can face serious complications,    including pneumonia and  in some cases  death.  
    Now, scientists studying the virus, led by researchers at    Washington University School of Medicine in St. Louis, have    found clues to how RSV causes disease. They mapped the    molecular structure of an RSV protein that interferes with the    bodys ability to fight off the virus. Knowing the structure of    the protein will help them understand how the virus impedes the    immune response, potentially leading to a vaccine or treatment    for this common infection.  
    We solved the structure of a protein that has eluded the field    for quite some time, said Daisy    Leung, PhD, an assistant professor of pathology and    immunology, and of biochemistry and molecular biophysics at    Washington University School of Medicine in St. Louis, and the    studys co-senior author. Now that we have the structure,    were able to see what the protein looks like, which will help    us define what it does and how it does it. And that could lead,    down the road, to new targets for vaccine or drug development.  
    The study is published June 30 in Nature Microbiology.  
    Each year in the United States, more than 57,000 children    younger than 5 years old are hospitalized due to RSV infection,    and about 14,000 adults older than 65 die from it.  
    There is no approved vaccine for RSV and treatment is limited     the antiviral drug ribavirin is used only in the most severe    cases because it is expensive and not very effective  so most    people with RSV receive supportive care to make them more    comfortable while their bodies fight off the virus.  
    For people with weakened immune systems, though, fighting RSV    can be tough because the virus can fight back. Scientists have    long known that a non-structural RSV protein is key to the    viruss ability to evade the immune response. However, the    structure of that protein, known as NS1, was unknown. Without    seeing what the protein looked like, scientists were unable to    determine exactly how NS1 interfered with the immune system.  
    Its an enigmatic protein. Everybody thinks it does many    different things, but weve never had a framework to study how    and why the protein does what it does, said co-senior author        Gaya Amarasinghe, PhD, an associate professor of pathology    and immunology.  
    Leung, Amarasinghe and colleagues used X-ray crystallography    a technique that involves crystallizing the protein,    bouncing X-rays off it, and analyzing the resulting patterns     to determine the 3-D structure of NS1. Then, in a detailed    analysis of the structure, they identified a piece of the    protein, known as the alpha 3 helix, which might be critical    for suppressing the immune response.  
    To test their hypothesis, the researchers created different    versions of the NS1 protein, some with the alpha 3 helix region    intact, and some with it mutated. In collaboration with others    Rohit Pappu,    PhD, the Edwin H. Murty Professor of Biomedical    Engineering, Michael    Holtzman, MD, the Selma and Herman Seldin Professor of    Medicine, Maxim    Artyomov, PhD, an assistant professor of pathology and    immunology, and Christopher Basler, PhD, of Georgia State    University  they tested the functional impact of helix 3 and    created a set of viruses containing the original or the mutant    NS1 genes, and measured the effect on the immune response when    they infected cells with these viruses.  
    They found that the viruses with the mutated helix region did    not suppress the immune response while the ones with the intact    helix region did.  
    One of the surprising things we found was that this protein    does not target just one set of genes related to the immune    response, but it globally modulates the immune response, said    Amarasinghe, also an associate professorof molecular    microbiology, and of biochemistry and molecular biophysics.  
    The findings show that the alpha 3 helix region is necessary    for the virus to dial the bodys immune response down. By    suppressing the immune response, the virus gives itself a    better chance of surviving and multiplying, or in other words,    of causing disease. RSV usually can only cause disease in    people whose immune systems are already weak, so a vaccine or    treatment that targets the alpha 3 helix to prevent immune    suppression may be just what people need to be able to    successfully fight off the virus, the researchers said.  
      Chatterjee S, Luthra P, Esaulova E, Agapov E, Yen BC, Borek      DM, Edwards MR, Mittal A, Jordan DS, Ramanan P, Moore ML,      Pappu RV, Holtzman MJ, Artyomov M, Basler CF, Amarasinghe GK,      Leung DW. Structural basis for human respiratory syncytial      virus NS1-mediated modulation of host responses. Nature      Microbiology. June 30, 2017.    
      This study was supported by the National Institutes of      Health, grant numbers R01AI107056, R01AI123926, R01AI114654,      U191099565, U19AI109945, U19AI109664, U19AI070489,      R01AI111605, R01AI130591, R01AI087798, U19AI095227, and      T32-CA09547-37; the Defense Threat Reduction Agency of the      Department of Defense, grant numbers HDTRA1-16-0033 and      HDTRA1-16-0033; the National Science Foundation, grant number      MCB-1121867; the Childrens Discovery Institute, a      partnership between Washington University School of Medicine      and St. Louis Childrens Hospital, grant number      PD-II-2013-272; and the American Heart Association,      15POST25140009.    
      Washington University      School of Medicines 2,100 employed and volunteer faculty      physicians also are the medical staff of Barnes-Jewish and St. Louis Childrens      hospitals. The School of Medicine is one of the leading      medical research, teaching and patient-care institutions in      the nation, currently ranked seventh in the nation by U.S.      News & World Report. Through its affiliations with      Barnes-Jewish and St. Louis Childrens hospitals, the School      of Medicine is linked to BJC      HealthCare.    
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New clues found to common respiratory virus | Washington ... - Washington University School of Medicine in St. Louis