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From VOA Learning English, this is the Health Report.
Infection by the influenza virus may be more complex than scientists first thought. Researchers in the United States reported recently that the flu virus appears to disarm the body’s first line of defense against disease. When the virus attacks, the body’s natural defenses produce white blood cells. These cells make antibodies that link up to the invading microorganism. They neutralize it and, in that way, prevent or lessen the severity of infection. The cells also remember the invading virus so they can fight it in the future. That is the traditional understanding of how the body fights the flu virus. Now biologists have discovered how the virus can disarm those white blood cells, known as B cells. Hidde Ploegh is with the Whitehead Institute for Biomedical Research in Cambridge, Massachusetts. He led the team of researchers. Their laboratory studies with special mice suggest the flu virus enters the B cells and interferes with the production of antibodies. This can kill the B cells and the body’s first line of defense. Mr. Ploegh says that may explain why some forms of influenza can cause a stronger physical reaction than others.
Normally, the frontline antibodies occupy lung cells to protect the body against future viral invasions through breathing. But the flu virus, having disabled the antibodies, may instead attack lung cells. In that way, the virus blocks the antibody’s ability to remember the invader. Hidde Ploegh says that by interfering with the body’s “frontline troops”, the virus has more time to reproduce and establish itself in the cells. A report on how influenza overcomes the body’s immune system was published in the journal Nature.