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NIMH Scientists Find New Details of HIV Viral Reproduction Process
National Institute of Mental Health Laboratory of Molecular Biology researchers have discovered "an unexpected step" in the process that HIV uses to evade natural barriers, infect human cells and weaken the immune system, according to an NIH release. HIV, a retrovirus whose RNA manufactures a DNA copy of itself when it enters a human cell and then integrates this copy into the cell's DNA to produce more viruses, has evolved around cells' natural resistance to infection. Most CD4+ T cells, the blood cells in which HIV replicates predominantly, exist in a resting state that resists HIV infection, as the cell must be active for HIV to reproduce. But the researchers explain in the Aug. 24 issue of Science Magazine that after the viral DNA replication of its RNA and before the viral DNA's integration into the cellular DNA, the HIV DNA "serves as a template" to make the viral proteins Nef and Tat. These proteins bring the CD4+ T cells out of their resting state, allowing the virus to integrate into the cellular DNA and replicate. Previous studies have shown that HIV-positive individuals have many cells in the brain and elsewhere that contain non-integrated HIV DNA, and although these cells do not produce new viruses, the new findings show that such cells do contribute to HIV disease progression by contributing to the production of Nef and Tat (NIH release, 8/23).
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