March 19, 2008
Researchers from the University of California-San Diego and Oak Ridge National Laboratory have discovered the genetic circuit in HIV that controls whether the virus is activated or remains dormant, according to a study published in the March 16 issue of the journal Nature Genetics, Xinhuanet reports (Xinhuanet, 3/18).
For the study, Leor Weinberger, professor of chemistry and biochemistry at UCSD, and colleagues examined HIV's genetic master circuit, called the Tat circuit, by building upon previous research by Weinberger, IANS/Sify reports. The previous research found that the circuit is driven by "cellular noise," or random events, which activate the circuit for a limited amount of time before it shuts off, according to IANS/Sify (IANS/Sify, 3/17). In the current study, the researchers used the noise in the Tat circuit to measure how long HIV remained activated in cells. The researchers found that the time the virus spent in the active state determined if it destroyed a cell or not. The researchers then increased the levels of the cellular gene SirT1 -- a gene associated with aging -- to reduce the lifespan of HIV, which forced cells infected with the virus to become dormant, the Press Trust of India reports (Shourie, Press Trust of India, 3/17).
According to Weinberger, the findings are significant because "many researchers are interested in determining which cellular processes generate biological noise." He added that the researchers "asked if the cellular noise could tell us anything about HIV and the cell -- and it did. What it told us is how a developmental decision is made by HIV." Weinberger said the findings do not indicate "how developmental decisions are made at the single-cell level" and "whether noise can drive this decision." He added, "Surprisingly, viruses appear to be good models for understanding this type of cellular decision-making." Weinberger and colleagues are conducting further studies on the feasibility of using this approach for HIV treatment, Xinhuanet reports (Xinhuanet, 3/18).
An abstract of the study is available online.
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