Posted on 06/27/2007 12:00:00 AM PDT by CarrotAndStick
CHICAGO: A popular theory on how HIV attacks the body's immune system is wrong, a new study has found.
Scientists have long believed that HIV causes the slow depletion of healthy white blood cells — the T cells which recognise infections so the body can fight them off — by causing infected T cells to produce virus particles before dying.
This ongoing cycle of infection, HIV production, reinfection and cell destruction has been called the "runaway" hypothesis.
But if this were so, the T cells would be killed off far too quickly, the researchers found.
Using a simple mathematical model, researchers in the United States and Britain showed the "runaway" model would deplete the body's healthy T cells in a matter of months, instead of the years it actually takes. The results show that a "slow process must be active" in the depletion of the T cells, the authors wrote in the current issue of the journal PLoS Medicine.
Identifying this process "will provide a key insight into the nature of HIV disease and indicate potential new approaches to therapy," they concluded. A potential explanation for the slow process could be that the virus slowly adapts over the course of the infection, the authors said.
"The virus is constantly mutating and there may be selection — in a Darwinian sense — over time for 'fitter' mutants of the virus in an infected person," said lead author Andrew Yates of Emory University in Atlanta, Georgia.
"There are several ways the virus could become fitter - for example by being able to infect new cells more readily, or by infected cells producing more new virus, or producing it more rapidly," he said in an e-mail interview.
"The virus adaptation hypothesis requires a lot more experimental investigation, however, and is only a tentative conclusion."
bttt
A virus does not become "fitter" by killing its host more quickly. I becomes "fitter" by not killing its host at all.
Smallpox learned that lesson the hard way.
A popular theory on how HIV attacks .....
I believe it comes up from behind its victim....
Old belief: Scientists have long believed that HIV causes the slow depletion of healthy white blood cells — the T cells which recognise infections so the body can fight them off — by causing infected T cells to produce virus particles before dying.
New belief: The results show that a "slow process must be active" in the depletion of the T cells, the authors wrote in the current issue of the journal PLoS Medicine.
HIV does not cause AIDS.
This fits with the known facts much better than any HIV=AIDS theory.
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