Study says AIDS hits immune cells in days
WASHINGTON -- Within days of infection, the AIDS virus destroys more than half of the immune cells that might recognize and help fight it, a finding that may force a reevaluation of how to tackle the deadly infection, two teams of US researchers reported yesterday.
Two separate studies in monkeys indicate that SIV -- the version of the human immunodeficiency virus, or HIV, that occurs among monkeys -- attacks CD4 memory T-cells very quickly and wipes out more than half of them.
''The findings may require a rethink of strategies to design HIV drugs and vaccines," Dr. Mario Roederer, of the National Institute of Allergy and Infectious Diseases, and colleagues wrote in one of two reports in the journal Nature.
The findings will be difficult to replicate in people because most people do not know the moment they are infected with the AIDS virus, which gradually destroys the immune system, leaving patients vulnerable to numerous infections. But SIV is a good model and works in a similar way.
Both teams worked with monkeys that they infected with SIV. They watched what happened to their immune cells.
Right away the virus attacked the CD4 T-cells that had the correct configuration for the virus. Normally during an infection such cells would recognize and latch onto an invader, helping other components of the immune system destroy it. But HIV is different because it targets the immune system, and the two studies show how quickly it makes it impossible for its victims to launch a defense.
Roederer's team used new, sensitive tests to demonstrate how the virus moves so quickly.
Dr. Ashley Haase of the University of Minnesota Medical School and colleagues made similar findings. Not only does the virus directly kill the CD4 cells, they found, but it also causes them to them to commit cell suicide.
There is no cure for HIV, which killed more than 3 million people globally last year and which infects 39 million people, according to the United Nations.
Drug cocktails can control the infection, but it comes back quickly if they are stopped.
