New study finds an altered immune response to viruses like HIV and hepatitis C
(PHILADELPHIA) -- After a viral infection, a small percentage of the T cells generated to kill virus-infected cells remain on guard to establish long-term immunity. These so-called memory T cells, which derive from a family of immune cells known as CD8 T cells, engage in a self-renewal process that is essential to their persistence. This ongoing process ensures effective protection against any repeat infection by the same virus, even decades later.
But not all infections are equal. While most viral infections are cleared from the body within a few days or weeks, some infections, such as HIV or hepatitis C infections, become chronic. Some studies have suggested that the virus-specific CD8 T cells generated during a chronic infection may not develop the same characteristics as the CD8 T cells that persist after an acute infection.
Now, scientists at The Wistar Institute have found that the CD8 T cells generated to fight a chronic infection operate under an entirely different maintenance scheme than do the CD8 T cells that become memory T cells following an acute infection, becoming wholly dependent upon the presence of virus for their continuation. Details of the study will appear in the April 16 issue of The Journal of Experimental Medicine, published online April 9.
http://www.eurekalert.org/pub_releases/2007-04/twi-hdt040607.php
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