Novel Therapy Eliminates Chronic Viral Infection in Mice

Although most viral infections are eliminated completely by the immune response, some become persistent (even lifelong) and can cause disease long after initial infection. During the normal immune response to a virus, lymphocytes leave the circulation, enter lymph nodes, and then reenter the circulation. However, lymph nodes sometimes “trap” entering lymphocytes within their densely concentrated populations of resident lymphocytes, which delays reentry. In animal experiments, researchers have found that delayed release of lymphocytes from lymph nodes greatly enhances the immune system’s ability to eradicate viral infections.

The molecule sphingosine-1-phosphate (S1P) appears to be the main signal that retards egress of lymphocytes from lymph…