Strengthening Fragile İmmune Memories To Fight Chronic İnfections

After recovering from the flu or another acute infection, your immune system is ready to react quickly if you run into the same virus again. White blood cells called memory T cells develop during the infection and help the immune system remember the virus and attack it if it comes back. But chronic infections such as those caused by viruses like HIV and hepatitis C are different. If the immune system can't clear the infection out of the body fast enough, the memory T cells that initially developed against the virus upon first encounter are lost. This poses a challenge for vaccine development.

Researchers at the Emory Vaccine Center have identified the conditions that make memory T cells slip away during persistent infections. They have also shown that a molecule called 2B4 on memory cells causes them to slow down during chronic infections. The results are published online this week in the journal Immunity.

The results have implications for vaccine design. The authors emphasize the importance of having vaccines that encourage the immune system to quickly control a potentially chronic infection or prevent it from gaining a foothold -- a task that some experimental vaccines against HIV's cousin SIV have accomplished.

"In a chronic infection, the memory T cells become so tightly regulated that they eventually are ineffective," says first author Erin West, an Emory graduate student in immunology and molecular pathogenesis. "This is why it's so important to have that initial strength at the beginning."

West and most of the co-authors are in the laboratory of Rafi Ahmed, PhD, director of the Emory Vaccine Center and a Georgia Research Alliance Eminent Scholar. Researchers from Harvard Medical School also contributed to the study, including W. Nicholas Haining and Cox Terhorst