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With its mysterious outbreaks, gruesome symptoms and propensity for killing, few viruses elicit so much fear as Ebola. But new research may have brought scientists a step closer to developing a vaccine against the dreaded disease. Contrary to the belief of some scientists that Ebola¿s lethal effects stem from an ability to suppress the immune system, the new findings indicate that the virus does, in fact, provoke a strong immune response.
Researchers from the Centers of Disease Control and Emory University studied a mouse strain of Ebola that was adapted from a human strain. As early as four days after infection with the virus, they found, the mice exhibited high levels of activated CD4 and CD8 T cells¿key players in the immune system¿s counterattack force. The team also detected high levels of interferon gamma¿a protein produced by T cells that blocks the growth of viruses and renders cells resistant to viral infection. Several days later, however, the mice died. Thus, Ebola appears to work not by preventing an immune response altogether but by moving so swiftly that the T cells do not have time to multiply enough to mount an effective counterattack.
The team further showed that CD8 T cells are the major source of cytokines in response to acute Ebola infection. Moreover, in the absence of anti-Ebola antibodies, so-called memory CD8 T cells can apparently stave off infection. The researchers hope to understand the mechanism of this immune protection through further research.
