<i>Bundibugyo ebolavirus</i> Survival Is Associated with Early Activation of Adaptive Immunity and Reduced Myeloid-Derived Suppressor Cell Signaling
Courtney Woolsey, Viktoriya Borisevich, Krystle N. Agans, Karla A. Fenton, Robert W. Cross, Thomas W. Geisbert
Abstract
Bundibugyo virus (BDBV) and Ebola virus (EBOV) are ebolaviruses endemic to Africa that cause severe, often fatal hemorrhagic disease. BDBV is considered a less pathogenic ebolavirus due to its reduced lethality during human outbreaks, as well as in experimentally infected nonhuman primates. The reduced mortality of BDBV in NHP models, resulting in a pool of survivors, afforded us the unique opportunity of identifying immune correlates that confer protection against ebolaviruses. In this study, we discovered that the survival of BDBV-infected nonhuman primates (NHPs) was dependent on early development of adaptive (memory) immune responses and reduced myeloid-derived suppressor cell (MDSC)-related signaling. MDSCs are a heterogenous group of immune cells implicated in a number of diseases that are powerful immunosuppressors of cellular and humoral immunity. Thus, MDSCs represent a novel therapeutic target to prevent ebolavirus disease. To our knowledge, this is the first study to link increased morbidity with recruitment of these potent immunosuppressive cells.