Comparative Efficacy of GP and GPΔTM for Protection against Ebola Virus Challenge

<div><p>(A) Kaplan-Meier survival curve of cynomolgus macaques, immunized as indicated, and challenged with 1,000 pfu of Zaire ebolavirus (strain Kikwit) 1 mo post immunization. The <i>x</i>-axis indicates weeks postchallenge. Different immunization groups had <i>n</i> = 3, except for the GP(Z) + NP (10¹²) group ( <i>n</i> = 4), and control ( <i>n</i> = 1). </p> <p>(B) Immune responses in immunized animals. Left and middle graphs: Intracellular flow cytometry was performed to quantify TNF-α production from Ebola-specific CD4⁺ or CD8⁺ lymphocytes, respectively, from animals immunized as indicated (the 10¹² group contains only three CD8 points due to technical error in one sample). Immune responses were measured at 3 wk postimmunization. Circles, diamonds, squares, and triangles indicate responses for individual animals. Horizontal line indicates the average of individual responses in the immunization group. Results represent the percent cytokine-positive in the gated lymphocyte group, and background stimulation (DMSO alone) has been subtracted from each sample. ELISA titers of Ebola GP-specific antibodies in sera of vaccinated animals collected at week 3 postimmunization (right graph). ELISA results represent endpoint dilution titers determined by optical density as described in <a href="http://www.plosmedicine.org/article/info:doi/10.1371/journal.pmed.0030177#s2" target="_blank">Methods</a>. </p>