Figure 1.
Humoral responses against vesicular stomatitis virus (VSV). A, Structure and design of VSV–Ebola virus (EBOV) vaccine. VSV glycoprotein G (G) is replaced by EBOV glycoprotein (GP), while nucleoprotein (N), phosphoprotein (P), matrix protein (M), and RNA-dependent RNA polymerase (L) correspond to the VSV backbone vector. B, VSV-M–specific antibodies were generated following VSV-EBOV immunization in humans. VSV-M antibody titers were assessed by enzyme-linked immunosorbent assay at baseline and days 14, 28, 56, 84, and 180 postvaccination. Results are expressed as corrected optical density (OD) values. The dashed line depicts the threshold for a positive antibody response, calculated as the median on day 0 of all subjects ± 3 standard deviations. VSV-M–specific antibodies are detectable in 8 subjects (3 × 105 plaque-forming units [PFU], 5 of 10 subjects; 3 × 106 PFU, 1 of 10 subjects; 2 × 107 PFU, 2 of 9 subjects). C, Positive correlation between OD values of VSV-M and EBOV-GP–specific immunoglobulin G (IgG) at day 56 postvaccination. D, VSV-M–positive subjects were analyzed for generation of neutralizing antibodies against VSV wild-type (VSVwt; (n = 8). Neutralizing antibodies against infectious EBOV isolate Mayinga but not against VSV-M were detected. Statistical analysis was performed with Mann–Whitney–Wilcoxon test.