Fig. 5: Humoral immune responses to VSV vector immunization and KFDV challenge in mice.

a KFDV-prM-E-specific IgG titers. Total IgG-specific antibodies to KFDV-prM-E were determined by ELISA on serum samples collected from animals immunized prime-only and prime-boost with VSV-KFDV1 (solid bars red and blue, respectively), VSV-KFDV2 (dotted bars red and blue, respectively), VSV-EBOV (solid bar black), and VSV-EBOV EBOV∆GC∆MLD (dotted bar black). Samples were collected prior to challenge on day -7 (n = 12) and following KFDV challenge on 8 dpi (n = 4) and 42 dpi (n = 8 for 100% survival and n = 7 for 87.5 % survival). b KFDV-specific neutralization titers. The same serum samples were tested for their neutralizing activity. The highest titer that completely neutralized 100 TCID₅₀ of KFDV are shown. c EBOV GP-specific IgG titers. Total IgG titers specific to EBOV GP were determined by ELISA on serum samples collected prior to challenge on day −7 (n = 6) of mice immunized prime-only with VSV-EBOV, VSV-EBOV∆GC∆MLD, VSV-KFDV1, and VSV-KFDV2. The cut-off for seropositivity is indicated by a horizontal dotted line. The value was set at 3 standard deviations above the mean absorbance of pre-immune serum at a dilution of 1:100. Statistical significance was analyzed using the unpaired T tests in Prism 7 (GraphPad)and results are indicated as *p < 0.05.