FIG 2.

A single dose of either mtdVSV-NS1 or two doses of DNA vaccination induced a high level of NS1-specific antibody response and provided partial protection against ZIKV infection in BALB/c mice. BALB/c mice were intranasally inoculated with DMEM or 10⁶ PFU of each recombinant virus. For DNA vaccination, mice were vaccinated intramuscularly with 50 μg of plasmid DNA and were boosted with the same dose 2 weeks later. At week 4, mice were intraperitoneally administered 1.8 mg of anti-IFNAR1 blocking antibody and 24 h later challenged intravenously with 10⁶ PFU of ZIKV Cambodian strain. (A) Dynamic of mouse body weight changes after vaccination. Data are averages for five mice ± the standard deviation. (B) Kinetics of ZIKV NS1-specific antibody induced by mtdVSV-NS1 vaccines and DNA vaccines. Recombinant rVSV-G1670A-prM-E was used as a control. Serum samples were collected weekly and analyzed by ELISA for NS1-specific serum IgG antibody. The data are expressed as the GMT of five mice ± the standard deviation. (C) Dynamic of body weight of changes after challenge with ZIKV. Mice were challenged with 10⁶ PFU of ZIKV Cambodian strain. After challenge, the body weight for each mouse was measured each day until day 7 postchallenge. Data are averages for five mice ± the standard deviation. (D) Viremia in mice on day 3 after challenge with ZIKV. After challenge, blood samples were collected at day 3, and the amount of ZIKV RNA was quantitated by real-time RT-PCR and calculated to log₁₀ PFU eq/ml. (E) Viremia in mice on day 7 after challenge with ZIKV. Viremia was expressed as log₁₀ PFU eq/ml. Data in panels D and E are the GMT of five mice (black bars) and were analyzed by using Student t test and compared to the empty vector rVSV-D1762A group or the pCI group (*, P < 0.05; **, P < 0.01; ***, P < 0.001; ****, P < 0.0001).