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Rapid development of a DNA vaccine for Zika virus

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Science  14 Oct 2016:
Vol. 354, Issue 6309, pp. 237-240
DOI: 10.1126/science.aai9137
  • Fig. 1 ZIKV DNA vaccine design and characterization.

    (A) Schematic representation of the ZIKV genome and ZIKV DNA vaccine constructs VRC5283 and VRC5288. UTR, untranslated region; C, capsid; NS, nonstructural. (B) Expression and secretion of ZIKV E was analyzed by Western blot of transfected 293 T cell lysates and SVP precipitate pelleted from culture supernatants through a 20% sucrose cushion, demonstrating that VRC5288 secretes more particles than VRC5283. (C) Particle-capture ELISA quantifying the secretion of ZIKV SVPs from transfected cells. (D) ZIKV SVPs were purified from the culture supernatant of VRC5288-transfected 293F cells and subjected to negative staining and electron microscopy. SVPs are labeled with arrowheads. The VRC8400 empty backbone plasmid vector was used as a control.

  • Fig. 2 ZIKV DNA vaccines elicit robust binding and neutralizing antibodies in nonhuman primates.

    Rhesus macaques (n = 6 per group) were either mock-immunized with VRC8400 empty backbone plasmid or vaccinated with VRC5283 or VRC5288 plasmids intramuscularly; doses and number of vaccinations are indicated. (A) Macaque sera were assayed weekly by ELISA for ZIKV binding antibodies. Each line represents the average titer of an individual animal from one or two technical duplicates, and the dashed line indicates the limit of detection (reciprocal titer of 64). Any measurement below the limit of detection was assigned a value of half the limit of detection for graphing and statistical purposes. (B) The NAb response elicited by vaccination was analyzed using ZIKV RVPs. The dilution of sera required for half-maximal inhibition of virus infection (EC50) was estimated by nonlinear regression analysis. Lines connect average EC50 values from two to five independent experiments, each performed with technical duplicates, for the individual monkeys in each group at each time point. The dotted line denotes the limit of confidence for the RVP assay (reciprocal titer of 60). Measurements below the limit of detection were assigned a value of 30. The average (C) binding antibody and (D) NAb responses for each vaccine group are shown. Throughout, error bars denote SEM.

  • Fig. 3 ZIKV DNA vaccines reduce viremia in ZIKV-challenged rhesus macaques.

    Eight weeks after the first vaccination, macaques were challenged with 103 FFU of ZIKV strain PRVABC59. (A) qPCR of the capsid gene was used to determine the number of genome copies per milliliter on days 1 to 5 and 7 after challenge. Each line represents an individual animal. (B) Mean viral load after challenge in each group. Error bars represent SEM. The dashed line indicates the limit of detection (100 copies/ml). Any value below the limit of detection was assigned a value half the limit of detection for graphing and AUC calculation.

  • Fig. 4 Protection from ZIKV challenge correlates with NAb titers present at challenge.

    Animals that had detectable viremia after challenge were analyzed with respect to prechallenge NAb activity. (A) The reciprocal EC50 NAb titer of each animal is individually plotted to reflect whether infection occurred. Lines represent individual animals. Protected (no detectable viremia) and infected (viremia detectable on 2 successive days) animals are represented by gray and red lines, respectively. The sole animal that received two 4-mg doses of VRC5288 and was found to have a low level of viremia on days 3 and 7 after challenge is denoted as “breakthrough” (circles with black outlines). (B) The probability of protection (logit) based on the reciprocal EC50 NAb titer is shown and indicates that prevention of viremia would be expected in ~70% of animals with NAb titers >1000. The colors of the circles indicate vaccination group (black, VRC8400, 4 mg × 2; blue, VRC5283, 4 mg × 2; light blue, VRC5283, 1 mg × 2; red, VRC5288, 4 mg × 2; pink, VRC5288, 1 mg × 1).

Supplementary Materials

  • Rapid development of a DNA vaccine for Zika virus

    Kimberly A. Dowd, Sung-Youl Ko, Kaitlyn M. Morabito, Eun Sung Yang, Rebecca S. Pelc, Christina R. DeMaso, Leda R. Castilho, Peter Abbink, Michael Boyd, Ramya Nityanandam, David N. Gordon, John Robert Gallagher, Xuejun Chen, John-Paul Todd, Yaroslav Tsybovsky, Audray Harris, Yan-Jang S. Huang, Stephen Higgs, Dana L. Vanlandingham, Hanne Andersen, Mark G. Lewis, Rafael De La Barrera, Kenneth H. Eckels, Richard G. Jarman, Martha C. Nason, Dan H. Barouch, Mario Roederer, Wing-Pui Kong, John R. Mascola, Theodore C. Pierson, Barney S. Graham

    Materials/Methods, Supplementary Text, Tables, Figures, and/or References

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    • Materials and Methods
    • Figs. S1 to S8
    • Table S1
    • References

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