Fig 1.
Schematic representation of the YFV virus genome and of the recombinant adenoviral vectored-vaccines used in this study.
Three vectors encoding antigens from the YF-17D virus were used: Ad-YF C,M,E, Ad-YF NS3 and Ad-YF NS3(201–325). The positions of the two previously identified murine MHC class I-restricted viral epitopes have been indicated.
Fig 2.
Analysis of immune responses induced by vaccination with Ad-YF vectors.
WT B6 mice were vaccinated with Ad-YF C,M,E, Ad-YF NS3 or YF-17D virus. a) Numbers of CD44+IFN-γ+ CD8+ T cells following ex vivo peptide stimulation with NS3(268–275) and E(4–12) are depicted as a function of time after vaccination; non-stimulated cells serve as controls; symbols denote individual animals. b) Neutralizing antibody titers as a function of time after vaccination. The dashed line indicates the median titer of the neutralizing antibody measured in WT B6 mice vaccinated with YF-17D virus (cf. ref. (21)); symbols denote individual animals.
Fig 3.
In vivo protection induced by vaccination with Ad-YF vectors.
WT B6 mice were vaccinated with Ad-YF C,M,E or Ad-YF NS3 and intracranial challenged with YF-17D virus. Survival of vaccinated mice are compared to that of sham vaccinated (PBS) animals. N = 5 in all groups. Experiment performed twice with similar results.
Fig 4.
Role of CD8+ T cells in mediating protection from YF viral challenge following Ad-YF NS3 vaccination.
WT B6 mice, H-2Kb KO mice, β2m KO mice, IFN-γ/Prf double KO mice and MHC class II KO mice were vaccinated with Ad-YF NS3 and 14 days later intracranial challenged with YF-17D virus. a) Survival curves are depicted; n = 5 in WT group and 10 in all other groups. b) Numbers of NS3(268–275)—specific CD8+ T cells in the spleen of WT B6 mice and MHC class II KO mice 8 days post Ad-YF NS3 vaccination are enumerated. Results are pooled from two independent experiments; symbols denote individual animals.
Fig 5.
Viral loads in the brains of mice vaccinated with Ad-YF NS3 or Ad-YF NS3 (201–325) reflect CD8+ T cell numbers.
Non-vaccinated, Ad-YF NS3 vaccinated or Ad-YF NS3 (201–325) vaccinated WT B6 mice (filled squares) as well as Ad-YF NS3 vaccinated H-2Kb KO mice (open squares) were challenged with YFV intracranial 14 after vaccination, and viral titers in the CNS were determined 7 days later. Symbols denote individual animals.
Fig 6.
Protection from lethal disease following vaccination with Ad-YF C,M,E relies on both T- and B-cell responses.
WT B6 mice, B cell KO mice and H-2Kb/Db KO mice were vaccinated with Ad-YF C,M,E and intracranial challenged 14 days later with YFV. Survival curves for each group of vaccinated KO mice are compared to that of vaccinated WT B6 mice. WT: n = 10; B cell KO: n = 7; H-2Kb/Db KO: n = 5. The depicted data are pooled from two independent experiments.
Fig 7.
Protection in Ad-YF C,M,E vaccinated mice reflects a combination of CD8 T-cell mediated and humoral immunity, while protection following NS3 entirely relies on cytolytic and/or cytokine producing CD8+ T cells.
a) WT B6 mice were vaccinated with Ad-YF C,M,E or Ad-YF NS3 and intracranial challenged with YFV 60 days later; part of the vaccinated animals were in vivo depleted of CD8+ T cells (α-CD8) 1 day prior to intracranial challenge, and again at days +1 and +4 after challenge. Viral titers in the CNS of Ad-YF vaccinated and Ad-YF vaccinated/CD8 depleted mice 7 days after challenge are compared to those in unvaccinated control animals. Dots represent individual animals. b) IFN-γ KO, Prf KO, IFN-γ/Prf double KO and WT B6 mice were vaccinated in the f.p. with Ad-YF NS3 and, 14 days later, intracranial challenged with YF-17D virus; viral titers in the CNS of vaccinated mice are compared to those of matched unvaccinated control animals at day 7 post YF challenge. Dots represent individual animals.
Fig 8.
Single vaccination with either adenovector induces long-lasting protection in WT mice.
WT B6 mice were vaccinated with Ad-YF C,M,E or Ad-YF NS3 and intracranial challenged with YFV 60 or 210 days later. On day 7 post challenge viral loads in the CNS of vaccinated animals are compared to those in unvaccinated control mice. Dots represent individual animals.