Immune responses in wild-type mice against prion proteins induced using a DNA prime-protein boost strategy / 生物医学与环境科学（英文）

ABSTRACT

<p><b>OBJECTIVE</b>To break immune tolerance to prion (PrP) proteins using DNA vaccines.</p><p><b>METHODS</b>Four different human prion DNA vaccine candidates were constructed based on the pcDNA3.1 vector PrP-WT expressing wild-type PrP, Ubiq-PrP expressing PrP fused to ubiquitin, PrP-LII expressing PrP fused to the lysosomal integral membrane protein type II lysosome-targeting signal, and PrP-ER expressing PrP locating the ER. Using a prime-boost strategy, three-doses of DNA vaccine were injected intramuscularly into Balb/c mice, followed by two doses of PrP protein. Two weeks after the last immunization, sera and spleens were collected and PrP-specific humoral and cellular immune responses evaluated by ELISA and ELISPOT tests.</p><p><b>RESULTS</b>Higher levels of serum PrP antibodies were detected in mice vaccinated using the strategy of DNA priming followed by protein boosting. Of these, WT-PrP, Ubiq-PrP, and PrP-LII induced significantly higher humoral responses. ELISPOT tests showed markedly increased numbers of IFN-γ-secreting T cells in mice vaccinated using the strategy of DNA priming followed by protein boosting after stimulation with recombinant PrP23-90 and PrP23-231. PrP-ER induced the strongest T-cell response.</p><p><b>CONCLUSION</b>Prion vaccines can break tolerance to PrP proteins and induce PrP-specific humoral and cellular immune responses.</p>