DNA vaccine encoding spike protein of SARS-coronavirus loaded polyethylenimine elicits antigen-specific immune responses in mice immunized through intranasal route (42.8)

Abstract

Abstract The spike protein (S) of severe acute respiratory syndrome (SARS) coronavirus-(CoV) is a ~180-kDa glycoprotein, which is essentially required its recognition of and binding to host receptors. It has been known that the receptor-binding motif of spike protein can produce neutralizing antibodies and therefore prevent the infection caused by SARS-CoV. Polyethylenimine (PEI) is one of the most widely used and effective nanoparticles, which have been tested for its use in the drug delivery system including DNA vaccine. In the present study, we examined the immune responses in BALB/c mice after immunized with SARS DNA vaccine in a pci-S/PEI complex form via intranasal (i.n.) route. PEI/pci-S nanoparticles showed a spherical shape with size around 194+/-99nm. The mice intranasally immunized with pci-S/PEI nanoparticles produced significantly (P<0.05) higher S-specific IgA as well as B220+ cells in the lung wash than those in mice treated with pci-S alone. CD80, CD86 and Class II MHC molecules (I-Ad) were increased on pulmonary dendritic (CD11c+) cells after vaccination. The percentage of IFN-gamma, TNF-alpha, and IL-2 producing cells were also higher in PEI/pci-S vaccinated mice than in either pci-S or pci-mock treated mice. Taken together, our results showed that immunization with pci-S/PEI nanoparticles induce antigen specific humoral and cellular immune responses.