[Construction of specifically targeted chimeric hepatitis E virus DNA vaccine and its efficacy assessment].
OBJECTIVE
To design chimeric DNA vaccine targeted to antigen-presenting cells (APCs) with enhanced efficacy to induce immunization.


METHODS
The plasmid containing the gene encoding cytotoxic T-lymphocyte antigen 4 (CTLA4), a surface molecule on T cells, was directly fused to the gene fragment HEVE2 coding for hepatitis E virus antigen by molecular engineering technology. The plasmid containing HEVE2 gene fragment alone was also constructed to serve as control and transfection of COS-7 cells with the 2 resultant plasmids was performed respectively, followed by assay of the expressions of CTLA4- HEVE2 fusion protein and HEVE2 protein in COS-7 cells by way of Western blotting. BALB/c mice were injected intracutaneously with the DNA vaccine (100 microgram) for 3 times at 2-week intervals, and the titer of anti-HEVE2 total IgG and IgG subclasses were determined by enzyme-linked immunosorbent assay (ELISA).


RESULTS
The mammalian expression plasmids of CTLA4-HEVE2 fusion protein or HEVE2 protein alone were cloned. The culture supernants of COS-7 cells transfected with the plasmids showed the production of CTLA4-HEVE2 and HEVE2 proteins, which were secreted in the form of dimers. Mice immunized with pCTLA2-HEVE2 produced high levels of specific anti-HEVE2 total IgG titers with IgG2a, IgG2b and IgG1 subclasses predominant in the serum, approximately 50- to 100-fold higher than those in mice immunized with pHEVE2, whose serum contained predominantly IgG1.


CONCLUSIONS
CTLA4-HEVE2 chimeric vaccine stimulates strong immune responses in mice, making it possible for further exploration into chimeric DNA vaccines that target the antigen to APCs.
Che
Xiao-Yan
XY
Central Laboratory, Zhujiang Hospital, First Military Medical University, Guangzhou 510282, China.
Qian
Qi-Jun
QJ
Liu
Si-Xing
SX
Huang
Jie
J
Qiu
Qing-Lin
QL
Xu
Hua
H
Wu
Wen-Hao
WH
D000818:Animals; D000938:Antigen-Presenting Cells / Q000276:immunology; D019556:COS Cells; D016751:Hepatitis E / Q000517:prevention & control*; D016752:Hepatitis E virus / Q000235:genetics / Q000276:immunology*; D007109:Immunity; D051379:Mice; D008807:Mice, Inbred BALB C; D023421:Models, Animal; D017063:Outcome Assessment, Health Care; D011993:Recombinant Fusion Proteins / Q000276:immunology; D019444:Vaccines, DNA / Q000008:administration & dosage* / Q000276:immunology; D014761:Viral Hepatitis Vaccines / Q000008:administration & dosage* / Q000276:immunology
D011993:Recombinant Fusion Proteins; D019444:Vaccines, DNA; D014761:Viral Hepatitis Vaccines