Intramuscular immunization with a plasmid DNA vaccine encoding prM-E protein from Japanese encephalitis virus: enhanced immunogenicity by co-administration of GM-CSF gene and genetic fusions of prM-E protein and GM-CSF.
OBJECTIVE
To investigate the immune responses elicited by pJME with or without various forms of granulocyte-macrophage colony-stimulating factor (GM-CSF) gene.


METHODS
The changes of the T lymphocyte subsets and the levels of Th cell intracellular cytokines IFN-gamma and IL-4 were evaluated by flow cytometric analysis. The cytotoxic T lymphocyte kill activity was assessed by lactate dehydrogenase activity release test. An 80% plaque reduction neutralization test was performed to titrate the neutralization antibody before and after viral challenge.


RESULTS
We demonstrated that simultaneous administration of pJME plus plasmid-ecoded GM-CSF (pGM-CSF) activated Th1 immune responses similar to those found by injecting pGM-CSF i.m. into mice 3 days before pJME vaccination, and enhancement of Th2 immunity predominated when the pGM-CSF was injected 3 days after pJME vaccination. Furthermore, the immunization with DNA vaccine encoding precursor membrane envelope/GM-CSF fusion protein was more effective in generating immune responses than that induced by immunization with pJME alone or in combination with pGM-CSF.


CONCLUSIONS
These observations support the potential of GM-CSF DNA adjuvant for the Th1/Th2 balance and the enhancement of immune responses by showing that the timing of the administration of pGM-CSF and the application of different forms of GM-CSF gene influence the outcome of the resultant immune responses.
Zhai
Yong-zhen
YZ
Department of Infectious Diseases, Shengjing Hospital of China Medical University, Shenyang, China.
Li
Xi-mei
XM
Zhou
Yan
Y
Ma
Li
L
Feng
Guo-he
GH
D000818:Animals; D003601:Cytotoxicity Tests, Immunologic; D004664:Encephalitis Virus, Japanese / Q000235:genetics / Q000276:immunology*; D005260:Female; D016178:Granulocyte-Macrophage Colony-Stimulating Factor / Q000235:genetics*; D007273:Injections, Intramuscular; D007371:Interferon-gamma / Q000096:biosynthesis; D015847:Interleukin-4 / Q000096:biosynthesis; D008562:Membrane Glycoproteins / Q000235:genetics / Q000276:immunology; D051379:Mice; D008807:Mice, Inbred BALB C; D009500:Neutralization Tests; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000276:immunology; D013601:T-Lymphocytes / Q000276:immunology; D019444:Vaccines, DNA / Q000008:administration & dosage / Q000276:immunology*; D014759:Viral Envelope Proteins / Q000235:genetics / Q000276:immunology; D014764:Viral Proteins / Q000235:genetics / Q000276:immunology*
D008562:Membrane Glycoproteins; D011993:Recombinant Fusion Proteins; D019444:Vaccines, DNA; D014759:Viral Envelope Proteins; D014764:Viral Proteins; C080628:glycoprotein E, Japanese encephalitis virus; D015847:Interleukin-4; D007371:Interferon-gamma; D016178:Granulocyte-Macrophage Colony-Stimulating Factor