Protective immune response in BALB/c mice induced by a suicidal DNA vaccine of the MIC3 gene of Toxoplasma gondii.
To evaluate the protective efficiency of a suicidal DNA vaccine against protozoal parasite Toxoplasma gondii, the microneme protein 3 (MIC3) gene was cloned into suicidal vector pSCA1 and conventional DNA vaccine vector pcDNA3.1+ respectively, their protection against T. gondii challenge were assessed in this study. The recombinant plasmids named pSCA/MIC3 and pcDNA/MIC3 were transfected into BHK-21 cells. The expression of MIC3 in BHK-21 cells was confirmed by RT-PCR and indirect immunofluorescence test. Then BALB/c mice were immunized with pSCA/MIC3 or pcDNA/MIC3. Anti-Tg-MIC3 antibodies were detected by indirect ELISA and the cell immune response were examined by lymphocyte proliferation assay and real time RT-PCR. The results showed that the titre of anti-Tg-MIC3 antibodies, stimulation index (SI) of lymphocyte proliferation response and IFN-gamma expression level induced by pSCA/MIC3 and pcDNA/MIC3 were significantly higher than controls (P<0.05), whereas IL-4 expression level in BALB/c mice immunized with either pSCA/MIC3 or pcDNA/MIC3 was lower than that in control group. After a lethal challenge against T. gondii, survival time of the mice immunized with this suicidal DNA vaccine pSCA/MIC3 and conventional DNA vaccine pcDNA/MIC3 were significantly prolonged in comparison with the control groups (P<0.05), but the difference of protective immune response in BALB/c mice between pSCA/MIC3 and pcDNA/MIC3 was not statistically significant (P>0.05). The findings demonstrated that like conventional DNA vaccine pcDNA/MIC3, suicidal DNA vaccine pSCA/MIC3 also provided favourable efficacy, but it could improve the biosafety of conventional vaccines. This result suggested that suicidal DNA vaccine pSCA/MIC3 is a potential candidate vaccine against toxoplasmosis.
Fang
Rui
R
State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan 430070, Hubei, PR China.
Nie
Hao
H
Wang
Zhengsong
Z
Tu
Pan
P
Zhou
Danna
D
Wang
Lixia
L
He
Lan
L
Zhou
Yanqin
Y
Zhao
Junlong
J
D000818:Animals; D017125:Genes, Protozoan; D051379:Mice; D008807:Mice, Inbred BALB C; D015800:Protozoan Proteins / Q000276:immunology*; D016052:Protozoan Vaccines / Q000276:immunology*; D014122:Toxoplasma / Q000235:genetics* / Q000472:pathogenicity; D014124:Toxoplasmosis, Animal / Q000517:prevention & control*; D019444:Vaccines, DNA / Q000276:immunology*; D014774:Virulence
C421382:MIC3 protein, Toxoplasma gondii; D015800:Protozoan Proteins; D016052:Protozoan Vaccines; D019444:Vaccines, DNA