Construction of a recombinant plasmid harbouring the rhoptry protein 1 gene of Toxoplasma gondii and preliminary observations on DNA immunity.
OBJECTIVE
To observe the immune responses elicited in BALB/c mice by a DNA vaccine. A gene encoding rhoptry protein 1 (ROP1) from Toxoplasma gondii (T. gondii) was cloned into vector pcDNA3.


METHODS
Amplifyied gene fragments coding for ROP1 from the genomic DNA of T. gondii ZS2 were inserted into cloning vector, pUC18, and sub-cloned into pcDNA3. Mice were injected at a dosage of 100 micrograms recombinant plasmid DNA by intramuscular injection and boosted after 2 weeks. pcDNA3 and normal saline were used as control. 30, 50 and 70 days after the second immunization, NK cell activity, T lymphocyte proliferation and sub-clusters and serum IgG antibody were assayed.


RESULTS
The specific gene fragment coding for ROP1 was amplified and a pcROP1 recombinant was constructed. At 30 days after immunization, the spleens of the mice were obviously enlarged evidently. NKC activity and the proliferation of spleen T lymphocytes seen on MTT assay were higher in pcROP1 group than in the controls. The number of CD4+ T cells exhibited no obvious increase compared with that of the control, but CD8+ T cells were obviously increased (P < 0.05). At 90 days after vaccination, the titer of IgG antibody in the serum of vaccinated mice was positive (1:100).


CONCLUSIONS
pcROP1 was constructed and it could elicit both cellular and humoral immune responses in immunized mice.
Chen
G
G
Institute of Parasitology, Sun Yat-sen University of Medical Sciences, Guangzhou 510089, China.
Guo
H
H
Lu
F
F
Zheng
H
H
D000818:Animals; D016054:DNA, Protozoan / Q000276:immunology*; D004274:DNA, Recombinant / Q000235:genetics; D005822:Genetic Vectors; D008565:Membrane Proteins / Q000235:genetics*; D051379:Mice; D008807:Mice, Inbred BALB C; D010957:Plasmids / Q000235:genetics*; D014122:Toxoplasma / Q000235:genetics*; D014611:Vaccination; D019444:Vaccines, DNA / Q000276:immunology*
D016054:DNA, Protozoan; D004274:DNA, Recombinant; D008565:Membrane Proteins; C117001:ROP 1 protein, Toxoplasma gondii; D019444:Vaccines, DNA