[Oral mixed DNA vaccine protects mice from infection of Toxoplasma gondii].
OBJECTIVE
To examine the immune response in BALB/c mice induced by oral mixed Toxoplasma gondii DNA vaccine delivered by live attenuated Salmonella typhimurium.


METHODS
Gene fragments SAG1 and SAG2 were amplified from the genomic DNA of T. gondii RH strain by PCR and were subcloned into pcDNA3.1(+/-) eukaryotic expression vector. The positive recombinant plasmid was transformed into aroA- and aroD-attenuated Salmonella typhimurium BRD509 (BRD509/pSAG1/SAG2). After screened by PCR, restrictive enzyme digestion and sequencing, recombinant Salmonella strain was used to immunize BALB/c mice by i.g. route, three times at 2-week interval. Humoral and cellular responses were assayed using ELISA for determining antibody, IFN-gamma and IL-4. MTT assay was used to detect the proliferation activity of T lymphocytes and the activity of NK killers. FCM was also used to sort the lymphocyte subsets of spleen cells All mice were then infected with highly virulent RH tachyzoites of T. gondii intraperitoneally.


RESULTS
Significant increase of specific IgG level was observed in immunized mice with a titer of 1:100. Proliferation activity of specific NK cells and T lymphocytes was highly enhanced in BRD509/ pSAG1/SAG2 vaccinated mice: the killing activity of NK cells was 85% +/- 7%, the proliferation SI of T lymphocytes was 2.83, which resulted in a 5 days longer survival time than mice in control group after challenge infection.


CONCLUSIONS
The oral mixed DNA vaccine delivered by attenuated Salmonella typhimurium shows an immunoprotection against T. gondii in mice.
Cong
Hua
H
Department of Parasitology, School of Medicine, Shandong University, Jinan 250012, China.
Gu
Qin-Min
QM
Zhou
Huai-Yu
HY
Guo
Lan
L
Yang
Ting-Ting
TT
He
Shen-Yi
SY
Li
Ying
Y
Zhao
Qun-Li
QL
D000284:Administration, Oral; D000818:Animals; D000913:Antibodies, Protozoan / Q000097:blood; D005260:Female; D007074:Immunoglobulin G / Q000097:blood; D051379:Mice; D008807:Mice, Inbred BALB C; D016052:Protozoan Vaccines / Q000008:administration & dosage / Q000276:immunology*; D012486:Salmonella typhimurium / Q000276:immunology*; D013154:Spleen / Q000276:immunology; D014122:Toxoplasma / Q000276:immunology*; D014124:Toxoplasmosis, Animal / Q000517:prevention & control*; D014613:Vaccines, Attenuated / Q000008:administration & dosage / Q000276:immunology; D019444:Vaccines, DNA / Q000008:administration & dosage / Q000276:immunology*
D000913:Antibodies, Protozoan; D007074:Immunoglobulin G; D016052:Protozoan Vaccines; D014613:Vaccines, Attenuated; D019444:Vaccines, DNA