[Preliminary study on regulable DNA vaccines against Plasmodium falciparum].
OBJECTIVE
To construct regulable DNA vaccine against Plasmodium falciparum by using tetracycline(Tet) regulable system.


METHODS
Eukaryotic expression vectors pTL-8/apical membrane antigen 1 (AMA-1) (tTA) and pTL-8/AMA-1(rtTA) gene which express trans-activator (tTA) or reverse trans-activator(rtTA), respectively, and AMA-1 gene of Plasmodium falciparum were constructed. BALB/c mice were immunized with these plasmids and doxycycline (dox) was administered to regulate the expression of AMA-1. For some mice immunized with pTL-8/AMA-1(rtTA), pUHS6-1, a plasmid containing trans-silencer (tTS) to suppress basal expression of AMA-1 from pTL-8/AMA-1(rtTA), was injected into these mice together with pTL-8/AMA-1(rtTA). The sera of the mice were isolated at 2,4,6 and 8 weeks post-immunization and the antibodies specific to AMA-1 were measured by ELISA.


RESULTS
pTL-8/AMA-1 and pTL-8/AMA-1(rtTA) were constructed successfully. The mice immunized by pTL-8/AMA-1(tTA) with dox or by pTL-8/AMA-1(rtTA) without dox (at these conditions, AMA-1 was expressed at basal level)developed significant antibodies against AMA-1. Mice immunized by pTL-8/AMA-1(rtTA) and pUHS6-1 without dox did not develop significantly antibodies against AMA-1. In contrast, the mice immunized by pTL-8/AMA-1(rtTA) and pUHS6-1 with dox produced high level of antibodies.


CONCLUSIONS
pTL-8/AMA-1(rtTA) combined with pUHS6-1 is a good regulable DNA vaccine candidate against Plasmodium falciparum.
Lei
Jun-chuan
JC
Department of Pathogenic Biology, Fourth Military Medical University, Xi'an 710032, China. leijunc2002@yahoo.com.cn
Miao
Jun
J
Li
Xun
X
Schonig
Kai
K
Bujard
Hermann
H
Xue
Cai-fang
CF
D000818:Animals; D000913:Antibodies, Protozoan / Q000378:metabolism*; D000953:Antigens, Protozoan / Q000096:biosynthesis* / Q000235:genetics; D004318:Doxycycline / Q000494:pharmacology*; D004926:Escherichia coli / Q000235:genetics; D005260:Female; D005786:Gene Expression Regulation / Q000187:drug effects; D017405:Herpes Simplex Virus Protein Vmw65 / Q000096:biosynthesis / Q000235:genetics; D008565:Membrane Proteins / Q000096:biosynthesis* / Q000235:genetics; D051379:Mice; D008807:Mice, Inbred BALB C; D010957:Plasmids; D010963:Plasmodium falciparum / Q000276:immunology*; D015800:Protozoan Proteins / Q000096:biosynthesis* / Q000235:genetics; D012097:Repressor Proteins / Q000096:biosynthesis* / Q000235:genetics; D037941:Silencer Elements, Transcriptional; D013752:Tetracycline; D014162:Transfection; D019444:Vaccines, DNA
D000913:Antibodies, Protozoan; D000953:Antigens, Protozoan; D017405:Herpes Simplex Virus Protein Vmw65; D008565:Membrane Proteins; D015800:Protozoan Proteins; D012097:Repressor Proteins; D019444:Vaccines, DNA; C090077:apical membrane antigen I, Plasmodium; C034811:tetracycline resistance-encoding transposon repressor protein; D013752:Tetracycline; D004318:Doxycycline