Immunisation with recombinant AMA-1 protects mice against infection with Plasmodium chabaudi.
The Plasmodium merozoite surface antigen apical membrane antigen-1 (AMA-1) has previously been shown to provide partial protection to Saimiri and rhesus monkeys immunised with recombinant Plasmodium fragile or parasite-derived Plasmodium knowlesi AMA-1, respectively. In the study reported here we have used the Plasmodium chabaudi/mouse model system to extend our pre-clinical assessment of an AMA-1 vaccine. We describe here the expression of the full-length Plasmodium chabaudi adami AMA-1 and the P. chabaudi adami AMA-1 ectodomain using both baculovirus and Escherichia coli. The ectodomain expressed in E. coli, which contained an N-terminal hexa-his tag, was purified by Ni-chelate chromatography and refolded in vitro in the presence of oxidised and reduced glutathione to generate intramolecular disulphide bonds. In a series of vaccine trials, in both inbred and outbred mice, highly significant protection was obtained by immunising with the refolded AMA-1 ectodomain. Protection was shown to correlate with antibody response and was dependent on intact disulphide bonds. Passive transfer of antibodies raised in rabbits against the refolded AMA-1 ectodomain was also protective. In view of this demonstration that E. coli expression of a soluble P. chabaudi AMA-1 domain can generate a vaccine that is effective in mice, we are pursuing a similar approach to generating a vaccine against P. falciparum for testing in human volunteers.
Anders
R F
RF
Cooperative Research Centre for Vaccine Technology, Post Office Royal Melbourne Hospital, Vic., Australia.
Crewther
P E
PE
Edwards
S
S
Margetts
M
M
Matthew
M L
ML
Pollock
B
B
Pye
D
D
D000818:Animals; D000913:Antibodies, Protozoan / Q000276:immunology; D000953:Antigens, Protozoan; D008288:Malaria / Q000276:immunology / Q000517:prevention & control*; D017780:Malaria Vaccines / Q000008:administration & dosage*; D008565:Membrane Proteins / Q000008:administration & dosage* / Q000096:biosynthesis; D051379:Mice; D008807:Mice, Inbred BALB C; D008809:Mice, Inbred C3H; D016788:Plasmodium chabaudi / Q000276:immunology*; D015800:Protozoan Proteins / Q000008:administration & dosage* / Q000096:biosynthesis; D011994:Recombinant Proteins / Q000008:administration & dosage
D000913:Antibodies, Protozoan; D000953:Antigens, Protozoan; D017780:Malaria Vaccines; D008565:Membrane Proteins; D015800:Protozoan Proteins; D011994:Recombinant Proteins; C090077:apical membrane antigen I, Plasmodium