In vivo expression and immunological studies of the 42-kilodalton carboxyl-terminal processing fragment of Plasmodium falciparum merozoite surface protein 1 in the baculovirus-silkworm system.
The 42-kDa carboxyl-terminal processing fragment of Plasmodium falciparum merozoite surface protein 1 (MSP-1(42)) is an anti-erythrocytic stage malaria vaccine candidate. In this study, MSP-1(42) was expressed by using the Bombyx mori nuclear polyhedrosis virus-silkworm expression system, and the antigenicity and immmunogenicity of the recombinant protein, Bmp42, were evaluated. The average yield of Bmp42, as determined by a sandwich enzyme-linked immunosorbent assay (ELISA), was 379 microg/ml of infected silkworm hemolymph, which was >100-fold higher than the level attainable in cell culture medium. N-terminal amino acid sequencing revealed that Bmp42 was correctly processed in silkworm cells. Data from immunoblotting, as well as from the inhibition ELISA, suggested that the conformational B-cell epitopes of MSP-1(42) were recreated in Bmp42. Immunization of rabbits with Bmp42 in complete Freund's adjuvant generated high-titer antibody responses against the immunogen. Specificity analyses of the anti-Bmp42 antibodies using several recombinant MSP-1(19) proteins expressing variant and conserved B-cell epitopes suggested that the anti-Bmp42 antibodies recognized primarily conserved epitopes on MSP-1(19). Furthermore, the anti-Bmp42 antibodies were highly effective in inhibiting the in vitro growth of parasites carrying homologous or heterologous MSP-1(42). Our results demonstrated that the baculovirus-silkworm expression system could be employed to express biologically and immunologically active recombinant MSP-1(42) at elevated levels; thus, it is an attractive alternative for producing a protective MSP-1(42) vaccine for human use.
Pang
Alan L Y
AL
Department of Biochemistry, Chinese University of Hong Kong, Shatin, Hong Kong.
Hashimoto
Caryn N
CN
Tam
Leslie Q
LQ
Meng
Z Q
ZQ
Hui
George S N
GS
Ho
Walter K K
WK
D000818:Animals; D000913:Antibodies, Protozoan / Q000276:immunology; D000953:Antigens, Protozoan / Q000235:genetics / Q000276:immunology; D012831:Bombyx; D002460:Cell Line; D015870:Gene Expression; D005822:Genetic Vectors; D007814:Larva; D020066:Merozoite Surface Protein 1 / Q000235:genetics* / Q000276:immunology; D017924:Nucleopolyhedroviruses; D010446:Peptide Fragments / Q000235:genetics / Q000276:immunology; D010963:Plasmodium falciparum / Q000235:genetics* / Q000276:immunology; D011499:Protein Processing, Post-Translational; D011817:Rabbits; D020539:Sequence Analysis, Protein; D014614:Vaccines, Synthetic / Q000276:immunology
D000913:Antibodies, Protozoan; D000953:Antigens, Protozoan; D020066:Merozoite Surface Protein 1; D010446:Peptide Fragments; D014614:Vaccines, Synthetic