Specific Antibodies against Recombinant MSP1 of Plasmodium falciparum Strongly Inhibit the Parasite Growth in vitro

ZHANG Dong-Mei², PAN Wei-Qing^1*, LU De-Ru²
( ¹Department of Etiological Biology and ²Institute of Medical Biotechnology & Molecular Genetics of Second Military Medical University, Shanghai 200433,China )

Abstract    In order to produce large amounts of protein for vaccine trials,a synthetic msp1-42 gene was inserted into Pichia pastoris expression vector and the plasmid was introduced into Pichia pastoris SMD1168 by electroporation.The expressed MSP1-42 was secreted into the protein-free medium.To measure the conformational properties of MSP1-42,16 monoclonal antibodies (11 recognizing conformational epitopes) were allowed to interact with the Pichia-derived MSP1-42, and all antibodies specific for conserved and K1 protype interacted with the protein. Interestingly, three monoclonal antibodies (e.g. 9.8, 13.1 and 7.3), that were shown not to interact with CHO-derived MSP1, could interact with the Pichia-derived MSP1-42. Rabbits were immunized with recombinant MSP1-42 formulated with CFA adjuvant four times.The rabbits were bled on the day 3 after last immunization, and total IgG isolated by protein A column from the immunized rabbits was shown to strongly inhibit the parasite growth in vitro dose-dependently, whereas IgG from rabbit with adjuvant had no inhibition.
Key words Plasmodium falciparum; merozoite surface protein 1 (MSP1); Pichia pastoris; in vitro inhibit assay

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