A single-chain antibody fragment specific for the Plasmodium berghei ookinete protein Pbs21 confers transmission blockade in the mosquito midgut

• Published in: Molecular and biochemical parasitology 1999-11, Vol.104 (2), p.195-204
• Main Authors: Yoshida, Shigeto, Matsuoka, Hiroyuki, Luo, Enjie, Iwai, Kuni, Arai, Meiji, Sinden, Robert E., Ishii, Akira
• Format: Article
• Language: English
• Subjects: Amino Acid Sequence; Animals; Anopheles - parasitology; Anopheles stephensi; Antibodies, Monoclonal - genetics; Antibodies, Monoclonal - immunology; Antibodies, Protozoan - genetics; Antibodies, Protozoan - immunology; Antibody Specificity; antigen-antibody reactions; AVH gene; AVL gene; Baculoviridae - genetics; Base Sequence; binding; biological development; Blotting, Western; cloning; Cloning, Molecular; Culicidae; disease transmission; disease vectors; Enzyme-Linked Immunosorbent Assay; genbank/ab028875; genbank/ab028876; Genes, Immunoglobulin; Immunoglobulin Fragments - genetics; Immunoglobulin Fragments - immunology; inhibition; Malaria; Malaria - immunology; Malaria - parasitology; Malaria - prevention & control; membrane proteins; midgut; Molecular Sequence Data; monoclonal antibodies; nucleotide sequences; oocysts; ookinetes; Pbs21; Pbs21 protein; Plasmodium berghei; Plasmodium berghei - growth & development; Plasmodium berghei - immunology; Protozoan Proteins - immunology; refractoriness; scFv gene; Single-chain antibody; Spodoptera; Stomach - parasitology; structural genes; surface antigens; Transmission blocking; transmission blocking antibodies
• ISSN: 0166-6851; 1872-9428
• DOI: 10.1016/S0166-6851(99)00158-9

Mouse monoclonal antibody 13.1 (mAb 13.1) directed against Pbs21, a 21-kDa sexual-stage surface protein of Plasmodium berghei, is known to inhibit oocyst development from gametocytes and ookinetes in the mosquito midgut. To examine the properties and potential uses of a single-chain antibody fragment (scFv) for blocking transmission of malaria parasites to mosquitoes, we have cloned and sequenced the genes encoding variable regions of the immunoglobulin heavy and light chains (V H and V L) of mAb 13.1. The V H and V L genes were assembled as an scFv gene, and expressed in a baculovirus expression system. Following purification of 13.1 scFv, Western blotting and inhibition ELISA assays confirmed that 13.1 scFv retained the binding specificity of the parent mAb 13.1 for Pbs21. Furthermore, 13.1 scFv bound to the surface of P. berghei ookinetes, and blocked oocyst development in the mosquito midgut by at least 93%, as assessed by oocyst counts in mosquitoes. We suggest that the 13.1 scFv gene could be useful not only in studying the mechanism of transmission blockade, but also in generating, by mosquito germline transformation, a model system to evaluate the production of mosquitoes refractory to malaria.