title: Construction of a human functional single-chain variable fragment (scFv) antibody recognizing the malaria parasite Plasmodium falciparum.
abstract: Falciparum malaria is one of the most deadly and profound human health problems around the tropical world. Antimalarial drugs are now considered to be a powerful treatment; however, there are drugs currently being used that are resistant to Plasmodium falciparum parasites spreading in different parts of the world. Although the protective immune response against intraerythrocytic stages of the falciparum malaria parasite is still not fully understood, immune antibodies have been shown to be associated with reduced parasite prevalence. Therefore antibodies of the right specificity present in adequate concentrations and affinity are reasonably effective in providing protection. In the present study, VH (variable domain of heavy chain) and VL (variable domain of light chain) were isolated from human blood lymphocytes of P. falciparum in one person who had high serum titre to RESA (ring-infected erythrocyte surface antigen). Equal amounts of VH and VL were assembled together with universal linker (G4S)3 to generate scFvs (single-chain variable fragments). The scFv antibodies were expressed with a phage system for the selection process. Exclusively, an expressed scFv against asynchronous culture of P. falciparum-infected erythrocytes was selected and characterized. Sequence analysis of selected scFv revealed that this clone could be classified into a VH family-derived germline gene (VH1) and Vkappa family segment (Vkappa1). Using an indirect immunofluorescence assay, we could show that soluble expressed scFv reacted with falciparum-infected erythrocytes. The results encourage the further study of scFvs for development as a potential immunotherapeutic agent.
authors.affiliation: Department of Biochemistry, Faculty of Science, Mahidol University, Rama VI Rd, Bangkok 10400, Thailand.
authors.forename: Sumet
authors.initials: S
authors.lastname: Wajanarogana
authors.forename: Teerawat
authors.initials: T
authors.lastname: Prasomrothanakul
authors.forename: Rachanee
authors.initials: R
authors.lastname: Udomsangpetch
authors.forename: Sumalee
authors.initials: S
authors.lastname: Tungpradabkul
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D017931:DNA Primers; D004912:Erythrocytes / Q000469:parasitology; D019084:Fluorescent Antibody Technique, Indirect; D006801:Humans; D007128:Immunoglobulin Fragments / Q000737:chemistry / Q000235:genetics / Q000276:immunology*; D008214:Lymphocytes / Q000276:immunology; D008969:Molecular Sequence Data; D010963:Plasmodium falciparum / Q000276:immunology*; D017386:Sequence Homology, Amino Acid
chemical_list: D017931:DNA Primers; D007128:Immunoglobulin Fragments