Induction of neutralizing antibodies against Tityus serrulatus toxins by immunization with a recombinant nontoxic protein.

An immunogenic nontoxic protein (TsNTxP) was purified from the venom of the scorpion Tityus serrulatus (Ts). This peptide is composed of 63 amino acid residues with a high degree of structural homology with the toxins isolated from Ts. The nucleotide sequence of the gene that encodes TsNTxP was obtained and also showed a high degree of similarity with genes encoding Tityus toxins [Guatimosim, S.C.F., Prado, V.F., Diniz, C.R., Chávez-Olórtegui, C.. Kalapothakis, E., 1999. Molecular cloning and genomic analysis of TsNTxP; an immunogenic protein from Tityus serrulatus scorpion venom. Toxicon 37, 507-517]. In the present study the TsNTxP gene was expressed in E. coli BL21DE3 cells as a fusion protein with maltose-binding protein. The recombinant protein (TsNTxPrec) was purified by affinity chromatography and used as an immunogen in rabbits. The antigenic specificity of anti-TsNTxPrec antibodies was compared by an enzyme-linked immunosorbent assay using TsNTxP, TstFG50 (the fraction of Ts venom that represents most of the toxicity of the crude venom) and the crude venom, to coat microtitration plates. Anti-TsNTxPrec antibodies had a comparable high cross-reactivity for all antigens tested. Concentrations of Ts venom equivalent to 20 LD50 were effectively neutralized by 1 ml of the anti-TsNTxPrec serum. This result provides basic data for the use of such recombinant scorpion protein as an immunogen in the development of antivenoms for clinical use.