MAPPING ANTIGENIC SITES OF TOXIN VII (g-TOXIN) FROM THE SCORPION Tityus serrulatus  WITH THE USE OF SYNTHETIC  PEPTIDES

NUNES, K. P., ANDREZ, R. M. A., HERMÓGENES, A. L. N., BOHÓRQUEZ, K., GRANIER, C., CHÁVEZ-OLÓRTEGUI, C.

Fundação Ezequiel Dias, Belo Horizonte, MG, Brasil and Institute de Biotechnologia et  Pharmacie, Université de Montpellier, France.

Toxin VII (TsVII), a b-type toxin also known as Ts g is the most potent neurotoxin in the venom of scorpion Tityus serrulatus. The immunization of animals with such toxic substances for the production of antibodies is a difficult  problem. As peptides derived from the sequence of scorpion toxins are nontoxic themselves, but might be immunogenic, the generation of anti-peptides antibodies able to recognize the parent toxin appeared to be an alternative strategy.  With the aim of localising  immunogenic areas, we have measured the ability of anti-TsVII neutralizing antibodies to bind to sets of immobilized synthetic peptides. Twenty four overlapping pentadecapeptides of uniform size, frameshifted by 2 residues, covering the complete amino acid sequences of TsVII were prepared on cellulose membranes according to the protocol previously desribed by Molina et al.,1996 (Peptide Res. 9, 151-155). The results of immunoassay with cellulose-bound peptides demonstrated that one main antigenic region was located in the N-terminal part of TsVII. Anti-TsVII antibodies also cross-reacted with the N-terminal part of Tsll, another b-type toxin and TsIV toxin (Tityus toxin of Diniz), a representative a-type toxin. As residues in the N-terminal region are conserved in scorpion toxins it is probable that residues 1-15 in the protein sequence are the key residues, for antibody recognition and neutralizing properties.

The results obtained in the present study indicate that the Spot synthesis method using the synthetic peptides covalently bound to the cellulose membrane should be used as the technique for the precise localization of  linear functional epitopes.

Supported by: CNPq, INSERM and FAPEMIG. 

CORRESPONDENCE TO:

KêniaPedrosa Nunes, Rua Saulo de Tarso, 121, Belo Horizonte, MG, CEP: 30620080, Brasil, Email: kpnunes@ig.com.br