A. Borges et al., Antibodies against Tityus discrepans venom do not abolish the effect of Tityus serrulatus venom on the rat sodium and potassium channels, TOXICON, 37(6), 1999, pp. 867-881
Anti-(Tityus serrulatus + Tityus bahiensis) and anti-Tityus discrepans veno
m polyclonal antisera were used to investigate whether antigenic difference
s exist between the venoms of the Brazilian T. serrulatus and the Venezuela
n T. discrepans scorpions. Both antisera recognised the toxin-containing el
ectrophoretic fractions of their cognate venoms and also those from Tityus
zulianus and Tityus trinitatis venoms on Western blots. The anti-T. discrep
ans antiserum reacted only weakly with T. serrulatus toxic polypeptides. Th
e effect of T. serrulatus alpha- or beta-toxins on rat skeletal muscle Nachannels expressed in Xenopus laevis oocytes was abolished by pre-incubatin
g the venom with anti-(T. serrulatus + T. bahiensis) serum but not with ant
i-T. discrepans serum. Nor did the Brazilian or the Venezuelan sera prevent
the reduction in K+ currents by T. serrulatus venom in X. laevis oocytes e
xpressing the rat brain delayed rectifying Shaker K+ channel (Kv1.2). These
results indicate that toxins from T. serrulatus and T. discrepans venoms,
which primarily target mammalian Na+ channels, are antigenically distinct,
although they probably share common epitopes. Our results also suggest that
Na+ channel-active toxins are the immunodominant antigens of the T. serrul
atus venom. (C) 1999 Elsevier Science Ltd. All rights reserved.