| dc.description.abstract | Knowledge on toxin immunogenicity at the molecular level can provide valuable information
for the improvement of antivenoms, as well as for understanding toxin structure–
function relationships. The aims of this study are two-fold: first, to identify the linear
B-cell epitopes of myotoxin II from Bothrops asper snake venom, a Lys49 phospholipase A2
homologue; and second, to use antibodies specifically directed against an epitope having
functional relevance in its toxicity, to probe the dimeric assembly mode of this protein in
solution. Linear B-cell epitopes were identified using a library of overlapping synthetic
peptides spanning its complete sequence. Epitopes recognized by a rabbit antiserum to
purified myotoxin II, and by three batches of a polyvalent (Crotalidae) therapeutic antivenom
(prepared in horses immunized with a mixture of B. asper, Crotalus simus, and
Lachesis stenophrys venoms) were mapped using an enzyme-immunoassay based on the
capture of biotinylated peptides by immobilized streptavidin. Some of the epitopes
identified were shared between the two species, whereas others were unique. Differences
in epitope recognition were observed not only between the two species, but also
within the three batches of equine antivenom. Epitope V, located at the C-terminal region
of this protein, is known to be relevant for toxicity and neutralization. Affinity-purified
rabbit antibodies specific for this site were able to immunoprecipitate myotoxin II, suggesting
that the two copies of epitope V are simultaneously available to antibody binding,
which would be compatible with the mode of dimerization known as “conventional”
dimer. | |
