A comparative study was performed on the
venoms of the crotaline snake Atropoides nummifer from Guatemala and Honduras. SDS-
polyacrylamide gel electrophoresis, under reducing conditions, revealed a highly similar pattern of these
venoms, and between them and the
venom of the same species from Costa Rica. Similar patterns were also observed in ion-exchange chromatography on CM-Shephadex C-25, in which a highly basic myotoxic fraction was present. This fraction was devoid of
phospholipase A(2) activity and strongly reacted, by
enzyme-immunoassay, with an antiserum against
Bothrops asper myotoxin II, a Lys-49
phospholipase A(2) homologue. A basic
myotoxin of 16 kDa was isolated to homogeneity from the
venom of A. nummifer from Honduras, showing
amino acid composition and N-terminal sequence similar to those of Lys-49
phospholipase A(2) variants previously isolated from other crotaline
snake venoms. Guatemalan and Honduran A. nummifer
venoms have a qualitatively similar toxicological profile, characterized by: lethal; hemorrhagic; myotoxic;
edema-forming;
coagulant; and defibrinating activities, although there were significant quantitative variations in some of these activities between the two
venoms. Neutralization of toxic activities by two commercially-available
antivenoms in the region was studied. Polyvalent
antivenom produced by Instituto Clodomiro Picado was effective in the neutralization of: lethal; hemorrhagic; myotoxic;
coagulant; defibrinating; and
phospholipase A(2) activities, but ineffective against
edema-forming activity. On the other hand, MYN polyvalent
antivenom neutralized: hemorrhagic; myotoxic;
coagulant; defibrinating; and
phospholipase A(2) activities, albeit with a lower potency than Instituto Clodomiro Picado
antivenom. MYN
antivenom failed to neutralize lethal and
edema-forming activities of A. nummifer
venoms.