IDENTIFICATION AND NEUTRALIZATION OF BIOLOGICAL-ACTIVITIES IN THE VENOMS OF LOXOSCELES SPIDERS

The biological activities of the venom of three species of spiders of the genus Loxosceles were studied (L. gaucho, L. laeta and L. intermed ia). The dermonecrotic and lethal activities are shared by all three L oxosceles venoms. Only low levels of proteolytic, myotoxic and phospho lipase A(2) activities were demonstrable even when a large amount of v enom was used. No direct hemolytic activitiy was detected. L. intermed ia venom was the most lethal (LD(50) 0.48 mg/kg), the L. laeta venom w as the least lethal (LD(50) 1.45 mg/kg) whereas L. gaucho venom showed an intermediate value (LD(50) 0.74 mg/kg). The anti-Loxosceles serum used (anti-arachnidic serum) was able to neutralize the most important activities (i.e., dermonecrotic and lethal activities) of the three v enoms. SDS-PAGE and immunoblotting using the anti-arachnidic serum sho wed that almost all venom antigens were recognized by this antiserum. The possible mechanisms of action of the Loxosceles venom are discusse d.