BIOLOGICAL AND BIOCHEMICAL-PROPERTIES OF VENOMS FROM MEDICALLY IMPORTANT LOXOSCELES (ARANEAE) SPECIES IN BRAZIL

1. The biological, immunochemical and biochemical properties of venoms from Loxosceles gaucho, L. laeta and L. intermedia were studied. 2. V enom from Loxosceles sp causes typical dermonecrotic lesion in bitten patients and rabbits but not in mice. 3. The dermonecrotic and lethal activities of the L. gaucho venom were located in its higher mel. wt c omponents (33.000-35.000). 4. The higher molecular component of the ve nom is the most immunogenic component in both patients and rabbits. 5. Analysis by SDS-PAGE showed the existence of many common components i n the three venoms but no individual antigen was found. 6. Antiserum t o each one of these venoms was able to neutralize the dermonecrotic an d lethal activities of all three venoms. 7. Venom from L, gaucho has a significant adjuvant effect that was associated with its higher mel. wt components. 8. The amino terminal sequence of 35 residues of L. gau cho active component was determined. A high level of identity (60%) an d similarity (86%) was found between the L. gaucho toxic protein and a fragment of L. reclusa venom toxic protein suggesting that they are h omologous proteins.