Neutralization of venoms from two Southern Pacific Rattlesnakes ( Crotalus helleri) with commercial antivenoms and endothermic animal sera

• Published in: Toxicon (Oxford) 2004-06, Vol.43 (7), p.791-799
• Main Authors: Galan, JA, Sanchez, EE, Rodriguez-Acosta, A, Perez, J
• Format: Article
• Language: English
• Subjects: Animal poisons toxicology. Antivenoms; Animals; Antivenins - pharmacology; Antivenom; Biological and medical sciences; California; Chromatography, Ion Exchange; Chromogenic Compounds - metabolism; Crotalid Venoms - antagonists & inhibitors; Crotalus; Crotalus helleri; Electrophoresis; Fibrinogen - metabolism; Gelatinases - metabolism; Hemorrhage - chemically induced; Immunoglobulin Fab Fragments - pharmacology; Immunoglobulin Fragments - pharmacology; Insulin - metabolism; Lethal Dose 50; Medical sciences; Natural resistance; Neutralization Tests; Organic Chemicals; Platelet Aggregation; Rodentia - blood; Serum - metabolism; Toxicology; Venom
• ISSN: 0041-0101; 1879-3150
• DOI: 10.1016/j.toxicon.2004.03.009

The Southern Pacific Rattlesnake ( Crotalus helleri) is found in southwestern California (USA), southward through north Baja California (MX) into the northern part of southern Baja California (MX). In this study, the venoms from two Southern Pacific Rattlesnakes were characterized. The two venoms were different in color, concentration, and enzyme activities. Two commercial antivenoms neutralized both C. helleri venoms differently. Antivipmyn (Fab 2H) and CroFab (FabO) neutralized both venoms but had different ED 50. Four times more Fab 2H antivenom was required to neutralize the C. helleri venom No. 011-084-009 than the venom from the snake No. 010-367-284. The hemorrhagic activity of two C. helleri venoms were neutralized differently by endothermic animal sera having a natural resistance to hemorrhagic activity of snake venoms. Opossums and Mexican ground squirrel sera did not neutralize the hemorrhagic activity of the venom No. 010-367-284. The sera of gray woodrats and hispid cotton rats neutralized all hemorrhagins in both C. helleri venoms. This is the first reported case in which opossum serum has not neutralized hemorrhagic activity of pit viper venom. Differences in the compositions of C. helleri venoms and their ability to be neutralized may help explain why snakebites are a difficult medical problem to treat and why effective polyvalent antivenoms are difficult to produce.