Neuwiedi Venom Research Articles

Coagulopathy after snake bite byBothrops neuwiedi: Case report and results of in vitro experiments

Coagulation studies were performed in a patient who had been bitten by a snake of the species Bothrops neuwiedi. The patient presented with hemorrhagic necrosis at the envenomization site and considerable bleeding from venous puncture sites. He developed a severe defibrination syndrome with a clottable fibrinogen level of approximately 0.1 g/l. Fibrinogen was not measurable by clotting time assay. Fibrin degradation products were greatly elevated. Treatment with antivenom caused an anaphylactic reaction within ten minutes and serum sickness after three days. In vitro experiments revealed that B. neuwiedi venom directly activates Factors II and X, but does not activate Factor XIII. In vivo consumption of Factor XIII after B. neuwiedi envenomization is ascribed to the action of Factor IIa. At low venom concentrations clotting is initiated by activation of prothrombin by the venom either directly or via Factor X activation. Treatment with heparin might be beneficial in coagulopathy secondary to snake bite by reducing circulating active thrombin. The venom contains thrombin-like proteases which cause slow clotting of fibrinogen, and plasmin-like components causing further proteolysis of fibrinogen and fibrin. Antivenom has no effect on the proteolytic action of the snake venom. The in vivo effects of antivenom are presumably caused by acceleration of the elimination of venom components from the circulation. Intravenous administration of antivenom caused normalization of blood coagulation parameters within 48 h.

Characterization of two hemorrhagic factors isolated from the venom of Bothrops neuwiedi (jararaca pintada)

Two hemorrhagic factors were isolated from the venom of Bothrops neuwiedi (jararaca pintada) by ammonium sulfate precipitation followed by chromatography on DEAE-Sephadex A-50 and DEAE-cellulose DE-32, gel filtration on Sephadex G-100 and polyacrylamide-gel electrophoresis. These factors were named neuwiedi hemorrhagic factors NHF a and NHF b. They are acidic proteins of pI 4.2–4.3 and consist of single polypeptide chains of molecular weights 46,000 and 58,000, respectively, as determined by sodium dodecyl sulfate polyacrylamide-gel electrophoresis. The hemorrhagic activity of NHF b is 23 times stronger than that of NHF a. Both hydrolyse casein, although NHF a is about 20 times more active than NHF b. They are metalloproteins inhibited by EDTA and 1,10-phenanthroline. NHF a and NHF b are serologically closely related antigens. These two factors are recognized as identical antigens by horse serum against crude Bothrops neuwiedi venom. However, the rabbit specific antiserum was able to differentiate NHF a from NHF b showing, nevertheless, that they have common determinants apart from specific determinants for each one.