A functional and thromboelastometric-based micromethod for assessing crotoxin anticoagulant activity and antiserum relative potency against Crotalus durissus terrificus venom

Factor XII-Deficient Chicken Plasma as a Useful Target for Screening of Pro- and Anticoagulant Animal Venom Toxins

“…In summary, three clear differences can be observed in our study, when the INTEM profiles of activated CP samples are compared with that of human plasma: (i) The CT parameter values of the control recalcified CP is comparatively greater (mean = 2247 ± 319 s versus 874 ± 230 s); (ii) a statistically significant difference between the minimum and maximal coagulant responses to the activator aPTT clot reagent occur within two orders of magnitude (from 0.6 to 60 µL); and (iii) the bvPLA 2 anticoagulant effect occurs in a dose-dependent manner. This unusual sensitivity of activated and recalcified CP to the bvPLA 2 anticoagulant effect described herein reinforces our previous studies with this pharmacological target [30,31].…”

“…By testing recalcified chicken plasma (CP) samples through rotational thromboelastometry, we recently published two studies in which we describe the abilities of the bothropic and crotalic antiserums in neutralizing the pro-and anticoagulant activities of Bothrops jararaca (B. jararaca) venom and crotoxin, respectively. We found a positive correlation between the data obtained with these in vitro assays and data from the in vivo lethality technique related to the B. jararaca and Crotalus durissus terrificus (C. d. terrificus) venoms [30,31]. Predictably, addition of the cofactors Ca 2+ and phospholipids factor XII-deficient CP elicited a time lapse sufficient for the elaboration of one typical dose-response curve, establishing its sensitivity to these agonists and to antagonists in the nanoscale range.…”

“…This may be due to a variation in the level of factor XII (Hageman factor) present [47]. Although it has a natural factor XII deficiency [22], CP possesses a fully functional extrinsic pathway, and its key coagulant proteins (factors V and X) could be considered as suitable targets or substrates for both procoagulant [30,48,49] and anticoagulant toxins [31] from several animal venoms.…”

“…In conclusion, we propose this functional assay as an alternative for (i) screening assays during the purification of fibrinolytics, pro-or anticoagulant toxins from whole animal venoms, (ii) assessing a specific antivenom's relative potencies against venom toxic components with both coagulant and lethal activities (such as B. jararaca venom [30] or with PLA 2 -like substances, such as those present in the venoms of the C. d. terrificus snake [31] or the A. mellifera bee, and (iii) studies for testing the relative potencies of prototypes of pharmaceutical agents or natural inhibitors of PLA 2 -like toxins from animal venoms in more diluted solutions, thus with less potential to affect the normal coagulation kinetic behavior.…”

Role of crotoxin in coagulation: novel insights into anticoagulant mechanisms and impairment of inflammation-induced coagulation

“…The PT and aPTT assays are two of the most known and prescribed methods for evaluating coagulation abnormalities associated with alterations in the components of the intrinsic (PT), extrinsic (aPTT) and common (PT and aPTT) pathways [28]. Therefore, the results obtained in the present study and in previous reports [12,29] show that CTX inhibits both in the PT and the aPTT clotting assay, indicates that the toxin can act on different pathway components. Several efforts have been made to evaluate coagulation targets for svPLA 2.…”