The nucleus of my research program is our blood coagulation testing to examine areas of evolutionary convergence and how these novel toxins can be used for drug design and development.
Sites of Coagulotoxin convergence, click here to download the associated paper
This research is facilitated by our core equipment: a Stago STA-R Max coagulation analyzer, a Flouroskan with CAT (calibrated automatic thrombogram) software, 2 TEG5000 thrombelastograph hemostasis analyzers and a Chronolog platelet aggregometer.
Our research into this area has been investigating a wide range of venoms while developing innovative protocols. For example, our recent paper on Echis (saw-scaled venoms) showed that the two African antivenoms were only effective against snakes from restricted ranges. The ICP Echi-Tab antivenom performed well against West African saw-scaled vipers with little cross-reactivity against East African venoms, reflective of only West African venoms being used in the immunising mixture. In contrast the SAVP Echis antivenom is made using both East and West African venoms and while it performed best against the East African saw-scaled vipers, it still neutralised West African venoms, albeit at a lower level than it did against East African and at a considerably lower level than Echi-Tab did against East African venoms. The Indian SII and VINS antivenoms failed against the Indian saw-scaled viper from a range different to the one used for the antivenom production, and failed completely against African saw-scaled vipers. The research highlights an urgent public health issue, as all four antivenoms are being sold in Africa to treat saw-scaled vipers’ bites. In African regions where Indian antivenoms have been used, the death rate increased twenty-fold due to their complete failure.
The protocols we developed in the study on Echis (saw-scaled venoms) challenged the long-used WHO protocols which ascertained efficacy through a prolonged preincubation (>30 minutes) of venom with antivenom prior to lethality challenges in mice. We considered this a biologically unrealistic period of time as venom and antivenom would not be in proximity to each other for so long in the blood stream as this is a dynamic, fast-moving system. In this study, we developed protocols that involved only 2 minute incubation times while also rigorously interrogating the venoms for their dependency upon the biochemical cofactors calcium and phospholipid, as we also did in the study on the tiger-snake clade consisting of Hoplocephalus, Notechis, Paroplocephalus and Tropidechis in addition to other Australian snakes such as brown snakes and the ontogenetic change in the venom and overseas snakes including boomslangs (Dispholidus typus) and twig snakes (Thelatornis mossambicus),
Comparison of the performance of each antivenom against a particular species. Equal volumes from each of the antivenoms was used as they all were of the same 10ml vial size. Thus the potency is relative to a consistent amount of antivenom used by volume not by stated protein content or efficacy claims. The data are thus direct head to head comparisons in this regard. Values are means of the ability to proportionally shift a curve, with the highest effect being ICP against Ghana which shifted the venom cuve of E. occelatus nearly sixty five times over (N=3 with error bars indicating standard deviation). Eca-I = E. carinatus (India), Ecs-P = E. c. sochureki (Pakistan), Ecs-U = E. c. sochureki (UAE), Eco-S = E. coloratus (Saudi Arabia), Ejo-S = E.jogeri (Senegal), Ele-M = E. leucogaster (Mali), Eoc-G = E. ocellatus (Ghana), Eoc-M = E. ocellatus (Mali), Eoc-N = E. ocellatus (Nigeria), Epl-K = E. pyramidum leakeyi (Kenya). Click here to download the associated paper
Ancestral state reconstruction of relative species selectivity for each antivenom where warmer colours represent better antivenom cross-reactivity. Values are normalised N=3 means within an antivenom. Bars indicate 95% confidence intervals for the estimate at each node. Note that due to the high dynamicity of venom evolution the ranges quickly become broad as one moves down the tree. Click here to download the associated paper