In India, polyvalent antivenom is the mainstay treatment for snakebite envenoming. Due to batch-to-batch variation in antivenom production, manufacturers have to estimate its efficacy at each stage ...of IgG purification using the median effective dose which involves 100–120 mice for each batch. There is an urgent need to replace the excessive use of animals in snake antivenom production using in vitro alternatives. We tested the efficacy of a single batch of polyvalent antivenom from VINS bioproducts limited on Echis carinatus venom collected from three different locations—Tamil Nadu (ECVTN), Goa (ECVGO) and Rajasthan (ECVRAJ)—using different in vitro assays. Firstly, size-exclusion chromatography (SEC-HPLC) was used to quantify antivenom–venom complexes to assess the binding efficiency of the antivenom. Secondly, clotting, proteolytic and PLA2 activity assays were performed to quantify the ability of the antivenom to neutralize venom effects. The use of both binding and functional assays allowed us to measure the efficacy of the antivenom, as they represent multiple impacts of snake envenomation. The response from the assays was recorded for different antivenom–venom ratios and the dose–response curves were plotted. Based on the parameters that explained the curves, the efficacy scores (ES) of antivenom were computed. The binding assay revealed that ECVTN had more antivenom–venom complexes formed compared to the other venoms. The capacity of antivenom to neutralize proteolytic and PLA2 effects was lowest against ECVRAJ. The mean efficacy score of antivenom against ECVTN was the greatest, which was expected, as ECVTN is mainly used by antivenom manufacturers. These findings pave a way for the development of in vitro alternatives in antivenom efficacy assessment.
Snakebite is a socio-economic problem in tropical countries and it is exacerbated by geographical venom variation of snakes. We investigated on venom variation in geographically distinct populations ...of Echis carinatus from three ecologically distinct regions: Tamil Nadu (ECVTN), Goa (ECVGO), and Rajasthan (ECVRAJ). Venom was fractionated by RP-HPLC, combined with SDS-PAGE, and subjected to tandem mass spectrometry. Toxins were identified, and their relative abundance was estimated. Using NCBI database of Echis genus, we queried the MS/MS spectra, and found 69, 38 and 38 proteins in ECVTN, ECVGO and ECVRAJ respectively, belonging to 8–10 different toxin families. The differences in the venom profiles were due to change in the relative composition of the toxin families. Snake venom metalloproteinase (svMP), Snaclecs and Phospholipase A2 (PLA2) were the major venom components in all the venoms. Heteromeric Disintegrins were found in ECVTN and absent in other venoms. ECVRAJ showed higher abundance of low-molecular-weight (>30 kDa) proteins than ECVTN and ECVGO. Cysteine-rich venom protein (CRISP) was highest in ECVRAJ (7.34%), followed by ECVTN (0.01%) and in ECVGO, it was not detected. These findings highlight the need for evaluating the efficacy of the polyvalent anti-venom to neutralize the toxins from geographically distinct venoms of E. carinatus.
Display omitted
•Relative abundance of toxin families in E. carinatus venom (ECV) varied in the three regions.•Heteromeric Disintegrins were found only in the ECV from Tamil Nadu.•Proteolytic processing of P-II and P-III svMP varied considerably in the venoms from different regions.•Efficacy of the polyvalent anti-venom on geographically distinct ECVs needs testing.
Snake venoms can exhibit remarkable inter- and intraspecific variation. While diverse ecological and environmental factors are theorised to explain this variation, only a handful of studies have ...attempted to unravel their precise roles. This knowledge gap not only impedes our understanding of venom evolution but may also have dire consequences on snakebite treatment. To address this shortcoming, we investigated the evolutionary ecology of venoms of Russell's viper (Daboia russelii) and spectacled cobra (Naja naja), India's two clinically most important snakes responsible for an alarming number of human deaths and disabilities. Several individuals (n = 226) of D. russelii and N. naja belonging to multiple clutches (n = 9) and their mothers were maintained in captivity to source ontogenetic stage-specific venoms. Using various in vitro and in vivo assays, we assessed the significance of prey, ontogeny and sex in driving venom composition, function, and potency. Considerable ontogenetic shifts in venom profiles were observed in D. russelii, with the venoms of newborns being many times as potent as juveniles and adults against mammalian (2.3-2.5 x) and reptilian (2-10 x) prey. This is the first documentation of the ontogenetic shift in viperine snakes. In stark contrast, N. naja, which shares a biogeographic distribution similar to D. russelii, deployed identical biochemical cocktails across development. Furthermore, the binding kinetics of cobra venom toxins against synthetic target receptors from various prey and predators shed light on the evolutionary arms race. Our findings, therefore, provide fascinating insights into the roles of ecology and life history traits in shaping snake venoms.
Snake envenoming is caused by many biological species, rather than a single infectious agent, each with a multiplicity of toxins in their venom. Hence, developing effective treatments is challenging, ...especially in biodiverse and biogeographically complex countries such as India. The present study represents the first genus-wide proteomics analysis of venom composition across
species (
,
, and
) found in mainland India. Venom proteomes were consistent between individuals from the same localities in terms of the toxin families present, but not in the relative abundance of those in the venom. There appears to be more compositional variation among
from different locations than among
. Immunoblotting and in vitro neutralization assays indicated cross-reactivity with Indian polyvalent antivenom, in which antibodies raised against
are present. However, we observed ineffective neutralization of PLA
activities of
venoms from locations distant from the source of immunizing venoms. Antivenom immunoprofiling by antivenomics revealed differential antigenicity of venoms from
and
, and poor reactivity towards 3FTxs and PLA
s. Moreover, there was considerable variation between antivenoms from different manufacturers. These data indicate that improvements to antivenom manufacturing in India are highly desirable.
A drawing of a plane graph G in which each edge is represented by a sequence of alternating horizontal and vertical line segments is called an orthogonal drawing. The points of intersection of ...horizontal and vertical line segments of an edge in an orthogonal drawing are called bends. The best known algorithm to find a bend-optimal orthogonal drawing of a plane graph takes time O(n1.5) where n is the number of vertices in the graph. In this paper we present a new linear time algorithm to find an orthogonal drawing of a plane 3-connected graph (with maximum degree 4) and give bounds on number of bends (in terms of number k of degree-4 vertices in the graph) in the resulting drawing with respect to the number b(G) of bends in the bend-optimal orthogonal drawing of the same graph. The bound is b(G)+3k.
Clinicians report low efficacy of Indian polyvalent antivenom (PAV), with >20 vials required for treatment of a snakebite envenoming. We hypothesize that the antivenom efficacy could be reduced due ...to insufficient antibodies against some venom toxins. To test this, we used third-generation antivenomics to reveal bound and unbound venom toxins of Echis carinatus venom from Goa (ECVGO) and Tamil Nadu (ECVTN). We used 60, 120, 180, 240, 300, and 360 μg of venom and passed through mini-columns containing ~5 mg Antivenom bound to CNBr beads. The non-retained (unbound) and retained (bound) toxins were identified using reverse-phase HPLC and tandem mass spectrometry. Low molecular weight toxins - Short disintegrins (5.3 kDa) and DIS domain of P-II SVMP from ECVGO and ECVTN showed poor binding with antivenom. The immunorecognition sites of antivenom saturated at the lower antivenom-venom ratio for ECVGO than for ECVTN. The immunoretained capacity of antivenom against ECVTN was 140.6 μg and ECVGO was 125.1 μg. The amount of immunoretained toxins quantified can further be used to estimate the efficacy of antivenom by correlating it with in-vivo studies. The unbound toxins identified from this study could be targeted to improve the effectiveness of antivenom.
Display omitted
•Third-generation antivenomics revealed that low-molecular weight Echis carinatus venom toxins do not bind to antivenom.•Toxin recognition sites in antivenom saturated at low antivenom-venom ratio for the venom from Goa.•There was no difference in the percentage binding yields of venoms from Goa and Tamil Nadu to the antivenom.•The Indian Polyvalent Antivenom had >25% binding yields for majority of the toxin families in the venoms.
Two important metrics used to characterise a graph are its triangle count and clustering coefficient. In this paper, we present methods to approximate these metrics for graphs.
Despite being famous as ‘the king’ of the snake world, the king cobra (Ophiophagus hannah) has remained a mysterious species, particularly with respect to its venom ecology. In contrast, venom ...research has largely focussed on the ‘big four’ snakes that are greatly responsible for the burden of snakebite in the Indian subcontinent. This study aims to bridge the current void in our understanding of the O. hannah venom by investigating its proteomic, biochemical, pharmacological, and toxinological profiles via interdisciplinary approaches. Considering their physical resemblance, the king cobra is often compared to the spectacled cobra (Naja naja). Comparative venomics of O. hannah and N. naja in this study provided interesting insights into their venom compositions, activities, and potencies. Our findings suggest that the O. hannah venom, despite being relatively less complex than the N. naja venom, is equally potent. Finally, our in vitro and in vivo assays revealed that both Indian polyvalent and Thai Red Cross monovalent antivenoms completely fail to neutralise the O. hannah venom. Our findings provide guidelines for the management of bites from this clinically important yet neglected snake species in India.
Maintenance treatment with vedolizumab, a monoclonal antibody that inhibits the gut-selective α4β7 integrin, is administered intravenously. Some patients might prefer a subcutaneous formulation of ...vedolizumab for maintenance treatment. Subcutaneous vedolizumab was investigated as maintenance treatment in patients with moderately to severely active ulcerative colitis.
We performed a phase 3, double-blind, double-dummy trial at 141 sites in 29 countries from December 18, 2015 through August 21, 2018. Patients with moderately to severely active ulcerative colitis received open-label treatment with intravenous vedolizumab 300 mg at weeks 0 and 2. At week 6, patients with clinical response were randomly assigned maintenance treatment with subcutaneous vedolizumab 108 mg every 2 weeks, intravenous vedolizumab 300 mg every 8 weeks, or placebo. The primary end point was clinical remission at week 52, which was defined as a total Mayo score of ≤2 and no subscore >1.
Among the randomized 216 patients, clinical remission at week 52 was achieved by 46.2%, 42.6%, and 14.3% of patients in the subcutaneous vedolizumab, intravenous vedolizumab, and placebo groups, respectively (subcutaneous vedolizumab vs placebo: Δ32.3%; 95% confidence interval, 19.7%–45.0%; P < .001). The subcutaneous vedolizumab group also had greater endoscopic improvement and durable clinical response at week 52 compared with placebo (both P < .001). The incidence of injection-site reactions was more frequent in patients given subcutaneous vedolizumab (10.4%) than intravenous vedolizumab (1.9%) or placebo (0%); these were not treatment limiting, most were mild, and none resulted in discontinuation. Subcutaneous and intravenous vedolizumab safety profiles were otherwise similar.
Subcutaneous vedolizumab is effective as maintenance therapy in patients with moderately to severely active ulcerative colitis who had a clinical response to intravenous vedolizumab induction therapy. It has a favorable safety and tolerability profile. ClinicalTrials.gov ID: NCT02611830; EudraCT 2015-000480-14.
Display omitted
PDF
