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Comparative proteomics of geographically distinct saw-scaled viper (Echis carinatus) venoms from India.

ABSTRACT: 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.

SUBMITTER: Bhatia S

PROVIDER: S-EPMC7322182 | biostudies-literature | 2020 Sep

REPOSITORIES: biostudies-literature

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Comparative proteomics of geographically distinct saw-scaled viper (<i>Echis carinatus</i>) venoms from India.

Bhatia Siddharth S Vasudevan Karthikeyan K

Toxicon: X 20200623

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 <i>Echis carinatus</i> 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 ...[more]

PMID: 32613195

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Project description:Saw-scaled or carpet vipers (genus Echis) are considered to cause a higher global snakebite mortality than any other snake. Echis carinatus sochureki (ECS) is a widely distributed snake species, also found across the thirteen provinces of Iran, where it is assumed to be responsible for the most snakebite envenomings. Here, we collected the Iranian specimens of ECS from three different geographically distinct populations, investigated food habits, and performed toxicity assessment and venom proteome profiling to better understand saw-scaled viper life. Our results show that the prey items most commonly found in all populations were arthropods, with scorpions from the family Buthidae particularly well represented. LD50 (median lethal dose) values of the crude venom demonstrate highly comparable venom toxicities in mammals. Consistent with this finding, venom characterization via top-down and bottom-up proteomics, applied to both crude venoms and size-exclusion chromatographic fractions, revealed highly comparable venom compositions among the different populations. By combining all proteomics data, we identified 22 protein families from 102 liquid chromatography and tandem mass spectrometry (LC-MS/MS) raw files, including the most abundant snake venom metalloproteinases (SVMPs, 29-34%); phospholipase A2 (PLA2s, 26-31%); snake venom serine proteinases (SVSPs, 11-12%); l-amino acid oxidases (LAOs, 8-11%), C-type lectins/lectin-like (CTLs, 7-9%) protein families, and many newly detected ones, e.g., renin-like aspartic proteases (RLAPs), fibroblast growth factors (FGFs), peptidyl-prolyl cis-trans isomerases (PPIs), and venom vasodilator peptides (VVPs). Furthermore, we identified and characterized methylated, acetylated, and oxidized proteoforms relating to the PLA2 and disintegrin toxin families and the site of their modifications. It thus seems that post-translational modifications (PTMs) of toxins, particularly target lysine residues, may play an essential role in the structural and functional properties of venom proteins and might be able to influence the therapeutic response of antivenoms, to be investigated in future studies.

Project description:BackgroundIn West Africa, envenoming by saw-scaled or carpet vipers (Echis ocellatus) causes great morbidity and mortality, but there is a crisis in supply of effective and affordable antivenom (ISRCTN01257358).MethodsIn a randomised, double-blind, controlled, non-inferiority trial, "EchiTAb Plus-ICP" (ET-Plus) equine antivenom made by Instituto Clodomiro Picado was compared to "EchiTAb G" (ET-G) ovine antivenom made by MicroPharm, which is the standard of care in Nigeria and was developed from the original EchiTAb-Fab introduced in 1998. Both are caprylic acid purified whole IgG antivenoms. ET-G is monospecific for Echis ocellatus antivenom (initial dose 1 vial) and ET-Plus is polyspecific for E. ocellatus, Naja nigricollis and Bitis arietans (initial dose 3 vials). Both had been screened by pre-clinical and preliminary clinical dose-finding and safety studies. Patients who presented with incoagulable blood, indicative of systemic envenoming by E. ocellatus, were recruited in Kaltungo, north-eastern Nigeria. Those eligible and consenting were randomly allocated with equal probability to receive ET-Plus or ET-G. The primary outcome was permanent restoration of blood coagulability 6 hours after the start of treatment, assessed by a simple whole blood clotting test repeated 6, 12, 18, 24 and 48 hr after treatment. Secondary (safety) outcomes were the incidences of anaphylactic, pyrogenic and late serum sickness-type antivenom reactions.FindingsInitial doses permanently restored blood coagulability at 6 hours in 161/194 (83.0%) of ET-Plus and 156/206 (75.7%) of ET-G treated patients (Relative Risk [RR] 1.10 one-sided 95% CI lower limit 1.01; P = 0.05). ET-Plus caused early reactions on more occasions than did ET-G [50/194 (25.8%) and 39/206 (18.9%) respectively RR (1.36 one-sided 95% CI 1.86 upper limit; P = 0.06). These reactions were classified as severe in 21 (10.8%) and 11 (5.3%) of patients, respectively.ConclusionAt these doses, ET-Plus was slightly more effective but ET-G was slightly safer. Both are recommended for treating E. ocellatus envenoming in Nigeria.Trial registrationCurrent Controlled Trials ISRCTN01257358.

Dataset Information

Comparative proteomics of geographically distinct saw-scaled viper (Echis carinatus) venoms from India.

Publications

Comparative proteomics of geographically distinct saw-scaled viper (<i>Echis carinatus</i>) venoms from India.

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