Green pit viper bite is a common public health problem in Southeast Asia. Although most patients experience only local swelling, some may suffer from severe systemic bleeding that can be delayed. Venom antigenaemia was measured by enzyme-linked immunosorbent assay and correlated with clinical findings in 42 patients. Initial venom antigenaemia was not predictive enough for clinical uses. A kinetic study (n = 27) showed highest levels at presentation and, then, progressive decline. The average half-life was 27.5 h during the first three days and over 50 h on days 5-7 after bite. Two small subsets (7.4% each) showed persistently detectable venom on day 14 and a subsequent rise in venom antigenaemia. They were associated with prolonged thrombocytopaenia and coagulopathy, respectively. These data demonstrated the long half-life of the venom, suggesting that waiting for spontaneous resolution of coagulopathy is not preferable. In addition, the delayed venom disappearance, not the initial values, was correlated with haemostatic disorders.
Although systemic administration of antivenom can promptly reverse coagulopathy, efficacy on local effects of viper venom remains to be determined. Currently, there has been no proven specific treatment for snakebite patients with severe local effects. This study is a randomized, double-blind, placebo-controlled trial. Patients bitten by green pit vipers (Trimeresurus albolabris or T. macrops) with marked limb swelling, but no severe coagulopathy requiring antivenom, were randomized to receive either equine F(ab')2 antivenom, or placebo. Twenty-eight cases were included, 14 in each group, and they had their limb circumferences measured on days 1, 2, 4 and 6 after interventions. The percentage reduction in limb circumference was significantly better in the antivenom group compared with the placebo group (ANOVA, P = 0.03), especially in the first 24 h (1.14 vs. 3.62%, in placebo and antivenom group, respectively, P = 0.014). The reduction in pain score was similar. The plasma venom levels were not different at presentation but lower in the antivenom group 24h after intervention (P = 0.033). These data suggest that intravenous antivenom could accelerate local oedema resolution in humans. However, the degree is not clinically significant, and, therefore, general use is not recommended.
The two venomous pit vipers, Trimeresurus macrops and T. hageni, are distributed throughout Thailand, although their abundance varies among different areas. No species-specific antivenom is available for their bite victims, and the only recorded treatment method is a horse antivenom raised against T. albolabris crude venom. To facilitate assessment of the cross-reactivity of heterologous antivenoms, protein profiles of T. macrops and T. hageni venoms were explored using mass-spectrometry-based proteomics. The results show that 185 and 216 proteins were identified from T. macrops and T. hageni venoms, respectively. Two major protein components in T. macrops and T. hageni venoms were snake venom serine protease and metalloproteinase. The toxicity of the venoms on human monocytes and skin fibroblasts was analyzed, and both showed a greater cytotoxic effect on fibroblasts than monocytic cells, with toxicity occurring in a dose-dependent rather than a time-dependent manner. Exploring the protein composition of snake venom leads to a better understanding of the envenoming of prey. Moreover, knowledge of pit viper venomics facilitates the selection of the optimum heterologous antivenoms for treating bite victims.
The ability of monovalent IgG and F(ab')2 antivenoms to neutralize lethality, phospholipase A2, and coagulant activities induced by Daboia siamensis venom was studied. Both antivenoms were produced from the same batch of hyperimmune horse plasma and were adjusted to the same potency against the lethal effect of D. siamensis venom in experiments involving preincubation of venom and antivenom. Intact neutralization experiments involving independent injection of venom and antivenoms showed that the F(ab')2 antivenom was slightly more effective. Significant differences in favour of F(ab')2 antivenom were observed with respect to neutralization of phospholipase A2 and coagulant activities. Both IgG and F(ab')2 antivenoms were able to activate human complement in vitro. IgG antivenom had a significantly higher anticomplementary activity than F(ab')2 antivenom.
This study evaluates the in vitro anti-snake venom potential of Peristrophe bivalvis (PB) extracts against Naja kaouthia (NK) and Trimeresurus albolabris (TA) venoms, including inhibition of cytotoxic effects and enzymatic activities, and the binding-precipitation of extracts and venom proteins analysis. In addition, the antioxidant, cytotoxic and in vivo acute oral toxic activities of PB extracts are also reported. The in vitro cytotoxic and enzymatic analysis reveals that the ethanol extracts of stems and leaves of PB showed good anti-snake venom activity against NK and TA venoms. In addition, the antioxidant result indicated that only the ethanol extract of leaves exhibited weak DPPH radical-scavenging activity. The ethanol whole-plant extract of PB also showed no cytotoxicity against four cell lines. Moreover, the in vivo acute oral toxicity result of the ethanol whole-plant extract showed that all treated rats did not exhibit abnormal toxic signs or deaths.
The venomic profile of Asian mountain pit viper Ovophis monticola is clarified in the present study. Using mass spectrometry-based proteomics, 247 different proteins were identified in crude venom of O. monticola found in Thailand. The most abundant proteins were snake venom metalloproteases (SVMP) (36.8%), snake venom serine proteases (SVSP) (31.1%), and phospholipases A2 (PLA2) (12.1%). Less abundant proteins included L-amino acid oxidase (LAAO) (5.7%), venom nerve growth factor (3.6%), nucleic acid degrading enzymes (3.2%), C-type lectins (CTL) (1.6%), cysteine-rich secretory proteins (CRISP) (1.2%) and disintegrin (1.2%). The immunoreactivity of this viper’s venom to a monovalent antivenom against green pit viper Trimeresurus albolabris, or to a polyvalent antivenom against hemotoxic venom was investigated by indirect ELISA and two-dimensional (2D) immunoblotting. Polyvalent antivenom showed substantially greater reactivity levels than monovalent antivenom. A titer for the monovalent antivenom was over 1:1.28x107 dilution while that of polyvalent antivenom was 1:5.12x107. Of a total of 89 spots comprising 173 proteins, 40 spots of predominantly SVMP, SVSP and PLA2 were specific antigens for antivenoms. The 49 unrecognized spots containing 72 proteins were characterized as non-reactive proteins, and included certain types of CTLs and CRISPs. These neglected venom constituents could limit the effectiveness of antivenom-based therapy currently available for victims of pit viper envenomation.
Because of the high incidence of Pseudomonas aeruginosa biofilms-related nosocomial infections, venoms from common Thai snakes were tested. Although venoms from king cobra (Ophiophagus hannah; OH) and green pit viper (Trimeresurus albolabris) showed the broadest antibacterial spectrum, OH venom demonstrated more profound anti-biofilm activities against P. aeruginosa. Additionally, purified l-amino acid oxidase from OH venom (OH-LAAO), using a three-step chromatography and protein identification, reduced biofilm mass as indicated by the downregulation of several genes, including the genes for biofilm synthesis (algD and pslB) and biofilm regulators (algU, gacA, and siaD). Moreover, OH-LAAO disrupted Pseudomonas-preformed biofilms via upregulation of several genes for biofilm dispersion (nbdA, bdlA, and dipA) and biofilm degradation (endA and pslG), resulting in a reduction of the biofilm biomass. Due to the antimicrobial effects and anti-biofilm activities (reduced production plus increased dispersion) neutralized by catalase, a hydrogen peroxide (H2O2)-degrading enzyme, the enhanced H2O2 by OH venom might be one of the anti-biofilm mechanisms. Hence, OH-LAAO was proposed as a novel agent against Pseudomonas biofilms for either treatment or prevention. More studies are interesting.
The ability of Russell's viper ( Daboia siamensis ) venom (total RVV) and phospholipase A 2 (purified PLA 2 ) to induce the local pathological effects were investigated by the local inflammatory events and the release of inflammatory mediators. Both 0.5 μg of total RVV/mouse and 0.15 μg of purified PLA 2 /mouse were administered via intra-peritoneal injection. After 30 min, 1 h, 2 h, and 4 h incubation time, the peritoneal cavity was flooded with normal saline and the total leukocytes were collected. The eicosanoids (lipid mediators) and the leukocyte expression of cyclooxygenase (COX-1 and COX-2) were investigated by ELISA assay and western blotting, respectively. The amounts of total leukocytes were increased from 30 min to 2 h, then decreased at 4 h, by both total RVV and purified PLA 2 . Both treatments also induced the expression of COX-2 which was increased at 2 h and then decreased at 4 h, whereas only purified PLA 2 induced the expression level of a COX-1 protein which was increased at 30 min, then constantly expressed until 4 h. In addition, total RVV and purified PLA 2 caused the release of the eicosanoids; PGE 2 , TXB 2 , and LTB 4 , which reached the peak after 2 h. The findings of this study indicate that purified PLA 2 has the potential effects to induce the local inflammation relating the amounts of leukocytes cells, lipid mediators and COX-2 more than the total RVV.
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