Cross-reactivity and neutralization of Indian King cobra (Ophiophagus hannah) venom by polyvalent and monovalent antivenoms

Frequency, geographical distribution, clinical characteristics, antivenom utilisation and outcomes of King Cobra (Ophiophagus hannah) bites in Malaysia

Snakebite envenomation remains an important, yet a neglected public health issue in most tropical and subtropical countries. Underdeveloped medical infrastructure, suboptimal medical services, poor documentation and failure to make snake-related injury a mandatory notifiable disease are important contributing factors. The King Cobra (Ophiophagus hannah) is a medically significant species encountered in Malaysia however, there have been few publications from the clinical perspective. The objectives of this study were to determine the frequency of King Cobra related injuries, geographical distribution, clinical presentation, type and frequency of antivenom utilization and the management outcome. This is a cross-sectional study of confirmed King Cobra related injuries consulted to Remote Envenomation Consultation Services (RECS) from 2015 to 2020. Data were extracted from the RECS database and descriptively analyzed. A total of 32 cases of King Cobra bite were identified. Most cases were from Peninsular Malaysia with the most frequent from the state of Pahang (n = 9, 28.1%). Most patients got bitten while attempting to catch or play with the snake (68.8%). Signs and symptoms of envenomation were documented in 24 (75.0%) cases and the most frequent systemic manifestation was ptosis (n = 13, 40.6%). Tracheal intubation and ventilatory support were required in 13 (40.6%) patients. Antivenom was administered to 22 (68.8%) patients with most (25.0%) receiving 10 vials (1 dose). The commonest antivenom used was monospecific King Cobra antivenom (50.0%) from Thai Red Cross. There was one death documented due to complications from necrotizing fasciitis and septicemia. Public awareness of the dangers and proper handling of King Cobras needs to be emphasised. Timely administration of the appropriate antivenom is the definitive treatment and leads to favorable outcomes.

Diosmin: A Daboia russelii venom PLA2s inhibitor- purified, and characterized from Oxalis corniculata L medicinal plant

ETHNOPHARMACOLOGICAL RELEVANCE

Oxalis corniculata L is a medicinal plant that belongs to the Oxalidaceae family. It is a little, slow-growing plant with a frail appearance typically found in mild temperate and tropical areas like Pakistan and India. This plant also includes many other bioactive substances, including alkaloids, flavonoids, terpenoids, cardiac glycosides, saponins, phlobatannins, and steroids.

AIM OF THE STUDY

To investigate the anti-inflammatory effects of Compound diosmin, which is derived from Oxalis corniculata L, on VRV-PL-5 and VRV-PL-8a isolated from Vipera russelli.

MATERIALS AND METHODS

Extraction, purification, and characterization of bioactive by TLC, HPTLC, FT-IR analysis, UV-Vis spectrophotometer, LC-MS/MS Analysis, NMR, XRD Analysis, In vitro evaluation, Circular dichroism spectroscopy, in vivo, and in silico studies.

RESULTS

In this study, the extract of Oxalis corniculata was evaluated for its in vitro and in vivo anti-inflammatory effect against PLA2. The methanolic extract decreased hemolytic activity by about 60% at 1:75 w/w and neutralized the hemolytic activity completely at 1:100 w/w concentration. Diosmin inhibited VRV-PL-5 and VRV-PL-8a in a dose-dependent manner, with the extent of inhibition being about 56% for VRV-PL-5120 μM and VRV-PL-8a by 62% at the same concentration with IC50 concentrations of 87.08 μM for VRV-PL-5 and 82.08 μM for VRV-PL-8a, while at 75 μM. Diosmin inhibited the hemolytic activity of VRV-PL-5 by about 85%, and at the same concentration, VRV-PL-8a inhibited by about 75%. UV-CD spectra at the IC50 concentration of diosmin disrupted the secondary structure of VRV-PL-5 &VRV-PL-8a. In vivo, studies showed decreased myotoxicity and cardiotoxicity of the VRV-PL-5 &VRV-PL-8a, which was seen in the decrease in cytoplasmic markers LDH and CPK levels in the serum when incubated with diosmin. Furthermore, Histopathological studies of Muscles and lungs revealed that diosmin considerably protects against cellular abnormality caused by VRV-PL-5 & VRV-PL-8a. Molecular docking, MM/GBSA, and molecular dynamics simulation studies show that the diosmin is a potent inhibitor for VRV-PL-5 and VRV-PL-8a.

CONCLUSION

This study shows that diosmin is a potentially effective VRV-PL-5 and VRV-PL-8a.

Proteomics and immunocharacterization of Asian mountain pit viper (Ovophis monticola) venom

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.

Prevention and improvement of clinical management of snakebite in Southern Asian countries: A proposed road map

In the Southern Asian countries, snakebite takes a substantial toll in terms of human life, inflicts acute morbidity and long term disability both physical and psychological, and therefore represents a neglected socio-economic problem and severe health issue that requires immediate medical attention. The 'Big Four' venomous snakes, viz. Daboia russelii, Naja naja, Bungarus caeruleus and Echis carinatus, are prominent, medically important species and are the most dangerous snakes of this region; therefore, the commercial polyvalent antivenom (PAV) contains antibodies against the venoms of these snakes. However, envenomations by species other than the 'Big Four' snakes are grossly neglected, and PAV is only partially effective in neutralizing the venom of these snakes. Many issues confounding effective treatment of snakebite are discussed in this review, and these hurdles preventing successful treatment of snakebite must be addressed. However, in South Asian countries, the pre-hospital treatment and appropriate first aid are equally important to mitigate the problem of snakebite and therefore, these issues are also highlighted here. Further, this review suggests a roadmap and guidelines for the prevention of snakebite and improvement of hospital management of snakebite in these Southern Asian countries.

Horse immunization with short-chain consensus α-neurotoxin generates antibodies against broad spectrum of elapid venomous species

Antivenoms are fundamental in the therapy for snakebites. In elapid venoms, there are toxins, e.g. short-chain α-neurotoxins, which are quite abundant, highly toxic, and consequently play a major role in envenomation processes. The core problem is that such α-neurotoxins are weakly immunogenic, and many current elapid antivenoms show low reactivity towards them. We have previously developed a recombinant consensus short-chain α-neurotoxin (ScNtx) based on sequences from the most lethal elapid venoms from America, Africa, Asia, and Oceania. Here we report that an antivenom generated by immunizing horses with ScNtx can successfully neutralize the lethality of pure recombinant and native short-chain α-neurotoxins, as well as whole neurotoxic elapid venoms from diverse genera such as Micrurus, Dendroaspis, Naja, Walterinnesia, Ophiophagus and Hydrophis. These results provide a proof-of-principle for using recombinant proteins with rationally designed consensus sequences as universal immunogens for developing next-generation antivenoms with higher effectiveness and broader neutralizing capacity.

Melatonin inhibits snake venom and antivenom induced oxidative stress and augments treatment efficacy

Snakebite is a neglected health hazard. Its patho-physiology has largely been focused on systemic and local toxicities; whereas, venom and antivenom induced oxidative stress has long been ignored. Antivenom therapy although neutralizes venom lethality and saves many lives, remains ineffective against oxidative stress. This prompted us to complement antivenom with an antioxidant molecule melatonin that would protect against oxidative stress and increase the efficacy of the existing snakebite therapy. Here we show that D. russelli and E. carinatus venoms induce strong oxidative stress that persists even after antivenom administration in mice model. Additionally, antivenoms also induce oxidative stress. Polyvalent antivenom induce more oxidative stress than monovalent antivenom. Strikingly, antivenom and melatonin together not only inhibit venom and antivenom induced oxidative stress but also significantly reduce the neutralizing antivenom dose. This study provides a therapeutic potential for enhancing the existing snakebite therapy. The combined treatment of antivenom+melatonin would prevent the upsurge of oxidative stress as well as minimize the antivenom load. Thus the investigation offers immense scope for physicians and toxinologists to reinvestigate, design new strategies and think beyond the conventional mode of antivenom therapy.