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Cross reactivity and lethality neutralization of venoms of Indonesian Trimeresurus complex species by Thai Green Pit Viper Antivenom

Tan CH, Liew JL, Tan NH, Ismail AK, Maharani T, Khomvilai S, et al.

Toxicon, 2017 Dec 15;140:32-37.
PMID: 29051104 DOI: 10.1016/j.toxicon.2017.10.014

Arboreal pit vipers of the Trimeresurus complex group are medically important species in Indonesia (west of Wallace's line), but there is no specific antivenom produced in the country for treating related envenomation. Instead, the exiting trivalent Indonesian antivenom, Biosave® Serum Anti Bisa Ular (SABU, indicated for envenoming by Malayan pit viper, Javan spitting cobra and banded krait) is often misused to treat Trimeresus envenoming resulting in poor therapeutic outcome. Here, we investigated the cross-reactivity and neutralization capability of Thai Green Pit Viper Antivenom (GPVAV) against the venoms of four Indonesian Trimeresurus species. Consistently, the venoms of Trimeresurus (Trimeresurus) insularis, Trimeresurus (Trimeresurus) purpureomaculatus, Trimeresurus (Parias) hageni and Trimeresurus (Craspedocephalus) puniceus of Indonesia showed stronger immunoreactivity on ELISA to GPVAV than to Biosave®. The findings correlated with in vivo neutralization results, whereby GPVAV was far more effective than Biosave® in cross-neutralizing the lethality of the venoms by a potency of at least 13 to 80 times higher. The efficacy of GPVAV is partly attributable to its cross-neutralization of the procoagulant effect of the venoms, thereby mitigating the progression of venom-induced consumptive coagulopathy. The paraspecific effectiveness of GPVAV against Trimeresurus species envenoming in Indonesia await further clinical investigation.
Characterizing and applying immunoglobulins in snakebite diagnostics: A simple and rapid venom detection assay for four medically important snake species in Southeast Asia

Lee LP, Tan CH, Khomvilai S, Sitprija V, Chaiyabutr N, Tan KY

Int J Biol Macromol, 2023 May 01;236:123727.
PMID: 36863668 DOI: 10.1016/j.ijbiomac.2023.123727

Snakebite envenoming is a medical emergency requiring urgent and specific treatment. Unfortunately, snakebite diagnostics are scarce, time-consuming and lacking specificity. Hence, this study aimed to develop a simple, quick and specific snakebite diagnostic assay using animal antibodies. Anti-venom horse immunoglobulin G (IgG) and chicken immunoglobulin Y (IgY) were produced against the venoms of four major medically important snake species in Southeast Asia, i.e., the Monocled Cobra (Naja kaouthia), Malayan Krait (Bungarus candidus), Malayan Pit Viper (Calloselasma rhodostoma), and White-lipped Green Pit Viper (Trimeresurus albolabris). Different capture:detection configurations of double-antibody sandwich enzyme-linked immunosorbent assay (ELISA) were constructed using both immunoglobulins, and the horse IgG:IgG-HRP configuration was found to be most selective and sensitive in detecting the corresponding venoms. The method was further streamlined to develop a rapid immunodetection assay, which is able to produce a visual color change within 30 min for discrimination between different snake species. The study shows it is feasible to develop a simple, quick and specific immunodiagnostic assay using horse IgG, which can be derived directly from antisera prepared for antivenom production. The proof-of-concept indicates it is a sustainable and affordable approach in keeping with on-going antivenom manufacturing activities for specific species in the region.
Cross neutralization of Hypnale hypnale (hump-nosed pit viper) venom by polyvalent and monovalent Malayan pit viper antivenoms in vitro and in a rodent model

Tan CH, Leong PK, Fung SY, Sim SM, Ponnudurai G, Ariaratnam C, et al.

Acta Trop, 2011 Feb;117(2):119-24.
PMID: 21073851 DOI: 10.1016/j.actatropica.2010.11.001

Hypnale hypnale (hump-nosed pit viper) is a medically important venomous snake in Sri Lanka and Southwestern India. Bite of this snake may result in hemostatic dysfunction, acute kidney injury and death. Clinical studies indicated that the locally available polyvalent antivenoms produced in India are not effective against hump-nosed pit viper envenoming. Hence, there is an urgent need to search for effective antivenom. In this paper, we examined the ability of Calloselasma rhodostoma (Malayan pit viper) monovalent antivenom and the Hemato polyvalent antivenom (both produced by Thai Red Cross Society, TRCS) to neutralize the lethality and toxic effects of H. hypnale venom, as C. rhodostoma is considered a sister taxon of H. hypnale. In vitro neutralization studies showed that the Hemato polyvalent antivenom effectively neutralized the lethality of H. hypnale venom (1.52mgvenom/mL antivenom) as well as the hemorrhagic, procoagulant and necrotic activities of the venom. The monovalent C. rhodostoma antivenom could also neutralize the lethality and toxic activities of the venom, but the potency was lower. The Hemato polyvalent antivenom also effectively protected mice from the lethal and local effects of H. hypnale venom in an in vivo rodent model of envenoming. Furthermore, the polyvalent antivenom could also effectively neutralize the venom of Daboia russelii (2.50mgvenom/mL antivenom), another common cause of snake bites in Sri Lanka and South India. These findings suggested that the Hemato polyvalent antivenom may be beneficial in the antivenom treatment of H. hypnale envenoming.
Geographical variations in king cobra (Ophiophagus hannah) venom from Thailand, Malaysia, Indonesia and China: On venom lethality, antivenom immunoreactivity and in vivo neutralization

Tan KY, Ng TS, Bourges A, Ismail AK, Maharani T, Khomvilai S, et al.

Acta Trop, 2020 Mar;203:105311.
PMID: 31862461 DOI: 10.1016/j.actatropica.2019.105311

The wide distribution of king cobra (Ophiophagus hannah), a medically important venomous snake in Asia could be associated with geographical variation in the toxicity and antigenicity of the venom. This study investigated the lethality of king cobra venoms (KCV) from four geographical locales (Malaysia, Thailand, Indonesia, China), and the immunological binding as well as in vivo neutralization activities of three antivenom products (Thai Ophiophagus hannah monovalent antivenom, OHMAV; Indonesian Serum Anti Bisa Ular, SABU; Chinese Naja atra monovalent antivenom, NAMAV) toward the venoms. The Indonesian and Chinese KCV were more lethal (median lethal dose, LD50 ~0.5 μg/g) than those from Malaysia and Thailand (LD50 ~1.0 μg/g). The antivenoms, composed of F(ab)'2, were variably immunoreactive toward the KCV from all locales, with OHMAV exhibited the highest immunological binding activity. In mice, OHMAV neutralized the neurotoxic lethality of Thai KCV most effectively (normalized potency = 118 mg venom neutralized per g antivenom) followed by Malaysian, Indonesian and Chinese KCV. In comparison, the hetero-specific SABU was remarkably less potent by at least 6 to10 folds, whereas NAMAV appeared to be non-effective. The finding supports that a specific king cobra antivenom is needed for the effective treatment of king cobra envenomation in each region.
Evaluating the physicochemical properties and efficacy of recently expired and aged antivenom products from Thailand and Taiwan

Tan KY, Liew ST, Tan QY, Abdul-Rahman FN, Azmi NI, Sim SM, et al.

Toxicon, 2019 Mar 15;160:55-58.
PMID: 30797900 DOI: 10.1016/j.toxicon.2019.02.010

Gel filtration chromatography and gel electrophoresis revealed minimal protein degradation in lyophilized antivenoms which were 2-year expired (Hemato Polyvalent, Neuro Polyvalent; Thailand) and 18-year expired (Hemato Bivalent, Neuro Bivalent; Taiwan). All expired antivenoms retained immunological binding activity, and were able to neutralize the hemotoxic or neurotoxic as well as lethal effects of the homologous snake venoms. The findings show that antivenoms under proper storage conditions may remain relatively stable beyond the indicated shelf life.
Fulltext Standards of diagnostic colonoscopy for early-stage neoplasia: Recommendations by an Asian private group

Sano Y, Chiu HM, Li XB, Khomvilai S, Pisespongsa P, Co JT, et al.

Dig Endosc, 2019 May;31(3):227-244.
PMID: 30589103 DOI: 10.1111/den.13330

BACKGROUND AND AIM: In recent years, the incidence of colorectal cancer has been increasing, and it is now becoming the major cause of cancer death in Asian countries. The aim of the present study was to develop Asian expert-based consensus to standardize the preparation, detection and characterization for the diagnosis of early-stage colorectal neoplasia.
METHODS: A professional group was formed by 36 experts of the Asian Novel Bio-Imaging and Intervention Group (ANBI2 G) members. Representatives from 12 Asia-Pacific countries participated in the meeting. The group organized three consensus meetings focusing on diagnostic endoscopy for gastrointestinal neoplasia. The Delphi method was used to develop the consensus statements.
RESULTS: Through the three consensus meetings with debating, reviewing the literature and regional data, a consensus was reached at third meeting in 2016. The consensus was reached on a total of 10 statements. Summary of statements is as follows: (i) Adequate bowel preparation for high-quality colonoscopy; (ii) Antispasmodic agents for lesion detection; (iii) Image-enhanced endoscopy (IEE) for polyp detection; (iv) Adenoma detection rate for quality indicators; (v) Good documentation of colonoscopy findings; (vi) Complication rates; (vii) Cecal intubation rate; (viii) Cap-assisted colonoscopy (CAC) for polyp detection; (ix) Macroscopic classification using indigocarmine spray for characterization of colorectal lesions; and (x) IEE and/or magnifying endoscopy for prediction of histology.
CONCLUSION: This consensus provides guidance for carrying out endoscopic diagnosis and characterization for early-stage colorectal neoplasia based on the evidence. This will enhance the quality of endoscopic diagnosis and improve detection of early-stage colorectal neoplasia.
Efficacy of international web-based educational intervention in the detection of high-risk flat and depressed colorectal lesions higher (CATCH project) with a video: A randomized trial

Iwatate M, Hirata D, Francisco CPD, Co JT, Byeon JS, Joshi N, et al.

Dig Endosc, 2022 Feb 04.
PMID: 35122323 DOI: 10.1111/den.14244

OBJECTIVE: Three high-risk flat and depressed lesions (FDLs), laterally spreading tumors non-granular type (LST-NG), depressed lesions, and large sessile serrated lesions (SSLs), are highly attributable to post-colonoscopy colorectal cancer (CRC). Efficient and organized educational programs on detecting high-risk FDLs are lacking. We aimed to explore whether a web-based educational intervention with training on FIND clues (fold deformation, intensive stool/mucus attachment, no vessel visibility, and demarcated reddish area) may improve the ability to detect high-risk FDLs.
METHODS: This was an international web-based randomized control trial that enrolled non-expert endoscopists in 13 Asian countries. The participants were randomized into either education or non-education group. All participants took the pre-test and post-test to read 60 endoscopic images (40 high-risk FDL, 5 polypoid, 15 no lesions) and answered whether there was a lesion. Only the education group received a self-education program (video and training questions and answers) between the tests. The primary outcome was a detection rate of high-risk FDLs.
RESULTS: In total, 284 participants were randomized. After excluding non-responders, the final data analyses were based on 139 participants in the education group and 130 in the non-education group. The detection rate of high-risk FDLs in the education group significantly improved by 14.7% (66.6% to 81.3%) compared with -0.8% (70.8% to 70.0%) in the non-education group. Similarly, the detection rate of LST-NG, depressed lesions, and large SSLs significantly increased only in the education group by 12.7%, 12.0%, and 21.6%, respectively.
CONCLUSION: Short self-education focusing on detecting high-risk FDLs was effective for Asian non-expert endoscopists. (UMIN000042348).