Displaying publications 1 - 20 of 69 in total

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  1. Wong KY, Tan KY, Tan NH, Tan CH
    Toxins (Basel), 2021 01 14;13(1).
    PMID: 33466660 DOI: 10.3390/toxins13010060
    The Senegalese cobra, Naja senegalensis, is a non-spitting cobra species newly erected from the Naja haje complex. Naja senegalensis causes neurotoxic envenomation in Western Africa but its venom properties remain underexplored. Applying a protein decomplexation proteomic approach, this study unveiled the unique complexity of the venom composition. Three-finger toxins constituted the major component, accounting for 75.91% of total venom proteins. Of these, cardiotoxin/cytotoxin (~53%) and alpha-neurotoxins (~23%) predominated in the venom proteome. Phospholipase A2, however, was not present in the venom, suggesting a unique snake venom phenotype found in this species. The venom, despite the absence of PLA2, is highly lethal with an intravenous LD50 of 0.39 µg/g in mice, consistent with the high abundance of alpha-neurotoxins (predominating long neurotoxins) in the venom. The hetero-specific VINS African Polyvalent Antivenom (VAPAV) was immunoreactive to the venom, implying conserved protein antigenicity in the venoms of N. senegalensis and N. haje. Furthermore, VAPAV was able to cross-neutralize the lethal effect of N. senegalensis venom but the potency was limited (0.59 mg venom completely neutralized per mL antivenom, or ~82 LD50 per ml of antivenom). The efficacy of antivenom should be further improved to optimize the treatment of cobra bite envenomation in Africa.
  2. Tan CH, Tan KY, Tan NH
    Methods Mol Biol, 2019;1871:83-92.
    PMID: 30276733 DOI: 10.1007/978-1-4939-8814-3_5
    Snake venoms are complex mixtures of proteins and peptides that play vital roles in the survival of venomous snakes. As with their diverse pharmacological activities, snake venoms can be highly variable, hence the importance of understanding the compositional details of different snake venoms. However, profiling venom protein mixtures is challenging, in particular when dealing with the diversity of protein subtypes and their abundances. Here we described an optimized strategy combining a protein decomplexation method with in-solution trypsin digestion and mass spectrometry of snake venom proteins. The approach involves the integrated use of C18 reverse-phase high-performance liquid chromatography (RP-HPLC), sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), and nano-electrospray ionization tandem mass spectrometry (nano-ESI-LC-MS/MS).
  3. Ratanabanangkoon K, Tan KY, Eursakun S, Tan CH, Simsiriwong P, Pamornsakda T, et al.
    PLoS Negl Trop Dis, 2016 Apr;10(4):e0004565.
    PMID: 27058956 DOI: 10.1371/journal.pntd.0004565
    Snakebite envenomation is a serious medical problem in many tropical developing countries and was considered by WHO as a neglected tropical disease. Antivenom (AV), the rational and most effective treatment modality, is either unaffordable and/or unavailable in many affected countries. Moreover, each AV is specific to only one (monospecific) or a few (polyspecific) snake venoms. This demands that each country to prepare AV against its local snake venoms, which is often not feasible. Preparation of a 'pan-specific' AV against many snakes over a wide geographical area in some countries/regions has not been possible. If a 'pan-specific' AV effective against a variety of snakes from many countries could be prepared, it could be produced economically in large volume for use in many countries and save many lives. The aim of this study was to produce a pan-specific antiserum effective against major medically important elapids in Asia. The strategy was to use toxin fractions (TFs) of the venoms in place of crude venoms in order to reduce the number of antigens the horses were exposed to. This enabled inclusion of a greater variety of elapid venoms in the immunogen mix, thus exposing the horse immune system to a diverse repertoire of toxin epitopes, and gave rise to antiserum with wide paraspecificity against elapid venoms. Twelve venom samples from six medically important elapid snakes (4 Naja spp. and 2 Bungarus spp.) were collected from 12 regions/countries in Asia. Nine of these 12 venoms were ultra-filtered to remove high molecular weight, non-toxic and highly immunogenic proteins. The remaining 3 venoms were not ultra-filtered due to limited amounts available. The 9 toxin fractions (TFs) together with the 3 crude venoms were emulsified in complete Freund's adjuvant and used to immunize 3 horses using a low dose, low volume, multisite immunization protocol. The horse antisera were assayed by ELISA and by in vivo lethality neutralization in mice. The findings were: a) The 9 TFs were shown to contain all of the venom toxins but were devoid of high MW proteins. When these TFs, together with the 3 crude venoms, were used as the immunogen, satisfactory ELISA antibody titers against homologous/heterologous venoms were obtained. b) The horse antiserum immunologically reacted with and neutralized the lethal effects of both the homologous and the 16 heterologous Asian/African elapid venoms tested. Thus, the use of TFs in place of crude venoms and the inclusion of a variety of elapid venoms in the immunogen mix resulted in antiserum with wide paraspecificity against elapid venoms from distant geographic areas. The antivenom prepared from this antiserum would be expected to be pan-specific and effective in treating envenomations by most elapids in many Asian countries. Due to economies of scale, the antivenom could be produced inexpensively and save many lives. This simple strategy and procedure could be readily adapted for the production of pan-specific antisera against elapids of other continents.
  4. Ratanabanangkoon K, Simsiriwong P, Pruksaphon K, Tan KY, Eursakun S, Tan CH, et al.
    Sci Rep, 2017 08 17;7(1):8545.
    PMID: 28819275 DOI: 10.1038/s41598-017-08962-3
    Snake envenomation is an important medical problem. One of the hurdles in antivenom development is the in vivo assay of antivenom potency which is expensive, gives variable results and kills many animals. We report a novel in vitro assay involving the specific binding of the postsynaptic neurotoxins (PSNTs) of elapid snakes with purified Torpedo californica nicotinic acetylcholine receptor (nAChR). The potency of an antivenom is determined by its antibody ability to bind and neutralize the PSNT, thus preventing it from binding to nAChR. The PSNT of Naja kaouthia (NK3) was immobilized on microtiter wells and nAChR was added to bind with it. The in vitro IC50 of N. kaouthia venom that inhibited 50% of nAChR binding to the immobilized NK3 was determined. Varying concentrations of antisera against N. kaouthia were separately pre-incubated with 5xIC50 of N. kaouthia venom. The remaining free NK3 were incubated with nAChR before adding to the NK3 coated plates. The in vitro and in vivo median effective ratio, ER50s of 12 batches of antisera showed correlation (R 2) of 0.9809 (p 
  5. Ratanabanangkoon K, Tan KY, Pruksaphon K, Klinpayom C, Gutiérrez JM, Quraishi NH, et al.
    Sci Rep, 2020 07 09;10(1):11261.
    PMID: 32647261 DOI: 10.1038/s41598-020-66657-8
    Snakebite envenomation is a neglected tropical disease of high mortality and morbidity largely due to insufficient supply of effective and affordable antivenoms. Snake antivenoms are mostly effective against the venoms used in their production. It is thus crucial that effective and affordable antivenom(s) with wide para-specificity, capable of neutralizing the venoms of a large number of snakes, be produced. Here we studied the pan-specific antiserum prepared previously by a novel immunization strategy involving the exposure of horses to a 'diverse toxin repertoire' consisting of 12 neurotoxic Asian snake toxin fractions/ venoms from six species. This antiserum was previously shown to exhibit wide para-specificity by neutralizing 11 homologous and 16 heterologous venoms from Asia and Africa. We now show that the antiserum can neutralize 9 out of 10 additional neurotoxic venoms. Altogether, 36 snake venoms belonging to 10 genera from 4 continents were neutralized by the antiserum. Toxin profiles previously generated using proteomic techniques of these 36 venoms identified α-neurotoxins, β-neurotoxins, and cytotoxins as predominant toxins presumably neutralized by the antiserum. The bases for the wide para-specificity of the antiserum are discussed. These findings indicate that it is feasible to generate antivenoms of wide para-specificity against elapid neurotoxic venoms from different regions in the world and raises the possibility of a universal neurotoxic antivenom. This should reduce the mortality resulting from neurotoxic snakebite envenomation.
  6. Mukari SZ, Tan KY, Abdullah A
    Int J Pediatr Otorhinolaryngol, 2006 May;70(5):843-51.
    PMID: 16246430
    This paper reports the performance of a newly implemented hospital-based universal newborn hearing screening programme and the challenges to the effective implementation.
  7. Ratanabanangkoon K, Simsiriwong P, Pruksaphon K, Tan KY, Chantrathonkul B, Eursakun S, et al.
    Sci Rep, 2018 06 26;8(1):9716.
    PMID: 29946111 DOI: 10.1038/s41598-018-27794-3
    In order to facilitate/expedite the production of effective and affordable snake antivenoms, a novel in vitro potency assay was previously developed. The assay is based on an antiserum's ability to bind to postsynaptic neurotoxin (PSNT) and thereby inhibit the PSNT binding to the nicotinic acetylcholine receptor (nAChR). The assay was shown to work well with antiserum against Thai Naja kaouthia which produces predominantly the lethal PSNTs. In this work, the assay is demonstrated to work well with antiserum/antivenom against Bungarus candidus (BC), which also produces lethal presynaptic neurotoxins, as well as antivenom against Sri Lankan Naja naja (NN), which produces an abundance of cytotoxins. The in vitro and in vivo median effective ratios (ER50s) for various batches of antisera against BC showed a correlation (R2) of 0.8922 (p 
  8. Pruksaphon K, Tan KY, Tan CH, Simsiriwong P, Gutiérrez JM, Ratanabanangkoon K
    PLoS Negl Trop Dis, 2020 Aug;14(8):e0008581.
    PMID: 32857757 DOI: 10.1371/journal.pntd.0008581
    The aim of this study was to develop an in vitro assay for use in place of in vivo assays of snake venom lethality and antivenom neutralizing potency. A novel in vitro assay has been developed based on the binding of post-synaptically acting α-neurotoxins to nicotinic acetylcholine receptor (nAChR), and the ability of antivenoms to prevent this binding. The assay gave high correlation in previous studies with the in vivo murine lethality tests (Median Lethal Dose, LD50), and the neutralization of lethality assays (Median Effective Dose, ED50) by antisera against Naja kaouthia, Naja naja and Bungarus candidus venoms. Here we show that, for the neurotoxic venoms of 20 elapid snake species from eight genera and four continents, the in vitro median inhibitory concentrations (IC50s) for α-neurotoxin binding to purified nAChR correlated well with the in vivo LD50s of the venoms (R2 = 0.8526, p < 0.001). Furthermore, using this assay, the in vitro ED50s of a horse pan-specific antiserum against these venoms correlated significantly with the corresponding in vivo murine ED50s, with R2 = 0.6896 (p < 0.01). In the case of four elapid venoms devoid or having a very low concentration of α-neurotoxins, no inhibition of nAChR binding was observed. Within the philosophy of 3Rs (Replacement, Reduction and Refinement) in animal testing, the in vitro α-neurotoxin-nAChR binding assay can effectively substitute the mouse lethality test for toxicity and antivenom potency evaluation for neurotoxic venoms in which α-neurotoxins predominate. This will greatly reduce the number of mice used in toxicological research and antivenom production laboratories. The simpler, faster, cheaper and less variable in vitro assay should also expedite the development of pan-specific antivenoms against various medically important snakes in many parts of the world.
  9. Tan CH, Tan NH, Tan KY, Kwong KO
    Toxins (Basel), 2015 Feb;7(2):572-81.
    PMID: 25690691 DOI: 10.3390/toxins7020572
    Sea snake envenomation is a serious occupational hazard in tropical waters. In Malaysia, the beaked sea snake (Hydrophis schistosus, formerly known as Enhydrina schistosa) and the spine-bellied sea snake (Hydrophis curtus, formerly known as Lapemis curtus or Lapemis hardwickii) are two commonly encountered species. Australian CSL sea snake antivenom is the definitive treatment for sea snake envenomation; it is unfortunately extremely costly locally and is not widely available or adequately stocked in local hospitals. This study investigated the cross-neutralizing potential of three regionally produced anti-cobra antivenoms against the venoms of Malaysian H. schistosus and H. curtus. All three antivenoms conferred paraspecific protection from sea snake venom lethality in mice, with potency increasing in the following order: Taiwan bivalent antivenom < Thai monocled cobra monovalent antivenom < Thai neuro polyvalent antivenom (NPAV). NPAV demonstrated cross-neutralizing potencies of 0.4 mg/vial for H. schistosus venom and 0.8 mg/vial for H. curtus, which translates to a dose of less than 20 vials of NPAV to neutralize an average amount of sea snake venom per bite (inferred from venom milking). The cross-neutralization activity was supported by ELISA cross-reactivity between NPAV and the venoms of H. schistosus (58.4%) and H. curtus (70.4%). These findings revealed the potential of NPAV as a second-line treatment for sea snake envenomation in the region. Further profiling of the cross-neutralization activity should address the antivenomic basis using purified toxin-based assays.
  10. Salmiati, Salim MR, Hassan RM, Tan KY
    Water Sci Technol, 2007;56(7):33-40.
    PMID: 17951865
    Biochemical products have been widely used for treatment of various types of wastewater. The treatment processes with the addition of biochemical products are quite attractive because of their simplicity, minimal use of equipment, they are environmentally friendly and are suitable for the removal of organic pollutants. The purpose of these products is to enhance the activities of beneficial microbes in order to improve treatment performance. This study was carried out to determine the potential of applying biochemical products in assisting and improving the performance of sewage treatment plants. In this study, four biochemical products, namely: Zeolite, Bio-C, Eco-B and Was-D, were applied to the sewage treatment plant. Analyses were carried out on several water quality parameters such as biochemical oxygen demand (BOD), chemical oxygen demand (COD), suspended solids (SS), oil & grease (O&G), phosphorus (P), ammoniacal nitrogen (AN) and sludge thickness (ST). From the results obtained, it can be seen that the overall performance of the treatment plant improved with most of the parameters studied were found to fulfill the DOE Standard B requirements. The performance of Bio-C was found to give better results than other products.
  11. Tan CH, Liew JL, Tan KY, Tan NH
    Sci Rep, 2016 11 21;6:37299.
    PMID: 27869134 DOI: 10.1038/srep37299
    Serum Anti Ular Bisa (SABU) is the only snake antivenom produced locally in Indonesia; however, its effectiveness has not been rigorously evaluated. This study aimed to assess the protein composition and neutralization efficacy of SABU. SDS polyacrylamide gel electrophoresis, size-exclusion liquid chromatography and shotgun proteomics revealed that SABU consists of F(ab')2 but a significant amount of dimers, protein aggregates and contaminant albumins. SABU moderately neutralized Calloselasma rhodostoma venom (potency of 12.7 mg venom neutralized per ml antivenom, or 121.8 mg venom per g antivenom protein) and Bungarus fasciatus venom (0.9 mg/ml; 8.5 mg/g) but it was weak against the venoms of Naja sputatrix (0.3 mg/ml; 2.9 mg/g), Naja sumatrana (0.2 mg/ml; 1.8 mg/g) and Bungarus candidus (0.1 mg/ml; 1.0 mg/g). In comparison, NPAV, the Thai Neuro Polyvalent Antivenom, outperformed SABU with greater potencies against the venoms of N. sputatrix (0.6 mg/ml; 8.3 mg/g), N. sumatrana (0.5 mg/ml; 7.1 mg/g) and B. candidus (1.7 mg/ml; 23.2 mg/g). The inferior efficacy of SABU implies that a large antivenom dose is required clinically for effective treatment. Besides, the antivenom contains numerous impurities e.g., albumins that greatly increase the risk of hypersensitivity. Together, the findings indicate that the production of SABU warrants further improvement.
  12. Kaliya-Perumal AK, Yeh YC, Luo CA, Joey-Tan KY
    Clin Orthop Surg, 2017 Mar;9(1):71-76.
    PMID: 28261430 DOI: 10.4055/cios.2017.9.1.71
    BACKGROUND: The technique used to administer a selective nerve root block (SNRB) varies depending on individual expertise. Both the anteroposterior (AP) subpedicular approach and oblique Scotty dog subpedicular approach are widely practiced. However, the literature does not provide a clear consensus regarding which approach is more suitable. Hence, we decided to analyse the procedural parameters and clinical outcomes following SNRBs using these two approaches.

    METHODS: Patients diagnosed with a single lumbar herniated intervertebral disc (HIVD) refractory to conservative management but not willing for immediate surgery were selected for a prospective nonrandomized comparative study. An SNRB was administered as a therapeutic alternative using the AP subpedicular approach in one group (n = 25; mean age, 45 ± 5.4 years) and the oblique Scotty dog subpedicular approach in the other group (n = 22; mean age, 43.8 ± 4.7 years). Results were compared in terms of the duration of the procedure, the number of C-arm exposures, accuracy, pain relief, functional outcome and the duration of relief.

    RESULTS: Our results suggest that the oblique Scotty dog subpedicular approach took a significantly longer duration (p = 0.02) and a greater number of C-arm exposures (p = 0.001). But, its accuracy of needle placement was 95.5% compared to only 72% using the AP subpedicular approach (p = 0.03). There was no significant difference in terms of clinical outcomes between these approaches.

    CONCLUSIONS: The AP subpedicular approach was simple and facile, but the oblique Scotty dog subpedicular approach was more accurate. However, a brief window period of pain relief was achieved irrespective of the approaching technique used.

  13. Lingam TMC, Tan KY, Tan CH
    PMID: 34508870 DOI: 10.1016/j.cbpc.2021.109186
    Snakebite envenomation caused by the Western and Eastern Russell's Vipers (Daboia russelii and Daboia siamensis) may potentially induce capillary leak syndrome (CLS), while the use of antivenom in treating this has not been well examined. This study investigated the CLS-inducing toxicity of Russell's Viper venoms from various sources and examined the neutralization activity of regionally available antivenoms, using a newly devised mouse model. D. russelii venoms demonstrated a more consistent vascular leakage activity (76,000-86,000 CLS unit of vascular leak index, a function of the diameter and intensity of Evans Blue dye extravasation into dermis) than D. siamensis venoms (33,000-88,000 CLS unit). Both species venoms increased hematocrits markedly (53-67%), indicating hemoconcentration. Regional antivenoms (DsMAV-Thailand, DsMAV-Taiwan, VPAV-India) preincubated with the venoms effectively neutralized the CLS effect to different extents. When the antivenoms were administered intravenously post-envenomation (challenge-rescue model), the neutralization was less effective, implying that CLS has a rapid onset that preceded the neutralizing activity of antivenom, and/or the antivenom has limited biodistribution to the venom's inoculation site. In conclusion, Russell's Viper venoms of both species from various locales induced CLS in mice. Antivenoms generally had limited efficacy in neutralizing the CLS effect. Innovative treatment for venom-induced CLS is needed.
  14. 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.
  15. Kue CS, Tan KY, Lam ML, Lee HB
    Exp Anim, 2015;64(2):129-38.
    PMID: 25736707 DOI: 10.1538/expanim.14-0059
    The chick embryo chorioallantoic membrane (CAM) is a preclinical model widely used for vascular and anti-vascular effects of therapeutic agents in vivo. In this study, we examine the suitability of CAM as a predictive model for acute toxicology studies of drugs by comparing it to conventional mouse and rat models for 10 FDA-approved anticancer drugs (paclitaxel, carmustine, camptothecin, cyclophosphamide, vincristine, cisplatin, aloin, mitomycin C, actinomycin-D, melphalan). Suitable formulations for intravenous administration were determined before the average of median lethal dose (LD50) and median survival dose (SD(50)) in the CAM were measured and calculated for these drugs. The resultant ideal LD(50) values were correlated to those reported in the literature using Pearson's correlation test for both intravenous and intraperitoneal routes of injection in rodents. Our results showed moderate correlations (r(2)=0.42 - 0.68, P<0.005-0.05) between the ideal LD(50) values obtained using the CAM model with LD(50) values from mice and rats models for both intravenous and intraperitoneal administrations, suggesting that the chick embryo may be a suitable alternative model for acute drug toxicity screening before embarking on full toxicological investigations in rodents in development of anticancer drugs.
  16. Tan KY, Tan CH, Chanhome L, Tan NH
    PeerJ, 2017;5:e3142.
    PMID: 28392982 DOI: 10.7717/peerj.3142
    BACKGROUND: The monocled cobra (Naja kaouthia) is a medically important venomous snake in Southeast Asia. Its venom has been shown to vary geographically in relation to venom composition and neurotoxic activity, indicating vast diversity of the toxin genes within the species. To investigate the polygenic trait of the venom and its locale-specific variation, we profiled and compared the venom gland transcriptomes of N. kaouthia from Malaysia (NK-M) and Thailand (NK-T) applying next-generation sequencing (NGS) technology.

    METHODS: The transcriptomes were sequenced on the Illumina HiSeq platform, assembled and followed by transcript clustering and annotations for gene expression and function. Pairwise or multiple sequence alignments were conducted on the toxin genes expressed. Substitution rates were studied for the major toxins co-expressed in NK-M and NK-T.

    RESULTS AND DISCUSSION: The toxin transcripts showed high redundancy (41-82% of the total mRNA expression) and comprised 23 gene families expressed in NK-M and NK-T, respectively (22 gene families were co-expressed). Among the venom genes, three-finger toxins (3FTxs) predominated in the expression, with multiple sequences noted. Comparative analysis and selection study revealed that 3FTxs are genetically conserved between the geographical specimens whilst demonstrating distinct differential expression patterns, implying gene up-regulation for selected principal toxins, or alternatively, enhanced transcript degradation or lack of transcription of certain traits. One of the striking features that elucidates the inter-geographical venom variation is the up-regulation of α-neurotoxins (constitutes ∼80.0% of toxin's fragments per kilobase of exon model per million mapped reads (FPKM)), particularly the long-chain α-elapitoxin-Nk2a (48.3%) in NK-T but only 1.7% was noted in NK-M. Instead, short neurotoxin isoforms were up-regulated in NK-M (46.4%). Another distinct transcriptional pattern observed is the exclusively and abundantly expressed cytotoxin CTX-3 in NK-T. The findings suggested correlation with the geographical variation in proteome and toxicity of the venom, and support the call for optimising antivenom production and use in the region. Besides, the current study uncovered full and partial sequences of numerous toxin genes from N. kaouthia which have not been reported hitherto; these include N. kaouthia-specific l-amino acid oxidase (LAAO), snake venom serine protease (SVSP), cystatin, acetylcholinesterase (AChE), hyaluronidase (HYA), waprin, phospholipase B (PLB), aminopeptidase (AP), neprilysin, etc. Taken together, the findings further enrich the snake toxin database and provide deeper insights into the genetic diversity of cobra venom toxins.

  17. Hia YL, Tan KY, Tan CH
    Acta Trop, 2020 Jul;207:105460.
    PMID: 32278639 DOI: 10.1016/j.actatropica.2020.105460
    The banded krait, Bungarus fasciatus is a medically important venomous snake in Asia. The wide distribution of this species in Southeast Asia and southern China indicates potential geographical variation of the venom which may impact the clinical management of snakebite envenomation. This study investigated the intraspecific venom variation of B. fasciatus from five geographical locales through a venom decomplexing proteomic approach, followed by toxinological and immunological studies. The venom proteomes composed of a total of 9 toxin families, comprising 22 to 31 proteoforms at varying abundances. The predominant proteins were phospholipase A2 (including beta-bungarotoxin), Kunitz-type serine protease inhibitor (KSPI) and three-finger toxins (3FTx), which are toxins that cause neurotoxicity and lethality. The venom lethality varied with geographical origins of the snake, with intravenous median lethal doses (LD50) ranging from 0.45-2.55 µg/g in mice. The Thai Bungarus fasciatus monovalent antivenom (BFMAV) demonstrated a dose-dependent increasing immunological binding activity toward all venoms; however, its in vivo neutralization efficacy varied vastly with normalized potency values ranging from 3 to 28 mg/g, presumably due to the compositional differences of dominant proteins in the different venoms. The findings support that antivenom use should be optimized in different geographical areas. The development of a pan-regional antivenom may be a more sustainable solution for the treatment of snakebite envenomation.
  18. Tan KY, Dutta A, Tan TK, Hari R, Othman RY, Choo SW
    PeerJ, 2020;8:e9733.
    PMID: 32953261 DOI: 10.7717/peerj.9733
    Background: Paraburkholderia fungorum (P. fungorum) is a Gram-negative environmental species that has been commonly used as a beneficial microorganism in agriculture as an agent for biocontrol and bioremediation. Its use in agriculture is controversial as many people believe that it could harm human health; however, there is no clear evidence to support.

    Methodology: The pangolin P. fungorum (pangolin Pf) genome has a genomic size of approximately 7.7 Mbps with N50 of 69,666 bps. Our study showed that pangolin Pf is a Paraburkholderia fungorum supported by evidence from the core genome SNP-based phylogenetic analysis and the ANI analysis. Functional analysis has shown that the presence of a considerably large number of genes related to stress response, virulence, disease, and defence. Interestingly, we identified different types of secretion systems in the genome of pangolin Pf, which are highly specialized and responsible for a bacterium's response to its environment and in physiological processes such as survival, adhesion, and adaptation. The pangolin Pf also shared some common virulence genes with the known pathogenic member of the Burkholderiales. These genes play important roles in adhesion, motility, and invasion.

    Conclusion: This study may provide better insights into the functions, secretion systems and virulence of this pangolin-associated bacterial strain. The addition of this genome sequence is also important for future comparative analysis and functional work of P. fungorum.

  19. Tan CH, Liew JL, Navanesan S, Sim KS, Tan NH, Tan KY
    PMID: 32742279 DOI: 10.1590/1678-9199-JVATITD-2020-0013
    Background: The Asiatic pit vipers from the Trimeresurus complex are medically important venomous snakes. These pit vipers are often associated with snakebite that leads to fatal coagulopathy and tissue necrosis. The cytotoxic venoms of Trimeresurus spp.; however, hold great potential for the development of peptide-based anticancer drugs.

    Methods: This study investigated the cytotoxic effect of the venom from Trimeresurus purpureomaculatus, the mangrove pit viper (also known as shore pit viper) which is native in Malaysia, across a panel of human cancer cell lines from breast, lung, colon and prostate as well as the corresponding normal cell lines of each tissue.

    Results: The venom exhibited dose-dependent cytotoxic activities on all cell lines tested, with median inhibition concentrations (IC50) ranging from 0.42 to 6.98 µg/mL. The venom has a high selectivity index (SI = 14.54) on breast cancer cell line (MCF7), indicating that it is significantly more cytotoxic toward the cancer than to normal cell lines. Furthermore, the venom was fractionated using C18 reversed-phase high-performance liquid chromatography and the anticancer effect of each protein fraction was examined. Fraction 1 that contains a hydrophilic low molecular weight (approximately 7.5 kDa) protein was found to be the most cytotoxic and selective toward the breast cancer cell line (MCF7). The protein was identified using liquid chromatography-tandem mass spectrometry as a venom disintegrin, termed purpureomaculin in this study.

    Conclusion: Taken together, the findings revealed the potent and selective cytotoxicity of a disintegrin protein isolated from the Malaysian T. purpureomaculatus venom and suggested its anticancer potential in drug discovery.

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