Kae Yi Tan
An active member of the Venom Research and Toxicology Laboratory (Vetox Lab) research team. His research interests focus on the understanding of the toxinological and pharmacological actions of snake venoms, contributing towards the clinical management of snakebite envenomation. Experienced and knowledgeable in molecular and bioinformatic analyses of venoms' proteomics and venom glands' transcriptomics.
Phone: 60379674953
Address: Department of Molecular Medicine, Faculty of Medicine, University of Malaya, 50603 Kuala Lumpur
Phone: 60379674953
Address: Department of Molecular Medicine, Faculty of Medicine, University of Malaya, 50603 Kuala Lumpur
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Biological significance
Comprehensive venom proteomes of D. russelii from different locales will facilitate better understanding of the geographical variability of the venom in both qualitative and quantitative terms. This is essential to provide scientific basis for the interpretation of differences in the clinical presentation of Russell's viper envenomation. The study revealed a unique venom proteome of the Pakistani D. russelii from the wild (Indus Delta), in which PLA2 predominated (~60% of total venom proteins). The finding unveiled remarkable differences in the venom compositions between the wild (present study) and the captive specimens reported previously. The integration of toxicity tests enabled the correlation of the venom proteome with the envenoming pathophysiology, where the venom showed potent lethality mediated through coagulopathic activity. The Indian VINS Polyvalent Antivenom (VPAV) showed binding activity toward the venom protein antigens; however the immunorecognition of small proteins and PLA2-dominating fractions was low to moderate. Consistently, the antivenom neutralized the toxicity of the wild Pakistani Russell's viper venom at moderate efficacies. Our results suggest that it may be possible to enhance the Indian antivenom potency against the Pakistani viper venom by the inclusion of venoms from a wider geographical range including that from Pakistan into the immunogen formulation.
Biological significance
This study reveals the compositional details of the venom proteome of Pakistani spectacled cobra (Naja naja). The protein subtypes, proteoforms, and relative abundances of individual proteins were comprehensively revealed in this study, following a venom decomplexing proteomic approach. The Pakistani cobra venom is unique among the rest of the N. naja venom composition reported thus far, as it contains a high abundance of alpha-neurotoxins (predominated by long neurotoxins); these are highly potent post-synaptic neuromuscular blockers that cause paralysis and are principal toxins that account for the high lethality of the venom (LD50 = 0.2 μg/g in mice). In contrast, previous reports showed that the N. naja venoms of India and Sri Lanka had a lower content of neurotoxins and a relatively higher value of LD50. The Pakistani cobra venom demonstrated sufficient immunoreactivity toward three antivenom products manufactured outside Pakistan (including the Indian product VINS), however the potency of antigen binding was the highest toward Naja kaouthia monovalent antivenom, a heterologous antivenom raised against a long neurotoxin-predominated venom of the Thai monocled cobra. From the practical standpoint, the findings indicate that the treatment of N. naja envenomation in Pakistan may be improved by the production of a locale-specific antivenom, in which the antivenom produced contains more antibodies that can target and react more specifically with the highly abundant lethal neurotoxins in the Pakistani N. naja venom.
reverse-phase HPLC fractions. Altogether 31 distinct forms of proteins were identified and clustered into three
toxin families: three-finger toxin (3FTX, 66.12% of total venom proteins), phospholipase A2 (PLA2, 33.26%) and
cysteine-rich secretory protein (CRiSP, 0.05%). The 3FTX were α-neurotoxins (five long neurotoxins, LNTX,
48.87%; two short neurotoxins, SNTX, 16.94%) and a trace amount of two cytotoxins (CTX, 0.31%). PLA2 were
presentwith a large diversity of homologues (≥20 forms), however none was annotated to the lethal proteoform
reported previously. The venom is highly lethal in mice (LD50 = 0.10 μg/g) and this is driven primarily by the
SNTX and LNTX (LD50 = 0.05–0.13 μg/g), since the PLA2 proteins were non-lethal up to 2 μg/g (20-time the
venom LD50). The SNTX and LNTX were effectively cross-neutralized by the heterologous Sea Snake Antivenom
(SSAV, Australian product) (potency=0.27mg toxin perml antivenom, and 0.40 mg/ml, respectively), corroborating
the cross-neutralization of thewhole venom(potency=1.09mg/ml) and its antigenic immunoreactivity
toward SSAV. Furthermore, compared with earlier studies, the present work reveals geographical variation of
venomcomposition for L. colubrinawhichmay have implication for the evolution and conservation of the species.
Biological significance: Laticauda colubrina (yellow-lipped sea krait) is a widely distributed, semi-aquatic venomous
snake species. The venom proteome at the level of protein family is unsophisticated and consistent with its
restricted prey selection. Nonetheless, the subproteomic findings revealed geographical variability of the venom
for this widely distributed species. In contrast to two previous reports, the results for the Balinese L. colubrina
venom showed that LNTX Neurotoxin a and Neurotoxin b were co-existent while the PLA2 lethal subtype
(PLA-II) was undetected bymeans of LCMS/MS and by in vivo assay. This is an observable trait of L. colubrina considered
divergent from specimens previously studied for the Philippines and the Solomon Islands. The stark geographical
variation might be reflective of trophic adaptation following evolutionary arms race between the snake
and the prey (eels) in different localities. The preferred traitwould likely propagate and remain significantwithin
the geographical population, since the strong behaviour of site fidelity in the specieswould haveminimized gene
flow between distant populations. Meanwhile, the in vivo neutralization study verified that the efficacy of the
heterologous Sea Snake Antivenom (Australian product) is attributable to the cross-neutralization of SNTX and
LNTX, two principal lethal toxins thatmade up the bulk of L. colubrina venomproteins. The findings also implied
that L. colubrina, though could be evolutionarily more related to the terrestrial elapids, has evolved a much
streamlined, neurotoxin- and PLA2-predominated venom arsenal, with major antigenicity shared among the
true sea snakes and the Australo-Papuan elapids. The findings enrich our current understanding of the complexity
of L. colubrina venom and the neutralizing spectrum of antivenom against the principal toxins from this
unique elapid lineage.
The venom is highly lethal in mice (intravenous median lethal dose = 0.09 μg/g). BioCSL Sea Snake Antivenom, raised against the venoms of beaked sea snake (Hydrophis schistosus) and N. scutatus (added for enhanced immunogenicity), neutralized the lethal effect of N. scutatus venom (potency = 2.95 mg/ml) much more effectively than the targeted H. schistosus venom (potency = 0.48 mg/ml). The combined venom immunogen may have improved the neutralization against phospholipases A2 which are abundant in both venoms, but not short-neurotoxins which are predominant only in H. schistosus venom.
Significance: A shotgun proteomic approach adopted in this study revealed the compositional details of the venom of common tiger snake from Australia, Notechis scutatus. The proteomic findings provided additional information on the relative abundances of toxins and the detection of proteins of minor expression unreported previously. The potent lethal effect of the venom was neutralized by bioCSL Sea Snake Antivenom, an anticipated finding due to the fact that the Sea Snake Antivenom is actually bivalent in nature, being raised against a mix
of venoms of the beaked sea snake (Hydrophis schistosus) and N. scutatus. However, it is surprising to note that bioCSL Sea Snake Antivenom neutralized N. scutatus venom much more effectively compared to the targeted sea snake venom by a marked difference in potency of approximately 6-fold. This phenomenon may be explained
by the main difference in the proteomes of the two venoms, where H. schistosus venom is dominated by short neurotoxins in high abundance – this is a poorly immunogenic toxin group that has been increasingly recognized in the venoms of a few cobras. Further investigations should be directed toward strategies to improve the neutralization of short-neurotoxins, in line with the envisioned production of an effective pan-regional elapid antivenom.
mix resulted in antiserum with wide para-specificity 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.
main bulk of toxins inNK-Mand NK-V venoms (up to 45%each), but less in NK-T venom(27%). The three venoms show different lethal potencies that generally reflect the proteomic findings. Despite the proteomic variations, the use of Thaimonovalent and Neuro polyvalent antivenoms for N. kaouthia envenomation in the three regions is appropriate as the different venoms were neutralized by the antivenoms albeit at different degrees of effectiveness.
Biological significance
Biogeographical variations were observed in the venom proteome of monocled cobra (Naja kaouthia) fromMalaysia, Thailand and Vietnam. The Thai N. kaouthia venomis particularly rich in long neurotoxins, while theMalaysian and Vietnamese specimens were predominated with
cytotoxins. The differentially expressed toxin profile accounts for the discrepancy in the lethal dose of the venom from different populations. Commercially available Thai antivenoms (monovalent and polyvalent) were able to neutralize the three venoms at different effective doses, hence supporting their uses in the three regions. While dose adjustment according to geographical region seems possible, changes to standard recommended dosage should only be made if further study validates that the monocled cobras within a population do not exhibit remarkable inter-individual venom variation.
investigated using reverse-phase HPLC, SDS-PAGE and high-resolution liquid chromatography-tandem mass
spectrometry. The findings revealed a minimalist profile with only 18 venom proteins. These proteins belong
to 5 toxin families: three-finger toxin (3FTx), phospholipase A2 (PLA2), cysteine-rich secretory protein (CRISP),
snake venom metalloprotease (SVMP) and L-amino acid oxidase (LAAO). The 3FTxs (3 short neurotoxins and
4 long neurotoxins) constitute 70.5% of total venom protein, 55.8% being short neurotoxins and 14.7% long
neurotoxins. The PLA2 family consists of four basic (21.4%) and three acidic (6.1%) isoforms. The minor proteins
include one CRISP (1.3%), two SVMPs (0.5%) and one LAAO (0.2%). This is the first report of the presence of long
neurotoxins, CRISP and LAAO in H. schistosus venom. The neurotoxins and the basic PLA2 are highly lethal in mice
with an intravenous median lethal dose of b0.2 μg/g. Cross-neutralization by heterologous elapid antivenoms
(Naja kaouthia monovalent antivenom and Neuro polyvalent antivenom) was moderate against the long
neurotoxin and basic PLA2, but weak against the short neurotoxin, indicating that the latter is the limiting factor
to be overcome for improving the antivenom cross-neutralization efficacy.
Biological significance
Comprehensive venom proteomes of D. russelii from different locales will facilitate better understanding of the geographical variability of the venom in both qualitative and quantitative terms. This is essential to provide scientific basis for the interpretation of differences in the clinical presentation of Russell's viper envenomation. The study revealed a unique venom proteome of the Pakistani D. russelii from the wild (Indus Delta), in which PLA2 predominated (~60% of total venom proteins). The finding unveiled remarkable differences in the venom compositions between the wild (present study) and the captive specimens reported previously. The integration of toxicity tests enabled the correlation of the venom proteome with the envenoming pathophysiology, where the venom showed potent lethality mediated through coagulopathic activity. The Indian VINS Polyvalent Antivenom (VPAV) showed binding activity toward the venom protein antigens; however the immunorecognition of small proteins and PLA2-dominating fractions was low to moderate. Consistently, the antivenom neutralized the toxicity of the wild Pakistani Russell's viper venom at moderate efficacies. Our results suggest that it may be possible to enhance the Indian antivenom potency against the Pakistani viper venom by the inclusion of venoms from a wider geographical range including that from Pakistan into the immunogen formulation.
Biological significance
This study reveals the compositional details of the venom proteome of Pakistani spectacled cobra (Naja naja). The protein subtypes, proteoforms, and relative abundances of individual proteins were comprehensively revealed in this study, following a venom decomplexing proteomic approach. The Pakistani cobra venom is unique among the rest of the N. naja venom composition reported thus far, as it contains a high abundance of alpha-neurotoxins (predominated by long neurotoxins); these are highly potent post-synaptic neuromuscular blockers that cause paralysis and are principal toxins that account for the high lethality of the venom (LD50 = 0.2 μg/g in mice). In contrast, previous reports showed that the N. naja venoms of India and Sri Lanka had a lower content of neurotoxins and a relatively higher value of LD50. The Pakistani cobra venom demonstrated sufficient immunoreactivity toward three antivenom products manufactured outside Pakistan (including the Indian product VINS), however the potency of antigen binding was the highest toward Naja kaouthia monovalent antivenom, a heterologous antivenom raised against a long neurotoxin-predominated venom of the Thai monocled cobra. From the practical standpoint, the findings indicate that the treatment of N. naja envenomation in Pakistan may be improved by the production of a locale-specific antivenom, in which the antivenom produced contains more antibodies that can target and react more specifically with the highly abundant lethal neurotoxins in the Pakistani N. naja venom.
reverse-phase HPLC fractions. Altogether 31 distinct forms of proteins were identified and clustered into three
toxin families: three-finger toxin (3FTX, 66.12% of total venom proteins), phospholipase A2 (PLA2, 33.26%) and
cysteine-rich secretory protein (CRiSP, 0.05%). The 3FTX were α-neurotoxins (five long neurotoxins, LNTX,
48.87%; two short neurotoxins, SNTX, 16.94%) and a trace amount of two cytotoxins (CTX, 0.31%). PLA2 were
presentwith a large diversity of homologues (≥20 forms), however none was annotated to the lethal proteoform
reported previously. The venom is highly lethal in mice (LD50 = 0.10 μg/g) and this is driven primarily by the
SNTX and LNTX (LD50 = 0.05–0.13 μg/g), since the PLA2 proteins were non-lethal up to 2 μg/g (20-time the
venom LD50). The SNTX and LNTX were effectively cross-neutralized by the heterologous Sea Snake Antivenom
(SSAV, Australian product) (potency=0.27mg toxin perml antivenom, and 0.40 mg/ml, respectively), corroborating
the cross-neutralization of thewhole venom(potency=1.09mg/ml) and its antigenic immunoreactivity
toward SSAV. Furthermore, compared with earlier studies, the present work reveals geographical variation of
venomcomposition for L. colubrinawhichmay have implication for the evolution and conservation of the species.
Biological significance: Laticauda colubrina (yellow-lipped sea krait) is a widely distributed, semi-aquatic venomous
snake species. The venom proteome at the level of protein family is unsophisticated and consistent with its
restricted prey selection. Nonetheless, the subproteomic findings revealed geographical variability of the venom
for this widely distributed species. In contrast to two previous reports, the results for the Balinese L. colubrina
venom showed that LNTX Neurotoxin a and Neurotoxin b were co-existent while the PLA2 lethal subtype
(PLA-II) was undetected bymeans of LCMS/MS and by in vivo assay. This is an observable trait of L. colubrina considered
divergent from specimens previously studied for the Philippines and the Solomon Islands. The stark geographical
variation might be reflective of trophic adaptation following evolutionary arms race between the snake
and the prey (eels) in different localities. The preferred traitwould likely propagate and remain significantwithin
the geographical population, since the strong behaviour of site fidelity in the specieswould haveminimized gene
flow between distant populations. Meanwhile, the in vivo neutralization study verified that the efficacy of the
heterologous Sea Snake Antivenom (Australian product) is attributable to the cross-neutralization of SNTX and
LNTX, two principal lethal toxins thatmade up the bulk of L. colubrina venomproteins. The findings also implied
that L. colubrina, though could be evolutionarily more related to the terrestrial elapids, has evolved a much
streamlined, neurotoxin- and PLA2-predominated venom arsenal, with major antigenicity shared among the
true sea snakes and the Australo-Papuan elapids. The findings enrich our current understanding of the complexity
of L. colubrina venom and the neutralizing spectrum of antivenom against the principal toxins from this
unique elapid lineage.
The venom is highly lethal in mice (intravenous median lethal dose = 0.09 μg/g). BioCSL Sea Snake Antivenom, raised against the venoms of beaked sea snake (Hydrophis schistosus) and N. scutatus (added for enhanced immunogenicity), neutralized the lethal effect of N. scutatus venom (potency = 2.95 mg/ml) much more effectively than the targeted H. schistosus venom (potency = 0.48 mg/ml). The combined venom immunogen may have improved the neutralization against phospholipases A2 which are abundant in both venoms, but not short-neurotoxins which are predominant only in H. schistosus venom.
Significance: A shotgun proteomic approach adopted in this study revealed the compositional details of the venom of common tiger snake from Australia, Notechis scutatus. The proteomic findings provided additional information on the relative abundances of toxins and the detection of proteins of minor expression unreported previously. The potent lethal effect of the venom was neutralized by bioCSL Sea Snake Antivenom, an anticipated finding due to the fact that the Sea Snake Antivenom is actually bivalent in nature, being raised against a mix
of venoms of the beaked sea snake (Hydrophis schistosus) and N. scutatus. However, it is surprising to note that bioCSL Sea Snake Antivenom neutralized N. scutatus venom much more effectively compared to the targeted sea snake venom by a marked difference in potency of approximately 6-fold. This phenomenon may be explained
by the main difference in the proteomes of the two venoms, where H. schistosus venom is dominated by short neurotoxins in high abundance – this is a poorly immunogenic toxin group that has been increasingly recognized in the venoms of a few cobras. Further investigations should be directed toward strategies to improve the neutralization of short-neurotoxins, in line with the envisioned production of an effective pan-regional elapid antivenom.
mix resulted in antiserum with wide para-specificity 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.
main bulk of toxins inNK-Mand NK-V venoms (up to 45%each), but less in NK-T venom(27%). The three venoms show different lethal potencies that generally reflect the proteomic findings. Despite the proteomic variations, the use of Thaimonovalent and Neuro polyvalent antivenoms for N. kaouthia envenomation in the three regions is appropriate as the different venoms were neutralized by the antivenoms albeit at different degrees of effectiveness.
Biological significance
Biogeographical variations were observed in the venom proteome of monocled cobra (Naja kaouthia) fromMalaysia, Thailand and Vietnam. The Thai N. kaouthia venomis particularly rich in long neurotoxins, while theMalaysian and Vietnamese specimens were predominated with
cytotoxins. The differentially expressed toxin profile accounts for the discrepancy in the lethal dose of the venom from different populations. Commercially available Thai antivenoms (monovalent and polyvalent) were able to neutralize the three venoms at different effective doses, hence supporting their uses in the three regions. While dose adjustment according to geographical region seems possible, changes to standard recommended dosage should only be made if further study validates that the monocled cobras within a population do not exhibit remarkable inter-individual venom variation.
investigated using reverse-phase HPLC, SDS-PAGE and high-resolution liquid chromatography-tandem mass
spectrometry. The findings revealed a minimalist profile with only 18 venom proteins. These proteins belong
to 5 toxin families: three-finger toxin (3FTx), phospholipase A2 (PLA2), cysteine-rich secretory protein (CRISP),
snake venom metalloprotease (SVMP) and L-amino acid oxidase (LAAO). The 3FTxs (3 short neurotoxins and
4 long neurotoxins) constitute 70.5% of total venom protein, 55.8% being short neurotoxins and 14.7% long
neurotoxins. The PLA2 family consists of four basic (21.4%) and three acidic (6.1%) isoforms. The minor proteins
include one CRISP (1.3%), two SVMPs (0.5%) and one LAAO (0.2%). This is the first report of the presence of long
neurotoxins, CRISP and LAAO in H. schistosus venom. The neurotoxins and the basic PLA2 are highly lethal in mice
with an intravenous median lethal dose of b0.2 μg/g. Cross-neutralization by heterologous elapid antivenoms
(Naja kaouthia monovalent antivenom and Neuro polyvalent antivenom) was moderate against the long
neurotoxin and basic PLA2, but weak against the short neurotoxin, indicating that the latter is the limiting factor
to be overcome for improving the antivenom cross-neutralization efficacy.