A Wolf in Another Wolf's Clothing: Post-Genomic Regulation Dictates Venom Profiles of Medically-Important Cryptic Kraits in India.

The Common Krait (Bungarus caeruleus) shares a distribution range with many other 'phenotypically-similar' kraits across the Indian subcontinent. Despite several reports of fatal envenomings by other Bungarus species, commercial Indian antivenoms are only manufactured against B. caeruleus. It is, therefore, imperative to understand the distribution of genetically distinct lineages of kraits, the compositional differences in their venoms, and the consequent impact of venom variation on the (pre)clinical effectiveness of antivenom therapy. To address this knowledge gap, we conducted phylogenetic and comparative venomics investigations of kraits in Southern and Western India. Phylogenetic reconstructions using mitochondrial markers revealed a new species of krait, Romulus' krait (Bungarus romulusi sp. nov.), in Southern India. Additionally, we found that kraits with 17 mid-body dorsal scale rows in Western India do not represent a subspecies of the Sind Krait (B. sindanus walli) as previously believed, but are genetically very similar to B. sindanus in Pakistan. Furthermore, venom proteomics and comparative transcriptomics revealed completely contrasting venom profiles. While the venom gland transcriptomes of all three species were highly similar, venom proteomes and toxicity profiles differed significantly, suggesting the prominent role of post-genomic regulatory mechanisms in shaping the venoms of these cryptic kraits. In vitro venom recognition and in vivo neutralisation experiments revealed a strong negative impact of venom variability on the preclinical performance of commercial antivenoms. While the venom of B. caeruleus was neutralised as per the manufacturer's claim, performance against the venoms of B. sindanus and B. romulusi was poor, highlighting the need for regionally-effective antivenoms in India.

Codon usage pattern and prediction of gene expression level in Bungarus species.

Codon bias study in an organism gains significance in understanding the molecular mechanism as well as the functional conservation of gene expression during the course of evolution. The prime focus in this study is to compare the codon usage patterns among the four species belonging to the genus Bungarus (B. multicinctus, B. fasciatus, B. candidus and B. flaviceps) using several codon bias parameters. Our results suggested that relatively low codon bias exists in the coding sequences of the selected species. The compositional constraints together with gene expression level might influence the patterns of codon usage among the genes of Bungarus species. Both natural selection and mutation pressure affect the codon usage pattern in Bungarus species as evident from correspondence analysis. Neutrality plot indicates that natural selection played a major role while mutation pressure played a minor role in codon usage pattern of the genes in Bungarus species.

Proteomic characterization and comparison of Malaysian Bungarus candidus and Bungarus fasciatus venoms.

Kraits (Bungarus spp.) are highly venomous elapids that are only found in Asia. In the current study, 103 and 86 different proteins were identified from Bungarus candidus and Bungarus fasciatus venoms, respectively. These proteins were classified into 18 different venom protein families. Both venoms were found to contain a high percentage of three finger toxins, phospholipase A2 enzymes and Kunitz-type inhibitors. Smaller number of high molecular weight enzymes such as L-amino acid oxidase, hyaluronidases, and acetylcholinesterase were also detected in the venoms. We also detected some unique proteins that were not known to be present in these venoms. The presence of a natriuretic peptide, vespryn, and serine protease families was detected in B. candidus venom. We also detected the presence of subunit A and B of ß-bungarotoxin and α-bungarotoxin which had not been previously found in B. fasciatus venom. Understanding the proteome composition of Malaysian krait species will provide useful information on unique toxins and proteins which are present in the venoms. This knowledge will assist in the management of krait envenoming. In addition, these proteins may have potential use as research tools or as drug-design templates. BIOLOGICAL SIGNIFICANCE: This study has revealed the proteome composition of Malaysian B. candidus and B. fasciatus venoms, two medically important snake species in Asia. Information on the venom proteome of these species will provide useful information for krait bite management and aid in antivenom selection. Venom proteome profiles of these venoms showed that there are significant differences in the venom protein family compositions. Detection of proteins and peptides that have not been documented in these species such as natriuretic peptides, vespryn and serine proteases provides new knowledge on the composition of these venoms. The roles of these new proteins and peptides in krait envenoming are still unknown. Discovery of these proteins and peptides may also be useful for future research tool and therapeutic development.

[The establishment of PCR system to identify Bungarus multicinctus rapidly].

The purpose of the present study is to establish a rapid and effective PCR method for the identification of B. multicinctus. Based on sequence alignment of B. multicinctus and its adulterants, we found that Cyt b gene is a good molecular genetic marker for the authentication of B. multicinctus. On the basis of the sequence data, a pair of highly specialized primers was designed. The templates were extracted by the DNA purification system. Key factors such as annealing temperature, concentration of Taq enzyme and cycle numbers were analyzed and optimized. The modified PCR program consisted of an initial denaturation step at 95 degrees C for 5 min, followed by 30 cycles of 95 degrees C for 30 s and 55 degrees C for 45 s and a final extension at 72 degrees C for 5 min. Thirteen samples of B. multicinctus were identified accurately from their 20 adulterants in 4 hours. The results indicated it is a highly accurate, rapid and applicable method for the authentication of B. multicinctus.

[High specific PCR identification of Bungarus multicinctus and its adulterants].

OBJECTIVE: To develop a convenient and effective method for the identification of Bungarus multicinctus. METHOD: Based on the sequence of Cyt b gene fragment of B. multicinctus and its adulterants, a pair of highly specific primer (HJL- and HJH-) were designed for distinguishing B. ulticinctus from other species of snake. To establish specific PCR reaction condition, the primers were employed to amplify the DNA templates extracted from B. multicinctus and 6 other species of snake, under different annealing temperature. Using this method, B. multicinctus was identified from 18 samples bought from many drugstores. RESULT: A 230 bp DNA fragment was amplified from B. multicinctus in PCR with annealed temperature at 67 degrees C, whereas no DNA fragment was amplified from other snake samples under the same reaction condition, B. multicinctus could be clearly distinguished from others by PCR reaction with the highly specific primers. In the present study, 18 sample, bought from different drugstores, were also identified by the highly specific PCR with the primers. The results indicated that 14 samples were B. multicinctus and the other 4 were adulterant, which was consistent with the conclusion of authentication based on morphological. CONCLUSION: The primers designed in the present study were highly specific for B. multicinctus.

Identifying the biting species in snakebite by clinical features: an epidemiological tool for community surveys.

The outcome of snakebite is related to the biting species but it is often difficult to identify the biting snake, particularly in community settings. We have developed a clinical scoring system suitable for use in epidemiological surveys, with the main aim of identifying the presumed biting species in those with systemic envenoming who require treatment. The score took into account ten features relating to bites of the five medically important snakes in Sri Lanka, and an algorithm was developed applying different weightings for each feature for different species. A systematically developed artificial data set was used to fine tune the score and to develop criteria for definitive identification. The score was prospectively validated using 134 species-confirmed snakebites. It correctly differentiated the bites caused by the three snakes that commonly cause major clinical problems (Russell's viper (RV), kraits and cobra) from other snakes (hump-nosed viper (HNV) and saw-scaled viper (SSV)) with 80% sensitivity and 100% specificity. For individual species, sensitivity and specificity were, respectively: cobra 76%, 99%; kraits 85%, 99%; and RV 70%, 99%. As anticipated, the score was insensitive in the identification of bites due to HNV and SSV.

[The identification of Bungarus multicinctus multicinctus and its confused species by SDS-PAGE].

The comparative study of the proteins of Bungarus multicinctus multicinctus and Natrix annularis was carried out by SDS-PAGE. The results showed that there were significant differences between their SDS-PAGE figures. On the basis of the study the molecular weights of their characteristic proteins were determined. The results could be regarded as a reference for identification of Bungarus multicinctus multicinctus and its confused species.

[Identification of powdered Bungarus multieinctus Blyth and its adulterants].

This paper reports the results of identification of powdered Bungarus muliteinctus and its adulterants (Natrix annularis; Dinodon rufozonatum and Bungarus fascitus). A comparative table of and a key to the characteristics are given.

[Sequencing of Cyt b gene fragments and PCR identification of "jinqian baihuashe" (Bungarus parvus) and its adulterants].

DNAs extracted from both "Jinqian Baihuashe" (Bungarus parvus) and its adulterants and original animals of the crude snake drugs were used as templates for Cyt b gene fragment amplification. The sequence data of the fragments showed that the differences of the sequence between Bungarus parvus and its adulterants were far greater than that between intraspecific variations of Bungarus parvus. Therefore, the Cyt b gene fragment was a good molecular genetic marker for the authentication of Bungarus parvus. On the basis of the sequence data, a pair of specialized primers, BuL-1 and BuH-1 was designed for the PCR identification of Bungarus parvus. The effectiveness of the primers were examined at a series of anneal temperatures. The results showed that Bungarus parvus samples could be absolutely distinguished when the anneal temperatures were 60 degrees C-65 degrees C, whereas no incorrect or missing discrimination was found at these temperatures. The results also showed that the powder of Bungarus parvus which was mixed with powders of three other crude snake drugs may be detected by the PCR identification. This indicates that PCR identification may be a new method for examining the compositions of Chinese patent medicine.