Bungarus fasciatus venom from eastern and north-east India: venom variation and immune cross-reactivity with Indian polyvalent antivenoms

Bungarus fasciatus is one of the medically important elapid snakes of South and South-eastern Asia and is responsible for several snakebite incidents some of which were fatal. In this study, the venom compositional variation of Bungarus fasciatus from three different geographical locations in eastern and north-east India: two adjacent villages of Hooghly (West Bengal), Aizawl (Mizoram) and Guwahati (Assam) are reported. In vitro biochemical assays exhibit variation in phospholipase A2 activity, fibrinogenolytic activity, caseinolytic activity and anti-coagulation activity. The immunoreactivity of three Indian polyvalent antivenoms against the venoms revealed incomplete recognition. Bharat Serums antivenom demonstrated that at a venom–antivenom ratio of 1:16, the antivenom exhibited different immunocapturing abilities for all the venom samples. The percentage of non-retained fractions was highest for Guwahati (60.00%) and lowest for Hooghly 1 (18.91%). The study demonstrates intra-population (or inter-individual) variation of B. fasciatus venom from two nearby locations of Hooghly (West Bengal), intra-specific variation of B. fasciatus from three geographical locations and also inter-specific venom variation with B. caeruleus from Tamil Nadu. Thus, the venom variation leads to partial immune cross-reactivity by Indian polyvalent antivenoms. Inclusion of non-recognized venom proteins in the immunization mixture during antivenom production would help to improve the efficacy of the antivenom. Further study of the neutralizing ability of Indian polyvalent antivenoms against medically important snakes from different geographical regions would help to understand the effectiveness of the antivenoms and would invariably assist in the designing and development of safe and effective antivenoms

Rational truncation of aptamer for cross-species application to detect krait envenomation

Abstract In majority of snakebite cases, the snake responsible for the bite remains unidentified. The traditional snakebite diagnostics method relies upon clinical symptoms and blood coagulation assays that do not provide accurate diagnosis which is important for epidemiological as well as diagnostics point of view. On the other hand, high batch-to-batch variations in antibody performance limit its application for diagnostic assays. In recent years, nucleic acid aptamers have emerged as a strong chemical rival of antibodies due to several obvious advantages, including but not limited to in vitro generation, synthetic nature, ease of functionalization, high stability and adaptability to various diagnostic formats. In the current study, we have rationally truncated an aptamer developed for α-Toxin of Bungarus multicinctus and demonstrated its utility for the detection of venom of Bungarus caeruleus. The truncated aptamer α-Tox-T2 (26mer) is found to have greater affinity than its 40-mer parent counterpart α-Tox-FL. The truncated aptamers are characterized and compared with parent aptamer for their binding, selectivity, affinity, alteration in secondary structure and limit of detection. Altogether, our findings establish the cross-species application of a DNA aptamer generated for α-Toxin of Bungarus multicinctus (a snake found in Taiwan and China) for the reliable detection of venom of Bungarus caeruleus (a snake found in the Indian subcontinent)

Molecular phylogeny reveals distinct evolutionary lineages of the banded krait, Bungarus fasciatus (Squamata, Elapidae) in Asia

The banded krait, Bungarus fasciatus is a widespread elapid snake, likely to comprise several distinct species in different geographic regions of Asia. Therefore, based on molecular phylogenetics and comparative morphology data, we present an overview of the systematic composition of the species to delimit potential biogeographic boundaries. Our phylogenetic analyses, based on four mitochondrial genes, reveal the existence of at least three evolutionary lineages within B. fasciatus, corresponding to Indo-Myanmar, Sundaic and eastern Asian lineages. We are convinced that there are at least three taxonomic entities within the nomen B. fasciatus and restrict the distribution of B. fasciatus sensu stricto to the Indo-Myanmar region. We also provide additional natural history data of the taxon from eastern India. Finally, we advocate further studies to establish the degree of reproductive isolation among these diverging evolutionary lineages and to reassess the systematic status of this species complex especially the Sundaic and eastern Asian lineages

Molecular phylogenetic analysis of the genus Gloydius (Squamata, Viperidae, Crotalinae), with description of two new alpine species from Qinghai-Tibet Plateau, China

We provide a molecular phylogeny of Asian pit vipers (the genus Gloydius) based on four mitochondrial genes (12S, 16S, ND4, and cytb). Sequences of Gloydius himalayanus, the only member of the genus that occurs south of the Himalayan range, are included for the first time. In addition, two new species of the genus Gloydius are described based on specimens collected from Zayu, Tibet, west of the Nujiang River and Heishui, Sichuan, east of the Qinghai-Tibet Plateau. The new species, Gloydius lipipengi sp. nov., can be differentiated from its congeners by the combination of the following characters: the third supralabial not reaching the orbit (separated from it by a suborbital scale); wide, black-bordered greyish postorbital stripe extending from the posterior margin of the orbit (not separated by the postoculars, covering most of the anterior temporal scale) to the ventral surface of the neck; irregular black annular crossbands on the mid-body; 23-21-15 dorsal scales; 165 ventral scales, and 46 subcaudal scales. Gloydius swild sp. nov. can be differentiated from its congeners by the narrower postorbital stripe (only half the width of the anterior temporal scale, the lower edge is approximately straight and bordered with white); a pair of arched stripes on the occiput; lateral body lakes black spots; a pair of round spots on the parietal scales; 21 rows of mid-body dorsal scales; zigzag dark brown stripes on the dorsum; 168–170 ventral scales, and 43–46 subcaudal scales. The molecular phylogeny in this study supports the sister relationship between G. lipipengi sp. nov. and G. rubromaculatus, another recently described species from the Qinghai-Tibet Plateau, more than 500 km away, and indicate the basal position of G. himalayanus within the genus and relatively distant relationship to its congeners

Phylogenetic and morphological analysis of Gloydius himalayanus (Serpentes, Viperidae, Crotalinae), with the description of a new species

Gloydius is a widespread pitviper group occurring from Eastern Europe to Korea and Siberia, with only one known species, G. himalayanus (Günther, 1864), found south of the Himalayas. We provide combined genetic and morphological data for G. himalayanus from specimens collected from Himachal Pradesh, India. Bayesian Inference and Maximum Likelihood phylogenetic analysis were performed on four concatenated mitochondrial genes, along with a multi-locus coalescent analysis of these and five additional nuclear genes. Our results indicate that G. himalayanus from the Chamba Valley, in western Himachal Pradesh, are highly distinct from the remaining studied populations. Haplotype networks of each nuclear locus showed that G. himalayanus contains high haplotype diversity with low haplotype sharing between the Chamba Valley population and populations from further west. Principal component analysis and canonical variate analysis conducted on morphological data of live and museum specimens also highlight the morphological distinctiveness of the Chamba population and we herein describe this population as a new species, Gloydius chambensis sp. nov. Recent descriptions of other new species of snakes from this valley underscores its isolation and suggests that further herpetological investigation of the highly dissected landscapes of the western Himalayas is needed to assess the true diversity of the region