Purification, crystallization and preliminary crystallographic analysis of a natural complex of phospholipase A2 from Echis carinatus (saw-scaled viper)

Revisiting saw-scaled viper (Echis carinatus) bites in the Jaffna Peninsula of Sri Lanka: distribution, epidemiology and clinical manifestations

In Sri Lanka, the saw-scaled viper (Echis carinatus) is distributed in the arid, dry and sandy coastal plains and in a prospective study we describe its bites in the Jaffna peninsula. Of the 304 snake bite admissions to the Jaffna Hospital in 2009, 217 (71.4%) were bitten by either venomous species or envenomed by unidentified snakes. There were 99 (45.6%) reported saw-scaled viper bites, of which 26 were confirmed cases. The length of the offending snakes ranged from 228-310mm and bites mainly occurred in the nearby islands. The median age of the confirmed cases was 34 years (range 1.5-72 years); occupations included housewives (8, 31%), school children (4, 15%) and farmers (2, 8%). In 18 patients (69%), bites occurred in daylight and in 8 (31%) within or near the compounds. The fingers were bitten in 8 (31%) and toes/foot in 11 (42%) cases. There were 2 (8%) dry bites and 19 patients (73%) developed local swelling; one patient developed haemorrhagic blisters. In 24 patients (92%), blood incoagulability manifested between 40 and 1095min after the bite, and three patients (12%) developed spontaneous bleeding. One patient (4%) developed mild acute renal dysfunction. The median time for correction of coagulopathy was 802min (range 180-1669min) with Indian polyvalent antivenom. All recovered. The saw scaled viper is responsible for most venomous bites in the Jaffna peninsula.

Molecular cloning of phospholipases A(2) from venom glands of Echis carpet vipers

Venom toxin-specific antibodies offer a more rational treatment of snake envenoming than conventional antivenom. Here, we describe novel cDNAs encoding phospholipase A(2) (PLA(2)) isoforms from venom gland RNA of Echis pyramidum leakeyi (Epl), Echis sochureki (Es) and Echis ocellatus (Eo). The deduced amino acid sequences of these cDNAs encoded proteins with high overall sequence identity to the viper group II PLA(2) protein family, including the 14 cysteine residues capable of forming seven disulphide bonds that characterize this group of PLA(2) enzymes. Comparison of the PLA(2) sequences from Echis with those from related vipers failed to make significant geographic, taxonomic or PLA(2)-function distinctions between these Echis PLA(2) isoforms. However, their deduced hydrophilicity profiles revealed a conserved tertiary structure that we will exploit, by epidermal DNA immunization, to generate PLA(2)-neutralizing antibodies with polyspecific potential.

Proteins from Mucuna pruriens and enzymes from Echis carinatus venom: characterization and cross-reactions

Mucuna pruriens seeds have been widely used against snakebite in traditional medicine. The antivenin property of a water extract of seeds was assessed in vivo in mice. The serum of mice treated with extract was tested for its immunological properties. Two proteins of Echis carinatus venom with apparent molecular masses of 25 and 16 kDa were detected by Western blot analysis carried out using IgG of mice immunized with extract or its partially purified protein fractions. By enzymatic in-gel digestion and electrospray ionization-mass spectrometry/mass spectrometry analysis of immunoreactive venom proteins, phospholipase A(2,) the most toxic enzyme of snake venom, was identified. These results demonstrate that the observed antivenin activity has an immune mechanism. Antibodies of mice treated with non-lethal doses of venom reacted against some proteins of M. pruriens extract. Proteins of E. carinatus venom and M. pruriens extract have at least one epitope in common as confirmed by immunodiffusion assay.