Purification and characterization of BmooAi: a new toxin from Bothrops moojeni snake venom that inhibits platelet aggregation

Comparative compositional and functional analyses of Bothrops moojeni specimens reveal several individual variations

Snake venoms are complex protein mixtures with different biological activities that can act in both their preys and human victims. Many of these proteins play a role in prey capture and in the digestive process of these animals. It is known that some snakes are resistant to the toxicity of their own venom by mechanisms not yet fully elucidated. However, it was observed in the Laboratory of Herpetology of Instituto Butantan that some Bothrops moojeni individuals injured by the same snake species showed mortalities caused by envenoming effects. This study analyzed the biochemical composition of 13 venom and plasma samples from Bothrops moojeni specimens to assess differences in their protein composition. Application of sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) showed distinct venom protein profiles, but very homogeneous plasma profiles. Western Blotting (WB) was performed with plasma samples, which were submitted to incubation with the respective venom. Some individuals showed an immunorecognized band zone around 25 kDa, indicating interaction between the same individual plasma and venom proteins. Crossed-WB assay using non-self-plasma and venom showed that this variability is due to venom protein composition instead of plasma composition. These venoms presented higher caseinolytic, collagenolytic and coagulant activities than the venoms without these regions recognized by WB. Mass spectrometry analyses performed on two individuals revealed that these individuals present, in addition to higher protein concentrations, other exclusive proteins in their composition. When these same two samples were tested in vivo, the results also showed higher lethality in these venoms, but lower hemorrhagic activity than in the venoms without these regions recognized by WB. In conclusion, some Bothrops moojeni specimens differ in venom composition, which may have implications in envenomation. Moreover, the high individual venom variability found in this species demonstrates the importance to work with individual analyses in studies involving intraspecific venom variability and venom evolution.

Inhibition of bovine platelets aggregation in response to Hyalomma anatolicum salivary gland proteins/peptides

Aim:

Ticks are obligate ectoparasites that have an impact on wide range of vertebrates and also act as a potential vector for the transmission of tropical theileriosis, babesiosis, etc., causing significant loss to livestock production worldwide. While feeding, they introduce their saliva containing different bioactive molecules into the host. These molecules have the capability to counteract the host hemostatic mechanism to suck host blood successfully. Therefore, the study was aimed to isolate anti-platelet aggregating peptides from salivary gland extract (SGE) of Hyalomma anatolicum ticks, a commonly available tick in India.

Materials and Methods:

Female H. anatolicum salivary glands were dissected out and SGE was prepared by homogenizing it in a suitable buffer under ice. Extract so obtained was fractionated by gel filtration chromatography using Sephacryl S-200 column. Total protein concentration in fractions was estimated and bovine platelets were isolated, stimulated with thrombin (positive control), treated with Gly-Pro-Arg-Pro amide (negative control) and with salivary gland fractions for identification of proteins/peptides having anti-platelet aggregating activities.

Results:

Proteins/peptides present in various salivary gland fractions inhibited the bovine platelet aggregation and the percent inhibition ranged between 33% and 35.8%.

Conclusion:

The results suggests that the fractions of H. anatolicum salivary glands possess thrombin-induced anti-platelet aggregating activity and which could be further exploited for raising anti-tick vaccine and also for therapeutic purpose.

Bioinformatics-Aided Venomics

Venomics is a modern approach that combines transcriptomics and proteomics to explore the toxin content of venoms. This review will give an overview of computational approaches that have been created to classify and consolidate venomics data, as well as algorithms that have helped discovery and analysis of toxin nucleic acid and protein sequences, toxin three-dimensional structures and toxin functions. Bioinformatics is used to tackle specific challenges associated with the identification and annotations of toxins. Recognizing toxin transcript sequences among second generation sequencing data cannot rely only on basic sequence similarity because toxins are highly divergent. Mass spectrometry sequencing of mature toxins is challenging because toxins can display a large number of post-translational modifications. Identifying the mature toxin region in toxin precursor sequences requires the prediction of the cleavage sites of proprotein convertases, most of which are unknown or not well characterized. Tracing the evolutionary relationships between toxins should consider specific mechanisms of rapid evolution as well as interactions between predatory animals and prey. Rapidly determining the activity of toxins is the main bottleneck in venomics discovery, but some recent bioinformatics and molecular modeling approaches give hope that accurate predictions of toxin specificity could be made in the near future.