Identification of proteins interacting with ammodytoxins in Vipera ammodytes ammodytes venom by immuno-affinity chromatography

Production of a murine mAb against Bothrops alternatus and B. neuwiedi snake venoms and its use to isolate a thrombin-like serine protease fraction

Accidents with snakes from the genus Bothrops represent ~90 % of all snakebites in Brazil. Monoclonal antibodies (mAbs) targeting venom components can be important assets for treating envenoming syndromes, for developing diagnostic tests and for research purposes. Therefore, in this study, we aimed to generate murine mAbs against the antigenic mixture of Bothropic venoms traditionally used as immunogen to produce Bothropic antivenoms in Brazil. ELISA showed that one of the produced mAbs recognizes B. alternatus and B. neuwiedi venoms (mAb anti-Ba/Bn) specifically and Western Blot revealed that this mAb binds to a single protein band of molecular mass of ≈50 kDa. MAb anti-Ba/Bn inhibited the coagulant activity but was unable to neutralize hemorrhagic and phospholipase A2 activities caused by the B. neuwiedi venom. MAb anti-Ba/Bn was immobilized to Sepharose beads and used for immunoaffinity chromatography of B. neuwiedi venom. Proteolytic activity assays indicated that the immunoaffinity-purified fraction (BnF-Bothrops neuwiedi fraction) has a serine protease thrombin-like profile, which was supported by coagulability assays in mice. Bottom-up proteomic analysis confirmed the prevalence of serine proteases in BnF using label-free quantification. In conclusion, this work characterized a mAb with neutralizing properties against B. neuwiedi coagulant activity and demonstrates that immunoaffinity chromatography using mAbs can be a useful technique for purification of bioactive toxic proteins from Bothrops spp. snake venoms.

Affinity monolith chromatography: A review of general principles and recent developments

Affinity monolith chromatography (AMC) is a liquid chromatographic technique that utilizes a monolithic support with a biological ligand or related binding agent to isolate, enrich, or detect a target analyte in a complex matrix. The target-specific interaction exhibited by the binding agents makes AMC attractive for the separation or detection of a wide range of compounds. This article will review the basic principles of AMC and recent developments in this field. The supports used in AMC will be discussed, including organic, inorganic, hybrid, carbohydrate, and cryogel monoliths. Schemes for attaching binding agents to these monoliths will be examined as well, such as covalent immobilization, biospecific adsorption, entrapment, molecular imprinting, and coordination methods. An overview will then be given of binding agents that have recently been used in AMC, along with their applications. These applications will include bioaffinity chromatography, immunoaffinity chromatography, immobilized metal-ion affinity chromatography, and dye-ligand or biomimetic affinity chromatography. The use of AMC in chiral separations and biointeraction studies will also be discussed.

The first Kunitz-type proteins from a viperid venom that potentiate neuromuscular transmission

Kunitz-type proteins that interfere with neuronal transmission have been thus far exclusively detected in venoms of elapid snakes. Here, we report for the first time that such proteins are also present in the venom of a viperid snake. From the venom of the nose-horned viper (Vipera ammodytes ammodytes; Vaa), we isolated Kunitz-type chymotrypsin inhibitors (VaaChi) and demonstrated that these molecules also significantly increase the amplitudes of an indirectly evoked simple muscle contraction of the mouse hemidiaphragm, the end-plate potential and the miniature end-plate potential. By facilitating neuromuscular transmission, these proteins resemble structurally homologous dendrotoxins from mamba (Dendroaspis spp.) venoms, which are blockers of voltage-dependent K⁺ channels at the presynaptic site of the neuromuscular junction. What is the mechanism behind facilitation of neuromuscular transmission by VaaChi has not been established yet, however, blocking of K⁺ channels does not seem to be the most probable option.

Biological Activities and Proteomic Profile of the Venom of Vipera ursinii ssp., a very Rare Karst Viper from Croatia

The karst viper (Vipera ursinii ssp.) favours high-mountain dry grasslands in southern and south-eastern Croatia. It is medically less important than other Vipera species, because of its remote habitat and the very small amount of venom that it injects by its relatively short fangs. The scientific literature on Vipera ursinii deals mostly with the morphology, ecology and distribution range of this snake, due to the species’ conservation issues, while the toxinological aspects of its venom have not so far been investigated. Here we report on the composition and biological activity of the Vipera ursinii ssp. venom. Using a proteomics approach, we have identified 25 proteins in the venom that belong to seven protein families: snake venom metalloproteinase, serine protease, secreted phospholipase A₂, cysteine-rich secretory protein, snake C-type lectin-like protein, serine protease inhibitor and nerve growth factor. The Vipera ursinii ssp. venom was found to be distinctively insecticidal. Its lethal toxicity towards crickets was more than five times greater than that of Vipera ammodytes ammodytes venom, while the opposite held in mice. Interestingly, the mode of dying after injecting a mouse with Vipera ursinii ssp. venom may suggest the presence of a neurotoxic component. Neurotoxic effects of European vipers have so far been ascribed exclusively to ammodytoxins and ammodytoxin-like basic secreted phospholipases A₂. Structural and immunological analyses of the Vipera ursinii ssp. venom, however, confirmed that ammodytoxin-like proteins are not present in this venom.

Comprehensive Study of the Proteome and Transcriptome of the Venom of the Most Venomous European Viper: Discovery of a New Subclass of Ancestral Snake Venom Metalloproteinase Precursor-Derived Proteins

The nose-horned viper, its nominotypical subspecies Vipera ammodytes ammodytes (Vaa), in particular, is, medically, one of the most relevant snakes in Europe. The local and systemic clinical manifestations of poisoning by the venom of this snake are the result of the pathophysiological effects inflicted by enzymatic and nonenzymatic venom components acting, most prominently, on the blood, cardiovascular, and nerve systems. This venom is a very complex mixture of pharmacologically active proteins and peptides. To help improve the current antivenom therapy toward higher specificity and efficiency and to assist drug discovery, we have constructed, by combining transcriptomic and proteomic analyses, the most comprehensive library yet of the Vaa venom proteins and peptides. Sequence analysis of the venom gland cDNA library has revealed the presence of messages encoding 12 types of polypeptide precursors. The most abundant are those for metalloproteinase inhibitors (MPis), bradykinin-potentiating peptides (BPPs), and natriuretic peptides (NPs) (all three on a single precursor), snake C-type lectin-like proteins (snaclecs), serine proteases (SVSPs), P-II and P-III metalloproteinases (SVMPs), secreted phospholipases A₂ (sPLA₂s), and disintegrins (Dis). These constitute >88% of the venom transcriptome. At the protein level, 57 venom proteins belonging to 16 different protein families have been identified and, with SVSPs, sPLA₂s, snaclecs, and SVMPs, comprise ∼80% of all venom proteins. Peptides detected in the venom include NPs, BPPs, and inhibitors of SVSPs and SVMPs. Of particular interest, a transcript coding for a protein similar to P-III SVMPs but lacking the MP domain was also found at the protein level in the venom. The existence of such proteins, also supported by finding similar venom gland transcripts in related snake species, has been demonstrated for the first time, justifying the proposal of a new P-IIIe subclass of ancestral SVMP precursor-derived proteins.

Mass spectrometry-based investigation of measles and mumps virus proteome

Background

Measles (MEV) and mumps virus (MUV) are enveloped, non-segmented, negative single stranded RNA viruses of the family Paramyxoviridae, and are the cause of measles and mumps, respectively, both preventable by vaccination. Aside from proteins coded by the viral genome, viruses are considered to contain host cell proteins (HCPs). The presence of extracellular vesicles (ECVs), which are often co-purified with viruses due to their similarity in size, density and composition, also contributes to HCPs detected in virus preparations, and this has often been neglected. The aim was to identify which virus-coded proteins are present in MEV and MUV virions, and to try to detect which HCPs, if any, are incorporated inside the virions or adsorbed on their outer surface, and which are more likely to be a contamination from co-purified ECVs.

Methods

MUV, MEV and ECVs were purified by ultracentrifugation, hydrophobic interaction chromatography and immunoaffinity chromatography, proteins in the samples were resolved by SDS-PAGE and subjected to identification by MALDI-TOF/TOF-MS. A comparative analysis of HCPs present in all samples was carried out.

Results

By proteomics approach, it was verified that almost all virus-coded proteins are present in MEV and MUV particles. Protein C in MEV which was until now considered to be non-structural viral protein, was found to be present inside the MeV virions. Results on the presence of HCPs in differently purified virus preparations imply that actin, annexins, cyclophilin A, moesin and integrin β1 are part of the virions.

Conclusions

All HCPs detected in the viruses are present in ECVs as well, indicating their possible function in vesicle formation, or that most of them are only present in ECVs. Only five HCPs were constantly present in purified virus preparations, regardless of the purification method used, implying they are likely the integral part of the virions. The approach described here is helpful for further investigation of HCPs in other virus preparations.

Electronic supplementary material

The online version of this article (10.1186/s12985-018-1073-9) contains supplementary material, which is available to authorized users.

Development of dot-ELISA for the detection of venoms of major Indian venomous snakes

India remained an epicenter for the snakebite-related mortality and morbidities due to widespread agricultural activities across the country and a considerable number of snakebites offended by Indian cobra (Naja naja), common krait (Bungarus caeruleus), Russell's viper (Daboia russelii), and saw-scaled viper (Echis carinatus). Presently, there is no selective test available for the detection of snake envenomation in India before the administration of snake antivenin. Therefore, the present study aimed to develop rapid, sensitive assay for the management of snakebite, which can detect venom, responsible snake species and serve as a tool for the reasonable administration of snake antivenin, which have scarcity across the world. The selective envenomation detection assay needs venom specific antibodies (VSAbs) for that monovalent antisera was prepared by hyperimmunization of rabbits with specific venom. However, obtained antibodies exhibit maximum activity towards homologous venom as well as quantifiable degree of cross-reactivity with heterologous venoms. Use of these antibodies for development of selective envenomation detection assay may create ambiguity in results, therefore needs to isolate VSAbs from monovalent antisera. The cross-reacting antibodies were specifically removed by immunoaffinity chromatography to obtain VSAbs. For the development of venom detection ELISA test (VDET), two different species of antibodies were used that offers enhanced sensitivity along with selective identification of the venoms of the responsible snakes. In conclusion, the developed VDET is rapid, specific, yet sensitive to detect venoms of offending snake species, and its venom concentration down to 1.0 ng/ml. However, the device observed with lowest venom concentration detection ability in the range <1.0 ng/ml from experimentally envenomated samples. The implementation of VDET will help in avoiding unnecessary usage and adverse reactions of snake antivenin. The test has all the merits to become a choice of method in envenomation diagnosis from medically important snakes of India.

Optimization of tetanus toxoid ammonium sulfate precipitation process using response surface methodology

Tetanus toxoid (TTd) is a highly immunogenic, detoxified form of tetanus toxin, a causative agent of tetanus disease, produced by Clostridium tetani. Since tetanus disease cannot be eradicated but is easily prevented by vaccination, the need for the tetanus vaccine is permanent. The aim of this work was to investigate the possibility of optimizing TTd purification, i.e., ammonium sulfate precipitation process. The influence of the percentage of ammonium sulfate, starting amount of TTd, buffer type, pH, temperature, and starting purity of TTd on the purification process were investigated using optimal design for response surface models. Responses measured for evaluation of the ammonium sulfate precipitation process were TTd amount (Lf/mL) and total protein content. These two parameters were used to calculate purity (Lf/mgPN) and the yield of the process. Results indicate that citrate buffer, lower temperature, and lower starting amount of TTd result in higher purities of precipitates. Gel electrophoresis combined with matrix-assisted laser desorption ionization-mass spectrometric analysis of precipitates revealed that there are no inter-protein cross-links and that all contaminating proteins have pIs similar to TTd, so this is most probably the reason for the limited success of purification by precipitation.

Venomics of Vipera berus berus to explain differences in pathology elicited by Vipera ammodytes ammodytes envenomation: Therapeutic implications

Vipera berus berus (Vbb) is the most widely distributed and Vipera ammodytes ammodytes (Vaa) the most venomous viper in Europe. In particular areas of the Old continent their toxic bites constitute a considerable public health problem. To make the current envenomation therapy more effective we have analysed the proteome of Vbb venom and compared it with that of Vaa. We found the proteome of Vbb to be much less complex and to contain smaller levels of particularly snaclecs and sPLA2s. Snaclecs are probably responsible for thrombocytopenia. The neurotoxic sPLA2s, ammodytoxins, are responsible for the most specific feature of the Vaa venom poisoning - induction of signs of neurotoxicity in patients. These molecules were not found in Vbb venom. Both venoms induce haemorrhage and coagulopathy in man. As Vaa and Vbb venoms possess homologous P-III snake venom metalloproteinases, the main haemorrhagic factors, the severity of the haemorrhage is dictated by concentration and specific activity of these molecules. The much greater anticoagulant effect of Vaa venom than that of Vbb venom lies in its higher extrinsic pathway coagulation factor-proteolysing activity and content of ammodytoxins which block the prothrombinase complex formation.

BIOLOGICAL SIGNIFICANCE

Envenomations by venomous snakes constitute a considerable public health problem worldwide, and also in Europe. In the submitted work we analysed the venom proteome of Vipera berus berus (Vbb), the most widely distributed venomous snake in Europe and compared it with the venom proteome of the most venomous viper in Europe, Vipera ammodytes ammodytes (Vaa). We have offered a possible explanation, at the molecular level, for the differences in clinical pictures inflicted by the Vbb and Vaa venoms. We have provided an explanation for the effectiveness of treatment of Vbb envenomation by Vaa antiserum and explained why full protection of Vaa venom poisoning by Vbb antiserum should not be always expected, especially not in cases of severe poisoning. The latter makes a strong case for Vaa antiserum production as we are faced with its shortage due to ceasing of production of two most frequently used products.

Development and characteristics of polymer monoliths for advanced LC bioscreening applications: A review

Biomedical research advances over the past two decades in bioseparation science and engineering have led to the development of new adsorbent systems called monoliths, mostly as stationary supports for liquid chromatography (LC) applications. They are acknowledged to offer better mass transfer hydrodynamics than their particulate counterparts. Also, their architectural and morphological traits can be tailored in situ to meet the hydrodynamic size of molecules which include proteins, pDNA, cells and viral targets. This has enabled their development for a plethora of enhanced bioscreening applications including biosensing, biomolecular purification, concentration and separation, achieved through the introduction of specific functional moieties or ligands (such as triethylamine, N,N-dimethyl-N-dodecylamine, antibodies, enzymes and aptamers) into the molecular architecture of monoliths. Notwithstanding, the application of monoliths presents major material and bioprocess challenges. The relationship between in-process polymerisation characteristics and the physicochemical properties of monolith is critical to optimise chromatographic performance. There is also a need to develop theoretical models for non-invasive analyses and predictions. This review article therefore discusses in-process analytical conditions, functionalisation chemistries and ligands relevant to establish the characteristics of monoliths in order to facilitate a wide range of enhanced bioscreening applications. It gives emphasis to the development of functional polymethacrylate monoliths for microfluidic and preparative scale bio-applications.

Identification of mumps virus protein and lipid composition by mass spectrometry

Background

Mumps virus is a negative-sense, single stranded RNA virus consisting of a ribonucleocapsid core enveloped by a lipid membrane derived from host cell, which causes mumps disease preventable by vaccination. Since virus lipid envelope and glycosylation pattern are not encoded by the virus but dependent on the host cell at least to some extent, the aim of this work was to analyse L-Zagreb (L-Zg) mumps virus lipids and proteins derived from two cell types; Vero and chicken embryo fibroblasts (CEF). Jeryl Lynn 5 (JL5) mumps strain lipids were also analysed.

Methods

Virus lipids were isolated by organic phase extraction and subjected to 2D-high performance thin layer chromatography followed by lipid extraction and identification by matrix-assisted laser desorption/ionization mass spectrometry (MALDI MS). Virus samples were also subjected to gel electrophoresis under denaturating conditions and protein bands were excised, in-gel trypsinized and identified by MS as well as tandem MS.

Results

Results showed that lipids of both mumps virus strains derived from Vero cells contained complex glycolipids with up to five monosaccharide units whereas the lipid pattern of mumps virus derived from CEF was less complex. Mumps virus was found to contain expected structural proteins with exception of fusion (F) protein which was not detected but on the other hand, V protein was detected. Most interesting finding related to the mumps proteins is the detection of several forms of nucleoprotein (NP), some of which appear to be C-terminally truncated.

Conclusions

Differences found in lipid and protein content of mumps virus demonstrated the importance of detailed biochemical characterization of mumps virus and the methodology described here could provide a means for a more comprehensive quality control in vaccine production.

Electronic supplementary material

The online version of this article (doi:10.1186/s12985-016-0463-0) contains supplementary material, which is available to authorized users.

Chip electrophoretic separation of highly homologous ammodytoxin isoforms: three neurotoxic phospholipases A2 of Vipera ammodytes ammodytes venom

Ammodytoxins (Atxs), a group of Ca(2+) -dependent neurotoxic phospholipases A2 of Vipera ammodytes ammodytes venom, are mainly responsible for venom toxicity. Within the Atx group, LD50 values between three isoforms, A, B, and C are differing with AtxA exhibiting an LD50 value by an order of magnitude lower (more toxic) than the other two isoforms. This difference in toxicity justifies the necessity to prepare suitable antibodies and thus isoform separation to characterize the Atx content of Vipera ammodytes ammodytes venom is of importance. However, a high homology between the three Atx isoforms (differences in only two, respectively, three residues within the last 18 amino acids at the C-terminus, total length 122 residues) hindered the successful separation of isoforms to date. As the investigated phospholipases A2 were reported to exhibit differences in pI values, we concentrate with the current work on the separation of Atx isoforms after fluorescence labeling via chip electrophoresis on a commercially available instrument to build the basis for a fast and easy to handle screening method. In the course of our work, we were able to show that samples of AtxA, AtxB, and AtxC declared to be homogenous by standard analytical techniques consisted indeed of more than one isoform of which the relative amounts were calculated by using the newly developed method.