Sequence identity and antigenic cross-reactivity of white face hornet venom allergen, also a hyaluronidase, with other proteins

Proteomic analyses of venom from a Spider Hawk, Pepsis decorata

Background

The composition of the venom from solitary wasps is poorly known, although these animals are considered sources of bioactive substances. Until the present moment, there is only one proteomic characterization of the venom of wasps of the family Pompilidae and this is the first proteomic characterization for the genus Pepsis.

Methods

To elucidate the components of Pepsis decorata venom, the present work sought to identify proteins using four different experimental conditions, namely: (A) crude venom; (B) reduced and alkylated venom; (C) trypsin-digested reduced and alkylated venom, and; (D) chymotrypsin-digested reduced and alkylated venom. Furthermore, three different mass spectrometers were used (Ion Trap-Time of Flight, Quadrupole-Time of Flight, and Linear Triple Quadruple).

Results

Proteomics analysis revealed the existence of different enzymes related to the insect's physiology in the venom composition. Besides toxins, angiotensin-converting enzyme (ACE), hyaluronidase, and Kunitz-type inhibitors were also identified.

Conclusion

The data showed that the venom of Pepsis decorata is mostly composed of proteins involved in the metabolism of arthropods, as occurs in parasitic wasps, although some classical toxins were recorded, and among them, for the first time, ACE was found in the venom of solitary wasps. This integrative approach expanded the range of compounds identified in protein analyses, proving to be efficient in the proteomic characterization of little-known species. It is our understanding that the current work will provide a solid base for future studies dealing with other Hymenoptera venoms.

Recombinant antigen 5 from Polybia paulista wasp venom (Hymenoptera, Vespidae): Antigen-specific antibody production and functional profile of CD4+ T cells in the immune response

Polybia paulista is a neotropical social wasp related to severe accidents and allergic reactions cases, including anaphylaxis, in southeastern Brazil. Antigen 5 (Poly p 5) is a major allergenic protein from its venom with potential use for component-resolved diagnostic. Therefore, the previous characterization of the immune response profile triggered by Poly p 5 should be evaluated. Recombinant Poly p 5 (rPoly p 5) was used to sensitize BALB/c mice with six weekly intradermal doses, and the specific antibody production and the functional profile of CD4+ T cells were assessed. rPoly p 5 induced the production of specific immunoglobulins (sIg) sIgE, sIgG1 and sIgG2a, which could recognize natural Poly p 5 presented in the venom of four different wasp species. rPoly p 5 stimulated in vitro the CD4+ T cells from immunized mice, which showed a significant proliferative response. These antigen-specific CD4+T cells produced IFN-γ and IL-17A cytokines and increased ROR-γT transcription factor expression. No differences between the control group and sensitized mice were found in IL-4 production and GATA-3 and T-bet expression. Interestingly, increased CD25+FoxP3+ regulatory T cells (Tregs) frequency was observed in the splenocyte cell cultures from rPoly p 5 immunized mice after the in vitro stimulation with both P. paulista venom extract and rPoly p 5. Here we showed that rPoly p 5 induces antigen-specific antibodies capable of recognizing Antigen 5 in the venom of four wasp species and modulates antigen-specific CD4+ T cells to IFN-γ production response associated with a Th17 profile in sensitized mice. These findings emphasize the potential use of rPoly p 5 as an essential source of a major wasp allergen with significant immunological properties.

Bioactive Peptides and Proteins from Wasp Venoms

Wasps, members of the order Hymenoptera, use their venom for predation and defense. Accordingly, their venoms contain various constituents acting on the circulatory, immune and nervous systems. Wasp venom possesses many allergens, enzymes, bioactive peptides, amino acids, biogenic amines, and volatile matters. In particular, some peptides show potent antimicrobial, anti-inflammatory, antitumor, and anticoagulant activity. Additionally, proteinous components from wasp venoms can cause tissue damage or allergic reactions in organisms. These bioactive peptides and proteins involved in wasp predation and defense may be potential sources of lead pharmaceutically active molecules. In this review, we focus on the advances in bioactive peptides and protein from the venom of wasps and their biological effects, as well as the allergic reactions and immunotherapy induced by the wasp venom.

Functional Profile of Antigen Specific CD4+ T Cells in the Immune Response to Phospholipase A1 Allergen from Polybia paulista Venom

Insect venom can cause systemic allergic reactions, including anaphylaxis. Improvements in diagnosis and venom immunotherapy (VIT) are based on a better understanding of an immunological response triggered by venom allergens. Previously, we demonstrated that the recombinant phospholipase A1 (rPoly p 1) from Polybia paulista wasp venom induces specific IgE and IgG antibodies in sensitized mice, which recognized the native allergen. Here, we addressed the T cell immune response of rPoly p 1-sensitized BALB/c mice. Cultures of splenocytes were stimulated with Polybia paulista venom extract and the proliferation of CD8⁺ and CD4⁺ T cells and the frequency of T regulatory cells (Tregs) populations were assessed by flow cytometry. Cytokines were quantified in cell culture supernatants in ELISA assays. The in vitro stimulation of T cells from sensitized mice induces a significant proliferation of CD4⁺ T cells, but not of CD8⁺ T cells. The cytokine pattern showed a high concentration of IFN-γ and IL-6, and no significant differences to IL-4, IL-1β and TGF-β1 production. In addition, the rPoly p 1 group showed a pronounced expansion of CD4⁺CD25⁺FoxP3⁺ and CD4⁺CD25^-FoxP3⁺ Tregs. rPoly p 1 sensitization induces a Th1/Treg profile in CD4⁺ T cell subset, suggesting its potential use in wasp venom immunotherapy.

Proteomic and toxinological characterization of Peruvian pitviper Bothrops brazili ("jergón shushupe"), venom

Bothrops brazili is a pitviper from Amazonian region, responsible for many accidents in Peru. Despite its relevance, its venom has not been extensively characterized. In the present work, Bothrops brazili venom (BbV) components were analyzed by RP-HPLC, SDS-PAGE and MALDI-TOF/TOF. Approximately 37 proteins were identified, belonging to 7 families. Snake venom metalloproteinases (SVMPs) were the most abundant proteins of the venom (33.05%), followed by snake venom serine proteinases (SVSPs, 26.11%), phospholipases A₂ (PLA₂, 25.57%), snake C-type lectins (CTLs, 9.61%), L-aminoacid oxidase (LAAO, 3.80%), cystein-rich secretory proteins (CRISP, 1.67%) and Bradykinin-potentiating peptide (BPP, 0.20%). In vitro enzymatic activities of BbV showed high levels of SVMP activity and reduced Hyal activity in comparison with other bothropic venoms. Furthermore, BbV reduced VERO cells viability. ELISA and Western Blotting showed that both Peruvian and Brazilian bothropic antivenoms were able to recognize BbV components. This work provides an overview of BbV venom content and indicates a potential efficiency of Peruvian and Brazilian antivenoms to treat accidents with this species.

Isolation and characterization of Conohyal-P1, a hyaluronidase from the injected venom of Conus purpurascens

Hyaluronidases are ubiquitous enzymes commonly found in venom and their main function is to degrade hyaluran, which is the major glycosaminoglycan of the extracellular matrix in animal tissues. Here we describe the purification and characterization of a 60kDa hyaluronidase found in the injected venom from Conus purpurascens, Conohyal-P1. Using a combined strategy based on transcriptomic and proteomic analysis, we determined the Conohyal-P1 sequence. Conohyal-P1 has conserved consensus catalytic and positioning domain residues characteristic of hyaluronidases and a C-terminus EGF-like domain. Additionally, the enzyme is expressed as a mixture of glycosylated isoforms at five asparagine sites. The activity of the native Conohyal-P1 was assess MS-based methods and confirmed by classical turbidimetric methods. The MS-based assay is particularly sensitive and provides the first detailed analysis of a venom hyaluronidase activity monitored with this method. The discovery of new hyaluronidases and the development of techniques to evaluate their performance can advance several therapeutic procedures, as these enzymes are widely used for enhanced drug delivery applications.

BIOLOGICAL SIGNIFICANCE

Cone snail venom is a remarkable source of therapeutically important molecules, as is the case of conotoxins, which have undergone extensive clinical trials for several applications. In addition to the conotoxins, a large array of proteins have been reported in the venom of several species of cone snails, including enzymes that were found in dissected and injected Conus venom. Here we describe the isolation and characterization of the hyaluronidase Conohyal-P1 from the injected venom of C. purpurascens. We employed a combined transcriptomic and proteomic analysis to obtain the full sequence of this hyaluronidase. The activity of Conohyal-P1 was assessed by a mass spectrometry-based method, which provide the first detailed venom hyaluronidase activity analysis monitored by mass spectrometry allowing the visualization of the substrate degradation by the enzyme.

Cloning, structural modelling and characterization of VesT2s, a wasp venom hyaluronidase (HAase) from Vespa tropica

Background

Wasp venom is a complex mixture containing proteins, enzymes and small molecules, including some of the most dangerous allergens. The greater banded wasp (Vespa tropica) is well-known for its lethal venom, whose one of the major components is a hyaluronidase (HAase). It is believed that the high protein proportion and activity of this enzyme is responsible for the venom potency.

Methods

In the present study, cDNA cloning, sequencing and 3D-structure of Vespa tropica venom HAase were described. Anti-native HAase antibody was used for neutralization assay.

Results

Two isoforms, VesT2a and VesT2b, were classified as members of the glycosidase hydrolase 56 family with high similarity (42–97 %) to the allergen venom HAase. VesT2a gene contained 1486 nucleotide residues encoding 357 amino acids whereas the VesT2b isoform consisted of 1411 residues encoding 356 amino acids. The mature VesT2a and VesT2b are similar in mass and pI after prediction. They are 39119.73 Da/pI 8.91 and 39571.5 Da/pI 9.38, respectively. Two catalytic residues in VesT2a, Asp107 and Glu109 were substituted in VesT2b by Asn, thus impeding enzymatic activity. The 3D-structure of the VesT2s isoform consisted of a central core (α/β)₇ barrel and two disulfide bridges. The five putative glycosylation sites (Asn79, Asn99, Asn127, Asn187 and Asn325) of VesT2a and the three glycosylation sites (Asn1, Asn66 and Asn81) in VesT2b were predicted. An allergenic property significantly depends on the number of putative N-glycosylation sites. The anti-native HAase serum specifically recognized to venom HAase was able to neutralize toxicity of V. tropica venom. The ratio of venom antiserum was 1:12.

Conclusions

The wasp venom allergy is known to cause life-threatening and fatal IgE-mediated anaphylactic reactions in allergic individuals. Structural analysis was a helpful tool for prediction of allergenic properties including their cross reactivity among the vespid HAase.

Comparative proteomic analysis of two wasps venom, Vespa tropica and Vespa affinis

Vespid venom is composed of many bioactive compounds. The venom of the banded tiger wasp (Vespa affinis, or VA) and the great banded wasp (Vespa tropica, or VT)-which are locally found in the northeastern part of Thailand and are well known for their life-threatening venom potency-were comparatively studied in terms of potency, composition and biological activity. Clinical studies that included word-of-mouth information shared by traditional healers in local areas noted that the venom of VT is more potent than that of VA. Our previous study showed that the venom of VA is lower in potency (PD50 = 12.5 μg/g body weight) than that of VT (PD50 = 3 μg/g body weight). Analysis with the PAGE technique showed that these two venoms showed similar patterns of active proteins. Most protein spots were basic proteins at an isoelectric point (pI) ranging from 5 to 10, with molecular weights between 27 and 50 kDa. These spots were identified as hyaluronidase, phospholipase, antigen 5, dipeptidyl peptidase and albumin-like protein. The proportion of hyaluronidase was 2.5 times higher in VT than in VA. VT also showed higher hyaluronidase, phospholipase and dipeptidyl peptidase activities, suggesting that these components made VT venom more potent than VA venom.

Sequence diversity and ligand-induced structural rearrangements of viper hyaluronidase

The study focuses on ligand-induced structural changes of viper hyaluronidase and also provides insight into structure-based drug design for eukaryotic hyaluronidases, which could be future drug targets in cancer treatment, and venom spreading.

Arthropod venom Hyaluronidases: biochemical properties and potential applications in medicine and biotechnology

Hyaluronidases are enzymes that mainly degrade hyaluronan, the major glycosaminoglycan of the interstitial matrix. They are involved in several pathological and physiological activities including fertilization, wound healing, embryogenesis, angiogenesis, diffusion of toxins and drugs, metastasis, pneumonia, sepsis, bacteremia, meningitis, inflammation and allergy, among others. Hyaluronidases are widely distributed in nature and the enzymes from mammalian spermatozoa, lysosomes and animal venoms belong to the subclass EC 3.2.1.35. To date, only five three-dimensional structures for arthropod venom hyaluronidases (Apis mellifera and Vespula vulgaris) were determined. Additionally, there are four molecular models for hyaluronidases from Mesobuthus martensii, Polybia paulista and Tityus serrulatus venoms. These enzymes are employed as adjuvants to increase the absorption and dispersion of other drugs and have been used in various off-label clinical conditions to reduce tissue edema. Moreover, a PEGylated form of a recombinant human hyaluronidase is currently under clinical trials for the treatment of metastatic pancreatic cancer. This review focuses on the arthropod venom hyaluronidases and provides an overview of their biochemical properties, role in the envenoming, structure/activity relationship, and potential medical and biotechnological applications.

Purification and characterization of a hyaluronidase from venom of the spider Vitalius dubius (Araneae, Theraphosidae)

BACKGROUND

Venom hyaluronidase (Hyase) contributes to the diffusion of venom from the inoculation site. In this work, we purified and characterized Hyase from the venom of Vitalius dubius (Araneae, Theraphosidae), a large theraphosid found in southeastern Brazil. Venom obtained by electrical stimulation of adult male and female V. dubius was initially fractionated by gel filtration on a Superdex® 75 column. Active fractions were pooled and applied to a heparin-sepharose affinity column. The proteins were eluted with a linear NaCl gradient.

RESULTS

Active fractions were pooled and assessed for purity by SDS-PAGE and RP-HPLC. The physicochemical tests included optimum pH, heat stability, presence of isoforms, neutralization by flavonoids and assessment of commercial antivenoms. Hyase was purified and presented a specific activity of 148 turbidity-reducing units (TRU)/mg (venom: 36 TRU/mg; purification factor of ~4). Hyase displayed a molecular mass of 43 kDa by SDS-PAGE. Zymography in hyaluronic-acid-containing gels indicated an absence of enzyme isoforms. The optimum pH was 4-5, with highest activity at 37°C. Hyase was stable up to 60°C; but its activity was lost at higher temperatures and maintained after several freeze-thaw cycles. The NaCl concentration (up to 1 M) did not influence activity. Hyase had greater action towards hyaluronic acid compared to chondroitin sulfate, and was completely neutralized by polyvalent antiarachnid sera, but not by caterpillar, scorpion or snakes antivenoms.

CONCLUSION

The neutralization by arachnid but not scorpion antivenom indicates that this enzyme shares antigenic epitopes with similar enzymes in other spider venoms. The biochemical properties of this Hyase are comparable to others described.

The Cuban scorpion Rhopalurus junceus (Scorpiones, Buthidae): component variations in venom samples collected in different geographical areas

Backgound

The venom of the Cuban scorpion Rhopalurus junceus is poorly study from the point of view of their components at molecular level and the functions associated. The purpose of this article was to conduct a proteomic analysis of venom components from scorpions collected in different geographical areas of the country.

Results

Venom from the blue scorpion, as it is called, was collected separately from specimens of five distinct Cuban towns (Moa, La Poa, Limonar, El Chote and Farallones) of the Nipe-Sagua-Baracoa mountain massif and fractionated by high performance liquid chromatography (HPLC); the molecular masses of each fraction were ascertained by mass spectrometry analysis. At least 153 different molecular mass components were identified among the five samples analyzed. Molecular masses varied from 466 to 19755 Da. Scorpion HPLC profiles differed among these different geographical locations and the predominant molecular masses of their components. The most evident differences are in the relative concentration of the venom components. The most abundant components presented molecular weights around 4 kDa, known to be K⁺-channel specific peptides, and 7 kDa, known to be Na⁺-channel specific peptides, but with small molecular weight differences. Approximately 30 peptides found in venom samples from the different geographical areas are identical, supporting the idea that they all probably belong to the same species, with some interpopulational variations. Differences were also found in the presence of phospholipase, found in venoms from the Poa area (molecular weights on the order of 14 to 19 kDa). The only ubiquitous enzyme identified in the venoms from all five localities studied (hyaluronidase) presented the same 45 kD molecular mass, identified by gel electrophoresis analysis.

Conclusions

The venom of these scorpions from different geographical areas seem to be similar, and are rich in peptides that have of the same molecular masses of the peptides purified from other scorpions that affect ion-channel functions.

Component-resolved diagnosis of vespid venom-allergic individuals: phospholipases and antigen 5s are necessary to identify Vespula or Polistes sensitization

BACKGROUND

Cross-reactivity between hymenoptera species varies according to the different allergenic components of the venom. The true source of sensitization must therefore be established to ensure the efficacy of venom immunotherapy.

OBJECTIVE

In the Mediterranean region, Polistes dominulus and Vespula spp. are clinically relevant cohabitating wasps. A panel of major vespid venom allergens was used to investigate whether serum-specific IgE (sIgE) could be used to distinguish sensitization to either vespid.

METHODS

Fifty-nine individuals with allergic reactions to vespid stings and positive ImmunoCAP and/or intradermal tests to vespid venoms were studied. sIgE against recombinant and natural venom components from each wasp species was determined using the ADVIA Centaur(®) system.

RESULTS

sIgE against recombinant antigen 5s sensitization to be detected in 52% of the patients tested (13/25). The sensitivity increased to 80% (20/25), when using natural antigen 5s, and to 100% with the complete panel of purified natural components, because the sIgE was positive to either the antigen 5s (Pol d 5/Ves v 5) or to the phospholipases (Pol d 1/Ves v 1) of the two vespids, or to both components at the same time. In 69% of cases, it was possible to define the most probable sensitizing insect, and in the rest, possible double sensitization could not be excluded. Vespula hyaluronidase was shown to have no additional value as regards the specificity of the assay.

CONCLUSIONS

The major allergens of P. dominulus' and Vespula vulgaris' venom, namely phoshpholipases and antigen 5s, are required to discriminate the probable sensitizing species in vespid-allergic patients.

Cloning and molecular characterization of BmHYA1, a novel hyaluronidase from the venom of Chinese red scorpion Buthus martensi Karsch

In this communication, the full protein sequence of a novel venom hyaluronidase BmHYA1 was reported. It is the first full hyaluronidase amino acid sequence from scorpion venom. It was deduced from nucleotide sequence by 3' Rapid Amplification of cDNA Ends (RACE) PCR cloning, followed by alignment with the N-terminal amino acid sequence, which was obtained by Edman degradation. BmHYA1 has 385 amino acid residues containing five potential N-glycosylation sites. The phylogenetic analysis indicates early divergence and independent evolution of BmHYA1 from other hyaluronidases.

Reassessing the role of hyaluronidase in yellow jacket venom allergy

BACKGROUND

Yellow jacket hyaluronidase (YJ-HYA) is considered a major allergen in yellow jacket allergy. It shows 50% homology with the hyaluronidase from honeybee venom, Api m 2. Recently, IgE binding to YJ-HYA and cross-reactivity with Api m 2 has been shown to be due to cross-reactive carbohydrate determinants (CCDs).

OBJECTIVE

We sought to quantify the importance of YJ-HYA in yellow jacket allergy and the cross-reactivity with Api m 2 by discriminating between carbohydrate and peptide epitopes.

METHODS

IgE binding to Vespula species venom was studied by means of Western blotting in 136 patients with yellow jacket allergy (31 in vitro single positive to yellow jacket venom and 105 in vitro double-positive to yellow jacket-honeybee). Inhibition studies were carried out with MUXF-BSA (isolated bromelain glycopeptides linked to bovine serum albumin) and purified Api m 2.

RESULTS

Among yellow jacket single-positive sera, only 1 of 31 bound with YJ-HYA, whereas this was the case in 87% of 105 double-positive sera. Of 83 patients in whom inhibitions were performed, 65% reacted with hyaluronidase through CCDs alone, 27% reacted with both CCDs and peptide epitopes, and 8% reacted only with the hyaluronidase peptide. The protein-specific reactivity with YJ-HYA was cross-inhibited by Api m 2 in 48% (14/29). Antigen 5 and phospholipase A(1) were each recognized by around 90% of sera from both groups, together identifying 97% of patients.

CONCLUSION

Hyaluronidase is a minor yellow jacket venom allergen, and only 10% to 15% of patients with yellow jacket allergy are estimated to have IgE against the hyaluronidase protein. Peptide-specific cross-reactivity with Api m 2 occurs in half of these sera. Component-resolved diagnosis with antigen 5 and phospholipase would detect virtually all patients with yellow jacket venom allergy.

Comparative and functional genomics of lipases in holometabolous insects

Lipases have key roles in insect lipid acquisition, storage and mobilisation and are also fundamental to many physiological processes underpinning insect reproduction, development, defence from pathogens and oxidative stress, and pheromone signalling. We have screened the recently sequenced genomes of five species from four orders of holometabolous insects, the dipterans Drosophila melanogaster and Anopheles gambiae, the hymenopteran Apis mellifera, the moth Bombyx mori and the beetle Tribolium castaneum, for the six major lipase families that are also found in other organisms. The two most numerous families in the insects, the neutral and acid lipases, are also the main families in mammals, albeit not in Caenorhabditis elegans, plants or microbes. Total numbers of the lipases vary two-fold across the five insect species, from numbers similar to those in mammals up to numbers comparable to those seen in C. elegans. Whilst there is a high degree of orthology with mammalian lipases in the other four families, the great majority of the insect neutral and acid lipases have arisen since the insect orders themselves diverged. Intriguingly, about 10% of the insect neutral and acid lipases have lost motifs critical for catalytic function. Examination of the length of lid and loop regions of the neutral lipase sequences suggest that most of the insect lipases lack triacylglycerol (TAG) hydrolysis activity, although the acid lipases all have intact cap domains required for TAG hydrolysis. We have also reviewed the sequence databases and scientific literature for insights into the expression profiles and functions of the insect neutral and acid lipases and the orthologues of the mammalian adipose triglyceride lipase which has a pivotal role in lipid mobilisation. These data suggest that some of the acid and neutral lipase diversity may be due to a requirement for rapid accumulation of dietary lipids. The different roles required of lipases at the four discrete life stages of holometabolous insects may also contribute to the diversity of lipases required by insects. In addition, insects use lipases to perform roles for which there are no correlates in mammals, including as yolk and male accessory gland proteins.

Hymenoptera venom allergy: analysis of double positivity to honey bee and Vespula venom by estimation of IgE antibodies to species-specific major allergens Api m1 and Ves v5

BACKGROUND

In patients with hymenoptera venom allergy diagnostic tests are often positive with honey bee and Vespula venom causing problems in selection of venoms for immunotherapy.

METHODS

100 patients each with allergic reactions to Vespula or honey bee stings and positive i.e. skin tests to the respective venom, were analysed for serum IgE to bee venom, Vespula venom and crossreacting carbohydrate determinants (CCDs) by UNICAP (CAP) and ADVIA Centaur (ADVIA). IgE-antibodies to species specific recombinant major allergens (SSMA) Api m1 for bee venom and Ves v5 for Vespula venom, were determined by ADVIA. 30 history and skin test negative patients served as controls.

RESULTS

By CAP sensitivity was 1.0 for bee and 0.91 for Vespula venom, by ADVIA 0.99 for bee and 0.91 for Vespula venom. None of the controls were positive with either test. Double positivity was observed in 59% of allergic patients by CAP, in 32% by ADVIA. slgE to Api m1 was detected in 97% of bee and 17% of Vespula venom allergic patients, slgE to Ves v5 in 87% of Vespula and 17% of bee venom allergic patients. slgE to CCDs were present in 37% of all allergic patients and in 56% of those with double positivity and were more frequent in bee than in Vespula venom allergic patients.

CONCLUSIONS

Double positivity of IgE to bee and Vespula venom is often caused by crossreactions, especially to CCDs. IgE to both Api m1 and Ves v5 indicates true double sensitization and immunotherapy with both venoms.

Isolation and characterization of a hyaluronidase from the venom of Chinese red scorpion Buthus martensi

A hyaluronidase, named BmHYA1, was purified from the venom of Chinese red scorpion (Buthus martensi), using successive chromatography. The homogeneity of BmHYA1 was confirmed by SDS-PAGE and MALDI-TOF mass spectrometry. The molecular mass of BmHYA1 was 48,696 Da determined by MALDI-TOF MS. The optimal temperature and pH of BmHYA1 were 50 degrees C and pH 4.5, respectively. It could be inhibited by DTT, Cu(2+), Fe(3+) or heparin, but not Mg(2+), Ca(2+), reduced glutathione, l-cysteine or EDTA. The sequence of thirty N-terminal amino acids of BmHYA1 was obtained by Edman degradation, as TSADF KVVWE VPSIM CSKKF KICVT DLLTS; but no similarity was found to other venom hyaluronidases. Further, BmHYA1 can hydrolyze hyaluronan into relatively smaller oligosaccharides and modulate the expression of CD44 variant in the breast cancer cell line MDA-MB-231.

Sensitization to wasp venom does not induce autoantibodies leading to infertility

Antigenic cross-reactivity has been described between the venom allergen (antigen 5) and mammalian testis proteins. Based on an allergen database we have previously shown that allergens can be represented by allergen motifs. A motif group was found containing venom antigen 5 sequences from different vespids. Using an optimized amino acid profile based on antigen 5 sequences for searching cross-reactive proteins, three human semen proteins belonging to the family of cysteine-rich secretory proteins (hCRISP) were found in the Swiss Protein database. To analyze antigenic cross-reactivity between antigen 5 and hCRISPs, antigen 5 from yellow jacket venom (Ves v 5) and two hCRISPs (CRISP-2 and -3) were chosen and produced as recombinant proteins in E. coli. A correlation was found between antibodies reacting with rVes v 5 and rhCRISP-2, -3 in a small human sera population indicating the presence of cross-reactive antibodies in human serum. Using intravenous immunoglobulin (IVIg), a therapeutic multidonor IgG preparation, cross-reactive antibodies were isolated that recognize rVes v 5, hCRISP-2 and -3 suggesting the presence of common epitopes between Ves v 5 and hCRISPs. However this cross-reactivity seems not to be linked to allergy to wasp venom as we could show no correlation between increasing CAP-class IgE level to wasp venom and IgG to sperm extract and hCRISPs. These data suggest that higher sensitization to wasp venom does not induce more antibodies against autoantigens and might not represent a higher risk to develop autoantibodies leading to infertility.

A phospholipase A1 platelet activator from the wasp venom of Vespa magnifica (Smith)

Wasp is an important venomous animal that can induce human fatalities. Aortic thrombosis and cerebral infarction are major clinical symptoms after massive wasp stings but the reason leading to the envenomation manifestation is still not known. In this paper, a toxin protein is purified and characterized by Sephadex G-75 gel filtration, CM-Sephadex C-25 cationic exchange and fast protein liquid chromatography (FPLC) from the venom of the wasp, Vespa magnifica (Smith). This protein, named magnifin, contains phospholipase-like activity and induces platelet aggregation. The cDNA encoding magnifin is cloned from the venom sac cDNA library of the wasp. The predicted protein was deduced from the cDNA with a sequence composed of 337 amino acid residues. Magnifin is very similar to other phospholipase A(1) (PLA(1)), especially to other wasp allergen PLA(1). Magnifin can activate platelet aggregation and induce thrombosis in vivo. The current results proved that PLA(1) in wasp venom could be contributable to aortic thrombosis after massive wasp stings.

The magic glue hyaluronan and its eraser hyaluronidase: a biological overview

Hyaluronan (HA) is a multifunctional high molecular weight polysaccharide found throughout the animal kingdom, especially in the extracellular matrix (ECM) of soft connective tissues. HA is thought to participate in many biological processes, and its level is markedly elevated during embryogenesis, cell migration, wound healing, malignant transformation, and tissue turnover. The enzymes that degrade HA, hyaluronidases (HAases) are expressed both in prokaryotes and eukaryotes. These enzymes are known to be involved in physiological and pathological processes ranging from fertilization to aging. Hyaluronidase-mediated degradation of HA increases the permeability of connective tissues and decreases the viscosity of body fluids and is also involved in bacterial pathogenesis, the spread of toxins and venoms, acrosomal reaction/ovum fertilization, and cancer progression. Furthermore, these enzymes may promote direct contact between pathogens and the host cell surfaces. Depolymerization of HA also adversely affects the role of ECM and impairs its activity as a reservoir of growth factors, cytokines and various enzymes involved in signal transduction. Inhibition of HA degradation therefore may be crucial in reducing disease progression and spread of venom/toxins and bacterial pathogens. Hyaluronidase inhibitors are potent, ubiquitous regulating agents that are involved in maintaining the balance between the anabolism and catabolism of HA. Hyaluronidase inhibitors could also serve as contraceptives and anti-tumor agents and possibly have antibacterial and anti-venom/toxin activities. Additionally, these molecules can be used as pharmacological tools to study the physiological and pathophysiological role of HA and hyaluronidases.

Hymenoptera venom allergens

Hymenoptera venoms each contain a variety of protein allergens. The major components have all been characterized, and most of the amino acid sequences are known. This article concentrates on the use of contemporary techniques including cloning, mass spectrometry and genomics in the characterization of venom allergens, and newer separation techniques for protein isolation. Examples of the use of these techniques with venom proteins are presented.

Snake venom hyaluronidase: a therapeutic target

The diffusion of toxins from the site of a bite into the circulation is essential for successful envenomation. Degradation of hyaluronic acid in the extracellular matrix (ECM) by venom hyaluronidase is a key factor in this diffusion. Hyaluronidase not only increases the potency of other toxins but also damages the local tissue. In spite of its important role, little attention has been paid to this enzyme. Hyaluronidase exists in various isoforms and generates a wide range of hyaluronic acid degradation products. This suggests that beyond its role as a spreading factor venom hyaluronidase deserves to be explored as a possible therapeutic target for inhibiting the systemic distribution of venom and also for minimizing local tissue destruction at the site of the bite.

Insect sting allergy

Insect sting allergy has served as an excellent model for the allergic process over the past century. In particular, during the last 30 years, a new form of diagnostic testing and treatment with vo m has been one of the great suc-cess stories in the entire field of allergy. VIT reduces the risk of recurrent life-threatening reactions from about 60% to less than 2%. Progress and further questions continue with a search for a definitive diagnostic test that more accurately predicts which patients are at risk for future reactions, and defines which patients can stop VIT and which ones need to continue treatment.

The N-glycans of yellow jacket venom hyaluronidases and the protein sequence of its major isoform in Vespula vulgaris

Hyaluronidase (E.C. 3.2.1.35), one of the three major allergens of yellow jacket venom, is a glycoprotein of 45 kDa that is largely responsible for the cross-reactivity of wasp and bee venoms with sera of allergic patients. The asparagine-linked carbohydrate often appears to constitute the common IgE-binding determinant. Using a combination of MALDI MS and HPLC of 2-aminopyridine-labelled glycans, we found core-difucosylated paucimannosidic glycans to be the major species in the 43-45 kDa band of Vespula vulgaris and also in the corresponding bands of venoms from five other wasp species (V. germanica, V. maculifrons, V. pensylvanica, V. flavopilosa and V. squamosa). Concomitant peptide mapping of the V. vulgaris 43 kDa band identified the known hyaluronidase, Ves v 2 (SwissProt P49370), but only as a minor component. De novo sequencing by tandem MS revealed the predominating peptides to resemble a different, yet homologous, sequence. cDNA cloning retrieved a sequence with 58 and 59% homology to the previously known isoform and to the Dolichovespula maculata and Polistes annularis hyaluronidases. Close homologues of this new, putative hyaluronidase b (Ves v 2b) were also the major isoform in the other wasp venoms.

Molecular components and toxicity of the venom of the solitary wasp, Anoplius samariensis

The solitary spider wasp, Anoplius samariensis, is known to exhibit a unique long-term, non-lethal paralysis in spiders that it uses as a food source for its larvae. However, neither detailed venom components nor paralytic compounds have ever been characterized. In this study, we examined the components in the low molecular weight fraction of the venom and the paralytic activity of the high molecular weight fraction. The major low molecular weight components of the venom were identified as gamma-aminobutyric acid and glutamic acid by micro-liquid chromatography/electrospray ionization mass spectrometry and nuclear magnetic resonance spectrometry analysis. The sodium dodecyl sulfate-polyacrylamide gel electrophoresis and mass analysis revealed that the A. samariensis venom contained the various proteins with weights of 4-100 kDa. A biological assay using Joro spiders (Nephila clavata) clearly showed that the high molecular weight fraction of the venom prepared by ultrafiltration exerted as potent non-lethal long-term paralysis as the whole venom, whereas the low molecular weight fraction was devoid of any paralytic activity. These results indicated that several venomous proteins in the high molecular weight fraction are responsible for the paralytic activity. Furthermore, we determined the primary structure of one component designated As-fr-19, which was a novel multiple-cysteine peptide with high sequence similarity to several sea anemone and snake toxins including dendrotoxins, rather than any insect toxic peptides identified so far. Taken together, our data showed the unprecedented molecular and toxicological profiles of wasp venoms.

Midgut and salivary gland transcriptomes of the arbovirus vector Culicoides sonorensis (Diptera: Ceratopogonidae)

Numerous Culicoides spp. are important vectors of livestock or human disease pathogens. Transcriptome information from midguts and salivary glands of adult female Culicoides sonorensis provides new insight into vector biology. Of 1719 expressed sequence tags (ESTs) from adult serum-fed female midguts harvested within 5 h of feeding, twenty-eight clusters of serine proteases were derived. Four clusters encode putative iron binding proteins (FER1, FERL, PXDL1, PXDL2), and two clusters encode metalloendopeptidases (MDP6C, MDP6D) that probably function in bloodmeal catabolism. In addition, a diverse variety of housekeeping cDNAs were identified. Selected midgut protease transcripts were analysed by quantitative real-time PCR (q-PCR): TRY1_115 and MDP6C mRNAs were induced in adult female midguts upon feeding, whereas TRY1_156 and CHYM1 were abundant in midguts both before and immediately after feeding. Of 708 salivary gland ESTs analysed, clusters representing two new classes of protein families were identified: a new class of D7 proteins and a new class of Kunitz-type protease inhibitors. Additional cDNAs representing putative immunomodulatory proteins were also identified: 5' nucleotidases, antigen 5-related proteins, a hyaluronidase, a platelet-activating factor acetylhydrolase, mucins and several immune response cDNAs. Analysis by q-PCR showed that all D7 and Kunitz domain transcripts tested were highly enriched in female heads compared with other tissues and were generally absent from males. The mRNAs of two additional protease inhibitors, TFPI1 and TFPI2, were detected in salivary glands of paraffin-embedded females by in situ hybridization.

Identification by immunoblot of venom glycoproteins displaying immunoglobulin E-binding N-glycans as cross-reactive allergens in honeybee and yellow jacket venom

BACKGROUND

IgE antibodies against carbohydrate epitopes have been identified recently as a major cause of in vitro double positivity to honeybee (HB) and vespid venom in patients with stinging-insect allergy. As these antibodies possibly have low clinical relevance they may be misleading in the diagnosis of venom allergy.

OBJECTIVE

To confirm the role of carbohydrate epitopes in double positivity and to locate the responsible glycoallergens in HB and yellow jacket (YJ) venom by western blot.

METHODS

Immunoblot inhibition using HB venom, YJ venom and two glycoprotein sources displaying 1-3-fucosylated N-glycans (i.e. oilseed rape (OSR) pollen, and the synthetic neo-glycoprotein fucosylated/xylosylated N-glycans from bromelain coupled to bovine serum albumin (MUXF-BSA)) as inhibitors were performed with sera from 15 double-positive patients with stinging-insect allergy. Additionally, reactivity with blotted hymenoptera venoms of a carbohydrate-specific rabbit antiserum against OSR pollen was investigated.

RESULTS

Major venom glycoallergens binding with carbohydrate-specific human IgE and rabbit IgG were detected in HB venom at 42 (hyaluronidase (HYA)), 46, 65 and 95 kDa, and in YJ venom at 38 and 43 kDa (HYA). Antibody binding to these allergens was completely lost after periodate treatment. Glycans of HB phospholipase were bound by patients' IgE only after protein denaturation. In 10 of the 15 patients the reactivity was with the second venom because of carbohydrates alone. The high-molecular-weight glycoallergens identified in HB venom probably correspond to similar proteins described earlier, including allergens B and C. The 38-kDa YJ allergen might represent a homologue of V mac 3.

CONCLUSIONS

The data confirm the proposed role of carbohydrate-specific IgE in double positivity to HB and YJ venom and shed new light on some previously described minor hymenoptera allergens of uncertain clinical significance. The consideration of carbohydrate-specific IgE may allow to discriminate between patients with potentially relevant and patients with non-relevant double sensitization.

Allergic cross-reactivity: from gene to the clinic

A large number of allergenic proteins have now their complete cDNA sequences determined and in some cases also the 3D structures. It turned out that most allergens could be grouped into a small number of structural protein families, regardless of their biological source. Structural similarity among proteins from diverse sources is the molecular basis of allergic cross-reactivity. The clinical relevance of immunoglobulin E (IgE) cross-reactivity seems to be influenced by a number of factors including the immune response against the allergen, exposure and the allergen. As individuals are exposed to a variable number of allergenic sources bearing homologous molecules, the exact nature of the antigenic structure inducing the primary IgE immune response cannot be easily defined. In general, the 'cross-reactivity' term should be limited to defined clinical manifestations showing reactivity to a source without previous exposure. 'Co-recognition', including by definition 'cross-reactivity', could be used to describe the large majority of the IgE reactivity where co-exposure to a number of sources bearing homologous molecules do not allow unequivocal identification of the sensitizing molecule. The analysis of reactivity clusters in diagnosis allows the interpretation of the patient's reactivity profile as a result of the sensitization process, which often begins with exposure to a single allergenic molecule.

Characterization of the major allergens purified from the venom of the paper wasp Polistes gallicus

Allergic reactions to vespid stings are one of the major causes of IgE-mediated anaphylaxis. Vespa and Vespula venoms are closely related; Polistes venom is more distantly related and its allergens are less well studied. There is limited cross-reactivity between Polistes and the other vespid venoms because of differences in the epitopes on the allergen molecules. In this study, the major allergens of Polistes gallicus are isolated and characterized. P. gallicus venom contains four major allergens: phospholipase, antigen 5 (Ag5), hyaluronidase and protease that were characterized by mass spectrometry and specific binding to IgE. The complete amino acid sequence of Ag5 and the sequence of the N-terminal region of phospholipase were also determined. The alignment of Ag5 from P. gallicus (European species) and Polistes annularis (American species) shows an 85% identity that increases to 98% within the same subgenus. This could suggest the presence of specific epitopes on Ag5 molecule being the variations on the superficial loops. The features of the P. gallicus allergens could explain the partial cross-reactivity found between the American and European Polistes venoms, and suggest that the use of European Polistes venoms would improve the diagnostic specificity and the therapy of European patients and of North American patients sensitized by European Polistes.

The dual functions of GPI-anchored PH-20: hyaluronidase and intracellular signaling

The ovulated mammalian oocyte is surrounded by the "cumulus ECM", composed of cells embedded in an extracellular matrix that is rich in hyaluronic acid (HA). The cumulus ECM is a viscoelastic gel that sperm must traverse prior to fertilization. Mammalian sperm have a GPI-anchored hyaluronidase which is known as PH-20 and also as SPAM 1. PH-20 is located on the sperm surface, and in the lysosome-derived acrosome, where it is bound to the inner acrosomal membrane. PH-20 appears to be a multifunctional protein; it is a hyaluronidase, a receptor for HA-induced cell signaling, and a receptor for the zona pellucida surrounding the oocyte. The zona pellucida recognition function of PH-20 was discovered first. This function is ascribed to the inner acrosomal membrane PH-20, which appears to differ biochemically from the PH-20 on the sperm surface. Later, when bee venom hyaluronidase was cloned, a marked cDNA sequence homology with PH-20 was recognized, and it is now apparent that PH-20 is the hyaluronidase of mammalian sperm. PH-20 is unique among the hyaluronidases in that it has enzyme activity at both acid and neutral pH, and these activities appear to involve two different domains in the protein. The neutral enzyme activity of plasma membrane PH-20 is responsible for local degradation of the cumulus ECM during sperm penetration. Plasma membrane PH-20 mediates HA-induced sperm signaling via a HA binding domain that is separate from the hyaluronidase domains. This signaling is associated with an increase in intracellular calcium and as a consequence, the responsiveness of sperm to induction of the acrosome reaction by the zona pellucida is increased. There is extensive evidence that GPI-anchored proteins are involved in signal transduction initiated by a diverse group of cell surface receptors. GPI-anchored proteins involved in signaling are often associated with signaling proteins bound to the cytoplasmic leaflet of the plasma membrane, typically Src family, non-receptor protein tyrosine kinases. PH-20 appears to initiate intracellular signaling by aggregating in the plasma membrane, and a 92-kDa protein may be the cell signaling molecule linked to PH-20.

Antibody binding to venom carbohydrates is a frequent cause for double positivity to honeybee and yellow jacket venom in patients with stinging-insect allergy

BACKGROUND

Up to 50% of patients with stinging-insect allergy have double-positive RAST results to honeybee and yellow jacket (YJ) venom. True double sensitization and crossreactivity through venom hyaluronidases are considered main reasons for this multiple reactivity.

OBJECTIVE

We investigated the role of antibodies against cross-reactive carbohydrate determinants in venom double positivity.

METHODS

CAP inhibition experiments were performed with crude oilseed rape (OSR) and timothy grass pollen extracts and a neoglycoprotein construct displaying a MUXF glycan, as present in pineapple-stem bromelain (MUXF-BSA). CAP to OSR was used as a rough measure for carbohydrate-specific IgE in individual sera.

RESULTS

CAP results to OSR pollen were positive in 2 of 14 single-positive honeybee venom sera, 2 of 16 single-positive YJ venom sera, and 33 (80.5%) of 41 double-positive sera (P < .00001, chi(2) test). CAP inhibition was performed in 16 selected patients with a CAP class of 3 or higher to both venoms. In 9 of 11 patients with a highly positive CAP result to OSR (CAP score to OSR > CAP score to second venom), pollen extracts, MUXF-BSA, or both were able to completely inhibit IgE binding to one of the venoms, whereas this was not the case in 5 patients with a negative or weakly positive CAP result to OSR (CAP score to OSR < CAP score to second venom).

CONCLUSIONS

The data suggest that carbohydrate-specific IgE is a major cause for the double positivity to honeybee and YJ venom seen in patients with Hymenoptera allergy. Because these antibodies may have low clinical relevance, they may severely impede the correct diagnosis of Hymenoptera venom allergy.

Hyal2--less active, but more versatile?

Hyal2 is one of several hyaluronidases present in vertebrates. The human gene encoding this enzyme is present on chromosome 3p.21.3, close to two additional hyaluronidase genes. cDNAs encoding Hyal2 homologues have been characterized from mouse and Xenopus laevis. These enzymes hydrolyze high molecular mass hyaluronan to intermediates of approximately 20 kDa, a finding which implies that structural domains of this size exist in this polysaccharide which was mostly thought to be a random coil. Hyal2 enzymes have an acidic pH-optimum with an activity that is considerably lower than observed for other types of hyaluronidases. Originally considered to be a typical lysosomal enzyme, more recent evidence has shown that Hyal2 proteins can also be exposed on the cell surface bound to the plasma membrane via a GPI anchor. Hyal2 is present in many tissues, one exception being the adult brain. In this tissue, the gene is silenced after birth by methylation. Current evidence about the role of Hyal2 in tumor growth, inflammation and frog embryogenesis is discussed.

The Western blot is a highly sensitive and efficient technique in diagnosing allergy to wasp venom

BACKGROUND

Diagnosis of allergy to wasp venom and decision to perform immunotherapy are based on the patient's history, along with skin and in vitro tests.

OBJECTIVE

Given the high prevalence of specific IgE also in non-allergic individuals, we evaluated the sensitivity and specificity of Western blots as a possible alternative to serum analyses of venom-specific IgE.

METHODS

Skin prick and/or intracutaneous tests were performed in 30 patients with allergy to wasp venom (generalized reaction following sting) along with serum analysis of venom-specific IgE (AlaSTAT microplate) and Western blots. Western blots were subsequently scanned and evaluated qualitatively and semiquantitatively by means of densitometry. Bands were scored 'positive' in cases of signal intensities beyond the mean plus 3 standard deviations of control sera. Twenty newborns (age 2-7 days) and 30 adults without systemic or increased local reactions to hymenoptera stings served as controls.

RESULTS

Western blot sensitivity reached 100% in the samples studied and was thus superior to the sensitivities of serum analysis of venom-specific IgE using AlaSTAT microplate assay (90%) and skin tests (87%). The sensitivity of detection of a phospholipase A1 and antigen 5-specific band was higher compared with a hyaluronidase-specific band (97%, 97% and 86%, respectively). Twenty-four out of twenty-nine (83%) patients exhibited specific IgE antibodies against at least three distinct allergens. With regard to the specificities, skin tests as well as AlaSTAT microplate assays were comparable (90% and 93%, respectively), whereas the specificity of the Western blots was 70% if the appearance of any single band was regarded as a positive result. However, when analysing the appearance of a specific band for antigen 5 or hyaluronidase the specificity and overall diagnostic value increased markedly, making it the most efficient test (specificity 97% and 100%, efficiency 96.8% and 93.2%, respectively).

CONCLUSION

As allergy to wasp venom is a severe and potentially life threatening disease, false-negative test results need to be minimized. Therefore, the superiority of the Western blot with regard to sensitivity, specificity and overall efficiency makes this technique a valuable tool for its diagnosis.

Crystal structure of hyaluronidase, a major allergen of bee venom

BACKGROUND

Hyaluronic acid (HA) is the most abundant glycosaminoglycan of vertebrate extracellular spaces and is specifically degraded by a beta-1,4 glycosidase. Bee venom hyaluronidase (Hya) shares 30% sequence identity with human hyaluronidases, which are involved in fertilization and the turnover of HA. On the basis of sequence similarity, mammalian enzymes and Hya are assigned to glycosidase family 56 for which no structure has been reported yet.

RESULTS

The crystal structure of recombinant (Baculovirus) Hya was determined at 1.6 A resolution. The overall topology resembles a classical (beta/alpha)(8) TIM barrel except that the barrel is composed of only seven strands. A long substrate binding groove extends across the C-terminal end of the barrel. Cocrystallization with a substrate analog revealed the presence of a HA tetramer bound to subsites -4 to -1 and distortion of the -1 sugar.

CONCLUSIONS

The structure of the complex strongly suggest an acid-base catalytic mechanism, in which Glu113 acts as the proton donor and the N-acetyl group of the substrate is the nucleophile. The location of the catalytic residues shows striking similarity to bacterial chitinase which also operates via a substrate-assisted mechanism.

Structure and biology of stinging insect venom allergens

Bees, fire ants and vespids cause insect sting allergy. These insects have unique as well as common venom allergens. Vespids, including hornets, paper wasps and yellow jackets, have common allergens. Bees and vespids have one common allergen with hyaluronidase activity; they also have unique allergens with different phospholipase activities. Fire ants and vespids have one common allergen, antigen 5 of unknown biologic activity. The common venom allergens with < 70% sequence identity have barely detectable levels of antigenic cross-reactivity. Possible uses of modified allergens for immunotherapy are described.

Identification of linear surface epitopes on the guinea pig sperm membrane protein PH-20

The sperm plasma membrane protein PH-20 has previously been shown to be an effective immunogen for protection against fertilization in guinea pigs. To identify immunodominant regions on gpPH-20 that may be related to this contraceptive effect, we used several high-titer immune sera obtained from animals rendered infertile by gpPH-20 injections to screen a set of overlapping peptides that cover the entire 494-residue sequence. Multiple clusters of peptide sequences exhibited specific reactivity. Some of these sequences were then constructed as octameric synthetic peptides and tested for immunogenicity in female guinea pigs. Our results indicated two regions (res. 94-119 and res. 424-444) to be highly immunogenic and both are surface accessible when native gpPH-20 is in solution or anchored on sperm surface. Both anti-peptide antibodies are specific for gpPH-20 and one of them inhibited hyaluronidase activity partially. These monospecific antibodies should be useful probes for further molecular definition of gpPH-20 structure-function relationships.