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Sol i 2 is a potent allergen in Solenopsis invicta venom, and most humans exhibit reactivity to it. The Sol gem 2 allergen found in the venom of the Thai tropical fire ant Solenopsis geminata was analysed in the present study. The protein was present in higher amounts than other proteins, as determined by SDS-PAGE, and presumably has allergenic properties similar to those of Sol i 2. Sol gem 2 molecular weight is 28 and 15 kDa, respectively, under non-reducing and reducing conditions, indicating that its native form is a dimer. LC-MS/MS analysis confirmed its similarity to Sol i 2. The mono/dimeric form of Sol gem 2 was determined to be relevant by proteomic approach and immunoblotting. An anti-Sol gem 2 antibody was produced in mice, with a titer greater than 1:800 according to the Western blotting analysis. The Sol gem 2-neutralising activity of this antibody was determined in crickets. The paralytic dose 50 (PD 50 ) of crude S. geminata venom was elevated from 0.18 mg/g of body weight to more than 0.90 mg/g of body weight after preincubation with antibody at a ratio of 1:1. These results suggest that Sol gem 2 plays an important role in mediating the effects of the piperidine derivatives in the venom.Key words: allergy, ant venom, hymenoptera, immunoreactivity. Original PaPer The Journal of Venomous Animals and Toxins including Tropical Diseases ISSN 1678-9199 | 2012 | volume 18 | issue 3 | pages 325-334 INTRODUCTIONVenomous insects such as bees, wasps, hornets, yellow jackets and fire ants belong to the order Hymenoptera. These insects have a stinging apparatus at the tail end of their abdominal segment and still comprise a serious problem in tropical climates. Every year, a large number of people are stung by these insects (1). The stings are capable of delivering between 100 ng (fire ants) and 50 μg (bees) of venom (2, 3). The venom is injected from a gland through the stinger and is used to catch prey and to defend against predators. The venom of these insects is composed of various biologically active peptide and protein components, some of which can cause toxicity or anaphylaxis in humans (4).Fire ants (Solenopsis sp.) are members of the Formicidae family. The medically important aggressive species are S. invicta, S. richteri, S. geminata and S. saevissima (5, 6). The venom components of these ants and their immunoreactivity have been extensively studied. Approximately 95% of fire ant venom consists of water-insoluble piperidine alkaloids, and approximately 0.1% of its weight (10 to 100 ng of protein in 0.04 to 0.11 μL per sting) is protein (7). The toxicity of the venom is thought to be due to solenopsins and methyl-, alkylor alkenyl-substituted piperidines (7-9). The venom has cytotoxic, insecticidal, antibiotic and antimicrobial properties as well (7,(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19). The protein components of venom, which are wellknown allergens, are believed to play important roles in accelerating the spread of solenopsins to nearby cells and tissues. Solenopsins are believed t...

BackgroundWasp 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.MethodsIn 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.ResultsTwo 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.ConclusionsThe 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.