A new anti-loxoscelic serum produced against recombinant sphingomyelinase D Results of preclinical trials

Envenomation by Loxosceles species (brown spider) can lead to local dermonecrosis and to serious systemic effects. The main toxic component in the venom of these spiders is sphingomyelinase D (SMase D) and various isoforms of this toxin are present in Loxosceles venoms. We have produced a new anti-loxoscelic serum by immunizing horses with recombinant SMase D. In the present study, we compared the neutralization efficacy of the new anti-loxoscelic serum and anti-arachnidic serum (the latter serum is used for therapy for loxoscelism in Brazil) against the toxic effects of venoms from spiders of the genus Loxosceles. Neutralization tests showed that anti-SMase D serum has a higher activity against toxic effects of L. intermedia and L. laeta venoms and similar or slightly weaker activity against toxic effects of L. gaucho than that of Arachnidic serum. These results demonstrate that recombinant SMase D can replace venom for anti-venom production and therapy.

Transcriptome analysis of Loxosceles laeta (Araneae, Sicariidae) spider venomous gland using expressed sequence tags

The bite of spiders belonging to the genus Loxosceles can induce a variety of clinical symptoms, including dermonecrosis, thrombosis, vascular leakage, haemolysis, and persistent inflammation. In order to examine the transcripts expressed in venom gland of Loxosceles laeta spider and to unveil the potential of its products on cellular structure and functional aspects, we generated 3,008 expressed sequence tags (ESTs) from a cDNA library. Results: All ESTs were clustered into 1,357 clusters, of which 16.4% of the total ESTs belong to recognized toxin-coding sequences, being the Sphingomyelinases D the most abundant transcript; 14.5% include "possible toxins", whose transcripts correspond to metalloproteinases, serinoproteinases, hyaluronidases, lipases, C-lectins, cystein peptidases and inhibitors. Thirty three percent of the ESTs are similar to cellular transcripts, being the major part represented by molecules involved in gene and protein expression, reflecting the specialization of this tissue for protein synthesis. In addition, a considerable number of sequences, 25%, has no significant similarity to any known sequence. Conclusion: This study provides a first global view of the gene expression scenario of the venom gland of L. laeta described so far, indicating the molecular bases of its venom composition.

Ordered mesoporous silica SBA-15 A new effective adjuvant to induce antibody response

The applicability of SBA-15 mesostructure as an adjuvant and evaluation of its efficiency to induce antibody response, was discussed. It was observed that better encapsulation of biomolecules of variable shape and size can be achieved using a antigen to SBA-15 weight ratio of 1: 2.5. Efficient antibody generation could be achieved because SBA-15 was able to attract antigens effectively due to its high surface area and proper mesopore size. The results show that SBA-15 and related silica mesostructures are promising nanosystems for vaccine delivery.

Mechanism of induction of complement susceptibility of erythrocytes by spider and bacterial sphingomyelinases

We have recently shown that the sphingomyelinase toxins P1 and P2 from the venom of the spider Loxosceles intermedia induce complement (C)-dependent lysis of autologous erythrocytes by induction of the cleavage of cell surface glycophorins through activation of an endogenous metalloproteinase facilitating the activation of the alternative pathway of C. Phospholipase D (PLD) from Corynebacterium pseudotuberculosis shows some degree of homology with the spider sphingomyelinases and can induce similar clinical symptoms to those observed after spider envenomation. The aim of this study was to investigate if the bacterial PLD-induced haemolysis of human erythrocytes was C dependent and if cleavage of glycophorins occurred. We show here that haemolysis of both PLD- and P1-treated human erythrocytes was C dependent, but while PLD-mediated haemolysis was dependent on activation of the classical pathway of C, P1 induced lysis via both the classical and alternative pathways. P1, but not PLD, induced cleavage of glycophorins and no change in expression of complement regulators was induced by either of the toxins. In both cases, annexin V binding sites were exposed, suggesting that the membrane asymmetry had been disturbed causing exposure of phosphatidylserine to the cell surface. Our results suggest that C susceptibility induced by L. intermedia and C. pseudotuberculosis PLD is a result of exposure of phosphatidylserine, and the higher potency of P1 toxin can be explained by its additional effect of cleavage of glycophorins.

Presença de Loxosceles similis Moenkhaus, 1898 (Araneae, Sicariidae) na Serra da Bodoquena, Estado de Mato Grosso do Sul, Brasil / Presence of Loxosceles similis Moenkhaus, 1898 (Araneae, Sicariidae) in Serra da Bodoquena, State of Mato Grosso do Sul, Brazil

The venom of Loxosceles spiders causes dermonecrotic lesion and induces complement-dependent intravascular haemolysis that characterizes a severe systemic effect. In Brazil, L. gaucho, L. intermedia and L. laeta, present in the anthropic environment, have been pointed out as the most important agents of the loxoscelism. Besides these species there are others that, by predominating in the natural environment, have not been evaluated regarding human health risk, as in the case of Loxosceles similis. The development of a research project in Bodoquena Range, for ecological observation and identification of insects of medical interest, enabled the capture of Loxosceles similis specimens in the [quot ]Pitangueiras[quot ] cave and [quot ]Lago Azul[quot ] cave, in Bodoquena Range, municipality of Bonito, State of Mato Grosso do Sul, Brazil. The objectives of this study were to define the parameters for identification, environmental features of the habitat of this species, as well as an update of its geographical distribution.

O veneno das aranhas do gênero Loxosceles causa lesão dermonecrótica e induz hemólise intravascular dependente de complemento, configurando um quadro clínico de intensa gravidade. No Brasil, as espécies L. gaucho L. intermedia e L. laeta, presentes no ambiente antrópico, têm sido apontadas como principais agentes do loxoscelismo. Além destas, existem outras espécies, que por predominarem no ambiente natural, não têm sido avaliadas quanto ao risco à saúde do homem, como é o caso de Loxosceles similis. O desenvolvimento de projeto de pesquisa, na Serra da Bodoquena, para observações ecológicas e identificação de insetos de interesse médico, possibilitou a captura de espécimens de Loxosceles similis na Serra da Bodoquena, Município de Bonito, Estado do Mato Grosso do Sul, Brasil, nas grutas Pitangueiras e do Lago Azul. Os parâmetros para identificação, características ambientais do habitat da espécie, bem como atualização de sua distribuição geográfica são objetos deste trabalho.