ABSTRACT
Bitis arietans is a venomous snake found in sub-Saharan Africa and in parts of Morocco and Saudi Arabia. The envenomation is characterized by local and systemic reactions including pain, blistering, edema and tissue damage, besides hemostatic and cardiovascular disturbances, which can cause death or permanent disabilities in its victims. However, the action mechanisms that provoke these effects remain poorly understood, especially the activities of purified venom components. Therefore, in order to elucidate the molecular mechanisms that make the Bitis arietans venom so potent and harmful to human beings, this study reports the isolation and biochemical characterization of a snake venom serine protease (SVSP). Methods: Solubilized venom was fractionated by molecular exclusion chromatography and the proteolytic activity was determined using fluorescent substrates. The peaks that showed serine protease activity were determined by blocking the proteolytic activity with site-directed inhibitors. In sequence, the fraction of interest was submitted to another cycle of molecular exclusion chromatography. The purified serine protease was identified by mass spectrometry and characterized biochemically and immunochemically. Results: A serine protease of 33 kDa with fibrinogen-degrading and kinin-releasing activities was isolated, described, and designated herein as Kn-Ba. The experimental Butantan Institute antivenom produced against Bitis arietans venom inhibited the Kn-Ba activity. Conclusions: The in vitro activities of Kn-Ba can be correlated with the capacity of the venom to provoke bleeding and clotting disorders as well as hypotension, which are common symptoms presented by envenomed victims. Obtaining satisfactory Kn-Ba inhibition through the experimental antivenom is important, given the WHO's recommendation of immunotherapy in cases of human accidents with venomous snakes.(AU)
Subject(s)
Animals , Snake Venoms , Fibrinogen , Antivenins , Substrates for Biological Treatment , Serine Proteases , Research Report , KininsABSTRACT
Objective: To report the first cases in our country of patients with latex allergy who developed anaphylaxis with urticaria and bronchospasm after eating maníoc, suggesting the presence of cross-reactivity between these allergens. Methods: Latex allergy was confirmed by assessing specific IgE through in vivo (prick tests) and in vitro (ImmunoCAP) tests. 5kin tests to aeroallergens, manioc and other foods were also conducted. Allergy to manioc was confirmed with oral challenge tests. ImmunoCAP inhibition assays were performed with extract of manioc and latex to assess cross reactivity. Results: 5kin tests to aeroallergens were negative. The skin prick tests with commerciallatex extracts were positive in both patients. Prick-to-prick with raw and cooked manioc was also positive. Both patients had positive skin tests for fresh papava and one of them for pineapple. Tests were negative for banana, kiwi and chestnut. Both had high serum specific IgE to latex. Both patients had a reaction with the open challenge test with manioc. ImmunoCAP inhibition assays revealed cross-reactivity between latex and manioc. Conclusion: Although previous reports have already suggested cross-reactivity between latex and manioc, this is the first report of cross reactivity between these allergens in our country, and indicates that manioc should definitely be added to the growing Iist of foods that present cross-reactívity with latex.
Objetivo: Primeira descrição em nosso meio de reação anafilátíca, com urticária e broncoespasmo após a ingestão de mandioca (Manihot utilissima) em pacientes com alergia ao látex, sugerindo a presença de uma reatividade cruzada entre estes dois alérgenos. Métodos: A alergia ao látex foi confirmada através da pesquisa de IgE específica in vivo (testes de puntura) e in vitro (ImmunoCAP, PHADIA, Brasil). Testes cutâneos para aeroalérgenos comuns, mandioca e outros alimentos também foram realizados. A alergia a mandioca foi avaliada pela determinação de IgE específica in vivo e confirmada através de testes de provocação oral com a mandioca. Ensaios de inibição do ImmunoCAP foram realizados com extrato de mandioca e de látex para avaliar a reatividade cruzada. Resultados: Os testes cutâneos para aeroalérgenos comuns foram negativos. Os testes cutâneos de puntura com extratos comerciais de látex foram positivo em ambos os pacientes. Prick-to-prick com mandioca crua e cozida também foram positivos. Ambos tiveram testes cutâneos positivos para mamão fresco e um deles para abacaxi. Os testes foram negativos para a banana, kiwi e castanha. Ambos tinham níveis séricos elevados de IgE específica ao látex. Ambos os pacientes tiveram reação com a provocação aberta com a mandioca. Ensaios de inibição do ImmunoCAP revelaram reatividade cruzada entre o látex e mandioca. Conclusão: Esse é o primeiro relato de reação cruzada entre estes dois alérgenos no Brasil. Os resultados reforçam que a mandioca deve ser definitivamente adicionada à crescente lista de alimentos que apresentam reação cruzada com o látex da borracha.