Métodos alternativos para determinação da potência de veneno e antiveneno botrópico: aplicações e perspectivas para o controle da qualidade / Alternative methods for potency evaluation for Bothrops venom and antivenom: applications and perspectives for quality control

Introdução: Acidentes com animais peçonhentos são classificados como doenças tropicais negligenciadas e são atualmente a mais frequente causa de intoxicação em humanos no Brasil. O único tratamento disponível é a rápida administração de antivenenos específicos e de qualidade garantida. Para assegurar a eficácia e a segurança desses produtos, são realizados ensaios de determinação da potência in vivo para veneno e antiveneno, desde as etapas de produção até sua liberação final. Apesar dos diversos estudos sobre métodos   alternativos ao ensaio murino, nenhum método foi efetivamente validado. Objetivo: Compilar os métodos alternativos desenvolvidos para os antivenenos botrópicos, avaliando sua disponibilidade, perspectivas e aplicações em laboratórios de produção e controle da qualidade. Método: Foi realizada uma busca nas bases PubMed, BVS e Scopus entre novembro de 2021 e junho de 2022. Foram identificados 89 trabalhos, dos quais 31 foram selecionados de acordo com os critérios de elegibilidade. Resultados: Nos métodos alternativos identificados, observamos a preferência de 42,80% dos estudos por metodologias que utilizem linhagens celulares como método alternativo aos ensaios murinos, sendo que a maioria destes trabalhos 58,30% optou pela linhagem celular Vero. Conclusões: Pela diversidade das toxinas encontradas em cada gênero de serpentes, entende-se que é de extrema importância que o ensaio de potência dos antivenenos tenha como base a avaliação e a quantificação precisa da inibição da atividade biológica dos venenos. Ensaios de citotoxicidade são amplamente utilizados e têm acumulado evidências de sua adequação como importante ferramenta alternativa ao ensaio murino para o controle da qualidade de veneno e antiveneno antibotrópico.

Introduction: Accidents with venomous animals are classified as neglected tropical diseases and are currently the most frequent cause of intoxication in humans in Brazil. The only available treatment is the rapid administration of specific, quality-assured antivenoms. To ensure the efficacy and safety of these products, in vivo potency determination tests for venom and antivenom are performed during the production stages, until final release. Despite several studies on alternative methods to the murine assay, no method has been effectively validated. Objective: To compile alternative methods developed for Bothrops antivenoms, assessing the availability of the methods and the prospects and applications in Bothrops venom and antivenom production and quality control laboratories. Method: A search was conducted in PubMed, BVS, and Scopus databases between November 2021 and June 2022. 89 articles were identified, of which 31 were selected according to the eligibility criteria. Results: We observed in the alternative methods identified a preference of 42.80% of the studies for methodologies that use cell lines as an alternative method to the murine assays, and most of these works (58.30%) opted for a VERO cell line. Conclusions: Due to the diversity of toxins found in each genus of snakes, it is understood that the potency assay for antivenoms should be based on the evaluation and precise quantification of the inhibition of biological activity of venoms. Cytotoxicity assays are widely used and have been accumulating evidence of their suitability as an important alternative tool to the murine assay for quality control for Bothrops venom and antivenom.

A Reassessment of the in vitro total protein content determination (TPC) with SIRC and 3T3 cells for the evaluation of the ocular irritation potential of shampoos: comparison with the in vivo Draize rabbit test

The aim of this work was to determine the correlation between results obtained from the Draize test and from the Total Protein Content Determination (TPC) to assess the ocular irritancy potential of 20 shampoos. For TPC, two established cell lines (SIRC and 3T3) were used. The concentration that induced 50 percent inhibition relative to controls (IC50) was calculated for each product. Among shampoos tested with SIRC, only one had a false positive result. However, for the 3T3, three false-negative results were found. Pearson coefficient related to the in vivo value of maximum average score (MAS) was -0.58 (p=0.007) with SIRC and -0.73 (p=0.007) with 3T3. These results showed that the TPC assay was capable to predict the ocular irritant potential of shampoos, and therefore was a promissory tool to be used as a preliminary assay for the detection of irritant products and to be part of a battery of screening tests to minimize the animal use in the Draize Test.

Influência do erro de micropipetas na dosagem espectrofotométrica do ensaio de endotoxina bacteriana (LAL cromogênico) aplicável a produtos sujeitos à Vigilância Sanitária / Effect of micropipette inaccuracy on performance of spectrophotometric assay for bacteria endotoxin dosage (chromogenic LAL) employed in products subjected to sanitary surveillance

Segundo a norma ISO 17.025, os instrumentos usados em experimento devem ser calibrados. No caso de micropipetas não há limite máximo de erro definido, sendo difícil estipular até que ponto uma micropipeta pode continuar a ser usada. O objetivo do trabalho foi o de determinar a porcentagem de erro no volume da micropipeta que não interfira nos resultados das diferentes etapas do ensaio toxicológico Lisado de Amebócitos de Limulus (LAL). Os percentuais de erro foram obtidos do levantamento de 44 certificados de micropipetas. Foram utilizados uma pipeta monocanal calibrada, de volume variável e kit LAL Cromogênio QCL-1000 (Lonza). A curva de endotoxina foi construída com as concentrações de 0,1; 0,25; 0,5 e 1 UE/mL. Os percentuais de erro de ±2%, ±4% e±10% foram comparados com a concentração de referência (0,5 UE/mL), e analisados pelo Student t-test (p<0,05). A análise estatística mostrou que, para a endotoxina padrão e para o substrato do LAL, erro acima de 2% interferenos resultados, cuja correção deve ser feita pelo ajuste do volume na pipeta. Nenhum erro testado causou interferência estatisticamente significativa na reação da cor do substrato. Micropipetas com erro superior a ±2% devem ser corrigidas.

Biodistribution study of the anaesthetic sodium phenobarbital labelled with technetium-99m in Swiss mice infected with Schistosoma mansoni Sambon, 1907

Technetium-99 (99m Tc) is a radionuclide that has negligible enviromnental impact, is easily available, inexpensive and can be used as a radioactive tracer in biological experiences. In order to know the mode of action of sodium phenobarbital in moving adult Schistosoma mansoni worms from mesenteric veins to the liver, we labelled sodium phenobarbital (PBBT) with 99m Tc and a biodistribution study in infected and non-infected Swiss mice was performed. The PBBT was incubated with stannous chloride used as reducing agent and with 99m Tc, as sodium pertechnetate. The radioactivity labelling (per cent) was determined by paper ascending chromatography performed with acetone (solvent). The 99m Tc-PBBT was administered by intraperitoneal route to Swiss mice infected eight weeks before. The animals were perfused after diferent periods of time (0,1,2,3,4 hr) when blood, spleen, liver, poral, vein, mesenteric veins, stomach, kidneys and adult worms were isolated. The radioactivity present in these samples was counted in a well counter and the percentage was determined. The radioactivity was mainly taken up by the blood, kidney, liver and spleen. No radioactivity was found on the worms. We concluded that the worm shiff was due to an action on the lost of the sodium phenobarbital.

Schistosoma mansoni Sambon, 1907: comparative morphological studies of some brazilian strains

A morfologia de vermes adultos machos de tres cepas de Schistosoma mansoni, mantidas por variacoes em camundongos albinos, foi comparada com uma cepa isolada do hospedeiro natural Nectomys squamipes (Rodentia:Maridae) e mantida, em laboratorio, neste mesmo roedor silvestre. Como caracteres taxonomicos foram analisados o comprimento total, o numero de testiculos, a distancia entre as ventosas e a distancia ocupada pelos testiculos nos especimes. Os vermes recuperados de N. squamipes apresentaram diferencas significativas (p<0,01) em relacao as outras cepas para quaisquer caracteres morfologicos estudados. A cepas mantidas em camundongos apresentaram diferenca estatistica em varios caracteres (p<0,01). Alguns vermes adultos alem da disposicao normal dos testiculos apresentaram tambem uma localizacao atipica destas glandulas sexuais.

Host-induced morphological changes of Schistosoma mansoni Sambon, 1907 male worms

In order to evaluate the permissiveness of Nectomys squamipes to Schistosoma mansoni and the influence of the albino mice on the morphological aspects of adult worms derived from a population isolated from N. squamipes, the morphology of adult S. mansoni Sambon, 1907 male worms was studied using a digital image analyser (MOP VIDEOPLAN) and light microscopy. Their sources were as follows: (1) recovered from the wild rodent N. squamipes Brants naturally infected from Sumidouro, RJ, Brazil; (2) recovered from albino mice experimentally infected with the strain derived from N. squamipes; (3) recovered after the isolation of a strain derived from aboriginal human infections in Sumidouro. Worms recovered from N. squamipes (group 1) showed body lenght and distance between suckers significantly bigger than those of the specimens maintained in mice (groups 2 and 3). The number of tests in group 1 was statistically less than of groups 2 and 3. Group 2 strains which were maintained in mice, presented the lenght of the worms as the only significant different character. Data show that: (1) N. squamipes is a more suitable host for the development of S. mansoni when compared to the albino mice; (2) a strain of S. mansoni isolated from a natural host undergoes morphological changes after its passage in the white mouse.