Marcos Vinícius da Silva

Standardization of dot-ELISA for the serological diagnosis of toxocariasis and comparision of the assay with ELISA

The dot-enzyme-linked immunosorbent assay (dot-ELISA) was standardized using somatic (S) and excretory-secretory (ES) antigens of Toxocara-canis for the detection of specific antibodies in 22 serum samples from children aged 1 to 15 years, with clinical signs of toxocariasis. Fourteen serum samples from apparently normal individuals and 28 sera from patients with other pathologies were used as controls. All samples were used before and after absorption with Ascaris suum extract. When the results were evaluated in comparison with ELISA, the two tests were found to have similar sensitivity, but dot-ELISA was found to be more specific in the presence of two antigens studied. Dot-ELISA proved to be effective for the diagnosis of human toxocariasis, presenting advantages in terms of yield, stability, time and ease of execution and low cost.

Sorovares de Leptospira interrogans isolados de casos de leptospirose humana em São Paulo, Brasil

Eighteen strains of L. interrogans isolated from human cases were serotyped by the Agglutinin-absorption test at Instituto Adolfo Lutz in Sao Paulo, Brazil. Fourteen were identified as serovar copenhageni (Icterohaemorrhagiae serogroup), 2 as canicola (Canicola serogroup), 1 as castellonis (Ballum serogroup) and 1 as Pomona serogroup (serovar not yet defined). The frequency of serovar copenhageni in 100% of the isolates in Icterohaemorrhagiae serogroup is emphasized and more studies to verify the real serovars prevalence as subsidy to the epidemiology of this infection are suggested by the authors

Immunodiagnosis of human leptospirosis using saliva

When the enzyme-linked immunosorbent assay for the detection of specific immunoglobulin M class antibodies was applied to paired saliva and serum samples from 40 patients with leptospirosis, positivity was 87.5% and 100%, respectively. No positive result was obtained with any saliva or serum sample from 60 individuals used as controls. These results suggest the alternative use of saliva for diagnosis and for epidemiological studies of human leptospirosis.

Estudo comparativo de testes sorológicos no diagnóstico imunológico da neurocisticercose

Estudamos comparativamente quatro tecnicas imunologicas para o diagnostico da neurocisticercose (NC) utilizando liquido cefalorraquiano (LCR) como especime clinico: as reacoes de fixacao de complemento (RFC), hemaglutinacao passiva (RHA), imunofluorescencia indireta (RIF) e teste imunoenzimatico ELISA Foram ensaiadas 125 amostras de LCR de pacientes com NC comprovada e 94 amostras de LCR do grupo controle (60 de pacientes com quadros clinicos neurologicos diversos e 34 de pacientes supostamente normais). Os indices de sensibilidade e especificidade obtidos para os testes foram, respectivamente, de 48,0% e 90,4% para a RFC; 88,8% e 96,8% para a RHA; 87,2 e 98,9% para a RIF e 97,6% e 98,9% para o teste ELISA. A diferenca significativa (p < 0,05) observada entre os testes permite concluir que o melhor teste para o diagnostico de NC foi o teste ELISA seguido das reacoes de HA e IF.

Imunodiagnóstico da leptospirose humana através do teste ELISA-IgM, empregando-se diferentes preparações antigênicas a partir de sorotipos prevalentes de Leptospira interrogans

Realizou-se estudo comparativo de diferentes sorotipos de Leptospira interrogans utilizados na preparacao de antigenos empregados no teste ELISA, para a deteccao de anticorpos da classe IgM, em amostras de soro na fase precoce e tardia da leptospirose humana. Foram utilizados dez sorotipos, escolhidos entre os que apresentaram maior reatividade na soroaglutinacao microscopica (SAM), na cidade de Sao Paulo. Os cinco sorotipos que apresentaram melhores resultados individualmente no teste ELISA-IgM (canicola, hebdomadis, icterohaemorrhagiae, cynopteri e brasiliensis), foram tambem estudados em mistura antigenica. Os antigenos nao tratados apresentaram maior reatividade do que os antigenos tratados com Triton X - 100 (4%) a temperatura de 50oC, durante 4 horas. O teste ELISA-IgM empregando os sorotipos nao tratados, isoladamente, e em mistura antigenica, mostrou-se altamente sensivel, podendo ser empregado como teste de triagem para o diagnostico precoce da leptospirose humana. Outra aplicacao do teste e permitir a deteccao do inicio de situacoes epidemicas ou de surtos, possibilitando acionar medidas de vigilância epidemiologica.

Teste imunoenzimático (ELISA) para detecção de anticorpos circulantes da classe IgM na leptospirose humana

An Enzyme-linked immunosorbent assay ELISA was evaluated for the detection of IgA antibodies in the human leptospirosis. The assay proved to be sensitive and specific when compared with the ELISA-IgM, in the examinated serum samples. The results found suggest that IgA antibodies became positive later in leptospirosis, and will can be an evolutive indicator in the development of the diseaseFoi avaliado o teste imunoenzimatico (ELISA), para deteccao de anticorpos da classe IgM na leptospirose humana. Nas amostras de soros analisadas, o teste ELISA demonstrou ser mais sensivel, especifico e precoce, quando comparado ao teste de soroaglutinacao microscopica. A analise dos resultados obtidos nesta avaliacao demonstra que o teste ELISA permite detectar niveis baixos de anticorpos circulantes, e tambem anticorpos nao aglutinantes. nao detectaveis atraves do teste de soroaglutinacao microscopica.

Teste imunoenzimático para pesquisa de anticorpos anti-Cysticercus cellulosae em líquidos cefalorraquianos de pacientes com meningites de etiologia indeterminada

The enzyme-linked-immunosorbent assay using a new type of support consisting of discs of synthetic fabric-resin (ELISA-d) with antigenic components of Cysticercus cellulosae covalently bound, was employed with the purpose of investigating the presence of specific antibodies to the cysticerci (neurocysticercosis) in the cerebrospinal fluid (CSF) of patients with meningitis without etiological agent determined by the conventional methods. The test was performed in 277 CSF samples (128 children and 149 adults). The mean of optical density values (OD) obtained for 22 CSF normal patients (the diagnostic hyphotesis of meningitis was discarded) was of 0.03. The 44 CSF of patients with meningitis caused by other agents but C. cellulosae, showed OD of 0.05. The cut off determined with these two groups (control group) was 0.13 (OD + 3 SD). The group of 13 CSF of neurocysticercotic meningitis presented OD of 0.41 (0.10 to 0.91). Among the 198 CSF samples of indetermined meningitis, 23 (11.6%) presented OD above the cut off, which suggests the possibility that Cysticercus cellulosae was the etiological agent in this meningitis episode. The ELISA-d test has proved to be efficient for the immunodiagnosis of neurocysticercosis when conducted on CSF samples. The alterations observed in the 23 CSF reactive on ELISA-d were: increased number of lymphomononuclear cells in five, of polymorphonuclear cells in 13 and both cells in five samples.

Avaliação do teste ELISA-lgM no diagnóstico precoce da leptospirose humana

Thirty-seven sera samples from patients with leptospirosis icterohaemorrhagic form were studied with a time interval of 2 to 12 days between the beginning of the symptoms and the collection blood samples. It was isolated leptospira of 5 patients heinocultures (13.5%) and from 4 of these the etiological agent pertained to the serogroup Icterohaemorrhagiae serovar copenhageni. Thirty-five of them (94.6%), including the four patients whose the etiological agent was isolated, showed reactivity in the enzyme linked immunosorbent (ELISA) IgM test. By this way, it was demonstrated that this test is important for a rapid diagnosis of human leptospirosis, even in the beginning of the disease, when there is still leptospiraemic phase.

Passive haemagglutination test for human neurocysticercosis immunodiagnosis: I. Standardization and evaluation of the passive haemagglutination test for the detection of anti-Cysticercus cellulosae antibodies

Foi padronizada e avaliada a reacao de hemaglutinacao passiva (RHA) para pesquisa de anticorpos especificos, anti-Cysticercus cellulosae, no liquido cefalorraquiano (LCR). Foram utilizadas hemacias humanas O Rh-formolizadas e sensibilizadas com extrato antigenico salino total de cisticercos, ainda pouco estudado. De 115 amostras estudadas de LCR de pacientes com neurocisticercose, 94 foram reagentes, resultando em 81,7% de sensibilidade, com intervalo de confianca de 95% de probabilidade (IC95%) abrangendo de 74,5% e 88,9%. Tambem foram ensaiadas 89 amostras de LCR de individuos do grupo controle, sendo tao reagentes em 94,4%, com IC95%, de 89,6% a 99,2%. Os valores preditivos positivo e negativo obtidos para a RHA foram, respectivamente, de 1,4% e 99,9%, considerando a prevalencia media de neurocisticercose na America Latina de 0,1%. Os resultados indicam que a RHA como um metodo simples, altamente reprodutivel e moderadamente sensivel para a deteccao de anticorpos especificos no LCR, porem apropriados para a triagem de infectados.

Avaliação da contraimunoeletroforese com antígenos dos sorovars icterohaemorrhagiae E patoc no diagnóstico sorológico da leptospirose humana

Counterimmunoelectrophoresis (CIE) was applied on paired sera from 135 pacients with leptospirosis and on 69 sera from a control group. The sera from pacients were subdivided in 4 groups according to the results obtained by the Microscopic Agglutination Test (MAT). The first samples sera from 58 pacientes were non reagent by MAT. Six monthly samples of sera were taken from 7 patients to follow-up and to determine the level of agglutinin and precipitin antibodies present using MAT and CIE. Serovars icterohaemorrhagie and patoc were used as antigens. Three types of antigens were compared, 1) Triton-X-100 extracted; 2) heat extacted and 3) a pool of them. The CIE using icterohaemorrhagiae derivated antigens types agreed with MAT in 92.64, 92.64 and 94.11% of the leptospirosis sera. The patoc antigens types reacted with the control group in 7.24, 86.95 and 84.05% of the samples, and consequently were eliminated from the present study. The icterohaemorrhagiae CIE reaction become positive earlier than MAT negative sera, and reverted to negative earlier in the follow-up samples from the pacients. The CIE was sensitive and specific, gave rapid results and was easy to perform.