Infecção por Treponema pallidum: análise serológica e pesquisa de DNA

RESUMO: A sífilis é uma infecção causada por T. pallidum que pode ser transmitida por via vertical, por contacto sexual ou por sangue, e cujo diagnóstico se baseia na associação entre manifestações clinicas e testes serológicos. Neste estudo utilizaram-se os testes serológicos RPR, TPHA, FTA-Abs, um teste rápido não comercializado (Signal-Spirolipin) que pesquisa anticorpos treponémicos (CDC-T) e não treponémicos (CDC-2) em simultâneo no mesmo dispositivo e uma técnica de PCR-multiplex para a pesquisa de ADN de T. pallidum. Da comparação das técnicas serológicas constatou-se que a sensibilidade dos testes RPR e TPHA foi de 84,5% e 98% respectivamente. A especificidade foi de 77,3% para o teste RPR e de 87,5% para o teste TPHA. Na avaliação do teste rápido a comparação do teste CDC-2 com o teste RPR resultou numa taxa de concordância de 93,1% enquanto que, a do teste CDC-T com o teste TPHA foi de 94,8%. A sensibilidade e especificidade obtidas pelos testes CDC-2 e CDC-T foram de 88,7% e 65% e de 94,9% e 91,3% respectivamente. Considerando o diagnóstico de sífilis activa com base na reactividade simultânea dos testes RPR e TPHA, avaliou-se a sensibilidade do teste rápido utilizando esse mesmo critério. A sensibilidade obtida foi de 98,4% para o teste rápido e de 97,2% para a associação dos testes RPR/TPHA. A técnica de PCR-multiplex apresentou fraca sensibilidade já que em apenas 33% dos casos de sífilis foi identificado ADN de T. pallidum. O teste rápido avaliado apresentou um comportamento idêntico aos testes geralmente utilizados na rotina laboratorial tais como os utilizados neste estudo. Apresenta a vantagem de pesquisar anticorpos treponémicos e não treponémicos, ao contrário dos testes rápidos comercializados que pesquisam apenas anticorpos treponémicos. Não sendo necessário para a sua execução equipamento laboratorial especializado poderá ser de grande utilidade para o clinico a exercer em locais sem laboratório.------------- ABSTRACT: Syphilis is an infection caused by T. pallidum. Transmission may be vertical, through sexual contact or blood. The diagnosis is based in both serology and clinical manifestations. In this study, we used the serological tests RPR, TPHA, FTA-Abs and a non -commercialized rapid test (Signal-Spirolipin) to detect both treponemal (CDC-T) and non – treponemal antibodies (CDC-2) in the same device. T. pallidum DNA was identified with a multiplex PCR technique. In this study, the RPR and TPHA tests sensitivity was 84,5% and 98%, respectively, and the specificity 77,3% for the RPR test and 87,5% for TPHA test, respectively. The concordance rate was 93,1% in the comparison between the RPR and the CDC2 tests and 94,8% between the CDC-T with the TPHA tests. Sensitivity and specificity of the CDC-2 and CDC-T tests were 88,7% and 65% and 94,9% e 91,3%, respectively. Taking into account that the diagnosis of active syphilis is made when both the RPR and TPHA tests are reactive, we evaluated the sensitivity of the rapid test (CDC2 and CDCT) in the diagnosis of active syphilis, using the above described criteria. The sensitivity was 98,4 % for the rapid test and 97,2 % for the association of reactivity in both RPA and TPHA tests. The multiplex PCR technique presented a low sensitivity, with T. pallidum DNA being identified in only 33% of the syphilis cases. The rapid test evaluated in this study presented identical results to the tests generally used in the routine laboratory diagnosis, such as those used here. However, it does have the advantage of detecting both treponemal and non – treponemal antibodies what is not the case of the commercialized rapid test. Furthermore, there is no need of specialized laboratory equipment, which makes it of great utility in regions where such conditions do not exist, as in developing countries.

Development of an enzyme-linked immunosorbent assay for detection of IgM antibodies to Babesia bigemina in cattle

A crude antigenic preparation of Babesia bigemina was used to develop an ELISA for the detection of IgM antibodies. Optimal dilutions of the antigen, using positive and negative reference sera, were determined by checkerboard titrations. Negative sera from cattle imported from tick-free areas, serum samples collected from infected B. bigemina cattle were used to validate the test. The specificity was 94% and sensitivity of the Elisa 87.5%. Sera from 385 cattle deriving from areas free from tick-borne diseases, which were submitted to a preimmunization process, were screened by this technique. The Elisa detected seroconversion on the 14th day post-inoculation in animals either infested with Boophilus microplus ticks (infected with B. bigemina), or inoculated with B. bigemina infected blood. Antibody titers decreased after day 33; however, all animals remained positive until the end of the experiment (124 days). The ELISA described may prove to be an appropriate serological test for the detection of IgM antibodies against B. bigemina.

Rabies neutralizing antibody detection by indirect immunperoxidase serum neutralization assay performed on chicken embryo related cell line

The aim of this study was to evaluate the indirect immunoperoxidase virus neutralization (IPVN) and mouse neutralization test (MNT) to detect antibodies against rabies virus from vaccinated dogs and cattle. The IPVN was set up for the ability to measure 0.5 International Units/ml (IU) of antibody required by the World Health Organization and the Office International des Epizooties as the minimum response for proof of rabies immunization. IPVN was developed and standardized in chicken embryo related (CER) cell line when 141 dog and 110 cattle sera were applied by serial five-fold dilutions (1:5, 1:25, 1:125) as well as the positive and negative reference controls, all added in four adjacent wells, of 96-well microplates. A 50 µl amount of CVS32 strain dilution containing 50-200 TCID50/ml was mixed to each serum dilution, and after 90 min 50 µl of 3 x 10(5) cells/mlcell suspension added to each well. After five days of incubation, the monolayers were fixed and the IPVN test performed. The correlation coefficient between the MNT and IPVN performed in CER cells was r = 0.9949 for dog sera (n = 100) and r = 0.9307 for cattle sera (n = 99), as well as good specificity (94.7%), sensitivity (87.5%), and agreement (96.6%) were also obtained. IPVN technique can adequately identify vaccinated and unvaccinated animals, even from low-responding vaccinated animals, with the advantage of low cost and faster then MNT standard test.

Multicenter study of a new fully automated HBsAg screening assay with enhanced sensitivity for the detection of HBV mutants.

In a multicenter study a new, fully automated Roche Diagnostics Elecsys HBsAg II screening assay with improved sensitivity to HBsAg mutant detection was compared to well-established HBsAg tests: AxSYM HBsAg V2 (Abbott), Architect HBsAg (Abbott), Advia Centaur HBsAg (Bayer) Enzygnost HBsAg 5.0 (Dade-Behring), and Vitros Eci HBsAg (Ortho). A total of 16 seroconversion panels, samples of 60 HBsAg native mutants, and 31 HBsAg recombinant mutants, dilution series of NIBSC and PEI standards, 156 HBV positive samples comprising genotypes A to G, 686 preselected HBsAg positive samples from different stages of infection, 3,593 samples from daily routine, and 6,360 unselected blood donations were tested to evaluate the analytical and clinical sensitivity, the detection of mutants, and the specificity of the new assay. Elecsys HBsAg II showed a statistically significant better sensitivity in seroconversion panels to the compared tests. Fifty-seven out of 60 native mutants and all recombinant mutants were found positive. Among 156 HBV samples with different genotypes and 696 preselected HBsAg positive samples Elecsys HBsAg II achieved a sensitivity of 100%. The lower detection limit for NIBSC standard was calculated to be 0.025 IU/ml and for the PEI standards ad and ay it was <0.001 and <0.005 U/ml, respectively. Within 2,724 daily routine specimens and 6.360 unselected blood donations Elecsys HBsAg II showed a specificity of 99.97 and 99.88%, respectively. In conclusion the new Elecsys HBsAg II shows a high sensitivity for the detection of all stages of HBV infection and HBsAg mutants paired together with a high specificity in blood donors, daily routine samples, and potentially interfering sera.

Undressing of Waddlia chondrophila to enrich its outer membrane proteins to develop a new species-specific ELISA.

Waddlia chondrophila, an obligate intracellular bacterium of the Chlamydiales order, is considered as an agent of bovine abortion and a likely cause of miscarriage in humans. Its role in respiratory diseases was questioned after the detection of its DNA in clinical samples taken from patients suffering from pneumonia or bronchiolitis. To better define the role of Waddlia in both miscarriage and pneumonia, a tool allowing large-scale serological investigations of Waddlia seropositivity is needed. Therefore, enriched outer membrane proteins of W. chondrophila were used as antigens to develop a specific ELISA. After thorough analytical optimization, the ELISA was validated by comparison with micro-immunofluorescence and it showed a sensitivity above 85% with 100% specificity. The ELISA was subsequently applied to human sera to specify the role of W. chondrophila in pneumonia. Overall, 3.6% of children showed antibody reactivity against W. chondrophila but no significant difference was observed between children with and without pneumonia. Proteomic analyses were then performed using mass spectrometry, highlighting members of the outer membrane protein family as the dominant proteins. The major Waddlia putative immunogenic proteins were identified by immunoblot using positive and negative human sera. The new ELISA represents an efficient tool with high throughput applications. Although no association with pneumonia and Waddlia seropositivity was observed, this ELISA could be used to specify the role of W. chondrophila in miscarriage and in other diseases.

Herpesviruses including novel gammaherpesviruses are widespread among phocid seal species in Canada.

Little is known about herpesviruses in Canadian pinnipeds. We measured prevalence of antibodies to herpesviruses in the sera from Canadian phocid seals by an indirect enzyme-linked immunosorbent assay. Wild harbor seals (Phoca vitulina) and captive harbor seals were positive for antibodies to Phocid herpesvirus 1 (PhoHV-1) at prevalences of 91% and 100%, respectively. Sera from wild hooded seals (Cystophora cristata), harp seals (Pagophilus groenlandica), and grey seals (Halichoerus grypus) were positive for antibodies to PhoHV-1 antigenically related herpesvirus antigens at 73%, 79%, and 96%, respectively. We isolated new herpesviruses in cell culture from two hunter-harvested ringed seals (Pusa hispida) in poor body condition from Ulukhaktok, Northwest Territories, Canada; one lethargic hooded seal from the St. Lawrence Estuary, Québec, Canada; and one captive, asymptomatic harp seal from the Magdalen Islands, Québec. Partial sequencing of the herpesvirus DNA polymerase gene revealed that all four virus isolates were closely related to PhoHV-2, a member of the Gammaherpesvirinae subfamily, with nucleotide similarity ranging between 92.8% and 95.3%. The new seal herpesviruses were genetically related to other known pinniped herpesviruses, such as PhoHV-1, Otariid herpesvirus 3, Hawaiian monk (Monachus schauinslandi) seal herpesvirus, and Phocid herpesvirus 5 with 47–48%, 55%, 77%, and 70–77% nucleotide similarities, respectively. The harp seal herpesvirus and both ringed seal herpesviruses were almost identical to each other, whereas the hooded seal herpesvirus was genetically different from the three others (92.8% nucleotide similarity), indicating detection of at least two novel seal herpesviruses. These findings are the first isolation, partial genome sequencing, and identification of seal gammaherpesviruses in three species of Canadian phocid seals; two species of which were suspected of exposure to one or more antigenically related herpesviruses based on serologic analyses.

Avaliação de um teste imunoenzimático competitivo no diagnóstico sorológico da brucelose em búfalos (Bubalus bubalis)

O trabalho teve por objetivo avaliar o teste imunoenzimático competitivo (CEIA) para uso no diagnóstico sorológico da brucelose em búfalos (Bubalus bubalis), comparando seus resultados com aqueles obtidos na reação de fixação de complemento (CFT) e no teste rosa Bengala (RBT). Foram examinados 477 soros por meio do CEIA e do RBT e 465, desses mesmos soros, por meio da CFT. Na CFT e no CEIA, soros com títulos maiores ou iguais a 1/4 foram considerados positivos. Para a determinação da sensibibilidade e da especificidade relativas do CEIA, foram considerados como doentes os animais com resultados positivos no RBT e na CFT e sãos os animais com resultados negativos nesses dois testes. Soros com resultados discordantes nesses duas provas foram eliminados da análise. Os resultados apontaram uma concordância de 97,42% entre o CEIA e a CFT e uma concordância de 95,39% entre o CEIA e o RBT. A sensibilidade relativa do CEIA foi de 100% e a especificidade relativa do teste foi de 98,55%. Esses dados mostram que o desempenho do CEIA diferiu pouco do desempenho dos outros dois testes, sugerindo que o mesmo pode constituir um recurso útil para o diagnóstico sorológico da brucelose em búfalos.

Ocorrência de animais persistentemente infectados pelo vírus da diarréia viral bovina em rebanhos bovinos nos Estados de Minas Gerais e São Paulo

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

An enzyme-linked immunosorbent assay for the detection of IgG antibodies against Babesia equi in horses

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Rabies neutralizing antibody detection by indirect immunperoxidase serum neutralization assay performed on chicken embryo related cell line

The aim of this study was to evaluate the indirect immunoperoxidase virus neutralization (IPVN) and mouse neutralization test (MNT) to detect antibodies against rabies virus from vaccinated dogs and cattle. The IPVN was set up for the ability to measure 0.5 International Units/ml (IU) of antibody required by the World Health Organization and the Office International des Epizooties as the minimum response for proof of rabies immunization. IPVN was developed and standardized in chicken embryo related (CER) cell line when 141 dog and 110 cattle sera were applied by serial five-fold dilutions (1:5, 1:25, 1:125) as well as the positive and negative reference controls, all added in four adjacent wells, of 96-well microplates. A 50 µl amount of CVS32 strain dilution containing 50-200 TCID50/ml was mixed to each serum dilution, and after 90 min 50 µl of 3 x 10(5) cells/mlcell suspension added to each well. After five days of incubation, the monolayers were fixed and the IPVN test performed. The correlation coefficient between the MNT and IPVN performed in CER cells was r = 0.9949 for dog sera (n = 100) and r = 0.9307 for cattle sera (n = 99), as well as good specificity (94.7%), sensitivity (87.5%), and agreement (96.6%) were also obtained. IPVN technique can adequately identify vaccinated and unvaccinated animals, even from low-responding vaccinated animals, with the advantage of low cost and faster then MNT standard test.

Development of an enzyme-linked immunosorbent assay for detection of IgM antibodies to Babesia bigemina in cattle

A crude antigenic preparation of Babesia bigemina was used to develop an ELISA for the detection of IgM antibodies. Optimal dilutions of the antigen, using positive and negative reference sera, were determined by checkerboard titrations. Negative sera from cattle imported from tick-free areas, serum samples collected from infected B. bigemina cattle were used to validate the test. The specificity was 94% and sensitivity of the Elisa 87.5%. Sera from 385 cattle deriving from areas free from tick-borne diseases, which were submitted to a preimmunization process, were screened by this technique. The Elisa detected seroconversion on the 14th day post-inoculation in animals either infested with Boophilus microplus ticks (infected with B. bigemina), or inoculated with B. bigemina infected blood. Antibody titers decreased after day 33; however, all animals remained positive until the end of the experiment (124 days). The ELISA described may prove to be an appropriate serological test for the detection of IgM antibodies against B. bigemina.

Desenvolvimento de uma prova de imunoadsorção enzimática para detecção de anticorpos contra Babesia bovis

Uma prova de imunoadsorção enzimática (ELISA) para detecção de anticorpos contra Babesia bovis foi desenvolvida e avaliada em comparação à imunofluorescência indireta (IFI). A sensibilidade e especificidade do ELISA, determinadas pela análise de 100 soros positivos de bovinos infectados experimentalmente com B. bovis e 108 soros negativos colhidos de bovinos livres de infecção por este hemoparasito, foram de 98,0% e 98,1%, respectivamente. Os valores preditivos positivo e negativo foram, respectivamente, 98,0% e 98,1% e a precisão do teste foi de 98,1%. Não foram detectadas reações cruzadas com 80 soros de bezerros experimentalmente inoculados com Babesia bigemina. O ELISA foi comparado à IFI usando 110 soros de rebanhos de área de estabilidade endêmica e 168 soros de rebanhos de áreas de instabilidade endêmica. em ambos os casos, houve concordância significativa (P=0,631 e 0,4725, respectivamente) entre os resultados demonstrados pelos dois testes. em um estudo epidemiológico realizado com o ELISA na região do Pantanal de Mato Grosso do Sul, com 1.365 soros de bovinos, 83,9% foram positivos para anticorpos contra B. bovis, caracterizando a região estudada como endemicamente estável.

Antigenic similarities to Paracoccidioides brasiliensis in thermo-dependent dimorphic fungi isolated from soil in Botucatu, SP, Brazil

We compared the antigenic characteristics of two thermo-dependent dimorphic fungi isolated from soil in Botucatu, an endemic area of paracoccidioidomycosis (PCM) and Paracoccidioides brasiliensis. The soil isolates grew as cerebriform colonies at 37 degrees C (yeast form) and as cottonous colonies at 25 degrees C (mycelial form). No pathogenicity for ddY mice or hamsters were observed. In immunodiffusion test, there were precipitation bands between the 2 soil isolates and pooled PCM patient sera. There were also common precipitation bands at 21, 50 and 58 kDa between the soil isolates antigens and PCM patient sera by Western-blotting, but no gp43 kDa band. No gene for gp43 kDa protein was detected in the soil isolates by PCR. The fact that these isolates were obtained from an endemic area of PCM and there were some antigenic similarities between the soil isolates and P. brasiliensis in immunodiffusion test and Western-blotting may have some importance in epidemiological surveys done with paracoccidioidin as well interfering with the immune response of the exposed population.

Pesquisa de anticorpos contra Brucella ovis em ovinos do Estado de São Paulo

Eight hundred and fifty sheep sera from 18 herds, located in 15 municipalities of the State of São Paulo, were examined by complement fixation test, indirect enzyme immunoassay and gel diffusion test for antibodies to Brucella ovis. The combination of the serological test results and the clinical and epidemiological data suggest that none of the examined animals was infected. The complement fixation and the gel diffusion tests showed good specificity, but the indirect enzyme immunoassay showed false positive results in nine of the sera.

Infecção congênita pelo citomegalovírus: estudo realizado na Fundação Santa Casa de Misericórdia do Pará

O citomegalovírus é um vírus de DNA, pertencente à família Herpesviridae, subfamília Beta-herpesvirinae. Sua distribuição é universal e pode causar infecções congênitas e perinatais, assim como durante a infância e na idade adulta. É um dos principais patógenos responsáveis pela morbidade e mortalidade em pacientes imunocomprometidos. Foi estudada a incidência da infecção congênita pelo citomegalovírus, na maternidade da Fundação Santa Casa Misericórdia do Pará, no período de novembro de 1994 a maio de 1995. A amostra trabalhada constou de 663 recém-nascidos e suas respectivas mães. O peso dos recém-nascidos variou de 900 a 5450 g, com uma média de 3046g. Em 11,4% das crianças foi observado baixo peso ao nascer. A avaliação pelo isolamento do vírus da saliva dos 663 recém-nascidos, através da inoculação em células primárias de fibroblasto de prepúcio humano, mostrou 3,2% (21) de positividade. A pesquisa de anticorpos IgM específicos para o CMV, através do método ELISA, utilizando-se sangue do cordão umbilical do mesmo grupo de recém-nascidos foi positiva em 2,1% (14). Para o diagnóstico da infecção congênita pelo CMV, a análise estatística pelo Teste de McNemar dos Pares Discordantes (p)=0,0233 e Teste do Qui-Quadrado da Homogeneidade (p)<0,01 demonstrou que o isolamento do citomegalovírus da saliva foi mais sensível que a detecção de anticorpos IgM no sangue do cordão umbilical. Dos 21 recém-nascidos infectados, 28,5% (6) apresentaram nas primeiras 24 horas de vida, sintomatologia sugestiva de infecção congênita. Os sinais e sintomas encontrados foram microcefalia (4), prematuridade (3), hepatoesplenomegalia (2), pequeno para a idade gestacional (2) e icterícia precoce (1). A pesquisa de anticorpos IgG específicos para o CMV, pelo método ELISA, foi positiva em 90,2% das puérperas. Das 21 mulheres que transmitiram o vírus para o concepto, foram detectados anticorpos IgM em 4. A entrevista pessoal com as mães dos recém-nascidos revelou nível socioeconômico baixo e assistência pré-natal deficiente, com 26,4% das puérperas sem nenhuma consulta durante o período gestacional. Em nossa amostra, a idade materna variou de 12 a 42 anos, com idade média de 22,2 anos, sendo que a idade das mães dos recém-nascidos infectados foi inferior a 25 anos.