RESUMO

This cross-sectional, observational, and descriptive study aims to investigate the epidemiology of Ehrlichia canis in healthy owned dogs from the Southeastern region of Rio de Janeiro, Brazil. Blood samples were collected from 390 households dogs. During the visits, an epidemiological questionnaire was filled out concerning the dogs' characteristics as well as the environments in which they lived. The variables were analyzed using a bivariate test, while the correlation analysis between the variables was performed via a phi test. The variables that had p-values lower than 0.2 in the bivariate analysis and had a low or moderate correlation were selected for the multivariate analysis. The model that had the lowest Akaike information criterion (AIC) value was retained. Among the 390 blood samples tested, 24.8% were considered positive for E. canis. The parsimonious logistic regression model presented an AIC value of 408.75 and showed three variables that favored the presence of E. canis DNA in the tested dogs: the animal's access to urban streets and neighborhoods (odds ratio [OR] = 1.91; p-value = 0.02; confidence interval [CI]: 1.14 - 3.18), tick infestation (OR = 2.01; p-value = 0.006; CI: 1.22 - 3.32), and poor hygienic conditions (OR = 2.19; p-value = 0.002; CI: 1.31 - 3.67). The model was considered well-calibrated based on the Hosmer-Lemeshow test (p = 0.39). According to the present study, dogs that have access to the street and neighborhood, are infested with ticks, and live under poor hygienic conditions are more likely to be infected with E. canis in the state of Rio de Janeiro, Brazil.

Assuntos

RESUMO

Rabies DNA vaccines based on full-length glycoprotein (G) induce virus neutralizing antibody (VNA) responses and protect against the virus challenge. Although conformational epitopes of G are the main target of VNAs, some studies have shown that a polypeptide linear epitope G5 is also able to induce VNAs. However, a G5 DNA vaccine has not been explored. While multiple doses of DNA vaccines are required in order to confer a protective immune response, this could be overcome by the inclusion of C3d-P28, a molecular adjuvant is know to improve the antibody response in several anti-viral vaccine models. To induce and enhance the immune response against rabies in mice, we evaluated two DNA vaccines based on the linear epitope G5 of Rabies Virus (RABV) glycoprotein (pVaxG5 vaccine) and another vaccine consisting of G5 fused to the molecular adjuvant C3d-P28 (pVaxF1 vaccine). VNA responses were measured in mice immunized with both vaccines. The VNA levels from the group immunized with pVaxG5 decreased gradually, while those from the group vaccinated with pVaxF1 remained high throughout the experimental study. After challenge with 22 LD50 of the Challenge Virus Strain (CVS), the survival rate of mice immunized with pVaxG5 and pVaxF1 was increased by 27% and 50% respectively, in comparison to the PBS group. Furthermore, the in vitro proliferation of anti-rabies specific spleen CD4+ and CD8+ T cells from mice immunized with pVaxF1 was observed. Collectively, these results suggest that the linear G5 epitope is a potential candidate vaccine. Furthermore, the addition of a C3d-P28 adjuvant contributed to enhanced protection, the sustained production of VNAs, and a specific T-cell proliferative response.

Assuntos

RESUMO

The aim of this study was to optimize a PCR assay that amplifies an 843 pb fragment from the p28 gene of Ehrlichia canis and compare it with two other PCR methods used to amplify portions of the 16S rRNA and dsb genes of Ehrlichia. Blood samples were collected from dogs suspected of having a positive diagnosis for canine ehrlichiosis. Amplification of the p28 gene by PCR produced an 843-bp fragment and this assay could detect DNA from one gene copy among 1 billion cells. All positive samples detected by the p28-based PCR were also positive by the 16S rRNA nested-PCR and also by the dsb-based PCR. Among the p28-based PCR negative samples, 55.3 percent were co-negatives, but 27.6 percent were positive in 16S rRNA and dsb based PCR assays. The p28-based PCR seems to be a useful test for the molecular detection of E. canis, however improvements in this PCR sensitivity are desired, so that it can become an important alternative in the diagnosis of canine ehrlichiosis.

O objetivo deste estudo foi aperfeiçoar um ensaio de PCR que amplificasse um fragmento de 843 pares de bases do gene p28 da Ehrlichia canis e compará-lo com outros dois métodos de PCR utilizados para amplificar partes do gene 16S rRNA e dsb do gênero Ehrlichia. Amostras sanguíneas foram colhidas de cães com diagnóstico clínico de erliquiose. A amplificação do gene p28 pela PCR produziu um fragmento de 843pb e esse ensaio permitiu a detecção do DNA de um parasita dentre 1 bilhão de células. Todas as amostras positivas detectadas pela PCR baseada no gene p28 foram também positivas pela nested PCR para detecção do gene 16S rRNA e também pela PCR dsb. Dentre as amostras negativas para a PCR p28, 55,3 por cento foram co-negativas, mas 27,6 por cento foram positivas pela PCR baseada nos genes 16S rRNA e dsb. A PCR p28 parece ser um teste útil para detecção molecular de E. canis, entretanto otimizações na sensibilidade nesta PCR são necessárias, para que esta técnica se torne uma importante alternativa no diagnóstico da erliquiose canina.

Assuntos

RESUMO

O objetivo deste estudo foi aperfeiçoar um ensaio de PCR que amplificasse um fragmento de 843 pares de bases do gene p28 da Ehrlichia canis e compará-lo com outros dois métodos de PCR utilizados para amplificar partes do gene 16S rRNA e dsb do gênero Ehrlichia. Amostras sanguíneas foram colhidas de cães com diagnóstico clínico de erliquiose. A amplificação do gene p28 pela PCR produziu um fragmento de 843pb e esse ensaio permitiu a detecção do DNA de um parasita dentre 1 bilhão de células. Todas as amostras positivas detectadas pela PCR baseada no gene p28 foram também positivas pela nested PCR para detecção do gene 16S rRNA e também pela PCR dsb. Dentre as amostras negativas para a PCR p28, 55,3% foram co-negativas, mas 27,6% foram positivas pela PCR baseada nos genes 16S rRNA e dsb. A PCR p28 parece ser um teste útil para detecção molecular de E. canis, entretanto otimizações na sensibilidade nesta PCR são necessárias, para que esta técnica se torne uma importante alternativa no diagnóstico da erliquiose canina.(AU)

The aim of this study was to optimize a PCR assay that amplifies an 843 pb fragment from the p28 gene of Ehrlichia canis and compare it with two other PCR methods used to amplify portions of the 16S rRNA and dsb genes of Ehrlichia. Blood samples were collected from dogs suspected of having a positive diagnosis for canine ehrlichiosis. Amplification of the p28 gene by PCR produced an 843-bp fragment and this assay could detect DNA from one gene copy among 1 billion cells. All positive samples detected by the p28-based PCR were also positive by the 16S rRNA nested-PCR and also by the dsb-based PCR. Among the p28-based PCR negative samples, 55.3% were co-negatives, but 27.6% were positive in 16S rRNA and dsb based PCR assays. The p28-based PCR seems to be a useful test for the molecular detection of E. canis, however improvements in this PCR sensitivity are desired, so that it can become an important alternative in the diagnosis of canine ehrlichiosis.(AU)

Assuntos

RESUMO

The aim of this study was to optimize a PCR assay that amplifies an 843 pb fragment from the p28 gene of Ehrlichia canis and compare it with two other PCR methods used to amplify portions of the 16S rRNA and dsb genes of Ehrlichia. Blood samples were collected from dogs suspected of having a positive diagnosis for canine ehrlichiosis. Amplification of the p28 gene by PCR produced an 843-bp fragment and this assay could detect DNA from one gene copy among 1 billion cells. All positive samples detected by the p28-based PCR were also positive by the 16S rRNA nested-PCR and also by the dsb-based PCR. Among the p28-based PCR negative samples, 55.3% were co-negatives, but 27.6% were positive in 16S rRNA and dsb based PCR assays. The p28-based PCR seems to be a useful test for the molecular detection of E. canis, however improvements in this PCR sensitivity are desired, so that it can become an important alternative in the diagnosis of canine ehrlichiosis.

O objetivo deste estudo foi aperfeiçoar um ensaio de PCR que amplificasse um fragmento de 843 pares de bases do gene p28 da Ehrlichia canis e compará-lo com outros dois métodos de PCR utilizados para amplificar partes do gene 16S rRNA e dsb do gênero Ehrlichia. Amostras sanguíneas foram colhidas de cães com diagnóstico clínico de erliquiose. A amplificação do gene p28 pela PCR produziu um fragmento de 843pb e esse ensaio permitiu a detecção do DNA de um parasita dentre 1 bilhão de células. Todas as amostras positivas detectadas pela PCR baseada no gene p28 foram também positivas pela nested PCR para detecção do gene 16S rRNA e também pela PCR dsb. Dentre as amostras negativas para a PCR p28, 55,3% foram co-negativas, mas 27,6% foram positivas pela PCR baseada nos genes 16S rRNA e dsb. A PCR p28 parece ser um teste útil para detecção molecular de E. canis, entretanto otimizações na sensibilidade nesta PCR são necessárias, para que esta técnica se torne uma importante alternativa no diagnóstico da erliquiose canina.

RESUMO

Caprine arthritis-encephalitis virus (CAEV) belongs to Retroviridae family, Lentivirus genus. This virus infects caprine all over the world causing arthritis, encephalitis, mammitis and progressive emaciating. This research showed chimera's building made by mixing up CAEV p28, with glutaraldehyde, and CPSMV, purified through the chromotography in biogel and sephadex (G-150). After that, some measures in a spectrophometric were developed to absorbance at 280nm. Peaks, which contained chimera, were collected and submitted to SDS-PAGE, evidencing the band relative to itself. Groups of swiss mice were immunized with chimeric virus, purified CPSMV and with p28 protein using incomplete Freund Adjuvant. CPSMV and p28 specific antibodies recognized chimeric protein in Western Blotting and ELISA showing the efficacy of the method. The results showed the covalent coupling between CPSMV and CAEV p28 was successfully archieved, originating a stable molecule, which no disestablished the capside from CPSMV. Besides, it showed that chimeric virus presents more immunogenicity than protein p28 isolated. It's suggesting CPSMV can be used as a carrier molecule in the production of vaccines to the virus, which infect animals.

O vírus da Artrite-encefalite caprina (CAEV) pertence à família Retroviridae, gênero Lentivirus. O CAEV infecta caprinos do mundo inteiro causando artrite, encefalite, mamite, pneumonia e emagrecimento progressivo. Este trabalho mostra a formação de uma quimera construída através da mistura da p28 do CAEV com glutaraldeído e CPSMV, purificada por meio de cromatografia em biogel e sephadex G-150. As cromatografias foram monitoradas através de leituras em espectrofotômetro no comprimento de onda de 280nm, dos líquidos coletados nos tubos. Os picos contendo a quimera foram coletados e submetidos à eletroforese (SDS-PAGE), sendo assim evidenciada a banda correspondente à mesma. Grupos de camundongos swiss foram imunizados com o vírus quimérico (CPSMV + p28), com o vírus CPSMV purificado e com a proteína p28 do CAEV, utilizando o adjuvante de Freund incompleto. Os anticorpos específicos produzidos contra o CPSMV e p28 reconheceram a proteína quimérica em Western Blotting e em teste de ELISA. Os anticorpos contra o vírus quimérico apresentaram títulos mais elevados do que os anticorpos produzidos contra a p28, demonstrando que o vírus quimérico apresenta maior imunogenicidade do que a proteína p28 sozinha. Os resultados mostraram que o acoplamento covalente entre o CPSMV e a p28 do CAEV foi obtido com sucesso, originando uma molécula estável não comprometendo a estrutura do capsídeo do CPSMV. Desta forma, sugere-se que o CPSMV possa ser utilizado como molécula carreadora na produção de vacinas para vírus que infectam animais.

RESUMO

Caprine arthritis-encephalitis virus (CAEV) belongs to Retroviridae family, Lentivirus genus. This virus infects caprine all over the world causing arthritis, encephalitis, mammitis and progressive emaciating. This research showed chimera's building made by mixing up CAEV p28, with glutaraldehyde, and CPSMV, purified through the chromotography in biogel and sephadex (G-150). After that, some measures in a spectrophometric were developed to absorbance at 280nm. Peaks, which contained chimera, were collected and submitted to SDS-PAGE, evidencing the band relative to itself. Groups of swiss mice were immunized with chimeric virus, purified CPSMV and with p28 protein using incomplete Freund Adjuvant. CPSMV and p28 specific antibodies recognized chimeric protein in Western Blotting and ELISA showing the efficacy of the method. The results showed the covalent coupling between CPSMV and CAEV p28 was successfully archieved, originating a stable molecule, which no disestablished the capside from CPSMV. Besides, it showed that chimeric virus presents more immunogenicity than protein p28 isolated. It's suggesting CPSMV can be used as a carrier molecule in the production of vaccines to the virus, which infect animals.

O vírus da Artrite-encefalite caprina (CAEV) pertence à família Retroviridae, gênero Lentivirus. O CAEV infecta caprinos do mundo inteiro causando artrite, encefalite, mamite, pneumonia e emagrecimento progressivo. Este trabalho mostra a formação de uma quimera construída através da mistura da p28 do CAEV com glutaraldeído e CPSMV, purificada por meio de cromatografia em biogel e sephadex G-150. As cromatografias foram monitoradas através de leituras em espectrofotômetro no comprimento de onda de 280nm, dos líquidos coletados nos tubos. Os picos contendo a quimera foram coletados e submetidos à eletroforese (SDS-PAGE), sendo assim evidenciada a banda correspondente à mesma. Grupos de camundongos swiss foram imunizados com o vírus quimérico (CPSMV + p28), com o vírus CPSMV purificado e com a proteína p28 do CAEV, utilizando o adjuvante de Freund incompleto. Os anticorpos específicos produzidos contra o CPSMV e p28 reconheceram a proteína quimérica em Western Blotting e em teste de ELISA. Os anticorpos contra o vírus quimérico apresentaram títulos mais elevados do que os anticorpos produzidos contra a p28, demonstrando que o vírus quimérico apresenta maior imunogenicidade do que a proteína p28 sozinha. Os resultados mostraram que o acoplamento covalente entre o CPSMV e a p28 do CAEV foi obtido com sucesso, originando uma molécula estável não comprometendo a estrutura do capsídeo do CPSMV. Desta forma, sugere-se que o CPSMV possa ser utilizado como molécula carreadora na produção de vacinas para vírus que infectam animais.