RESUMO
Although the culture of Mycobacterium avium subsp. paratuberculosisis is the gold standard for the diagnosis of paratuberculosis, this bacterium is difficult to grow. In contrast, serological tests like ELISAs are inexpensive, rapid, and easy to perform. The aims of this study were to evaluate the accuracy of three different ELISAs: one with the commercial antigen PPA-3, another one with L5P (a recently described lipopentapeptide), and a third one with an in-house antigen whole cell lysates (WCL) of M. avium (MAA) strain D4ER (Study 1), and to compare them with other tests for paratuberculosis (PTB) diagnosis (Study 2). In Study 1, the sensitivities of the three ELISAs tested were 74.1%, 37% and 74.1%, respectively, whereas their specificities were 98.9%, 100% and 100%, respectively. In Study 2, we compared the three above-mentioned ELISAs with the intradermal reaction test using Avian PPD (PPDa) and fecal culture associated with Ziehl-Neelsen stain and PCR tests, in a dairy herd with 4.6% of cows with clinical signs of PTB. The results showed that fecal samples from 14 cows (16%) were culture-positive and that fecal samples from nine cows (10%) were PPDa-positive. Most of these animals (culture-positive and PPDa-positive) were detected as positive with any of the three ELISAs tested. Serological results showed that 31% of the animals were positive to ELISA-PPA-3, 17% to ELISA-L5P and 42.5% to ELISA-WCL. The combination of these three ELISAs identified 50.6% of the animals as positive in the infected herd. In particular, the results show that the locally developed ELISA seems to be useful for identifying many infected animals in a herd.
Assuntos
Doenças dos Bovinos/diagnóstico , Ensaio de Imunoadsorção Enzimática/métodos , Paratuberculose/diagnóstico , Animais , Bovinos , Doenças dos Bovinos/microbiologia , Ensaio de Imunoadsorção Enzimática/economia , Ensaio de Imunoadsorção Enzimática/veterinária , Fezes/microbiologia , Feminino , Mycobacterium avium subsp. paratuberculosis/genética , Mycobacterium avium subsp. paratuberculosis/imunologia , Paratuberculose/microbiologia , Distribuição Aleatória , Sensibilidade e EspecificidadeRESUMO
Brucella abortus INTA2, a novel mutant strain, was constructed by inactivation of two B. abortus S19 genes: bp26 and bmp18, with the objective of obtaining a mutant strain that could be compatible with a diagnostic test and have less residual virulence than strain 19. The double mutant was constructed by replacing a large section of the bp26 coding region with the luciferase (luc) coding gene, resulting in mutant strain B. abortus M1luc, followed by partial deletion of bmp18 coding sequence. Both genes were inactivated by allelic replacement assisted by sacB counter-selection. Luciferase expression was evaluated and confirmed that it is a valid marker in the construction of mutant strains. When B. abortus INTA2 was inoculated in BALB/c mice, significantly fewer colony forming units (CFUs) were recovered from mice spleens during initial phase of infection. No splenomegaly was observed in strain INTA2-immunized mice at any time suggesting that strain INTA2 has lost some residual virulence of the parental strain. Nevertheless, similar protection levels against virulent challenge were observed in mice immunized with strains INTA2 or S19. Although strain INTA2 would still induce O-side antibodies, it does not express BP26. This would allow differentiation of INTA2-vaccinated animals from animals infected with field strains by measuring anti-BP26 antibodies, either by an agglutination test or ELISA using BP26 as antigen. Altogether these results indicate that B. abortus INTA2 might be a promising vaccine strain against brucellosis.
Assuntos
Brucella abortus/genética , Brucella abortus/patogenicidade , Proteínas de Membrana/genética , Animais , Vacinas Bacterianas/imunologia , Vacinas Bacterianas/normas , Brucella abortus/imunologia , Brucelose/diagnóstico , Brucelose/imunologia , Brucelose/prevenção & controle , Farmacorresistência Bacteriana/genética , Feminino , Inativação Gênica , Marcadores Genéticos , Imunização , Luciferases/análise , Luciferases/genética , Camundongos , Camundongos Endogâmicos BALB C , Mutagênese , Plasmídeos/genética , VirulênciaRESUMO
Ratones inmunizados con antígeno 140 S de Aftovirus tipo C3 Arg84 fueron inoculados con Sarcoma 180 TG. Los líquidos ascíticos obtenidos por punción ventral contenían niveles de anticuerpos semejantes a los alcanzados por los sueros, según fueron determinados por las técnicas de seronertralización y ELISA; siendo sus volúmenes de 10 a 20 veces mayores que los correspondientes sueros sanguíneos
Assuntos
Camundongos , Animais , Anticorpos Antivirais/biossíntese , Aphthovirus/imunologia , Imunização , Líquido Ascítico/imunologia , Sarcoma 180/patologia , Anticorpos Antivirais/análise , Antígenos Virais/imunologia , Ensaio de Imunoadsorção EnzimáticaRESUMO
Ratones inmunizados con antígeno 140 S de Aftovirus tipo C3 Arg84 fueron inoculados con Sarcoma 180 TG. Los líquidos ascíticos obtenidos por punción ventral contenían niveles de anticuerpos semejantes a los alcanzados por los sueros, según fueron determinados por las técnicas de seronertralización y ELISA; siendo sus volúmenes de 10 a 20 veces mayores que los correspondientes sueros sanguíneos (AU)