RESUMO
Strains of Mycoplasma mycoides subspecies capri (Mmc) are frequently isolated from goats with contagious agalactia, but they can also be recovered from herds that have shown no clinical signs of mycoplasmosis for several years. The present study was conducted in order to explore the potential genetic and antigenic differences existing between an Mmc strain isolated from an outbreak (septicaemic) and a strain isolated from the ear canal of a goat belonging to a herd with no recent episode of mycoplasmosis (carriage strain). The genomes of the two strains, compared by suppression subtractive hybridization, were shown to be poorly divergent. The two strains were inoculated into goats to produce specific antisera, but both induced fatal mycoplasmosis. These results indicate that septicaemic and carriage strains cannot be distinguished by their genetic background or by their pathogenic capacity under experimental conditions.
Assuntos
Doenças das Cabras/microbiologia , Mycoplasma mycoides/isolamento & purificação , Pleuropneumonia Contagiosa/microbiologia , Sepse/veterinária , Animais , Genômica , Doenças das Cabras/patologia , Doenças das Cabras/transmissão , Cabras , Mycoplasma mycoides/genética , Mycoplasma mycoides/imunologia , Hibridização de Ácido Nucleico/métodos , Pleuropneumonia Contagiosa/patologia , Pleuropneumonia Contagiosa/transmissão , Sepse/microbiologia , Sepse/patologia , Análise de Sequência de DNA , Especificidade da EspécieRESUMO
AIMS: The analysis by Denaturing Gradient Gel Electrophoresis (DGGE) of the PCR-amplified V3 region of 16S rRNA gene was previously shown to detect and differentiate a large number of human and animal mycoplasmas. In this study, we further assessed the suitability of the technique for epidemiological surveillance of mycoplasmas belonging to the 'Mycoplasma mycoides' cluster, a phylogenetic group that includes major ruminant pathogens. METHODS AND RESULTS: The V3 region of 16S rRNA genes from approx. 50 field strains was amplified and analysed by DGGE. Detection and identification results were compared with the ones obtained by antigenic testing and sequence analysis. CONCLUSIONS: The DGGE technique is robust and valuable as a first-line test, but the patterns obtained for strains belonging to the 'M. mycoides' cluster were too variable within a taxon and in contrast too conserved between taxa to allow an unequivocal identification of isolates without further analysis. SIGNIFICANCE AND IMPACT OF THE STUDY: Issues raised by the quest for a single universal test able to detect and identify any mycoplasma in one clinical sample are thoroughly documented.
