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A quantitative study of single and mixed infection of the chicken trachea by Mycoplasma gallisepticum
The interaction between Mycoplasma gallisepticum (MG) and the tracheal mucosa of the young chicken was studied. The use of a selective plating method permitted differentiation between a pathogenic tylosin-resistant strain (227) and a less pathogenic tylosin-sensitive vaccine strain (F). Both MG stra...
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Published in: | Avian diseases 1987-01, Vol.31 (1), p.1-12 |
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Main Authors: | , |
Format: | Article |
Language: | English |
Subjects: | |
Citations: | Items that cite this one |
Online Access: | Get full text |
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Summary: | The interaction between Mycoplasma gallisepticum (MG) and the tracheal mucosa of the young chicken was studied. The use of a selective plating method permitted differentiation between a pathogenic tylosin-resistant strain (227) and a less pathogenic tylosin-sensitive vaccine strain (F). Both MG strains adhered to the tracheal mucosa and colonized equally well. In mixed infection, the presence or absence of the second strain did not change the efficiency of colonization by either strain. When chickens were exposed to the vaccine strain 24 hr or 2 weeks before superinfection by the pathogen, there was no significant reduction in the efficiency of superinfection, despite the presence of 106colony-forming units of MG strain F in the trachea. However, chickens had an increased ability to resist superinfection 5 weeks after exposure via the air sac. These results suggest that the biological mechanism underlying protection of F-strain-vaccinated chickens against adventitious infection by the homologous species does not involve competition for adherence sites or blockage by prior colonization. /// Se estudió la interacción entre Mycoplasma gallisepticum (MG) y la mucosa traqueal en pollos jóvenes. El uso de un método selectivo de siembra permitió la diferenciación entre una cepa patógena (227) resistente a la tilosina y una cepa vacunal menos patógena, sensible a la tilosina (F). Ambas cepas de MG se adhirieron a la mucosa traqueal y la colonizaron en forma similar, con la misma eficiencia en presencia o ausencia de la segunda cepa. En el caso de la infección con la cepa vacunal aplicada 24 horas o 2 semanas antes de la infección con la cepa patógena, no se encontró una disminución significante en la eficiencia de infección a pesar de la presencia en la tráquea de 106unidades formadoras de colonia de MG. Sin embargo, en pollos a las 5 semanas después de la exposición a la infección vía saco aéreo, se observó un aumento en la capacidad de resistencia a la infección. Estos resultados sugieren que el mecanismo biológico por el cual la cepa F da protección frente a la infección con cepas homólogas en pollos vacunados no se debe a la competencia por sitios de adhesión o bloqueo antes de la colonización. |
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ISSN: | 0005-2086 1938-4351 |
DOI: | 10.2307/1590765 |