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Evolución paralela de la virulencia en el Escherichia coli patógeno
S D Reid1, C J Herbelin, A C Bumbaugh
1Institute of Molecular Evolutionary Genetics, Pennsylvania State University, University Park 16802, USA.
Nature
|July 14, 2000
Resumen
La evolución de Escherichia coli patógeno, incluyendo E. coli O157: H7, comenzó hace millones de años. La selección natural favoreció la adquisición ordenada de genes de virulencia, lo que condujo a un aumento de la amenaza de patógenos.
Área de la Ciencia:
- Microbiología Microbiología.
- Biología evolutiva Biología evolutiva.
- Genética La genética.
Sus antecedentes:
- Las vías evolutivas que conducen a nuevos patógenos bacterianos siguen siendo en gran medida desconocidas.
- Comprender la aparición de la Escherichia coli patógena (E. coli) es crucial para la salud pública.
Objetivo del estudio:
- Para aclarar la historia evolutiva y la adquisición de genes de virulencia en cepas patógenas de E. coli.
- Para reconstruir las relaciones filogenéticas y la línea de tiempo de la evolución del patógeno E. coli.
Principales métodos:
- Secuenciación de siete genes de limpieza para construir un árbol filogenético.
- Análisis de compatibilidad para evaluar el impacto de la recombinación en las señales filogenéticas.
- Estimación de los tiempos de divergencia utilizando las tasas de sustitución sinónimas para E. coli y Salmonella enterica.
Principales resultados:
- El análisis filogenético reveló que la recombinación no ha oscurecido por completo las señales cromosómicas ancestrales.
- La radiación de los clones de E. coli se inició hace aproximadamente 9 millones de años.
- La altamente virulenta E. coli O157:H7 divergió de un antepasado de E. coli K-12 hace unos 4,5 millones de años.
- Los linajes más antiguos de E. coli adquirieron independientemente factores de virulencia idénticos, como islas de patogenicidad, hemolisinas y toxinas Shiga.
Conclusiones:
- La evolución paralela de los factores de virulencia sugiere fuertes presiones selectivas en la E. coli patógena.
- La selección natural ha impulsado una adquisición ordenada de genes, aumentando progresivamente la virulencia bacteriana.
- Este estudio proporciona información sobre el desarrollo gradual de los mecanismos patógenos en E. coli.
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