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Dos sistemas de defensa eliminan los plásmidos de la séptima pandemia de Vibrio cholerae

Milena Jaskólska¹, David W Adams², Melanie Blokesch³

¹Laboratory of Molecular Microbiology, Global Health Institute, School of Life Sciences, Station 19, EPFL-SV-UPBLO, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland.

|April 7, 2022

Resumen

Se identificaron dos nuevos sistemas de defensa de plásmidos, DdmABC y DdmDE, en cepas pandémicas de Vibrio cholerae. Estos sistemas eliminan los plásmidos y se defienden contra los bacteriófagos, impactando la evolución bacteriana y la propagación de la resistencia a los antibióticos.

Área de la Ciencia:

Genética y evolución bacteriana
Patogénesis microbiana
Elementos genéticos móviles

Sus antecedentes:

La transferencia horizontal de genes (HGT) impulsa la adaptación bacteriana a través de elementos genéticos móviles como los plásmidos y los bacteriófagos.
Las bacterias poseen diversos mecanismos de defensa contra los elementos genéticos móviles invasores.
Las cepas de Vibrio cholerae El Tor responsables de la séptima pandemia de cólera tienen características genéticas únicas.

Objetivo del estudio:

Identificar y caracterizar los sistemas de defensa del plásmido en la pandemia de Vibrio cholerae.
Investigar los mecanismos y objetivos de estos sistemas de defensa.
Comprender el papel de estos sistemas en la configuración de la evolución de la pandemia de V. cholerae y la difusión de la resistencia a los antibióticos.

Principales métodos:

Análisis genético de las cepas de Vibrio cholerae El Tor.
Ensayos de desafío de plásmidos y bacteriófagos.
Mecanismo de estudios de acción para los sistemas de defensa DdmABC y DdmDE.
Pruebas de aptitud para las células portadoras de plásmidos.

Principales resultados:

Se identificaron dos sistemas de defensa de plásmidos conservados, DdmABC y DdmDE, en la pandemia de V. cholerae.
Estos sistemas cooperan para degradar pequeños plásmidos multicopiados.
DdmABC proporciona defensa contra los bacteriófagos a través de la infección abortiva (Abi) e impone un costo de aptitud a las células que transportan plásmidos grandes, incluidos los plásmidos multirresistentes IncC.
Los plásmidos son raros en las cepas pandémicas de V. cholerae, en contraste con su abundancia en las cepas ambientales.

Conclusiones:

Los sistemas DdmABC y DdmDE son factores clave en la evolución de la pandemia de V. cholerae mediante el control del transporte de plásmidos.
Estos hallazgos explican la baja prevalencia de plásmidos en cepas pandémicas y tienen implicaciones para comprender la diseminación de plásmidos resistentes a los antibióticos.
La interacción de estos sistemas de defensa ha dado forma al éxito del linaje pandémico dominante de V. cholerae.

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