Understanding the host-adapted state of Citrobacter rodentium by transcriptomic analysis

Area of Science:

• Microbiology
• Pathogen Biology
• Host-Pathogen Interactions

Background:

• Citrobacter rodentium (Cr) is a mouse pathogen causing attaching and effacing (A/E) lesions, similar to enteropathogenic Escherichia coli.
• Host-adapted (HA) Cr shed during peak infection shows hyper-infectivity, but the underlying mechanisms are unclear due to rapid loss of HA status in lab cultures.

Purpose of the Study:

• To elucidate the molecular mechanisms behind the hyper-infectivity and transmission of host-adapted Citrobacter rodentium.
• To characterize the unique transcriptome of HA Cr directly from the host environment.

Main Methods:

• Whole transcriptome sequencing of Citrobacter rodentium directly from infected mouse feces.
• Comparative analysis of gene expression patterns between host-adapted Cr and laboratory-cultured Cr.

Main Results:

• Significant differential expression of transcriptional machinery and regulators in HA Cr compared to lab-grown cells.
• High expression of major adhesion and effector genes (e.g., tir, eae) and genes within the Loci of Enterocyte Effacement (LEE 1-5) regions in HA Cr.
• Absence of expression for 19 fimbrial operons, non-fimbrial adhesins, and several non-LEE encoded effectors in HA Cr.

Conclusions:

• Host-adapted Citrobacter rodentium possesses a distinct transcriptome characterized by upregulation of key virulence factors.
• This unique gene expression profile in HA Cr is associated with its enhanced infectivity and increased host transmission potential.