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A naturally occurring prfA truncation in a Listeria monocytogenes field strain contributes to reduced replication and cell-to-cell spread. | LitMetric

AI Article Synopsis

  • Listeria monocytogenes can become an intracellular pathogen, causing serious health issues like gastroenteritis and central nervous system infections; this study focuses on strain JF5171 isolated from a cow's placenta linked to abortion.
  • The genome of JF5171 was sequenced and analyzed, showing reduced invasion, replication, and intercellular spread compared to the standard strain EGD-e, as well as lower enzyme activities related to virulence.
  • A deletion in the prfA gene, which regulates virulence, led to a truncated protein contributing to JF5171's weakened ability to infect cells; restoring prfA from EGD-e improved its virulence, while the truncated version did not.

Article Abstract

Listeria (L.) monocytogenes is an environmental bacterium that may become an intracellular pathogen upon ingestion to cause gastroenteritis, septicaemia, abortions, and/or fatal infections of the central nervous system. We here describe a L. monocytogenes field strain (JF5171) isolated from a bovine placenta in the context of abortion, which exhibited attenuation in bovine brain-slice cultures. The whole genome of strain JF5171 was sequenced, and the invasion, replication, and intercellular spread of JF5171 were further analyzed by quantification of colony forming units and immunofluorescence studies. Phospholipase and hemolysis activity of JF5171 were also quantified along with transcription levels of actA, hly and prfA. The data obtained were compared to those of the widely used L. monocytogenes reference strain, EGD-e. JF5171 exhibited reduced replication and lower levels of phospholipase and hemolysis activity. Invasion and cell-to-cell spread was strongly decreased compared to EGD-e, and actin polymerization was absent. A frame shift deletion was identified in the JF5171 coding region of the major regulator for virulence, prfA. This resulted in a truncated C-terminus sequence (WEN* vs. WGKLN*). In addition, a point mutation resulted in a lysine to arginine substitution at amino acid position 197. Complementation with prfA from EGD-e and with (EGD-e) prfA-K197N increased the replication and spread efficiency of JF5171. In contrast, complementation with the truncated version of prfA had no effect. Taken together, these results suggest that the truncated C-terminus of prfA considerably contributes to the strongly attenuated phenotype observed in vitro.

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Source
http://dx.doi.org/10.1016/j.vetmic.2015.03.002DOI Listing

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