title: A naturally occurring prfA truncation in a Listeria monocytogenes field strain contributes to reduced replication and cell-to-cell spread.
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.
authors: Division of Neurological Sciences, Department of Clinical Research and Veterinary Public Health, Vetsuisse Faculty, University of Bern, Bern CH-3001, Switzerland; Graduate School for Cellular and Biomedical Sciences, University of Bern, Bern CH-3012, Switzerland.
authors: Sebastian
authors: S
authors: Rupp
authors: Institute of Veterinary Bacteriology, Department of Infectious Diseases and Pathobiology, University of Bern, Bern CH-3001, Switzerland.
authors: Lisandra
authors: L
authors: Aguilar-Bultet
authors: Institute of Genetics, Department of Clinical Research and Veterinary Public Health, Vetsuisse Faculty, University of Bern, Bern CH-3001, Switzerland.
authors: Vidhya
authors: V
authors: Jagannathan
authors: Division of Neurological Sciences, Department of Clinical Research and Veterinary Public Health, Vetsuisse Faculty, University of Bern, Bern CH-3001, Switzerland.
authors: Claudia
authors: C
authors: Guldimann
authors: Institute of Genetics, Department of Clinical Research and Veterinary Public Health, Vetsuisse Faculty, University of Bern, Bern CH-3001, Switzerland.
authors: Cord
authors: C
authors: Drögemüller
authors: Department of Anatomy, University of Veterinary Medicine Hannover, Hannover D-30173, Germany.
authors: Christiane
authors: C
authors: Pfarrer
authors: Veterinary Public Health Institute, Department of Clinical Research and Veterinary Public Health, Vetsuisse Faculty, University of Bern, Bern CH-3097, Switzerland.
authors: Beatriz
authors: B
authors: Vidondo
authors: Division of Neurological Sciences, Department of Clinical Research and Veterinary Public Health, Vetsuisse Faculty, University of Bern, Bern CH-3001, Switzerland.
authors: Torsten
authors: T
authors: Seuberlich
authors: Institute of Veterinary Bacteriology, Department of Infectious Diseases and Pathobiology, University of Bern, Bern CH-3001, Switzerland.
authors: Joachim
authors: J
authors: Frey
authors: Division of Neurological Sciences, Department of Clinical Research and Veterinary Public Health, Vetsuisse Faculty, University of Bern, Bern CH-3001, Switzerland. Electronic address: anna.oevermann@vetsuisse.unibe.ch.
authors: Anna
authors: A
authors: Oevermann
mesh_terms: D000034:Abortion, Veterinary; D000595:Amino Acid Sequence; D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism; D002417:Cattle; D002418:Cattle Diseases / Q000382:microbiology*; D002460:Cell Line; D005260:Female; D015964:Gene Expression Regulation, Bacterial; D016680:Genome, Bacterial / Q000235:genetics*; D006461:Hemolysis; D006801:Humans; D008089:Listeria monocytogenes / Q000235:genetics / Q000302:isolation & purification / Q000502:physiology*; D008088:Listeriosis / Q000382:microbiology / Q000662:veterinary*; D008969:Molecular Sequence Data; D020125:Mutation, Missense; D010454:Peptide Termination Factors / Q000235:genetics* / Q000378:metabolism; D010641:Phenotype; D010740:Phospholipases / Q000378:metabolism; D011247:Pregnancy; D016415:Sequence Alignment; D014774:Virulence
chemical_list: D001426:Bacterial Proteins; D010454:Peptide Termination Factors; C545356:PrfA protein, Listeria monocytogenes; D010740:Phospholipases
keywords: Abortion isolate; Listeria monocytogenes; PrfA; Reduced virulence; Truncation