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Exploring the chicken embryo as a possible model for studying Listeria monocytogenes pathogenicity
Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine).
Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine).
Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine).
2014 (English)In: Frontiers in Cellular and Infection Microbiology, E-ISSN 2235-2988, Vol. 4, 170Article in journal (Refereed) Published
Abstract [en]

Listeria monocytogenes is a bacterial pathogen capable of causing severe infections in humans, often with fatal outcomes. Many different animal models exist to study L. monocytogenes pathogenicity, and we have investigated the chicken embryo as an infection model: What are the benefits and possible drawbacks? We have compared a defined wild-type strain with its isogenic strains lacking well-characterized virulence factors. Our results show that wild-type L. monocytogenes, already at a relatively low infection dose (similar to 5 x 10(2) cfu), caused death of the chicken embryo within 36 h, in contrast to strains lacking the main transcriptional activator of virulence, PrfA, or the cytolysin LLO. Surprisingly, strains lacking the major adhesins InIA and InIB caused similar mortality as the wild-type strain. In conclusion, our results suggest that the chicken embryo is a practical model to study L. monocytogenes infections, especially when analyzing alternative virulence pathways independent of the InIA and InIB adhesins. However, the route of infection might be different from a human infection. The chicken embryo model and other Listeria infection models are discussed.

Place, publisher, year, edition, pages
2014. Vol. 4, 170
Keyword [en]
Listeria monocytogenes, chicken embryo, PrfA, virulence: InIA, LLO, InIB
National Category
Medical and Health Sciences
URN: urn:nbn:se:umu:diva-100984DOI: 10.3389/fcimb.2014.00170ISI: 000349152600003PubMedID: 25540772OAI: diva2:795430
Available from: 2015-03-16 Created: 2015-03-16 Last updated: 2016-01-13Bibliographically approved
In thesis
1. Regulatory pathways and virulence inhibition in Listeria monocytogenes
Open this publication in new window or tab >>Regulatory pathways and virulence inhibition in Listeria monocytogenes
2016 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Listeria monocytogenes is a rod-shaped Gram positive bacterium. It generally exist ubiquitously in nature, where it lives as a saprophyte. Occasionally it however enters the food chain, from where it can be ingested by humans and cause gastro-intestinal distress. In immunocompetent individuals L. monocytogenes is generally cleared within a couple of weeks, but in immunocompromised patients it can progress to listeriosis, a potentially life-threatening infection in the central nervous system. If the infected individual is pregnant, the bacteria can cross the placental barrier and infect the fetus, possibly leading to spontaneous abortion.

The infectivity of L. monocytogenes requires a certain set of genes, and the majority of them is dependent on the transcriptional regulator PrfA. The expression and activity of PrfA is controlled at several levels, and has traditionally been viewed to be active at 37 °C (virulence conditions) where it bind as a homodimer to a “PrfA-box” and induces the expression of the downstream gene.

One of these genes is ActA, which enables intracellular movement by recruiting an actin polymerizing protein complex. When studying the effects of a blue light receptor we surprisingly found an effect of ActA at non-virulent conditions, where it is required for the bacteria to properly react to light exposure.

To further study the PrfA regulon we tested deletion mutants of several PrfA-regulated virulence genes in chicken embryo infection studies. Based on these studies we could conclude that the chicken embryo model is a viable complement to traditional murine models, especially when investigating non-traditional internalin pathogenicity pathways. We have also studied the effects of small molecule virulence inhibitors that, by acting on PrfA, can inhibit L. monocytogenes infectivity in cell cultures with concentrations in the low micro-molar range.

Place, publisher, year, edition, pages
Umeå: Umeå Universitet, 2016. 37 p.
Umeå University medical dissertations, ISSN 0346-6612 ; 1772
Listeria monocytogenes, PrfA, ActA, infection
National Category
Cell and Molecular Biology
Research subject
Molecular Biology
urn:nbn:se:umu:diva-114085 (URN)978-91-7601-397-7 (ISBN)
Public defence
2016-02-04, KB3B1, KBC-huset, Umeå, 09:00 (English)
Available from: 2016-01-14 Created: 2016-01-12 Last updated: 2016-01-26Bibliographically approved

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Gripenland, JonasAndersson, ChristopherJohansson, Jörgen
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