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[Different species of Legionella plasmids and virulence]

B I Marakusha, N D Temezhnikova, I S Tartakovskiĭ

    Molekuliarnaia Genetika, Mikrobiologiia I Virusologiia
    |June 16, 2005
    PubMed

    Insights

    Plasmids are common in Legionella bacteria, including virulent strains. However, experiments showed these plasmids did not affect the bacteria's virulence in animal models, suggesting they play no role in Legionella pathogenesis.

    Area of Science:

    • Microbiology
    • Molecular Biology
    • Bacterial Genetics

    Context:

    • Legionella strains, including high-virulence L. pneumophila and L. bozemanii, frequently harbor plasmids (2.5-80 MD).
    • These bacteria were isolated from diverse global sources, indicating widespread plasmid presence.
    • Plasmid-free derivatives were generated from L. pneumophila to investigate plasmid function.

    Purpose:

    • To determine the role of plasmids in the virulence of Legionella species.
    • To assess the impact of plasmid carriage on bacterial pathogenicity in relevant infection models.

    Summary:

    • Plasmids were detected in various Legionella strains, including virulent L. pneumophila serogroup 1 and L. bozemanii.
    • Plasmid-free L. pneumophila derivatives retained the virulence of their parent strains in chicken embryo and guinea pig models.
    • Virulence was comparable to that of serum-resistant strains, indicating plasmids did not influence pathogenicity in these models.

    Impact:

    • Current infection models do not demonstrate a direct link between plasmid presence and Legionella virulence.
    • Further research may be needed to elucidate the specific functions of Legionella plasmids.
    • Findings contribute to understanding the genetic basis of Legionella pathogenicity.

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