Intracellular Behaviour of Three Legionella pneumophila Strains within Three Amoeba Strains, Including Willaertia magna C2c Maky

Abstract

<i>Legionella pneumophila</i> is a facultative intracellular pathogen found in aquatic environments as planktonic cells within biofilms and as intracellular parasites of free-living amoebae such as <i>Acanthamoeba castellanii</i>. This pathogen bypasses the elimination mechanism to replicate within amoebae; however, not all amoeba species support the growth of <i>L. pneumophila</i>. <i>Willaertia magna</i> C2c Maky, a non-pathogenic amoeba, was previously demonstrated to possess the ability to eliminate the <i>L. pneumophila</i> strain Paris. Here, we study the intracellular behaviour of three <i>L. pneumophila</i> strains (Paris, Philadelphia, and Lens) within <i>W. magna</i> C2c Maky and compare this strain to <i>A. castellanii</i> and <i>W. magna</i> Z503, which are used as controls. We observe the intracellular growth of strain Lens within <i>W. magna</i> Z503 and <i>A. castellanii</i> at 22 °C and 37 °C. Strain Paris grows within <i>A. castellanii</i> at any temperature, while it only grows at 22 °C within <i>W. magna</i> Z503. Strain Philadelphia proliferates only within <i>A. castellanii</i> at 37 °C. Within <i>W. magna</i> C2c Maky, none of the three legionella strains exhibit intracellular growth. Additionally, the ability of <i>W. magna</i> C2c Maky to decrease the number of internalized <i>L. pneumophila</i> is confirmed. These results support the idea that <i>W. magna</i> C2c Maky possesses unique behaviour in regard to <i>L. pneumophila</i> strains.