<em>Listeria monocytogenes</em> is a Gram-positive bacterium, mobile by means of flagella. CANNOT form capsules and / or endospores; It is a pathogenic bacterium, normally present in the environment. It is capable of living both in the soil and in the cytosol of a eukaryotic cell.
<em>L. monocytogenes</em> can enter host cells through endocytosis, this phagocytic vacuole is rapidly lysed by the listeriolysin O (LLO) toxin produced by the bacteria. Once free in the cytosol, it expresses the genes to acquire the necessary nutrients for intracellular multiplication and spread between cells and this is precisely what allows it to evade the humoral immune response.
