Jarvis N A, Donaldson J R, O'Bryan C A, Ricke S C, Crandall P G
Center for Food Safety, Department of Food Science, University of Arkansas, Fayetteville.
Department of Biological Sciences, Mississippi State University, Mississippi State.
Poult Sci. 2017 Apr 1;96(4):950-956. doi: 10.3382/ps/pew358.
Listeria monocytogenes can be carried by and infect poultry, although the clinical disease in birds is rare. Escape from macrophage phagocytosis is a key step in pathogenesis for L. monocytogenes. Therefore, we investigated the infection of the chicken macrophage-like cell line HD11 with 2 strains of L. monocytogenes EGD-e and Scott A. After infection, L. monocytogenes was quantified by spread plating and HD11 was quantified with trypan blue exclusion stain before enumeration. The standard macrophage killing protocols require washing the cell monolayers 3 times with PBS, which was found to negatively influence HD11 monolayers. Maximum bacterial densities within macrophages were not different between the 2 Listeria strains. HD11 required more than 11 h to effectively reduce intracellular L. monocytogenes Scott A, and Scott A was more susceptible to HD11 killing than EGD-e. It appears that Listeria infection initially causes attenuation of HD11 growth, and infected HD11 cells do not begin to lyse until at least 11 h post infection. These results suggest that there are subtle strain to strain differences in response to HD11 macrophage phagocytosis. The long lead-time required for HD11 to kill L. monocytogenes cells means that there is sufficient time available for chicken macrophages to circulate in the blood and transfer the intracellular Listeria to multiple tissues.
单核细胞增生李斯特菌可寄生于禽类并使其感染，尽管禽类的临床疾病较为罕见。逃避巨噬细胞吞噬是单核细胞增生李斯特菌致病的关键步骤。因此，我们研究了两株单核细胞增生李斯特菌EGD-e和Scott A对鸡巨噬细胞样细胞系HD11的感染情况。感染后，通过平板涂布法对单核细胞增生李斯特菌进行定量，在计数前用台盼蓝排斥染色法对HD11进行定量。标准的巨噬细胞杀伤方案要求用PBS洗涤细胞单层3次，结果发现这对HD11单层细胞有负面影响。两株李斯特菌在巨噬细胞内的最大细菌密度没有差异。HD11需要超过11小时才能有效减少细胞内的单核细胞增生李斯特菌Scott A，并且Scott A比EGD-e更容易被HD11杀伤。看来李斯特菌感染最初会导致HD11生长减弱，并且受感染的HD11细胞直到感染后至少11小时才开始裂解。这些结果表明，在对HD11巨噬细胞吞噬的反应中，菌株之间存在细微差异。HD11杀死单核细胞增生李斯特菌细胞所需的较长时间意味着鸡巨噬细胞有足够的时间在血液中循环，并将细胞内的李斯特菌转移到多个组织。
