Nishibori T, Cooray K, Xiong H, Kawamura I, Fujita M, Mitsuyama M
Department of Bacteriology, Niigata University School of Medicine, Japan.
Microbiol Immunol. 1995;39(5):343-9. doi: 10.1111/j.1348-0421.1995.tb02211.x.
Five chromosomal genes, prfA, plcA, hlyA, mpl and plcB, are implicated in the virulence of Listeria monocytogenes and some of these genes have been used for the identification of bacteria by polymerase chain reaction (PCR). Using 6 strains of L. monocytogenes and 3 L. innocua strains, the relationship was examined between the presence of five virulence-associated genes and actual virulence to mice in terms of 50% lethal dose (LD50), bacterial viability in the organ of infected mice and the intracellular growth in cultured macrophages. None of the five genes could be amplified by PCR in all the L. innocua strains and they were actually avirulent to mice. All L. monocytogenes strains were shown to be virulent and to have intact virulence-associated genes except for the strain ATCC15313. This particular strain was revealed to be avirulent and defective in hlyA and plcA in PCR amplification. It was suggested that PCR detection of genes prfA, mpl, or plcB may not be sufficient to detect virulent strains of L. monocytogenes. It appeared that the ability to produce listeriolysin O (LLO), which is encoded by hlyA, was critical for the expression of virulence regardless of the amount of LLO produced.
五个染色体基因，即prfA、plcA、hlyA、mpl和plcB，与单核细胞增生李斯特菌的毒力有关，其中一些基因已被用于通过聚合酶链反应（PCR）鉴定细菌。使用6株单核细胞增生李斯特菌和3株无害李斯特菌，就50%致死剂量（LD50）、感染小鼠器官中的细菌活力以及在培养巨噬细胞中的细胞内生长情况，研究了五个毒力相关基因的存在与对小鼠的实际毒力之间的关系。在所有无害李斯特菌菌株中，这五个基因均无法通过PCR扩增，并且它们实际上对小鼠无毒力。除了ATCC15313菌株外，所有单核细胞增生李斯特菌菌株均显示有毒力且具有完整的毒力相关基因。在PCR扩增中，该特定菌株被发现无毒力且hlyA和plcA存在缺陷。有人提出，PCR检测prfA、mpl或plcB基因可能不足以检测单核细胞增生李斯特菌的有毒力菌株。似乎由hlyA编码的产李斯特菌溶血素O（LLO）的能力对于毒力的表达至关重要，而与LLO的产生量无关。
