Listeriolysin as a virulence factor in Listeria monocytogenes infection of neonatal mice and murine decidual tissue.
Listeriolysin is a 60-kDa protein which allows the growth of Listeria monocytogenes in macrophages and other cells and has been shown to be a virulence factor in Listeria infections of adult mice. However, the neonate and fetoplacental unit are major populations susceptible to listeriosis. Recent data indicate that macrophage and T-cell functions are markedly inhibited in these young mice, and the virulence of listeriolysin-negative (HLY-) and listeriolysin-positive (HLY+) Listeria cells in the setting of such inhibited macrophage and T-cell functions has not previously been examined. We now compare CNL 85/162, a transposon-induced, HLY- Listeria strain, and CNL 85/163, a spontaneous HLY+ revertant. We found that all 18 neonates injected with CNL 85/163 (HLY+) died within 12 days after an injection of 10(4) Listeria cells per mouse. In contrast, all 16 neonates injected with 1,000 times more CNL 85/162 (HLY-) cells survived more than 14 days. Three days after injection, growth of CNL 85/163 (HLY+) in the internal organs was more than 5 log greater than that of CNL 85/162 (HLY-). We also found that CNL 85/162 (HLY-) did not proliferate well in decidual tissue, which is a major component of the placental region. Our studies indicate that HLY- bacteria are not virulent in the neonate and the fetoplacental unit despite the inhibited immune functions at these sites.
McKay
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Department of Internal Medicine, University of Texas Southwestern Medical School, Dallas 75235-8856.
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D000818:Animals; D000831:Animals, Newborn; D001427:Bacterial Toxins; D003656:Decidua / Q000382:microbiology*; D005260:Female; D006360:Heat-Shock Proteins / Q000633:toxicity*; D006460:Hemolysin Proteins; D008089:Listeria monocytogenes / Q000472:pathogenicity*; D008088:Listeriosis / Q000382:microbiology*; D051379:Mice; D011555:Pseudopregnancy
D001427:Bacterial Toxins; D006360:Heat-Shock Proteins; D006460:Hemolysin Proteins; C038705:hlyA protein, Listeria monocytogenes