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.
Department of Internal Medicine, University of Texas Southwestern Medical School, Dallas 75235-8856.
D B
DB
McKay
C Y
CY
Lu
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