title: Growth of Listeria monocytogenes in the guinea pig placenta and role of cell-to-cell spread in fetal infection.
abstract: Listeria monocytogenes causes foodborne outbreaks that lead to infection in human and other mammalian fetuses. To elucidate the molecular and cellular mechanisms involved in transplacental transmission, we characterized placental-fetal infection in pregnant guinea pigs inoculated with wild-type (wt) or mutant L. monocytogenes strains. The wt strain increased in number in the placenta by >1000-fold during the first 24 h after inoculation--an increase that was unparalleled in other maternal organs. The ActA- mutant, which is impaired in cell-to-cell spread and attenuated in maternal organs, increased in the placenta by a similar amount, although, in fetal infection, the number of ActA- mutant bacteria was 100-fold lower, compared with that of the wt strain. Furthermore, a mutant impaired in vacuolar escape was rapidly eliminated from maternal organs but persisted in the placenta. We concluded that cell-to-cell spread facilitates maternal-to-fetal transmission. Furthermore, the placenta provides a protective niche for growth of L. monocytogenes.
authors.affiliation: Department of Molecular and Cell Biology, University of California, Berkeley, California 94720-3202, USA. annaib@berkeley.edu
authors.forename: Anna I
authors.initials: AI
authors.lastname: Bakardjiev
authors.forename: Brian A
authors.initials: BA
authors.lastname: Stacy
authors.forename: Daniel A
authors.initials: DA
authors.lastname: Portnoy
mesh_terms: D000818:Animals; D005260:Female; D006168:Guinea Pigs; D018445:Infectious Disease Transmission, Vertical; D007668:Kidney / Q000382:microbiology; D008089:Listeria monocytogenes / Q000235:genetics / Q000254:growth & development / Q000472:pathogenicity*; D008088:Listeriosis / Q000382:microbiology / Q000635:transmission*; D008099:Liver / Q000382:microbiology; D008168:Lung / Q000382:microbiology; D009154:Mutation; D010920:Placenta / Q000382:microbiology*; D011247:Pregnancy; D011251:Pregnancy Complications, Infectious / Q000382:microbiology*; D013154:Spleen / Q000382:microbiology; D013997:Time Factors