Transcriptional activation of the Listeria monocytogenes hemolysin gene in Bacillus subtilis.

The prfA gene of Listeria monocytogenes was recently reported to be required for expression of hly, which encodes a pore-forming hemolysin essential for pathogenicity (M. Leimeister-Wachter, C. Haffner, E.

Innate immunity to a facultative intracellular bacterial pathogen.

The murine response to Listeria monocytogenes has long been considered a paradigm of T-cell-mediated immunity. There is, however, substantial evidence that T-cell-deficient mice are capable of surviving a L. monocytogenes challenge.

Acute aortic occlusion secondary to Aspergillus endocarditis in an intravenous drug abuser.

A 55-year-old black man, an intravenous substance abuser who had an acute arterial embolus to the distal aorta originating from his mitral valve, was noted on pathologic examination of the clot to have aspergillosis emboli. The infective endocarditis also resulted in emboli to the brain with subsequent death.

Listeria monocytogenes mutants lacking phosphatidylinositol-specific phospholipase C are avirulent.

A number of bacterial species secrete phosphatidylinositol-specific phospholipase C (PI-PLC). In this report, we show that the facultative intracellular bacterial pathogen, Listeria monocytogenes, contains a gene, plcA, predicting a polypeptide with 31% amino acid identity to a Bacillus thuringiensis PI-PLC. Accordingly, L.

Presentation of Listeria monocytogenes to CD8+ T cells requires secretion of hemolysin and intracellular bacterial growth.

Cell-mediated immunity to Listeria monocytogenes (LM) involves both CD4+ and CD8+ T cell responses. An important virulence factor in the pathogenesis of infection and development of protective immunity to LM is secretion of the sulfhydryl-activated hemolysin (Hly), listeriolysin. Listeria secretion of Hly allows LM to escape the endosomal compartment and enter the cytosol of the cell where intracellular growth can occur.

Actin filament nucleation by the bacterial pathogen, Listeria monocytogenes.

Shortly after Listeria is phagocytosed by a macrophage, it dissolves the phagosomal membrane and enters the cytoplasm. 1 h later, actin filaments coat the Listeria and then become rearranged to form a tail with which the Listeria moves to the macrophage surface as a prelude to spreading. If infected macrophages are treated with cytochalasin D, all the actin filaments associated with the Listeria break down leaving a fine, fibrillar material that does not decorate with subfragment 1 of myosin.

Isolation of Listeria monocytogenes small-plaque mutants defective for intracellular growth and cell-to-cell spread.

To dissect the regulatory and structural requirements for Listeria monocytogenes intracellular growth and cell-to-cell spread, we designed a protocol based on transposon mutagenesis and the isolation of mutants which form small plaques in monolayers of mouse L2 cell fibroblasts. Two different transposable elements were used to generate libraries of insertion mutants: Tn916 and a derivative of Tn917-lac, Tn917-LTV3. Ten classes of mutants were isolated and evaluated for growth and cell-to-cell spread in J774 mouse macrophagelike cells, Henle 407 human epithelial cells, and mouse bone marrow-derived macrophages.

Listeria monocytogenes moves rapidly through the host-cell cytoplasm by inducing directional actin assembly.

Listeria monocytogenes is an intracellular parasite that can readily infect the macrophage-like cell line J774 and the kidney epithelial cell PtK2. After being ingested, the organism escapes from the phagolysosome into the host-cell cytoplasm. N-(7-Nitrobenz-2-oxa-1,3-diazol-4-yl)-phallacidin, a specific stain for actin filaments (F-actin), demonstrates that within 1 hr of initiation of infection, the bacteria become surrounded by host-cell cytoplasmic actin filaments.

Bacillus subtilis expressing a haemolysin gene from Listeria monocytogenes can grow in mammalian cells.

Intracellular parasites can be classified into those that reside within a host vacuole and those which grow directly in the host cytoplasm. Members of the latter group, which includes Rickettsia, Shigellae, Trypanosoma cruzi, and Listeria monocytogenes, possess haemolytic activity associated with the ability to enter the host cytoplasm. Therefore mutants of L.

Gamma interferon limits access of Listeria monocytogenes to the macrophage cytoplasm.

The effect of rIFN-gamma and rTNF on the fate of hemolytic and nonhemolytic (hly-) Listeria monocytogenes in cultured mouse peritoneal macrophages was investigated. In untreated macrophages, approximately 80% of the hemolytic bacteria were killed during the first 2 h of incubation, but the survivors doubled between two and three times. In rIFN-gamma-treated macrophages, although the bacterial killing was identical to the controls during the first 2 h, there was no subsequent bacterial growth, and bactericidal activity continued for the duration of the experiment.

Actin filaments and the growth, movement, and spread of the intracellular bacterial parasite, Listeria monocytogenes.

Listeria monocytogenes was used as a model intracellular parasite to study stages in the entry, growth, movement, and spread of bacteria in a macrophage cell line. The first step in infection is phagocytosis of the Listeria, followed by the dissolution of the membrane surrounding the phagosome presumably mediated by hemolysin secreted by Listeria as nonhemolytic mutants remain in intact vacuoles. Within 2 h after infection, each now cytoplasmic Listeria becomes encapsulated by actin filaments, identified as such by decoration of the actin filaments with subfragment 1 of myosin.

Intracellular methicillin selection of Listeria monocytogenes mutants unable to replicate in a macrophage cell line.

To dissect the determinants of Listeria monocytogenes that are required for pathogenicity, we designed an intracellular selection protocol based on penicillin selection to isolate mutants defective for intracellular growth. Eight independent mutants obtained by insertion of Tn916 were isolated that were resistant to methicillin treatment following internalization by the J774 macrophage-like cell line. Seven mutants were absolutely defective for intracellular growth, whereas one showed abortive intracellular growth.

Role of hemolysin for the intracellular growth of Listeria monocytogenes.

Listeria monocytogenes insertion mutants defective in hemolysin production were generated using the conjugative transposons Tn916 and Tn1545. All of the nonhemolytic mutants (hly-) lacked a secreted 58-kD polypeptide, presumedly hemolysin, and were avirulent in a mouse model. An intracellular multiplication assay was established in monolayers of mouse bone marrow-derived macrophages, the J774 macrophage-like cell line, the CL.

Structural heterogeneity and functional domains of murine immunoglobulin G Fc receptors.

Binding of antibodies to effector cells by way of receptors to their constant regions (Fc receptors) is central to the pathway that leads to clearance of antigens by the immune system. The structure and function of this important class of receptors on immune cells is addressed through the molecular characterization of Fc receptors (FcR) specific for the murine immunoglobulin G isotype. Structural diversity is encoded by two genes that by alternative splicing result in expression of molecules with highly conserved extracellular domains and different transmembrane and intracytoplasmic domains.

Cloning and characterization of a mouse cysteine proteinase.

cDNA clones encoding a mouse cysteine proteinase were isolated from a cDNA library constructed from mRNA derived from the macrophage-like cell line J774. The DNA sequence predicts a protein that is closely related to, but distinct from, the lysosomal enzyme cathepsin H. Alignment of the predicted amino acid sequence with the known protein sequences for seven other cysteine proteinases suggests that the cloned DNA encodes a 334-residue protein containing both a 17-amino acid pre-region and a 96-amino acid pro-region.

A retrospective study of doxycycline in the treatment of genitourinary infections.

A retrospective study was conducted to assess the prevalence of Chlamydia trachomatis, Ureaplasma ureolyticum, and Mycoplasma sp in patients with suspected genital infection, and to assess the efficacy of doxycycline and other current antibiotic therapies. Over a three-year period, 1,048 records of patients (64% female; 36% male) were reviewed. C trachomatis, U ureolyticum, or Mycoplasma hominis was found in 39% of the men and 49% of the women.

Increased number of Leu-2-bearing non-T cells with natural killer activity in chimpanzees.

Peripheral blood lymphocytes from adult and adolescent chimpanzees, as well as adult humans, were studied for phenotypic surface markers by flow cytometry. Lymphocytes from chimpanzees were found to have increased numbers of Leu-1-, Leu-2+ cells as compared to humans. These cells, following preparative electronic cell sorting, were shown to possess natural killer function.

Reuse of permanent cardiac pacemakers.

Cardiac pacemakers are part of a growing group of expensive implantable electronic devices; hospitals in which 100 pacemakers are implanted per year must budget over $300 000 for these devices. This cost represents a considerable burden to health care resources. Since the "life-span" of modern pacemakers often exceeds that of the patients who receive them, the recovery and reuse of these devices seems logical.

Expression of the temperature-inducible outer membrane proteins of yersiniae.

The expression of the temperature-inducible plasmid-coded outer membrane proteins (YOPs) of Yersinia pseudotuberculosis was studied. These proteins were not recovered in the outer membrane fraction when the strain was grown in minimal medium at 37 degrees C, but they were expressed under these conditions. A strict correlation was found between Ca2+ dependency in the virulent strain, YPIII(pIB1), and ability to express YOPs.

Transfer of the virulence plasmid of Yersinia pestis to Yersinia pseudotuberculosis.

Transposon Tn5 insertion derivatives of the virulence plasmid pYV019 of Yersinia pestis were transferred by P1 transduction into a plasmid-free strain of Y. pseudotuberculosis. One of these plasmid derivatives conferred virulence upon the Y.

Treatment of intestinal cryptosporidiosis with spiramycin.

Nine male patients with the acquired immunodeficiency syndrome and one female patient who had an allogeneic bone marrow transplant for acute myeloblastic leukemia in relapse developed severe debilitating diarrhea. Cryptosporidium species were found in the stools of all patients. After receiving treatment with spiramycin for 1 week, five patients had complete resolution of the diarrhea and four patients had symptomatic improvement.

Rosoxacin in the therapy of uncomplicated gonorrhea.

In this randomized, multicentered study, 157 males and 130 females with laboratory-confirmed, uncomplicated anogenital Neisseria gonorrhoeae infections were evaluated to determine the efficacy and safety of a single 300-mg oral dose of rosoxacin versus 3.5 g of ampicillin plus 1 g of probenecid. A total of 130 males and 101 females were evaluated.

Characterization of common virulence plasmids in Yersinia species and their role in the expression of outer membrane proteins.

The virulence plasmids pYV019, pYV8081, and pIB1 from Yersinia pestis, Yersinia enterocolitica, and Yersinia pseudotuberculosis, respectively, were characterized by restriction endonuclease analysis. The three plasmids exhibited a region of common DNA previously shown to encode determinants which confer Ca2+ dependence. The plasmids from Y.