cytochalasin-d and Swine-Diseases

Swine hemagglutinating encephalomyelitis virus (HEV) causes encephalomyelitis or vomiting and wasting disease in suckling piglets. Neurotoropism of the virus has been demonstrated in previous in vivo studies. In the present study, we investigated the infectivity and propagation of HEV in comparison with those of pseudorabies virus (PRV), another neurotropic virus, using dorsal root ganglia cells of newborn mice containing nerve cells and non-neuronal cells. HEV infected nerve cells but did not infect non-neuronal cells, whereas PRV infected both cell types. By using cytoskeletal inhibitors, it was suggested that propagation of HEV and PRV within and among nerve cells depended on microtubules and intermediate filaments of nerve cells, indicating that the viruses may be transported between the cell body and axonal terminals of neurons by fast axonal flow.

Topics: Acrylamide; Animals; Animals, Newborn; Coronavirus; Coronavirus Infections; Cytochalasin D; Cytoskeleton; Ganglia, Spinal; Herpesvirus 1, Suid; Immunohistochemistry; Mice; Mice, Inbred ICR; Microscopy, Confocal; Neurons; Nocodazole; Pseudorabies; Swine; Swine Diseases

Salmonella Typhimurium DT104 is an emerging enteric pathogen in swine of increasing medical importance. In this study, the time course and the actin-dependent host signaling processes necessary for invasion of a S. Typhimurium DT104 field isolate were investigated in IPEC J2 epithelial cells derived from porcine small intestine. Internalized bacteria were quantified by a gentamicin resistance assay. DT104 internalization into epithelial monolayers increased steadily between 15 and 120min after apical inoculation. Internalization was reduced by the Rho GTPase inhibitor mevastatin, the N-WASP inhibitor wiskostatin and the actin-disrupting agent cytochalasin D, but not the Rac1 GTPase inhibitor NSC-23766. Early DT104 invasion of porcine enterocytes appears to be mediated by Rac1 GTPase-independent changes in epithelial actin assembly.

Topics: Animals; Carbazoles; Cell Line; Colony Count, Microbial; Cytochalasin D; Electric Impedance; Epithelial Cells; Hydroxymethylglutaryl-CoA Reductase Inhibitors; Intestine, Small; Lovastatin; Nucleic Acid Synthesis Inhibitors; Propanolamines; Salmonella Infections, Animal; Salmonella typhimurium; Swine; Swine Diseases; Time Factors

Bordetella bronchiseptica causes respiratory disease in swine, yet there are no studies examining the interaction of B. bronchiseptica with swine alveolar macrophages. A swine isolate of B. bronchiseptica was able to adhere to, and survive intracellularly in, swine alveolar macrophages, but the relative ability of the bacteria to accomplish these functions was dependent on its phenotypic phase and culture conditions. More bacteria were observed extracellularly as well as intracellularly by immunofluorescent staining when B. bronchiseptica was cultured at 23 degrees C as compared to 37 degrees C. However, more bacteria cultured at 37 degrees C were found surviving intracellularly after the macrophages were cultured with polymyxin B to kill extracellular bacteria. Similar results were seen in experiments performed with an isogenic Bvg(-) phase-locked mutant of B. bronchiseptica cultured at 37 or 23 degrees C, indicating that another temperature dependent mechanism in addition to bvg may play a role in adhesion and intracellular survival. B. bronchiseptica was cytotoxic for swine alveolar macrophages in the Bvg(+) phase only. The cytotoxicity of B. bronchiseptica for alveolar macrophages, and its ability to survive phagocytosis, are no doubt important to escape from immune clearance mechanisms and establish infection, and could leave the host susceptible to secondary respiratory pathogens.

Topics: Animals; Antibodies, Bacterial; Bacterial Adhesion; Bacterial Outer Membrane Proteins; Bacterial Proteins; Benzenesulfonates; Bordetella bronchiseptica; Bordetella Infections; Cells, Cultured; Cytochalasin D; Fluorescent Dyes; Gene Expression Regulation; Immunoblotting; Macrophages, Alveolar; Mutation; Nucleic Acid Synthesis Inhibitors; Polymyxin B; Rabbits; Swine; Swine Diseases; Temperature; Transcription Factors; Virulence

The mechanisms of entry of Ileal symbiont intracellularis into IEC-18 rat enterocyte cells and subsequent bacterial proliferation were examined in centrifuge-assisted and static infections. Live, oxygen or neomycin damaged, and formalin killed bacteria, each rapidly entered viable cells. Live or damaged bacteria did not enter cells nor proliferate within cells after static infection of cells cooled to 5 degrees C. Infection of cells was greatly reduced at 20 degrees or 32 degrees compared to infection at 37 degrees C. Centrifuge-assisted infection was also reduced by chilling the cells. Cytochalasin D but not B inhibited the entry process indicating an actin-dependent infection, although other pathways may also be involved in centrifuge-assisted infections. Drugs capable of modifying cell membrane charge, heparin receptors or trypsin-labile proteins were all inactive in preventing or enhancing infection. We therefore conclude that infection of enterocytes by IS intracellularis is dependent on host cell activity and actin polymerization, but is independent of bacterial viability.

Topics: Actins; Animals; Cell Division; Cells, Cultured; Colchicine; Cycloheximide; Cytochalasin B; Cytochalasin D; Endocytosis; Epithelium; Gram-Negative Bacteria; Intestine, Small; Kinetics; Rats; Swine; Swine Diseases; Temperature; Time Factors; Tubulin Modulators