ABSTRACT
This review describes horizontal gene transfer from a historical point of view, with descriptions of the first instances of the different bacterial transfer mechanisms: conjugation, transduction and transformation, as well as examples of some of the early acknowledged transfer events. Gene transfer from four selected foodborne pathogens: Escherichia coli, Listeria monocytogenes,Staphylococcus aureus and Salmonella are highlighted.
Subject(s)
Bacteria/genetics , Food Microbiology , Gene Transfer, Horizontal , Virulence Factors/genetics , Animals , Bacteria/pathogenicity , Conjugation, Genetic/genetics , Escherichia coli/genetics , Escherichia coli/pathogenicity , Food Supply , Listeria monocytogenes/genetics , Listeria monocytogenes/pathogenicity , Mice , Salmonella/genetics , Salmonella/pathogenicity , Staphylococcus aureus/genetics , Staphylococcus aureus/pathogenicity , Transduction, Genetic , Transformation, Bacterial/geneticsABSTRACT
Bacteria use various ways to transfer genetic information. These methods include: conjugation, which requires cell to cell contact between cells, transduction, which is bacteriophage-facilitated transfer of genetic information, and transformation, which is the uptake of free DNA from the environment. Usually the genes to be transferred lie on mobile genetic elements, pieces of DNA that encode proteins important to facilitate movement of DNA within or between genomes. This review highlights the transfer methods and the role of the assorted mobile genetic elements in the evolution of four foodborne bacterial pathogens: Escherichia coli O157:H7, Salmonella, Staphylococcus aureus and Listeria monocytogenes.
Subject(s)
Bacteria/genetics , Bacterial Infections/genetics , Bacterial Infections/transmission , Gene Transfer, Horizontal , Host-Pathogen Interactions/physiology , Bacteria/pathogenicity , Escherichia coli O157/genetics , Escherichia coli O157/pathogenicity , Evolution, Molecular , Food Microbiology , Listeria monocytogenes/genetics , Listeria monocytogenes/pathogenicity , Salmonella/genetics , Salmonella/pathogenicity , Staphylococcus aureus/genetics , Staphylococcus aureus/pathogenicityABSTRACT
Genes encoding virulence determinants are transferred between species in many different environments. In this review we describe gene transfer events to and from different species of bacteria, from bacteria to plants, and from plants to bacteria. Examples of the setting for these transfer events include: the GI tract, the rumen, the oral cavity, and in food matrixes. As a case study, the flux of virulence factors from E.coli O157:H7 is described as an example of gene flow in the environment.
Subject(s)
Bacteria/genetics , Gene Transfer, Horizontal , Host-Pathogen Interactions/physiology , Plants/genetics , Virulence Factors/genetics , Animals , Bacteria/metabolism , Bacteria/pathogenicity , Escherichia coli O157/genetics , Escherichia coli O157/metabolism , Escherichia coli O157/pathogenicity , Food Microbiology , Gastrointestinal Tract/microbiology , Humans , Mouth/microbiology , Plants/metabolism , Rumen/microbiologyABSTRACT
Both Epstein-Barr virus (EBV) and p53 have independently been associated with idiopathic pulmonary fibrosis (IPF). This study explores further whether a relationship potentially exists between EBV and p53 in IPF, thereby providing a possible mechanism for the role of EBV in the disease progression of IPF. Lung tissue from open lung biopsies of 14 IPF patients was compared with a control group of 19 patients. EBV status was determined using both immunohistochemistry and PCR, while p53 expression was assessed with immunohistochemistry Seven of 14 IPF patients expressed p53 compared to one of 19 control subjects (P = 0.011). Eight IPF patients and no controls were positive for EBV (P < 0.01). Four IPF patients demonstrated both EBVand p53 expression compared with no controls, (P = 0.05). This study suggests that a relationship between EBV and p53 may exist in patients with IPF.
Subject(s)
Herpesvirus 4, Human/isolation & purification , Lung/chemistry , Lung/virology , Pulmonary Fibrosis/metabolism , Pulmonary Fibrosis/virology , Tumor Suppressor Protein p53/analysis , Case-Control Studies , Epithelial Cells/chemistry , Epithelial Cells/virology , Epstein-Barr Virus Infections/complications , Female , Genes, Viral , Herpesvirus 4, Human/genetics , Humans , Immunohistochemistry/methods , Male , Middle Aged , Polymerase Chain Reaction/methods , Statistics, NonparametricABSTRACT
Following the establishment of a chronic varicella-zoster virus infection in the rat, behavioural allodynia and hyperalgesia were observed in the injected, but not the contralateral hind limb up to 33 days post-infection. This model may prove useful in investigating mechanisms involved in the establishment of post-herpetic neuralgia.
Subject(s)
Behavior, Animal , Herpes Zoster/psychology , Animals , Herpes Zoster/physiopathology , Hyperalgesia , Male , Pain/physiopathology , Rats , Rats, Wistar , Viral Proteins/analysisABSTRACT
Idiopathic pulmonary fibrosis (IPF) is a clinical syndrome in which the precipitating factors are unclear. An association between Epstein-Barr Virus (EBV) and IPF had previously been suggested using serology and immunohistochemistry. This study sought confirmation of the presence of EBV DNA in the lung tissue of patients with IPF. Lung tissue obtained surgically from 27 patients with IPF and 28 control subjects was investigated for the presence of EBV by immunohistochemistry and polymerase chain reaction (PCR) analysis. Immunohistochemistry used antibodies specific for EBV lytic cycle antigens (gp340/220 and VCA). Nested PCR analysis used oligonucleotide primers specific for EBV and was sensitive to one copy of EBV DNA. Twelve of the 27 patients with IPF (44%) and three of the 28 control subjects (10%) were EBV positive by immunohistochemistry (p = 0.005). Thirteen of the patients with IPF (48%) and four of the control subjects (14%) were EBV positive by PCR (p = 0.007). Eleven of the patients with IPF (41%) and none of the control subjects were EBV positive by both immunohistochemistry and PCR (p = < 0.001). These data further suggest an association between EBV and IPF. In addition it defines a novel method for detecting EBV in lung tissue. EBV may be involved in the pathogenesis of the disease; however, further studies are required to establish a causal relationship.
Subject(s)
Capsid Proteins , DNA, Viral/analysis , Herpesvirus 4, Human/isolation & purification , Lung/virology , Pulmonary Fibrosis/virology , Adult , Aged , Antigens, Viral/analysis , Capsid/immunology , Female , Herpesvirus 4, Human/genetics , Humans , Immunohistochemistry , Male , Middle Aged , Polymerase Chain Reaction , Viral Matrix Proteins/analysisABSTRACT
The feasibility and acceptability of an external quality assurance scheme in veterinary histopathology were assessed for one year. The format of the scheme is described and the results are discussed. It is suggested that a self-financing scheme for all laboratories offering histopathological diagnosis should be introduced as a contribution to the maintenance of standards.
Subject(s)
Pathology, Veterinary/standards , Animals , Feasibility Studies , Histological Techniques , London , Pilot Projects , Quality ControlABSTRACT
The intraerythrocytic multiplication of two strains of Theileria annulata was studied with parasites maintained in stationary cultures and in the blood of infected cattle. In cultures established with blood from infected cattle 20-60% of single T. annulata piroplasms divided into quadruplet forms by day 6 in vitro. Transmission electron microscopic studies of T. annulata in culture showed that piroplasms possess intracytoplasmic food vacuoles and cytostomes during a pre-division trophozoite stage. The onset of intraerythrocytic multiplication was marked by the appearance of rhoptries and electron-dense plaques beneath the parasite's plasmalemmal membrane. The plaques developed into short segments of subplasmalemmal double membranes which were closely associated with the rhoptries. It was concluded that multiplication of T. annulata in erythrocytes occurred by schizogony, as nuclear division preceded cytoplasmic division and the final separation of merozoites. The four merozoites produced by intraerythrocytic schizogony had the same ultrastructural features as the T. annulata merozoites produced by intralymphocytic schizogony. Clusters of four merozoites, identical to those observed in stationary cultures, were also seen in the erythrocytes of persistently infected cattle and appeared to represent the most significant dividing forms of T. annulata in vivo.
