The factors of bacterial pathogenicity and their role in the development of the infectious process

The latest data concerning the characterization of the pathogenicity factors of bacteria and the evaluation of their role in the realization of definite phases of the development of the infectious process are presented. The infectious process is regarded as the result of the complicated simultaneous interaction of microorganisms and different cells and tissues of the host body. The problems of the polydeterminant character of pathogenicity factors, tho possibility of the joint action of different factors at one and the same stage of the development of the infectious process and, vice versa, the action of the same factors at different stages of the interaction of the infective agent and the susceptible host are discussed. Modern data on the genetic control of pathogenicity factors, on the localization of their genetic determinants on the chromosome and the virulence plasmids, information of pathogenicity "islets" which jointly determine the pathogenic potential of the infective agent are given. The emphasis is made on fact that the general principle of the genetic control of bacterial pathogenicity is complicated relationship between chromosomal and nonchromosomal determinants; some of them form a part of genetic pathogenicity "islets", simultaneously regulating and expressing the pathogenicity factors of the infective agent.     

烟曲霉关键致病因子研究进展

烟曲霉是侵袭性真菌病常见的致病菌之一。近年来一些细胞表面蛋白（如GPI锚定蛋白）以及分泌的毒素被认为是烟曲霉的关键致病因子。现从烟曲霉的细胞壁蛋白、多糖,细胞外基质成分,烟曲霉的分泌产物几方面综述已发现的烟曲霉关键致病因子,并对未来的研究方向进行展望。     

Factors and genetics of pathogenicity of group B Streptococci

In this review data on the pathogenicity factors of streptococci and their genetic control are presented. Attention is paid mainly to protein antigens alpha and beta, C5a peptidase, CAMP factor, R, Rib and X proteins. The problems of making the genetic and physical charts of the genome of group B streptococci, the genetic regulation of the synthesis of pathogenicity factors and the specific features of the damaging action of the infective agent are discussed.     

A Bioassay for Determining Pathogenicity of Entomogenous Fungi on Whiteflies

A simple and effective laboratory bioassay method for determining the pathogenicity of entomogenous fungi to whiteflies is presented. The bioassay is based on characterization of the growth rate and development of entomogenous fungi on fourth instar nymphs of the silverleaf whitefly (SLWF), Bemisia argentifolii (Bemisia tabaci, Strain B), and is useful in determining the effects of environmental factors (e.g., temperature and humidity) and additives (e.g., surfactants, adjuvants, and pesticides) on the development of entomogenous fungi. Such information can provide a better understanding of the influence of these factors on the performance of entomogenous fungi when tested under field conditions. The bioassay has been successfully implemented for the evaluation of the pathogenicity of Paecilomyces fumosoroseus, Verticillium lecanii, and Beauveria bassiana against fourth instar nymphs of SLWF. It has the potential to be useful as a screening tool for determining pathogenicity of new fungal isolates and for the standardization and quality control of commercial fungal preparations for viability and virulence against insect pests before they are used far field applications.     

Biochemical components and immunobiological activity of factors of Staphylococci pathogenicity

Materials on biochemical components of factors of pathogenicity of Staphylococcus aureus and research of their immunobiolocal influence on the microorganism are presented in the review.     

Immunoproteomic to Analysis the Pathogenicity Factors in Leukopenia Caused by Klebsiella Pneumonia Bacteremia

Incidences of leukopenia caused by bacteremia have increased significantly and it is associated with prolonged hospital stay and increased cost. Immunoproteomic is a promising method to identify pathogenicity factors of different diseases. In the present study, we used immunoproteomic to analysis the pathogenicity factors in leukopenia caused by Klebsiella Pneumonia bacteremia. Approximately 40 protein spots localized in the 4 to 7 pI range were detected on two-dimensional electrophoresis gels, and 6 differentially expressed protein spots between 10 and 170 kDa were identified. Pathogenicity factors including S-adenosylmethionine synthetase, pyruvate dehydrogenase, glutathione synthetase, UDP-galactose-4-epimerase, acetate kinase A and elongation factor tu (EF-Tu). In validation of the pathogenicity factor, we used western blotting to show that Klebsiella pneumonia had higher (EF-Tu) expression when they accompanied by leukopenia rather than leukocytosis. Thus, we report 6 pathogenicity factors of leukopenia caused by Klebsiella pneumonia bacteremia, including 5 housekeeping enzymes and EF-Tu. We suggest EF-Tu could be a potential pathogenicity factor for leukopenia caused by Klebsiella pneumonia.     

Variability of the pathogenicity traits of populations of staphylococci in a surgical hospital

The results of the study of heterogeneity of staphylococcal populations at a surgical ward are presented. The study deals with qualitative and quantitative characteristics of three groups of pathogenicity factors: protease (the penetration factor), protein A (the function of protection from phagocytosis) and alpha-hemolysin (the toxic function). The study shows that the greatest number of S. aureus strains with a high content of protein A has been isolated from patients with postoperative and wound infections. On the basis of the data obtained in this study the groups of strains have been defined in accordance with the association of the signs of pathogenicity. These groups reflect pronounced heterogeneity of staphylococcal strains at a surgical ward.     

Bacterial pathogenicity islands

The information on the key pathogenicity factors of uropathogenic and enteropathogenic Escherichia coli, Shigella, Salmonella, Vibrio cholerae, Yersinia, Listeria and Helicobacter pylori is reviewed. The analysis of data on pathogenicity "islands" and "islets" of infective agents is given. The problems of the genetic control of pathogenicity factors and the functions of pathogenicity "islands", found in infective agents, are discussed.     

Participation of mobile elements in formation of properties of pathogenic bacteria]

Published reports about structural organization of genes coding for pathogenicity factors are reviewed. Many of such genes are often united into "virulence blocks" or "pathogenicity islands" and are surrounded by mobile genetic elements, promoting their transposition between related bacteria genomes and leading to changes in virulence in the course of evolution. Data on the similarity of nucleotide sequences of virulence genes in different bacteria are presented, despite differences in their localization in the relevant genomes. The role of rRNA genes in dissemination of virulence genes among different bacteria during transduction or conjugation is shown.     

Secreted pathogenicity factors of enterobacteria

Data on the secreted pathogenicity factors of different enterobacterial species are reviewed. Update information on toxin classification is presented. The main cytotoxic and cytotonic enterotoxins, transient pore forming toxins (RTX), cytotoxic necrotizing factor and injection toxins have been analyzed. Problems connected with the mechanism of action and genetic control of known enterobacterial toxins are discussed.     

Pathogenicity factors of opportunistic enterobacteria and its role in development of diarrhea

The data of pathogenicity factors of opportunistic enterobacteria, including Klebsiella, Enterobacter, Citrobacter, Proteus, Providencia and Hafnia species are submitted. The genetic control and a role of pathogenicity factors of opportunistic enterobacteria in development of diarrhea syndrome are presented. Data about adhesins, hemolysins, cytotoxic necrotizing factors and bacterial modulins are described. The characteristic of cytotonic and cytotoxic enterotoxins, including LT, ST, Shiga-like and cytolethal toxins, and mechanisms of diarrheagenic action are analysed. The role of bacterial lipopolysaccharide (endotoxin) and induction of locally synthesized proinflammatory cytokins in pathogenisis of diarrhea are discussed.     

Plasmids and mobile genetic elements of pathogenic Yersinia bacteria

The review of literature is devoted to molecular and genetic organization of movable genetic elements responsible for synthesis of pathogenicity factors of Yersinia bacteria. General characterization of Yersinia pathogenicity factors is given. We analysed the role of plasmids in expression of the pathogenic properties of these bacteria and the role of IS elements of Yersinia in expression of genes encoding synthesis of the pathogenicity factors. Replicative properties of Yersinia plasmids are described. The role of chromosomal genes in regulation of synthesis of the plasmid-specific pathogenicity factors is discussed.     

Do plant and human pathogens have a common pathogenicity strategy?

Recently, a novel 'two-step' model of pathogenicity has been described that suggests host-cell-derived vasculoproliferative factors play a crucial role in the pathogenesis of bacillary angiomatosis, a disease caused by the human pathogenic bacterium Bartonella henselae. The resulting proliferation of endothelial cells could be interpreted as bacterial pathogens triggering the promotion of their own habitat: the host cell. Similar disease mechanisms are well known in the plant pathogen Agrobacterium tumefaciens, which causes crown gall disease. There are notable similarities between the pathogenicity of A. tumefaciens leading to tumourous disease in plants and to the B. henselae-triggered proliferation of endothelial cells in humans. Here, we hypothesize that this pathogenicity strategy might be common to several bacterial species in different hosts owing to shared pathogenicity factors.     

Molecular and infection biology of the horse pathogen Rhodococcus equi

The soil actinomycete Rhodococcus equi is a pulmonary pathogen of young horses and AIDS patients. As a facultative intracellular bacterium, R. equi survives and multiplies in macrophages and establishes its specific niche inside the host cell. Recent research into chromosomal virulence factors and into the role of virulence plasmids in infection and host tropism has presented novel aspects of R. equi infection biology and pathogenicity. This review will focus on new findings in R. equi biology, the trafficking of R. equi -containing vacuoles inside host cells, factors involved in virulence and host resistance and on host–pathogen interaction on organismal and cellular levels.     

The nematode Caenorhabditis elegans as a model for the study of host-pathogen interactions

For certain pathogens capable of infecting a broad range of organisms, there exist universal virulence factors, necessary for full pathogenicity regardless of the host. This has been most clearly demonstrated by Ausubel and colleagues for the human opportunistic pathogen Pseudomonas aeruginosa. As a consequence, one can use non-mammalian model systems, including the nematode worm Caenorhabditis elegans, to assay for such virulence factors. A significant number of pathogens of C. elegans, that provoke a range of diseases, are now known, including the opportunistic human pathogen Serratia marcescens. After explaining the practical advantages associated with the use of C. elegans, and briefly reviewing previous studies, the results of a screen for S. marcescens virulence factors will be presented.     

An Annotated List of Protozoan Parasites,Hyperparasites, and Commensals of Decapod Crustacea*

SYNOPSIS. An approximately complete list of the known protozoan associates (exclusive of a few aberrant forms like Amallocystis) of decapods is presented. A few taxonomic changes are suggested. Host, site of infection and geographic location are mentioned. Some comments on pathogenicity are made.     

Safe biotechnology. Part 6. Safety assessment,in respect of human health,of microorganisms used in biotechnology

The assessment of microorganisms in respect to human health is an important step for the introduction of new natural and genetically modified production strains to biotechnology. This report outlines the potential hazards posed by industrial microorganisms, important considerations related to pathogenicity, such as routes and portals of entry into the human body, mechanisms of spread of biological material and a definition of pathogenicity.Furthermore the most important steps in the assessment of pathogenicity of unknown strains are described. A short overview on characterization and in vitro and in vivo tests is presented. The hazard related to allergens and toxic metabolites is reviewed and the choice of methods and the handling of strains with unknown potential are discussed.     

申克孢子丝菌毒力因子及宿主抗感染免疫的研究进展

申克孢子丝菌是一种重要的双相型真菌,其引起的孢子丝菌病是一种常见的侵袭性皮肤感染.研究该菌毒力因子及宿主对其抗感染免疫对于深入了解其致病性及防治该病具有重要意义.该文介绍了申克孢子丝菌毒力因子及宿主对其抗感染免疫方面的研究进展.     

Bacteriophages and pathogenicity: more than just providing a toxin?

An increasing number of pathogenicity factors carried by bacteriophages have been discovered. This review considers bacteriophage-bacterium interaction and its relation to disease processes. We discuss the search for new bacteriophage-associated pathogenicity factors, with emphasis on recent advances brought by the use of genomic sequence data and the techniques of genomic epidemiology.