Telomeres, located at the ends of linear chromosomes, are essential for genome stability and integrity. Advances in telomere researches have linked telomere dysfunction with cellular aging and a number of age-related human diseases. Recent studies further expanded our knowledge of telomere functions - telomeres are shown to be important for microbial pathogen virulence and telomere proteins have important non-telomeric cellular functions.
Host Factors in Infection
For any infectious process to occur, the pathogen and the host must first encounter each other. Factors such as geography, environment, and behavior thus influence the likelihood of infection. Although the initial encounter between a susceptible host and a virulent organism frequently results in disease, some organisms can be harbored in the host for years before disease becomes clinically evident. For a complete view, individual patients must be considered in the context of the population to which they belong.
Tuyển tập các báo cáo nghiên cứu về bệnh học thý y được đăng trên tạp chí Acta Veterinaria Scandinavica cung cấp cho các bạn kiến thức về bệnh thú y đề tài: Comparative studies on the pathogenicity and tissue distribution of three virulence variants of classical swine fever virus, two field isolates and one vaccine strain, with special regard to immunohistochemical investigations...
Ralstonia solanacearum is an aerobic non-sporing, Gram-negative plant pathogenic bacterium. R.solanacearum is soil-borne and motile with a polar flagellar tuft. It colonises the xylem, causing bacterial wilt in a very wide range of potential host plants. It is known as Granville wilt when it occurs in tobacco. Bacterial wilts of tomato, pepper, eggplant and Irish
potato caused by Ralstonia solanacearum were among the first diseases that Erwin Frink Smith proved to be caused by a bacterial pathogen.
Phthiocerol dimycocerosates and related compounds are important mole-cules in the biology of Mycobacterium tuberculosis, playing a key role in
the permeability barrier and in pathogenicity. Both phthiocerol dimyco-cerosates, the major compounds, and phthiodiolone dimycocerosates, the
minor constituents, are found in the cell envelope ofM. tuberculosis, but
their specific roles in the biology of the tubercle bacillus have not been
Lipopolysaccharide (LPS) andb-glucan from Francisella victoria, a fish
pathogen and close relative of highly virulent mammal pathogenFrancisella
tularensis, have been analyzed using chemical and spectroscopy methods.
The polysaccharide part of the LPS was found to contain a nonrepetitive
sequence of 20 monosaccharides as well as alanine, 3-aminobutyric acid,
and a novel branched amino acid, thus confirmingF. victoriaas a unique
Tuyển tập các báo cáo nghiên cứu về y học được đăng trên tạp chí y học Wertheim cung cấp cho các bạn kiến thức về ngành y đề tài: Genomic acquisition of a capsular polysaccharide virulence cluster by non-pathogenic Burkholderia isolates...
Hfq is an RNA chaperone that functions as a pleiotropic regulator for
RNA metabolism in bacteria. In several pathogenic bacteria, Hfq contrib-utes indirectly to virulence by binding to riboregulators that modulate the
stability or translation efficiency of RNA transcripts. To characterize the
role of Hfq in the pathogenicity ofNeisseria gonorrhoeae, we generated an
N. gonorrhoeae hfqmutant.
Wild birds have taken much of the blame for the spread of H5N1 across the world
but this report by Compassion in World Farming unveils evidence showing that the
development of highly pathogenic strains of bird flu lies at the door of factory
The past two decades have seen a complete transformation in the poultry industry
with a 300% increase in production across the world. This increase is, by and large,
thanks to reliance on intensive farms and a transnational production system. Poultry
production is now a global affair.
Bacteria are non-chlorophyllated unicellular organisms that reproduce by fission and do not
present nuclear envelope. Gram´s stain is a staining technique used to classify bacteria based
on the different characteristic of their cell walls. Gram-positive or Gram-negative bacteria
are determined by the amount and location of peptidoglycan in the cell wall, exhibiting
different chemical compositions and structures, cell-wall permeabilities, physiologies,
metabolisms, and pathogenicities.
Hospitals, by their very nature, are dangerous places. Sick and infected patients
are clustered together in one institution, often in close proximity to those who are
immunosuppressed due to recent surgery, chemotherapy or transplantation. Contact
between these various patient groups is easily achieved via the hands of healthcare
workers (HCWs), use of shared equipment or the hospital’s air handling system.
Transmission to New Hosts
As part of the pathogenic process, most microbes are shed from the host, often in a form infectious for susceptible individuals. However, the rate of transmissibility may not necessarily be high, even if the disease is severe in the infected individual, as transmissibility and virulence are not linked traits.
Enteric pathogens have developed a variety of tactics to overcome host defenses. Understanding the virulence factors employed by these organisms is important in the diagnosis and treatment of clinical disease.
The number of microorganisms that must be ingested to cause disease varies considerably from species to species. For Shigella, enterohemorrhagic Escherichia coli, Giardia lamblia, or Entamoeba, as few as 10–100 bacteria or cysts can produce infection, while 105–108Vibrio cholerae organisms must be ingested orally to cause disease.
Association of Virulence Mechanisms with Specific Meningococcal Infections Specific disease manifestations of meningococcal infections have specific virulence and pathogenic mechanisms, as described below for fulminant meningococcemia and meningitis.
Purpura Fulminans Fulminant meningococcemia is perhaps the most rapidly lethal form of septic shock experienced by humans. It differs from most other forms of septic shock by the prominence of hemorrhagic skin lesions (petechiae, purpura; see Fig. 52-5) and the consistent development of DIC.
Harrison's Internal Medicine Chapter 129. Staphylococcal Infections
Staphylococcal Infections: Introduction Staphylococcus aureus, the most virulent of the many staphylococcal species, has demonstrated its versatility by remaining a major cause of morbidity and mortality despite the availability of numerous effective antistaphylococcal antibiotics. S. aureus is a pluripotent pathogen, causing disease through both toxin-mediated and non-toxin-mediated mechanisms.
Aspergillus fumigatusis an important human fungal pathogen. The Asper-gillus fumigatus genome contains 14 nonribosomal peptide synthetase
genes, potentially responsible for generating metabolites that contribute to
organismal virulence. Differential expression of the nonribosomal peptide
synthetase gene,pes1, in four strains of Aspergillus fumigatuswas observed.
Over the past three decades, molecular studies of the pathogenesis of microorganisms have yielded an explosion of information about the various microbial and host molecules that contribute to the processes of infection and disease. These processes can be classified into several stages: microbial encounter with and entry into the host; microbial growth after entry; avoidance of innate host defenses; tissue invasion and tropism; tissue damage; and transmission to new hosts.
Staphylococcus aureus, the most virulent of the many staphylococcal species, has demonstrated its versatility by remaining a major cause of morbidity and mortality despite the availability of numerous effective antistaphylococcal antibiotics. S. aureus is a pluripotent pathogen, causing disease through both toxin-mediated and non-toxin-mediated mechanisms. This organism is responsible for both nosocomial and community-based infections that range from relatively minor skin and soft tissue infections to life-threatening systemic infections. ...
Bacillus cereusis an opportunistic pathogenic bacterium closely related to
Bacillus anthracis, the causative agent of anthrax in mammals. A significant
portion of theB. cereuschromosomal genes are common to B. anthracis,
including genes which in B. anthraciscode for putative virulence and sur-face proteins.