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At least 127 records · Page 7Linked to original sources
PubMed1995

Viruses, virulence and pathogenicity.

Pathogenicity is a complex process with stringent requirements of both the host cell and the infecting virion. Among these requirements are a port of entry into host cells, a means of replication for the virus, and a means by which infection damages host cells. Damage to the host can result from multiple mechanisms including transformation, suppression of cellular metabolism, apoptosis, autoimmune responses directed against infected or uninfected tissues, or by molecular mimicry. In the attempt to identify new associations between viral infection and disease, investigators should be mindful that variable host factors as well as viral infection may be required for pathogenesis. Efforts to associate specific viral infections with specific diseases may be obscured by final common pathways through which multiple agents damage host cells in similar ways.

Animals↗
PubMed1978

Primary amoebic meningoencephalitis.

As a serendipitous by-product of polio virus research, a highly fatal amoebic meningoencephalitis was recognized in animals. The causative microorganisms, contaminants of the viral cultures, were identified as small soil amoebae. These organisms, previously considered non-pathogenic, are prevalent throughout the world. Based on animal studies, the original investigators suggested the possibility of a similar disease in humans. Seven years later, human cases of amoebic meningoencephalitis were reported from widely separated areas of the world. Since 1965, a total of 79 cases have been reported. The literature of primary amoebic meningoencephalitis is presented. The history of the discovery and elucidation of this disease is reviewed. The 79 cases reported in the world literature are divided into two groups, those diagnosed retrospectively after reviewing previous deaths from meningoencephalitis, and those diagnosed at the time of the illness. The classification, morphology, pathogenicity, virulence and distribution of pathogenic soil amoebae are reviewed. The presenting clinical findings, diagnostic procedures, pathology, and management of this recently recognized, highly fatal, human disease is presented along with a report of a new case. Otolaryngologists should become familiar with this serious disorder with a transnasal portal of entry.

Amebiasis↗
PubMed1993

Biochemical markers of pathogenicity and virulence of Acanthamoeba sp. strains.

The aim of our study was to demonstrate a possible correlation between some biochemical and biological markers of the degree of virulence of the investigated strains of Acanthamoeba sp. The results obtained demonstrated a significant correlation between the activity of proteases, peroxidases, and superoxide dismutase and the degree of virulence of the strains as previously defined by tests on mice. The results also proved that the strains that killed some of the infected mice were characterized by the highest value recorded for the activity of peroxidase and the lowest value obtained for the activity of superoxide dismutase.

Acanthamoeba↗
PubMed1999

Type III machines of Gram-negative pathogens: injecting virulence factors into host cells and more.

Many Gram-negative bacteria that cause disease in either mammals or plants share a strategy of delivering toxic proteins into the cytoplasm of host cells known as type III secretion. Recent advances have provided a glimpse at the molecular nature of these lethal injection machines. Several groups have reported fibrous structures on bacterial surfaces that appear to be extensions of type III machines and necessary for toxin injection into host cells. Other research revealed complex mechanisms of secretion substrate recognition that presumably function to direct toxins to different locations during infection.

Animals↗
PubMedDate not supplied

Opportunistic infections in patients with AIDS: clues to the epidemiology of AIDS and the relative virulence of pathogens.

The frequency of nine reactivating or opportunistic infections and Kaposi's sarcoma among patients with the acquired immunodeficiency syndrome (AIDS) was reviewed. The diagnoses of 87 patients reported from the Colorado AIDS registry and 359 others from literature reports were abstracted, and data were placed in one of 11 categories on the basis of the risk group of the patient. Pneumocystis carinii infection was significantly commoner among blood or blood-product recipients than among natives of the tropics (P less than .001). Tuberculosis and toxoplasmosis each were significantly commoner among natives of the tropics than natives of developed countries (P less than .001), whereas disseminated Mycobacterium avium-Mycobacterium intracellulare infections were present more often in the latter group. Among natives of the tropics treated in developed countries, cytomegaloviral infection was diagnosed significantly less often (22%) than among persons from developed countries in whom sexual transmission was presumed (47%; P = .0005). These data suggest that the pattern of infections manifested in AIDS could provide clues about transmission and that there may be a hierarchy of reactivation of latent infections in which populations with exposure to multiple agents manifest these preferentially to Pneumocystis carinii.

Acquired Immunodeficiency Syndrome↗
PubMed2004

[Genetic regulation of pathogenicity and virulence factors in bacteria Erwinia carotovora subsp. atroseptica: identification of kduD gene].

A mutant that cannot utilize pectin substances of plant cell walls was obtained via insertion of mini-mini-Tn5xylE transposon into the chromosome of phytopathogenic bacteria Erwinia carotovora subsp. atroseptica. The inability of mutant cells to utilize these substrates was caused by a failure to accomplish the catabolism of unsaturated digalacturonic acid (UDA). Study of enzymatic activities has established that mutant bacteria lost the ability to produce 2,5-diketo-3-deoxygluconate dehydrogenase, an enzyme of intracellular UDA utilization. Molecular cloning of the mutant gene was conducted, and its nucleotide sequence was determined. It was shown that the nucleotide sequence of this gene had an 82% homology with the sequence of Erwinia chrysanthemi EC3937 kduD gene encoding 2,5-diketo-3-deoxygluconate dehydrogenase. The intergene kdul-kduD region in bacteria Erwinia carotovora subsp. atroseptica is shorter in length by 98 nucleotides than the corresponding region of Erwinia chrysanthemi and does not contain promoter sequences. The kduD gene was located at 126.8 min of the Erwinia carotovora subsp. atroseptica genetic map.

Base Sequence↗
PubMed1985

Pathogenicity and virulence of methicillin resistant Staphylococcus aureus: slime layer production.

Nine methicillin-resistant (MR) mutants and three methicillin-sensitive (MS) substrains, all derived from naturally occurring heteroresistant isolates of Staphylococcus aureus were examined for slime production. All strains showed an increased mucoid character when cultured on a modified Staphylococcus Medium No. 110. The uranic acid content of the slime layer ranged from 2% to 6% in the MR mutants and from 1.3% to 5.1% in the MS substrains. The amount of uronic acid per g of dry bacteria ranged from 82.5 mg to 143.8 mg in the MR mutants, and between 51.4 mg and 98.8 mg in the MS substrains. In 3 pairs of MR mutants and MS substrains originating from the same parents, the MR cells possessed more of uronic acid than their MS counterparts. The partially purified polysaccharide part of the slime contained D-galactose, D-mannose, D-xylose, D-galacturonic acid, D-galactosamine and D-glucuronic acid in all strains studied. Its quantitative composition was identical in each pair of the MR mutant and MS substrain; there were, however, considerable differences among the strains and between the pairs. Methicillin resistance and slime formation seem to be independent properties in S. aureus. The presumable significance of the readiness of slime production by MR cocci during infections is discussed.

Anti-Bacterial Agents↗