Studies on the response of ewes to live chlamydiae adapted to chicken embryos or tissue culture.
(1/481)
Ewes infected before gestation with chicken embryo or tissue culture adapted chlamydial strain B-577 were challenge inoculated with the homologous strain at four to 18 weeks of gestation. The ewes responsed with group specific complement fixing antibody titers of 1:8 to 1:256 by the second week after initial infection. A secondary antibody response in the surviving challenge inoculated ewes occurred at the time of lambing and reached titers of 1:32 to 1:256 by the second week after parturition. Group specific complement fixing antibodies did not appear to play a significant role in resistance to chlamydial infection. Ewes infected with the chicken embryo adapted strain B-577 excreted chlamydiae in their feces 60 days after inoculation. However, chlamydiae were not recovered from feces of ewes infected with the tissue culture adapted strain B-577. Placentas of ewes challenge inoculated by the intravenous route were consistently infected. Chlamydiae were recovered from placentas, some fetuses and lambs. In two instances when challenge inoculation was given by the intramuscular route, infection was detected only by the direct fluorescent antibody method. (+info)
Chlamydia infections and heart disease linked through antigenic mimicry.
(2/481)
Chlamydia infections are epidemiologically linked to human heart disease. A peptide from the murine heart muscle-specific alpha myosin heavy chain that has sequence homology to the 60-kilodalton cysteine-rich outer membrane proteins of Chlamydia pneumoniae, C. psittaci, and C. trachomatis was shown to induce autoimmune inflammatory heart disease in mice. Injection of the homologous Chlamydia peptides into mice also induced perivascular inflammation, fibrotic changes, and blood vessel occlusion in the heart, as well as triggering T and B cell reactivity to the homologous endogenous heart muscle-specific peptide. Chlamydia DNA functioned as an adjuvant in the triggering of peptide-induced inflammatory heart disease. Infection with C. trachomatis led to the production of autoantibodies to heart muscle-specific epitopes. Thus, Chlamydia-mediated heart disease is induced by antigenic mimicry of a heart muscle-specific protein. (+info)
The in-vitro activity of HMR 3647, a new ketolide antimicrobial agent.
(3/481)
The in-vitro activity of HMR 3647, a novel ketolide, was investigated in comparison with those of erythromycin A, roxithromycin, clarithromycin (14-membered ring macrolides), amoxycillin-clavulanate and ciprofloxacin against 719 recent clinical Gram-positive, Gram-negative and anaerobic isolates and type cultures. HMR 3647 generally demonstrated greater activity than the other compounds with MIC90s of < or =0.5 mg/L, except for Staphylococcus epidermidis (MIC90 > 128 mg/L), Haemophilus influenzae (MIC90 = 2 mg/L), Enterococcus faecalis (MIC90 = 2 mg/L), Enterococcus faecium (MIC90 = 1 mg/L) and the anaerobes, Bacteroides fragilis (MIC90 = 2 mg/L) and Clostridium difficile (MIC90 = 1 mg/L). In general, an increase in the size of the inoculum from 10(4) to 10(6) cfu on selected strains had little effect on the MICs of HMR 3647. Additionally, the in-vitro activity of HMR 3647 was not affected by the presence of either 20 or 70% (v/v) human serum. The antichlamydial activity of HMR 3647 was generally greater than that of commonly used antichlamydial antimicrobials. (+info)
Chlamydia infection of epithelial cells expressing dynamin and Eps15 mutants: clathrin-independent entry into cells and dynamin-dependent productive growth.
(4/481)
Chlamydiae enter epithelial cells via a mechanism that still remains to be fully elucidated. In this study we investigated the pathway of entry of C. psittaci GPIC and C. trachomatis LGV/L2 into HeLa cells and demonstrated that it does not depend on clathrin coated vesicle formation. We used mutant cell lines defective in clathrin-mediated endocytosis due to overexpression of dominant negative mutants of either dynamin I or Eps15 proteins. When clathrin-dependent endocytosis was inhibited by overexpression of the dynK44A mutant of dynamin I (defective in GTPase activity), Chlamydia entry was not affected. However, in these cells there was a dramatic inhibition in the proliferation of Chlamydia and the growth of the chlamydia vacuole (inclusion). When clathrin-dependent endocytosis was inhibited by overexpression of an Eps15 dominant negative mutant, the entry and growth of Chlamydia was unaltered. These results indicate that the effect on the growth of Chlamydia in the dynK44A cells was not simply due to a deprivation of nutrients taken up by endocytosis. Instead, the dominant-negative mutant of dynamin most likely affects the vesicular traffic between the Chlamydia inclusion and intracellular membrane compartments. In addition, cytochalasin D inhibited Chlamydia entry by more than 90%, indicating that chlamydiae enter epithelial cells by an actin-dependent mechanism resembling phagocytosis. Finally, dynamin is apparently not involved in the formation of phagocytic vesicles containing Chlamydia. (+info)
Gamma interferon and interleukin-10 gene expression in synovial tissues from patients with early stages of Chlamydia-associated arthritis and undifferentiated oligoarthritis and from healthy volunteers.
(5/481)
Genetically determined differences in interleukin-10 (IL-10) and gamma interferon (IFN-gamma) responses in mice correlate with clearance of Chlamydia pneumonitis infection. We measured the synovial expression of IL-10 and IFN-gamma and additional cytokine genes in patients who had recent-onset Chlamydia-associated arthritis (Chl-AA). IL-10 and IFN-gamma mRNA were relatively abundant in recent-onset Chl-AA. (+info)
Comparative in-vitro activity of moxifloxacin, minocycline and azithromycin against Chlamydia spp.
(6/481)
The in-vitro activity of moxifloxacin, a new 8-methoxyquinolone, was compared with minocycline and azithromycin against 40 strains of Chlamydia trachomatis, Chlamydia pneumoniae and Chlamydia psittaci. Both the MIC and the MBC of moxifloxacin ranged from 0.03 to 0.125 mg/L. MICs of minocycline ranged from 0.015 to 0.06 mg/L and MBCs between 0.03 and 0.25 mg/L. MICs of azithromycin ranged from 0.03 to 0.125 mg/L and the MBCs between 0.06 and 0.5 mg/L. MBC values of moxifloxacin were the same as MICs in 32 (80%) of 40 strains tested, whereas those of minocycline and azithromycin were two to four times higher than their MICs. These data confirm those previously obtained indicating that quinolones kill chlamydial strains at concentrations equivalent to their MICs. (+info)
Genomic relatedness of Chlamydia isolates determined by amplified fragment length polymorphism analysis.
(7/481)
The genomic relatedness of 19 Chlamydia pneumoniae isolates (17 from respiratory origin and 2 from atherosclerotic origin), 21 Chlamydia trachomatis isolates (all serovars from the human biovar, an isolate from the mouse biovar, and a porcine isolate), 6 Chlamydia psittaci isolates (5 avian isolates and 1 feline isolate), and 1 Chlamydia pecorum isolate was studied by analyzing genomic amplified fragment length polymorphism (AFLP) fingerprints. The AFLP procedure was adapted from a previously developed method for characterization of clinical C. trachomatis isolates. The fingerprints of all C. pneumoniae isolates were nearly identical, clustering together at a Dice similarity of 92.6% (+/- 1.6% standard deviation). The fingerprints of the C. trachomatis isolates of human, mouse, and swine origin were clearly distinct from each other. The fingerprints of the isolates from the human biovar could be divided into at least 12 different types when the presence or absence of specific bands was taken into account. The C. psittaci fingerprints could be divided into a parakeet, a pigeon, and a feline type. The fingerprint of C. pecorum was clearly distinct from all others. Cluster analysis of selected isolates from all species revealed groups other than those based on sequence data from single genes (in particular, omp1 and rRNA genes) but was in agreement with available DNA-DNA hybridization data. In conclusion, cluster analysis of AFLP fingerprints of representatives of all species provided suggestions for a grouping of chlamydiae based on the analysis of the whole genome. Furthermore, genomic AFLP analysis showed that the genome of C. pneumoniae is highly conserved and that no differences exist between isolates of respiratory and atherosclerotic origins. (+info)
Epitheliocystis agents in sea bream Sparus aurata: morphological evidence for two distinct chlamydia-like developmental cycles.
(8/481)
The morphology of membrane-bound intracellular inclusions, or 'cysts', of epitheliocystis from sea bream Sparus aurata is described. Inclusions under the light microscope appear either granular or amorphous. Granular inclusions do not elicit a proliferative host reaction and contain the 3 distinctive developmental stages of chlamydial organisms: the highly pleomorphic reproductive form or reticulate body, the condensing form or intermediate body and the infective non-dividing rather uniform elementary body. Amorphous inclusions may elicit a proliferative host reaction and contain prokaryotic organisms which differ morphologically from those reported within granular cysts. More or less elongated electron-lucent organisms divide by fission to give rise to electron-dense non-dividing small cells with a dense nucleoid. Vacuolated and non-vacuolated small cells are reported. The morphology and developmental cycle of sea bream epitheliocystis agents would support their chlamydial nature; however, the immunohistochemical study conducted on gill samples which carried both inclusions failed to demonstrate the expression of lipopolysaccharide (LPS) chlamydial antigen. The different stages of the 2 distinct developmental cycles described in the present study are compared with electron microscope observations of epitheliocystis organisms reported from different host species. The hypothesis that epitheliocystis infection in the sea bream might be caused by a unique highly pleomorphic chlamydia-like agent, the life history of which includes 2 entirely different developmental cycles, is discussed. (+info)