Chlamydial Strains Research Articles

Distribution of plasmid sequences in avian and mammalian strains of Chlamydia psittaci.

Plasmid DNA from an avian strain of Chlamydia psittaci was purified and estimated to be 7.9 kb in size using restriction endonuclease analysis. A 5.9 kb fragment of this plasmid was cloned, mapped and used to screen a range of chlamydial strains. Hybridizing DNA was absent from ovine abortion and arthritis isolates and also from the Cal 10 strain but related sequences were detected in C. psittaci strains of feline pneumonitis, guinea-pig inclusion conjunctivitis, ovine conjunctivitis and C. trachomatis serovar L2. The plasmid DNA from the feline strain was shown to have a distinct restriction endonuclease profile. Similar plasmid sequences were detected in all avian isolates tested: thus the clone may have a useful diagnostic role for the detection of the pathogen in its natural host and in zoonotic episodes.

Monoclonal antibodies to Chlamydia psittaci: characteristics and antigenic analysis.

Twenty-seven hybrid cell lines producing monoclonal antibodies to Chlamydia psittaci were prepared by fusion of the mouse myeloma cells with spleen lymphocytes of mice immunized with C.psittaci pigeon or budgerigar strain. Reactions of these monoclonal antibodies were examined with five strains of C.psittaci and two of C.trachomatis serovars L2 and J by enzyme-linked immunosorbent assay, the microimmunofluorescent test and the complement fixation test. According to the reaction patterns to eight chlamydial strains, fifteen antibodies to a pigeon strain, P-1041, were divided into three groups: three genus-specific, eight subspecies-specific and four strain-specific antibodies. Twelve antibodies to a budgerigar strain, Izawa, were also tested to eight chlamydial strains and divided into two groups: two genus-specific and ten subspecies-specific antibodies. Physicochemical properties of the antigens recognized by different monoclonal antibodies were examined by KIO4, pronase and heat treatments and by the immuno-blotting technique. Most genus-specific antibodies recognized the KIO4-sensitive antigen, which was a pronase-resistant and heat-stable component of about 10, 000 daltons. Subspecies- and strain-specific monoclonal antibodies recognized the antigens, which were pronase-sensitive and heat-labile components of about 40, O00 or 90, O0O daltons.

Immunomodulation and Chlamydia: immunosuppression and the protective immune response to C. psittaci in mice.

Mice immunized intramuscularly with a low dose, viable inoculum of C. psittaci survived an otherwise lethal intraperitoneal challenge with the homologous chlamydial strain. Immunized animals were not protected from intraperitoneal challenge by the unrelated pathogen, Listeria monocytogenes. Spleen cells from animals that exhibited protective immunity were suppressed in their proliferative responses to mitogens or chlamydial antigen in an in vitro blastogenic assay. This suppression was transferable to normal spleen cells by adding irradiated cells from immunized animals to normal cell populations. The degree of normal cell blastogenic suppression was dependent on the ratio of irradiated immune to normal cells present in the assay medium. Suppression of humoral responses was demonstrated in vivo. Immunized animals were incapable of producing antibody secreting cells to sheep red blood cells after an intraperitoneal inoculation of SRBC. Unimmunized animals produced a significant number of plaque forming cells as measured by a direct plaque forming cell assay. Lymphokine activity was not impaired in spleen cells from mice that exhibited other manifestations of suppression. Taken together, these data provide evidence to indicate that the induction of suppression may not correlate with increased pathogenesis, but rather be closely associated with protective immunity. Data also provide circumstantial evidence to indicate that lymphokine induction may be important in the development of protective immunity to C. psittaci in the mouse.

Cloning of a chlamydial plasmid: Its use as a probe and in vitro analysis of encoded polypeptides

A chlamydial plasmid, 7 kb long, was isolated from the LGV2 strain ofChlamydia trachomatis and cloned in pBR 322, and a restriction enzyme cleavage map of the clone, PDCPB, was constructed. The plasmid DNA served as a probe in a sensitive hybridization assay, which was able to detect 1–5 pg DNA; 15C. trachomatis serovars and oneC. psittaci strain showed homology to the probe. Four polypeptides with molecular weights of 52, 43, 32, and 20 kilo-Daltons were shown to be encoded by PDCPB in an in vitroEscherichia coli-directed transcription translation system. The possible location of their genes is discussed.

Prevalence in human beings of antibodies to Chlamydia IOL-207, an atypical strain of chlamydia

Samples of serum from 18353 persons from the U.K. and abroad, were tested for type-specific antibodies to Chlamydia spp. Antibodies to an atypical strain, Chlamydia IOL-207, were detected in each population tested. Overall, the prevalence of these antibodies (19.9%) was similar to that of antibodies to C. trachomatis (21.6%). In the U.K., antibodies to C. IOL-207 were rare in children under the age of 5 years but became more common with increasing age. In adults the prevalence of these antibodies increased annually between 1979 and 1984. Antibodies to C. IOL-207 were not associated with sexually transmitted disease and only rarely with ocular disease. Their association with a common complaint such as mild respiratory illness is postulated. The presence of these antibodies within a population may lead to the over-diagnosis of C. trachomatis infections or psittacosis if only genus-specific serological tests are used.

Persistent infection of L cells with an ovine abortion strain of Chlamydia psittaci.

L cells inoculated at multiplicities of infection greater than or equal to 1 inclusion-forming unit of the abortigenic chlamydial strain B577 were destroyed within 10 to 15 days. Upon continued incubation in fresh medium, a few surviving cells repopulated the flasks, and the reemerging cultures remained persistently infected. The persistent state was characterized by cycles of repopulation with a low ratio of infected cells and cycles of extensive cytopathic changes in which greater than 90% of the cells had chlamydial inclusions and which could be delayed or even terminated by penicillin treatment. Immunofluorescence and superinfection during the period of repopulation revealed that the persistently infected cells could adsorb chlamydiae but their multiplication was arrested. This nonpermissive state could be terminated by the specific action of cycloheximide. L cells spontaneously cured from a persistent infection exhibited no change in susceptibility to chlamydiae when compared with normal L cells. However, chlamydiae derived from L cells after 7.5 months of persistence destroyed L-cell monolayers more rapidly and at lower multiplicities of infection than the wild type. This state of chlamydia-host cell interaction could not be established with the arthropathogenic strain LW613 because chlamydial infectivity was lost after the first cytolytic burst of infection in the cell cultures. The persistence described for the strain B577-L-cell system appears to differ from previously described models involving other chlamydial strains.

Characterization of Chlamydia trachomatis serotypes by human T-lymphocyte clones.

T cells primed to Chlamydia trachomatis serotypes A, F, and K were cloned by limiting dilution. All T-lymphocyte clones obtained reacted only with C. trachomatis antigens. The proliferative capacity of 89 clones was studied with autologous non-T cells as antigen-presenting cells and the chlamydia serotypes A, B, D, F, K, and LGV-2 as antigens. Most of the clones reacted to several of the chlamydia strains, indicating common antigenic determinants. Other T-cell clones reacted with only a few serotypes. On the basis of the proliferation of the T-cell clones to the chlamydia strains and to interleukin-2, different reactivity patterns were obtained, which possibly can be used to differentiate among the chlamydia strains.

Establishment of hybridomas secreting monoclonal antibodies to Chlamydia psittaci

Eleven stable anti- Chlamydia hybrid clones by fusions between X63-Ag8653 myelomas and immune splenocytes from Chlamydia psittaci immunized F1 (C57BL6×BALB/c) mice have been established which react with the 12 reference Chlamydia strains (seven C. trachomatis and five C. psittaci. Ten of these monoclonal antibodies are directed against the genera-specific epitope (40,000 MW component) for which prolonged immunization seems to be responsible.

In vitro and in vivo properties of chemically induced temperature-sensitive mutants of Chlamydia psittaci var. ovis: screening in a murine model.

Two temperature-sensitive (ts) strains, 1B and 1H, were obtained after nitrosoguanidine treatment of the wild-type virulent abortive ovine strain Chlamydia psittaci AB7. Optimum growth temperature on McCoy cells was 38 degrees C for the three strains, but at the restrictive temperature, 39.5 degrees C, ts strains differed from the parental strain in their total infective yield of chlamydiae, their efficiency of plating, and the morphology of the plaques and cytoplasmic inclusions. Their survival at 51 degrees C was also reduced compared with that of the wild field strains. The virulence of the two ts strains was attenuated for pregnant mice, but these two ts strains were able to multiply in mice and to induce a strong immunity to virulent challenge with either the parental AB7 strain or the caprine or bovine abortive field strains.

Recovery ofChlamydia trachomatis by inoculation of McCoy cell suspensions

Growth of two laboratory strains ofChlamydia trachomatis (Gambia 17 and UW 5) was compared in McCoy cell monolayers 1–3 days old and McCoy cells inoculated while in suspension (day 0). Both cell preparations were treated with cytochalasin B. Each chlamydial strain produced more inclusions in the cell suspension preparations than in monolayers. Efforts to inoculate cycloheximide-treated cells in suspension were unsuccessful because of the toxic effect of this chemical. When patient specimens were tested in cell suspensions and in monolayers, all positives were detected comparably in both systems, although bacterial contamination was more pronounced in the cell suspensions. The results indicate that cell suspensions can be used as a convenient and rapid supplement to preformed monolayers for chlamydial culture tests.

Use of the enzyme-linked immunosorbent assay for detection of antibodies to Chlamydia trachomatis.

An enzyme-linked immunosorbent assay (ELISA) using a soluble antigen prepared from the D strain of Chlamydia trachomatis was used for titration of IgG antibodies to Chlamydia trachomatis in 153 sera from 126 patients with non-specific genital infection and from 27 healthy subjects. The results were compared to those obtained with the micro-immunofluorescence method and were in complete agreement in 143 of the 153 sera. The ELISA proved to be reproducible and as sensitive as the micro-immunofluorescence method.

Isolation in McCoy cells ofChlamydia Psittaciobtained from the domestic duck(anas platyrhyncos)

Chlamydia psittaci has been isolated from several organs and conjunctivae of domestic Pekin ducks. McCoy cells were susceptible to infection by this chlamydial strain as demonstrated by the formation of inclusion bodies within 48 hours post-inoculation. A good correlation was found between the isolation of C. psittaci from ducks and positive ELISA serology results.

A case of good management

This paper reports an incident involving the exposure of eight employees who were handling a strain of Chlamydia in a production process. The report shows how a change of strain can alter the pathogenicity of the organism and how it is important to review handling precautions before any change of strain or procedure is undertaken.

A mouse model to compare virulence of abortive and intestinal ovine strains of Chlamydia psittaci: Influence of the route of inoculation

Strains of Chlamydia psittaci isolated from faeces of a clinically healthy ewe (intestinal strain IB1) and from the foetus of an aborted ewe (abortive strain AB7) were injected into pregnant mice via the intraperitoneal route and into non-pregnant mice via the footpad route. In pregnant mice the response to inoculation was followed by recording the performance and viability of infant mice, and in the non-pregnant mice by an enlargement of the spleen and colonization of both the spleen and popliteal lymph node. The intestinal Chlamydia strain was less virulent than the abortive strain, but the actual difference of virulence depends upon the route of inoculation. Thus the intestinal strain was at least 500 times less virulent than the abortive strain and was rapidly ruled out when injected subcutaneously into the footpad, whereas it was even less than 100 times less virulent than the abortive strain, and able to induce death of some infant mice, when given intraperitoneally in pregnant mice. The mouse model of experimental subcutaneous infection via the footpad route could be used to easily test the differences of virulence between different strains of C. psittaci.

Ovine enzootic abortion: the acquisition of infection and consequent abortion within a single lambing season.

The spread of enzootic abortion was observed in a flock of 37 unvaccinated Scottish blackface ewes, in mid-pregnancy at the start of the trial. Eight ewes were infected with the ZC 26 strain of chlamydia and allowed to run with 29 untreated controls until lambing was completed. All eight inoculated ewes aborted between 26 and 51 days after infection and chlamydial infection was demonstrated in seven of the abortions. Complement fixing antibodies were not detected in the controls until nine days after the first infected abortion, but within four weeks 69 per cent of the control ewes had developed significant complement fixation titres. Ten of the control ewes lost lambs, chlamydial infection was demonstrated in seven cases, two were undiagnosed and one was attributed to dystocia. The seven infected cases occurred between 69 and 87 days after the start of the trial and coincided with a further rise in the percentage of seropositive controls to a maximum of 90 per cent by the end of lambing.

Attachment of cell walls of Chlamydia psittaci to mouse fibroblasts (L cells).

(14)C-labeled cell walls of the 6BC strain of Chlamydia psittaci, prepared from intrinsically labeled chlamydial cells by digestion with deoxycholate and trypsin, associated with mouse fibroblasts (L cells) in a manner comparable to that of intact C. psittaci. Almost half of the host cell-associated cell walls were not dissociated by trypsin, suggesting that they had been attached and then ingested. The attachment of cell walls to L cells was inhibited by a number of treatments known to block association of intact C. psittaci with L cells: heating the cell walls for 3 min or reacting them with antiserum against intact C. psittaci, or pretreating the L cells with trypsin or wheat germ agglutinin. Unlike intact cells of C. psittaci, cell walls were not immediately toxic for L cells, and they did not measurably adsorb neutralizing antibody. As revealed by making cell walls from intact C. psittaci labeled with (125)I by lactoperoxidase-catalyzed iodination, cell walls contained a much smaller number of surface-labeled proteins than did whole chlamydial cells. The most abundant surface-labeled protein was one with an apparent molecular weight of 43,000. In the final step of cell wall preparation, tryptic digestion of deoxycholate-extracted cells, this major surface protein was partially cleaved to a 40,000-dalton product. When the major surface protein (both the 43,000- and 40,000-dalton moieties) was electrophoretically separated from the other cell wall proteins and used to immunize a rabbit, antibodies that neutralized the infectivity of intact C. psittaci were elicited. It was concluded that cell walls retain the ability to associate with L cells in much the same way as do intact cells of C. psittaci, but, despite the simpler structure of cell walls, the element that binds C. psittaci to host cells cannot yet be identified.

Virus infecting the reticulate bodies of an avian strain ofChlamydia psittaci

Virus infecting the reticulate bodies of an avian strain of<i>Chlamydia psittaci</i>

Infectivity of Chlamydia trachomatis in tissue culture with newborn calf serum

By using representative strains of Chlamydia trachomatis serotypes, the efficacy of substituting fetal bovine serum with newborn calf serum for the isolation of this organism in tissue culture was examined. The criteria used were the quality and quantity of the iodine-stained cytoplasmic inclusions and the characteristics of the McCoy cells. Complete substitution of fetal bovine serum with newborn calf serum produced a detrimental change in the quality of the cytoplasmic inclusions and a dramatic decline in the inclusion count (P less than 0.001) with all of the chlamydial strains tested. There appeared to be no significant alteration in the characteristics of the McCoy cells. It is recommended from this preliminary investigation that newborn calf serum should not be used for the isolation of C. trachomatis in tissue culture.

Monoclonal antibodies to Chlamydia trachomatis: antibody specificities and antigen characterization.

Nineteen independent hybrid cell lines that produce monoclonal antibodies to Chlamydia trachomatis surface antigens were prepared by the fusion of mouse myeloma cells with lymphocytes of mice that were immunized with C. trachomatis immunotypes B, C, and L2. Seven serologically distinct reaction patterns were detected by microimmunofluorescence (micro-IF) of elementary body (EB) preparations when culture fluids were tested against a panel of 18 chlamydial serotyping reference strains. These reaction patterns demonstrated genus-, species-, subspecies-, and type-specific distributions. Additionally, these antibodies were tested in parallel against reticulate body (RB) preparations of several chlamydial strains. Monoclonal antibodies that reacted with genus-specific antigens reacted preferentially with RB, whereas antibodies that reacted to species-, subspecies-, or type-specific antigens reacted equivalently to both RB and EB. Physiochemical characterization of antigens recognized by the different monoclonal antibodies was assessed by heat treatment, pronase digestion, periodate oxidation, and immuno-blot techniques. The genus-specific antigen was a heat-stable, pronase-resistant, and relatively periodate-sensitive component of less than 10,000 m.w. The species-, subspecies-, and type-specific antigens were heat stable, pronase sensitive, and periodate resistant. The antibodies that detected species- and subspecies-specific antigens predominantly reacted in immuno-blots with the 40,000 m.w. major outer membrane protein. These monoclonal antibodies now provide a new approach for the precise serologic classification and detection of different C. trachomatis strains.

Bovine chlamydial abortions

Chlamydial agents are obligate intracellular pathogens of prokaryotic pature, and they comprise a large group of antigenically related and culturally, morphologically, and tinctorially similar microorganisms. One property characterizing chlamydial strains of several animal species is their ability to establish placental and fetal infection irrespective of the type of placentation. Chlamydial agents were first suspected as a cause of abortions in cattle in Germany in 1956. Since then they were proven, by isolation from fetuses or placentas, as well as through serological evidence, to be a cause of reproductive failure of cattle. Chlamydiae were identified as a cause of bovine abortions in North America, in most countries of western and eastern Europe, in South Africa, and in some Asian countries.&#x0D; Characteristics of experimentally induced chlamydial abortions will be analyzed in this contribution from clinical and pathogenetic aspects and from etiological, serological, and pathological viewpoints. In the process, the experimentally induced disease will be compared with, and related to, the more complex problem of abortion that confronts the practitioner and the diagnostician.