Unique ultrastructure in the elementary body of Chlamydia sp. strain TWAR

Insights Into a Chlamydia pneumoniae-Specific Gene Cluster of Membrane Binding Proteins

Chlamydia pneumoniae is an obligate intracellular pathogen that causes diseases of the upper and lower respiratory tract and is linked to a number of severe and chronic conditions. Here, we describe a large, C. pneumoniae-specific cluster of 13 genes (termed mbp1-13) that encode highly homologous chlamydial proteins sharing the capacity to bind to membranes. The gene cluster is localized on the chromosome between the highly diverse adhesin-encoding pmp genes pmp15 and pmp14. Comparison of human clinical isolates to the predicted ancestral koala isolate indicates that the cluster was acquired in the ancestor and was adapted / modified during evolution. SNPs and IN/DELs within the cluster are specific to isolates taken from different human tissues and show an ongoing adaptation. Most of the cluster proteins harbor one or two domains of unknown function (DUF575 and DUF562). During ectopic expression in human cells these DUF domains are crucial for the association of cluster proteins to the endo-membrane system. Especially DUF575 which harbors a predicted transmembrane domain is important for binding to the membrane, while presence of the DUF562 seems to be of regulatory function. For Mbp1, founding member of the cluster that exhibits a very limited sequence identity to the human Rab36 protein, we found a specific binding to vesicles carrying the early endosomal marker PtdIns(3)P and the endosomal Rab GTPases Rab11 and Rab14. This binding is dependent on a predicted transmembrane domain with an α-helical / β-strand secondary structure, as the mutant version Mbp1mut, which lacks the β-strand secondary structure, shows a reduced association to PtdIns(3)P-positive membranes carrying Rab11 and Rab14. Furthermore, we could not only show that Mbp1 associates with Rab36, but found this specific Rab protein to be recruited to the early C. pneumoniae inclusion. Detection of endogenous Mbp1 and Mbp4 reveal a colocalization to the chlamydial outer membrane protein Momp on EBs. The same colocalization pattern with Momp was observed when we ectopically expressed Mbp4 in C. trachomatis. Thus, we identified a C. pneumoniae-specific cluster of 13 membrane binding proteins (Mbps) localizing to the bacterial outer membrane system.

Chlamydia Species Strain TWAR

The chlamydia have long been recognized as ubiquitous pathogens capable of producing a wide spectrum of disease both in children and in adults. Common infections caused by this pathogen include pneumonia in infants, trachoma in children, and genital tract disease in adults. While neonatal chlamydial pneumonia is commonly described, chlamydial pneumonia in adults is less commonly recognized and was originally associated only with exposure to psittacine birds. Instances of person-to-person transmission of a chlamydial pneumonia were first identified in San Francisco in 1941. The organism isolated was a chlamydia-like agent with glycogen-staining characteristics unlike those of the well-studied avian chlamydia but much more difficult to maintain in culture. This finding lapsed into obscurity until 1965, when a chlamydial organism again demonstrating a Chlamydia psittaci-like staining pattern was isolated from a Taiwanese child in a trachoma study. This isolate was eventually named TW183. It was not until 1983, however, when a patient with atypical pneumonia was found to be infected with a similar pathogen, dubbed AR39, that the question of prevalence was raised. As the behavior of these isolates was characterized in Grayston's laboratory, it became apparent that they represented a novel human pathogen and the name TWAR (Taiwan acute respiratory agent) was adopted. Subsequent epidemiologic studies of this agent have shown broad exposure over a wide geographic distribution with almost 40% of tested populations showing serologic evidence of exposure.

Lysine acetylation of major Chlamydia trachomatis antigens

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Chlamydia trachomatis causes trachoma and sexually transmitted diseases.

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Molecular mechanisms of chlamydial pathogenesis and immunity remain unclear.

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Acetylation of lysine is a post-translational modification that occurs in prokaryotes.

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Lysine acetylation sites were discovered in major chlamydial antigens.

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60 kDa chaperonin, EF-G and PmpB showed the highest degree of acetylation.

Chlamydia trachomatis (Ct) is a human pathogen causing trachoma and infertility. We investigated acetylation at lysine residues of chlamydial antigenic proteins: major outer membrane protein (MOMP), 60 kDa chaperonin (chlamydial Hsp60), elongation factor G (EF-G), enolase and the polymorphic membrane proteins PmpB, PmpE and PmpF. 60 kDa chaperonin, EF-G and PmpB showed the highest degree of acetylation.

Our data show that important Ct antigens could be post-translationally modified by acetylation of lysine residues at multiple sites. Further studies are needed to investigate total acetylome of Ct and the impact PTMs might have on Ct biology and pathogenicity.

Electron tomography and cryo-SEM characterization reveals novel ultrastructural features of host-parasite interaction during Chlamydia abortus infection

Chlamydia (C.) abortus is a widely spread pathogen among ruminants that can be transmitted to women during pregnancy leading to severe systemic infection with consecutive abortion. As a member of the Chlamydiaceae, C. abortus shares the characteristic feature of an obligate intracellular biphasic developmental cycle with two morphological forms including elementary bodies (EBs) and reticulate bodies (RBs). In contrast to other chlamydial species, C. abortus ultrastructure has not been investigated yet. To do so, samples were fixed by high-pressure freezing and processed by different electron microscopic methods. Freeze-substituted samples were analysed by transmission electron microscopy, scanning transmission electron microscopical tomography and immuno-electron microscopy, and freeze-fractured samples were analysed by cryo-scanning electron microscopy. Here, we present three ultrastructural features of C. abortus that have not been reported up to now. Firstly, the morphological evidence that C. abortus is equipped with the type three secretion system. Secondly, the accumulation and even coating of whole inclusion bodies by membrane complexes consisting of multiple closely adjacent membranes which seems to be a C. abortus specific feature. Thirdly, the formation of small vesicles in the periplasmic space of RBs in the second half of the developmental cycle. Concerning the time point of their formation and the fact that they harbour chlamydial components, these vesicles might be morphological correlates of an intermediate step during the process of redifferentiation of RBs into EBs. As this feature has also been shown for C. trachomatis and C. pneumoniae, it might be a common characteristic of the family of Chlamydiaceae.

Divergent outcomes following transcytosis of IgG targeting intracellular and extracellular chlamydial antigens

Antibodies can have a protective but non-essential role in natural chlamydial infections dependent on antigen specificity and antibody isotype. IgG is the dominant antibody in both male and female reproductive tract mucosal secretions, and is bi-directionally trafficked across epithelia by the neonatal Fc receptor (FcRn). Using pH-polarized epididymal epithelia grown on Transwells, IgG specifically targeted at an extracellular chlamydial antigen; the major outer membrane protein (MOMP), enhanced uptake and translocation of infection at pH 6-6.5 but not at neutral pH. This was dependent on FcRn expression. Conversely, FcRn-mediated transport of IgG targeting the intracellular chlamydial inclusion membrane protein A (IncA), induced aberrant inclusion morphology, recruited autophagic proteins independent of lysosomes and significantly reduced infection. Challenge of female mice with MOMP-specific IgG-opsonized Chlamydia muridarum delayed infection clearance but exacerbated oviduct occlusion. In male mice, MOMP-IgG elicited by immunization afforded no protection against testicular chlamydial infection, whereas the transcytosis of IncA-IgG significantly reduced testicular chlamydial burden. Together these data show that the protective and pathological effects of IgG are dependent on FcRn-mediated transport as well as the specificity of IgG for intracellular or extracellular antigens.

Raman microspectroscopy reveals long-term extracellular activity of Chlamydiae

The phylum Chlamydiae consists exclusively of obligate intracellular bacteria. Some of them are formidable pathogens of humans, while others occur as symbionts of amoebae. These genetically intractable bacteria possess a developmental cycle consisting of replicative reticulate bodies and infectious elementary bodies, which are believed to be physiologically inactive. Confocal Raman microspectroscopy was applied to differentiate between reticulate bodies and elementary bodies of Protochlamydia amoebophila and to demonstrate in situ the labelling of this amoeba symbiont after addition of isotope-labelled phenylalanine. Unexpectedly, uptake of this amino acid was also observed for both developmental stages for up to 3 weeks, if incubated extracellularly with labelled phenylalanine, and P. amoebophila remained infective during this period. Furthermore, P. amoebophila energizes its membrane and performs protein synthesis outside of its host. Importantly, amino acid uptake and protein synthesis after extended extracellular incubation could also be demonstrated for the human pathogen Chlamydia trachomatis, which synthesizes stress-related proteins under these conditions as shown by 2-D gel electrophoresis and MALDI-TOF/TOF mass spectrometry. These findings change our perception of chlamydial biology and reveal that host-free analyses possess a previously not recognized potential for direct experimental access to these elusive microorganisms.

In vitro characterisation of koala Chlamydia pneumoniae: morphology, inclusion development and doubling time

Chlamydia pneumoniae is a common human and animal pathogen associated with upper and lower respiratory tract infections. Of the animal C. pneumoniae isolates, the koala nasal isolate (LPCoLN) is by far the best genetically characterised. This current study was designed to characterise the morphology and developmental events for the LPCoLN isolate, and our results showed several striking in vitro growth differences when compared to the human isolate, AR39. The LPCoLN inclusion size and morphology was distinct from AR39, and a much faster doubling time (3.4-4.9h versus 5.9-8.7h doubling time) was observed when grown in HEp-2 cell monolayers. Confocal and electron microscopy of LPCoLN confirmed large (9-30 microm in diameter) inclusions, that were heterogeneously shaped, compared to the small (5-9 microm in diameter), uniformly shaped inclusions of AR39. The morphology of the LPCoLN elementary body was round, and had a narrow or nonexistent periplasmic space, compared to the 'pear-shaped' morphology of AR39 EBs. While both isolates showed evidence of inclusion fusion, the level of fusion was much higher for LPCoLN (100%) compared to AR39 (30-40%). Our findings have provided new insights and identified key differences in the in vitro doubling time, size and morphology of an animal C. pneumoniae isolate.

A comparative ultrastructural and molecular biological study on Chlamydia psittaci infection in alpha-1 antitrypsin deficiency and non-alpha-1 antitrypsin deficiency emphysema versus lung tissue of patients with hamartochondroma

BACKGROUND

Chlamydiales are familiar causes of acute and chronic infections in humans and animals. Human pulmonary emphysema is a component of chronic obstructive pulmonary disease (COPD) and a condition in which chronic inflammation manifested as bronchiolitis and intra-alveolar accumulation of macrophages is common. It is generally presumed to be of infectious origin. Previous investigations based on serology and immunohistochemistry indicated Chlamydophila pneumoniae infection in cases of COPD. Furthermore, immunofluorescence with genus-specific antibodies and electron microscopy suggested involvement of chlamydial infection in most cases of pulmonary emphysema, but these findings could not be verified by PCR. Therefore, we examined the possibility of other chlamydial species being present in these patients.

METHODS

Tissue samples from patients having undergone lung volume reduction surgery for advanced alpha-1 antitrypsin deficiency (AATD, n = 6) or non-alpha-1 antitrypsin deficiency emphysema (n = 34) or wedge resection for hamartochondroma (n = 14) were examined by transmission electron microscopy and PCR.

RESULTS

In all cases of AATD and 79.4% of non-AATD, persistent chlamydial infection was detected by ultrastructural examination. Intra-alveolar accumulation of macrophages and acute as well as chronic bronchiolitis were seen in all positive cases. The presence of Chlamydia psittaci was demonstrated by PCR in lung tissue of 66.7% AATD vs. 29.0% non-AATD emphysema patients. Partial DNA sequencing of four positive samples confirmed the identity of the agent as Chlamydophila psittaci. In contrast, Chlamydophila pneumoniae was detected only in one AATD patient. Lung tissue of the control group of non-smokers with hamartochondroma was completely negative for chlamydial bodies by TEM or chlamydial DNA by PCR.

CONCLUSIONS

These data indicate a role of Chlamydophila psittaci in pulmonary emphysema by linking this chronic inflammatory process to a chronic infectious condition. This raises interesting questions on pathogenesis and source of infection.

Chlamydia pneumoniae in coronary bypass grafts of redo patients. The concept of the ‘adventitial baseline infection’

The pathogenic role of Chlamydia pneumoniae in late coronary bypass graft failure has not yet been extensively investigated. We examined failed and new arterial/venous bypass grafts using immunohistochemistry, polymerase chain reaction (PCR), and serology. Thirty-four long-term failed grafts and 28 new grafts were examined in 21 patients undergoing redo coronary artery bypass grafting (CABG). Immunohistochemically, 28 (82%) failed grafts were positive in the intimal-medial compartment, and 33 grafts (97%) were positive for C. pneumoniae in the adventitia. Thirteen (46%) and 27 (96%) new grafts showed infection in the intima-media and in the adventitia, respectively (p < 0.05). Immunohistochemically, the overall presence of C. pneumoniae in all vessels examined was 66% in the intima-media and 97% in the adventitia (p < 0.05). C. pneumoniae was detected by PCR in 19 (31%) of all the vessels examined. C. pneumoniae seems to be frequently present in grafts of patients considered for redo CABG in Hungary. The adventitia of both failed, and new grafts particularly often contained C. pneumoniae. The results suggest that there exists an adventitial baseline infection from which infection of the inner wall layers develops, depending on local microenvironmental conditions. This is the first study to evaluate chlamydial infection in arterial/venous coronary grafts by immunohistochemistry, PCR, and serology.

Intracellular growth of Legionella pneumophila gives rise to a differentiated form dissimilar to stationary-phase forms

When Legionella pneumophila grows in HeLa cells, it alternates between a replicative form and a morphologically distinct "cyst-like" form termed MIF (mature intracellular form). MIFs are also formed in natural amoebic hosts and to a lesser extent in macrophages, but they do not develop in vitro. Since MIFs accumulate at the end of each growth cycle, we investigated the possibility that they are in vivo equivalents of stationary-phase (SP) bacteria, which are enriched for virulence traits. By electron microscopy, MIFs appeared as short, stubby rods with an electron-dense, laminar outer membrane layer and a cytoplasm largely occupied by inclusions of poly-beta-hydroxybutyrate and laminations of internal membranes originating from the cytoplasmic membrane. These features may be responsible for the bright red appearance of MIFs by light microscopy following staining with the phenolic Giménez stain. In contrast, SP bacteria appeared as dull red rods after Giménez staining and displayed a typical gram-negative cell wall ultrastructure. Outer membranes from MIFs and SP bacteria were equivalent in terms of the content of the peptidoglycan-bound and disulfide bond cross-linked OmpS porin, although additional proteins, including Hsp60 (which acts as an invasin for HeLa cells), were detected only in preparations from MIFs. Proteomic analysis revealed differences between MIFs and SP forms; in particular, MIFs were enriched for an approximately 20-kDa protein, a potential marker of development. Compared with SP bacteria, MIFs were 10-fold more infectious by plaque assay, displayed increased resistance to rifampin (3- to 5-fold) and gentamicin (10- to 1,000-fold), resisted detergent-mediated lysis, and tolerated high pH. Finally, MIFs had a very low respiration rate, consistent with a decreased metabolic activity. Collectively, these results suggest that intracellular L. pneumophila differentiates into a cyst-like, environmentally resilient, highly infectious, post-SP form that is distinct from in vitro SP bacteria. Therefore, MIFs may represent the transmissible environmental forms associated with Legionnaires' disease.

Chlamydia pneumoniae major outer membrane protein is a surface-exposed antigen that elicits antibodies primarily directed against conformation-dependent determinants

The major outer membrane protein (MOMP) of Chlamydia trachomatis serovariants is known to be an immunodominant surface antigen. Moreover, it is known that the C. trachomatis MOMP elicits antibodies that recognize both linear and conformational antigenic determinants. In contrast, it has been reported that the MOMP of Chlamydia pneumoniae is not surface exposed and is immunorecessive. We hypothesized that the discrepancies between C. trachomatis and C. pneumoniae MOMP exposure on intact chlamydiae and immunogenic properties might be because the focus of the host's immune response is directed to conformational epitopes of the C. pneumoniae MOMP. We therefore conducted studies aimed at defining the surface exposure of MOMP and the conformational dominance of MOMP antibodies. We present here a description of C. pneumoniae species-specific monoclonal antibody (MAb), GZD1E8, which recognizes a conformational epitope on the surface of C. pneumoniae. This MAb is potent in the neutralization of C. pneumoniae infectivity in vitro. Another previously described C. pneumoniae species-specific monoclonal antibody, RR-402, displayed very similar characteristics. However, the antigenic determinant recognized by RR-402 has yet to be identified. We show by immunoprecipitation of C. pneumoniae with GZD1E8 and RR-402 MAbs and by mass spectrometry analysis of immunoprecipitated proteins that both antibodies GZD1E8 and RR-402 recognize the MOMP of C. pneumoniae and that this protein is localized on the surface of the organism. We also show that human sera from C. pneumoniae-positive donors consistently recognize the MOMP by immunoprecipitation, indicating that the MOMP of C. pneumoniae is an immunogenic protein. These findings have potential implications for both C. pneumoniae vaccine and diagnostic assay development.

Background and current knowledge of Chlamydia pneumoniae and atherosclerosis

Attributes of Chlamydia pneumoniae of potential importance to a relationship with atherosclerosis are described. Among these are that C. pneumoniae is not new. It is unique. It is a pathogen with which everyone is infected, and it is difficult to treat. It causes immunopathology, myocarditis, and endocarditis and chronicity is a hallmark of Chlamydia infection. Current knowledge of the relation of C. pneumoniae and atherosclerosis comes from observational (e.g., seroepidemiology and tissue studies) and experimental studies. The limitations of the serologic studies of chronic infection are noted as is the conclusive demonstration of an association of C. pneumoniae and atherosclerosis by the repeated and frequent finding of the organism in atherosclerotic tissue. Experimental studies are needed to determine if the association is causal. Such studies should include animal models, basic mechanisms, and secondary prevention antibiotic treatment trials.

Ultrastructural analysis of developmental events in Chlamydia pneumoniae-infected cells

Chlamydia pneumoniae is an obligate intracellular parasite with a developmental cycle believed to be common to all members of the genus Chlamydia. We present a detailed description based on transmission and scanning electron microscopy of temporal events and inclusion structures throughout the C. pneumoniae AR-39 developmental cycle.

Genome sequences of Chlamydia trachomatis MoPn and Chlamydia pneumoniae AR39

The genome sequences of Chlamydia trachomatis mouse pneumonitis (MoPn) strain Nigg (1 069 412 nt) and Chlamydia pneumoniae strain AR39 (1 229 853 nt) were determined using a random shotgun strategy. The MoPn genome exhibited a general conservation of gene order and content with the previously sequenced C.trachomatis serovar D. Differences between C.trachomatis strains were focused on an approximately 50 kb 'plasticity zone' near the termination origins. In this region MoPn contained three copies of a novel gene encoding a >3000 amino acid toxin homologous to a predicted toxin from Escherichia coli O157:H7 but had apparently lost the tryptophan biosyntheis genes found in serovar D in this region. The C. pneumoniae AR39 chromosome was >99.9% identical to the previously sequenced C.pneumoniae CWL029 genome, however, comparative analysis identified an invertible DNA segment upstream of the uridine kinase gene which was in different orientations in the two genomes. AR39 also contained a novel 4524 nt circular single-stranded (ss)DNA bacteriophage, the first time a virus has been reported infecting C. pneumoniae. Although the chlamydial genomes were highly conserved, there were intriguing differences in key nucleotide salvage pathways: C.pneumoniae has a uridine kinase gene for dUTP production, MoPn has a uracil phosphororibosyl transferase, while C.trachomatis serovar D contains neither gene. Chromosomal comparison revealed that there had been multiple large inversion events since the species divergence of C.trachomatis and C.pneumoniae, apparently oriented around the axis of the origin of replication and the termination region. The striking synteny of the Chlamydia genomes and prevalence of tandemly duplicated genes are evidence of minimal chromosome rearrangement and foreign gene uptake, presumably owing to the ecological isolation of the obligate intracellular parasites. In the absence of genetic analysis, comparative genomics will continue to provide insight into the virulence mechanisms of these important human pathogens.

Analysis of partial 16S rRNA nucleotide sequences of Chlamydia pecorum and C. psittaci

Partial 16S nucleotide sequences of Chlamydia psittaci isolates S26/3 (abortion), P94/1 (pigeon) and Chlamydia pecorum isolates W73 (enteric) and E58 (encephalomyelitis) were determined. Analysis of these data indicates very high levels of interspecies sequence conservation, with C. psittaci being more closely related to C. pecorum than to C. pneumoniae or C. trachomatis. Restriction enzyme analysis of nucleotide sequences indicated that BslI can be used to clearly distinguish C. psittaci and C. pecorum isolates. Psittacine and non-psittacine (pigeon) avian isolates of C. psittaci were distinguished using MaeI.

Continuous isolation and characterization of Chlamydia pneumoniae from a patient with diffuse panbronchiolitis

We succeeded in isolating Chlamydia pneumoniae organisms continuously from a 70-year-old man who had received chemotherapeutic treatment with low dosages of erythromycin for five years to improve diffuse panbronchiolitis (DPB). He had two episodes of acute exacerbation of DPB and a total of six strains of C. pneumoniae were isolated at different stages during the past 13 months. The morphological properties and protein profiles of the elementary bodies of all the C. pneumoniae isolates were similar to each other. Interestingly, his serological response against C. pneumoniae in immunoblotting tests was differed between two episodes. The sera collected during the first episode reacted weakly to the major outer membrane protein (MOMP), whereas those collected during the second episode reacted strongly to the 60-kDa protein and weakly to MOMP. These facts suggest that the two different episodes occurred as a result of different mechanisms. Additionally, in spite of the low antibody titer by micro-immunofluorescence test in the second episode as compared with that of the first episode, the immune response against 60-kDa immunodominant protein increased markedly in the second episode, and we suspect that the second episode was due to an allergic reaction caused by this 60-kDa protein. These findings suggest that repeated or prolonged exposure to C. pneumoniae may be associated with acute exacerbations of chronic obstructive pulmonary disease, and that the patient should be noted as a possible source of C. pneumoniae infection.

Further characterization of Chlamydia pneumoniae specific monoclonal antibodies

Studies using monoclonal antibodies have demonstrated species-specific reactivities with Chlamydia pneumoniae. In this study, further characterization of C. pneumoniae specific monoclonal antibodies TT-205 and RR-402 and description of C. pneumoniae specific antibodies prepared against other isolates are presented. TT-205 and RR-402 were shown to neutralize infectivity. Neutralization in cell culture was specific and enhanced by complement. Attempts to characterize the reactive antigen by immunoblotting, immunoaffinity chromatography and radioimmunoprecipitation were unsuccessful, probably due to difficulties in solubilizing the immunoreactive epitope without denaturing it. Recognition of the determinant by the monoclonal antibodies is labile to physical and chemical treatments suggesting that the reactive epitope is conformational.

Chlamydia psittaci infections: a review with emphasis on avian chlamydiosis

In the first part of this article the general characteristics of Chlamydia psittaci namely the history, taxonomy, morphology, reproductive cycle, metabolism and genetics are reviewed. For the taxonomy in particular, a considerable amount of new information has become available in recent years, following the application of monoclonal antibodies and restriction enzymes. Using these techniques isolates of Chlamydia psittaci from birds have been subdivided in different serovars, a number of isolates have been classified in a new species (Chlamydia pecorum) and isolates from animals have been classified as Chlamydia trachomatis. In the second part of the article, the current knowledge on avian chlamydiosis is summarized. Emphasis is put on clinical signs, lesions, pathogenesis, epizootiology, immunity, diagnosis, prevention and treatment. Also the public health considerations are reviewed. It is concluded that the diagnosis of avian chlamydiosis is laborious and that there is still a need for more accurate, simple and rapid diagnostic tools, both for antigen and antibody detection in various species of birds.

Characterization of a Chlamydia pneumoniae strain isolated from a 57-year-old man

The isolation of Chlamydia pneumoniae, especially from elderly persons, is generally not easy. Recently, we succeeded in isolating a chlamydial strain, which was designated KKpn-15, from a 57-year-old man suffering from acute bronchitis. It was compared with well established strains of C. pneumoniae, C. trachomatis and C. psittaci, and its biological properties, such as the morphology of elementary bodies (EBs) and inclusions, and the immunochemistry of EB proteins, were investigated. Based on the results obtained in the present study, it was confirmed that the new chlamydial strain, KKpn-15, is a member of the C. pneumoniae strain and that the organisms of KKpn-15 are useful as an antigen for the serodiagnosis and epidemiology of C. pneumoniae infection.

Comparison of Chlamydia pneumoniae isolates by western blot (immunoblot) analysis and DNA sequencing of the omp 2 gene

The 60-kDa cysteine-rich outer membrane protein gene (omp 2) from nine Chlamydia pneumoniae isolates (TW-183, CM-1, CWL-050, CWL-011, IOL-207, FIL, Kajaani-6, Helsinki-12, and Parjaanonen) was amplified by PCR and sequenced from positions 1 to 580. In contrast to the sequence differences previously observed in this gene in other chlamydial species, all nine C. pneumoniae isolates were 100% identical. However, when sera from C. pneumoniae microimmunofluorescence-positive patients (with clinical signs of persistent cough or asthma) were immunoblotted against five C. pneumoniae isolates, distinct antigenic differences were observed. TW-183 was characterized by major bands at 35 and 43 kDa. In contrast, the other four isolates tested produced similar, though not identical, immunoblot profiles, characterized by strong bands at 18, 25, 29, 40, 46, and 53 kDa. These data support the fact that significant differences do exist between C. pneumoniae isolates, but unlike the case with other chlamydial species, these differences do not reside in either of the commonly studied outer membrane protein genes, omp 1 or omp 2.

Antigenic characterization of Chlamydia pneumoniae isolated in Hiroshima, Japan

The morphology and antigenic property of elementary bodies (EBs) of new Chlamydia pneumoniae YK-41 strain isolated in Hiroshima, Japan, were compared with those of C. pneumoniae strains TW-183 and AR-39, C. trachomatis L2/434/Bu strain and C. psittaci Cal 10 and Budgerigar-1 strains by SDS-PAGE and immunoblotting techniques. In spite of a clear difference in EB morphology between the YK-41 and the other C. pneumoniae strains used, protein profile of the YK-41 strain in SDS-PAGE was similar to that of the other strains. However, some quantitative difference in 200 and 98 kDa peptides and a faint difference in SDS-PAGE pattern was also observed in the molecular masses from 42 to 50 kDa. Immunoblot analysis with the patient serum at the convalescent stage revealed the presence of genus-specific and species-specific antigens in YK-41 EBs: i.e., the major outer membrane protein and 73 kDa peptides were genus-specific and the peptides of 43, 46, 53, 60 and 98 kDa appeared to be C. pneumoniae-specific.

Infection due to Chlamydia trachomatis in pregnancy and the newborn

Bacteria in the genus Chlamydia comprise three species, C. trachomatis, C. psittaci and C. pneumoniae. C. trachomatis infection is common, varying in prevalence in women from 0% to 37%. In the United States, the prevalence rate is estimated currently to be about 5%. Pregnancy may predispose to an increased chance of infection with C. trachomatis, through physiological immunosuppression and/or cervical ectopy. Maternal antibodies to C. trachomatis provide limited, if any, protection for the newborn. C. trachomatis causes pelvic inflammatory disease--which can result in tubal infertility or ectopic pregnancy and postabortal or late postpartum endometritis. It may also cause chorioamnionitis and premature delivery of the fetus. The incidence of vertical transmission of chlamydiae from mother to baby varies; if the mother is untreated, 20-50% of the newborns will develop conjunctivitis and 10-20% will develop pneumonia. C. psittaci infection in pregnancy is rare, but can cause spontaneous abortion. Whether C. pneumoniae infection in pregnancy has any influence on the outcome has not been ascertained. C. trachomatis can be detected by one or more of several methods; enzyme immunoassays are the least sensitive, but the most widely used. Screening for C. trachomatis in pregnancy may be of benefit in areas of high prevalence, and is generally regarded as being cost-effective if the prevalence rate is more than 5%. Pregnant women are best treated with erythromycin, 250 mg four times daily for 7 days. This will prevent infection of the newborn in more than 90% of cases. The infected neonate should be treated with erythromycin, given systemically and also with topical tetracycline if conjunctivitis is present.

Seroprevalence of Chlamydia pneumoniae in Taiwan

Chlamydia pneumoniae (TWAR) is a relatively newly discovered respiratory tract pathogen which was first isolated in Taiwan. In order to describe the seroepidemiology of C. pneumoniae in Taiwan, we evaluated 1,085 stored serum samples: 904 from patients, 97 from umbilical cord blood samples, and 84 from medical personnel at the Veterans General Hospital-Kaohsiung, between January 1 and April 30, 1991. Antibodies were determined by the use of a microimmunofluorescence test using elementary bodies of C. pneumoniae AR-39 as antigen. Sera were tested with screening titres of 16 and 512 for immunoglobulin G antibody. The antibody prevalence was found to be 23.1% in young children (6 months to 10 years old), rising to 66.7% in teenagers, and to 96.2% in older age groups. These rates were higher than any reported earlier. The progressively increasing rates of seropositivity found in older individuals indicated a surge of reinfection in these age groups. Only 5 cases were found with micro-IF IgG titres equal to or greater than 512. All were asymptomatic according to the hospital records. In addition to a high prevalence rate in Taiwan, the data also showed high infection rates in teenagers and elderly people.

Chlamydial infections of the heart

Chlamydiae are common human pathogens, causing a broad spectrum of infectious diseases. Chlamydial infections involving the heart have been described in numerous previous reports. These organisms are documented to cause endocarditis, myocarditis and pericarditis. Furthermore, Chlamydia pneumoniae, the recently discovered respiratory pathogen, has also been implicated in coronary artery disease. For the first time the literature on involvement of the heart in chlamydial infections is reviewed. Information on the discovery of Chlamydia species is also included and the problem of the species determination of Chlamydia in interpretation of the older literature is mentioned.

Postoperative spindle-cell nodule of urinary bladder with unusual intracytoplasmic inclusions

Postoperative spindle-cell nodule of the urinary bladder (or in the absence of previous surgical procedure, inflammatory pseudotumor) is a reactive process of unknown etiology mimicking a sarcoma. Intracytoplasmic inclusion bodies were noted inside the atypical spindle cells on Diff-Quik stained smears in a recent case of this entity. Although fluorescence was noted in the inclusion bodies with monoclonal antibodies against the major outer membrane protein of the Chlamydia species, the exact nature of these inclusion bodies remains unknown.

Chlamydiae as pathogens--an overview of diagnostic techniques, clinical features, and therapy of human infections

Chlamydiae are Gram-negative bacteria with obligate intracellular reproduction and disability to synthesize high-energy compounds such as ATP. Their cycle of development is unique among the prokaryotes: the host cells, mainly epithelial cells, are infected by so-called elementary bodies (EB) which undergo reorganization to form metabolically active reticulate bodies (RB). These RB multiply by binary fission, and after transition into infectious EB they are released within 48-72 hours. Chlamydiae cause prolonged subclinical infections of the conjunctiva, lung, cervix, and urethra. Complications in newborns are inclusion conjunctivitis, nasopharyngitis and pneumonia; in females, salpingitis, infertility, and perihepatitis; in male patients, epididymitis and prostatitis; and in both sexes, Chlamydiae-induced arthritis. Identification of the pathogenic agent confirms clinical diagnosis; tissue culture identification remains the diagnostic method of choice. Therapeutical drugs are tetracycline, erythromycin, josamycin, and in certain cases quinolone derivatives.

Chlamydia pneumoniae elementary body antigenic reactivity with fluorescent antibody is destroyed by methanol

Methanol, used for fixing chlamydia organisms to microscopic slides, was shown to eliminate the antigenic reactivity of Chlamydia pneumoniae elementary bodies with fluorescent antibodies. Acetone fixation had no adverse effect. Chlamydia trachomatis and Chlamydia psittaci were not affected by methanol fixation. The effect of methanol on C. pneumoniae is another characteristic that differentiates this species from the other two chlamydia species.

Antigenic variation among strains of Chlamydia pneumoniae

The antigenic profiles of six strains of Chlamydia pneumoniae were analyzed by the microimmunofluorescence test (MIF) and immunoblotting with human serum and murine monoclonal antibody. MIF-derived antibody titers in serum samples from culture-positive patients were four- to eightfold higher against autologous isolate antigen than they were against the prototype antigen strain TW-183. Sera of patients with respiratory illness that were culture negative and complement fixation positive for Chlamydia spp. produced higher titers by MIF against a strain of C. pneumoniae isolated in the area than they did against TW-183. For two of five cases, the criteria for establishing the diagnosis of acute infection were met only with use of the antigen from the local strain; TW-183 was inadequate for this purpose. Immunoblot profiles revealed antigenic differences between strains that varied with the human serologic response; i.e., unique antigens were recognized by the sera of some individuals and not by the sera of others. Using the reactivity of a genus-specific monoclonal antibody against a major outer membrane protein, we found that strain CWL-011, isolated in Atlanta, Ga., may possess a major outer membrane protein with a molecular mass between those of C. trachomatis L2 and other C. pneumoniae strains. These data provide evidence of several new and unique serotypes of C. pneumoniae and suggest that the serologic diagnosis of C. pneumoniae infection may require the use of antigens from more than one strain of this species.

Evidence that the major outer membrane protein of Chlamydia trachomatis is glycosylated

The major outer membrane protein (MOMP) of Chlamydia trachomatis was determined to be a glycoprotein on the basis of susceptibility to glycosidase digestion and the presence of carbohydrate by staining and radiolabeling. The MOMP of the serovar L2 organisms was isolated by electroelution from the protein band excised from the gel after sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). The incubation of MOMP with N-glycosidase F, an endoglycosidase that cleaves the N-glycan, and periodate resulted in two new molecular weight species. While MOMP treated with N-glycosidase F showed a lower-molecular-weight mobility, the periodate-treated MOMP increased in molecular weight. Both treatments abolished the ability of the MOMP to bind to HeLa cell components. In the immunoblot, the reactivity to the monoclonal antibody specific against the C. trachomatis species was preserved. The endoglycosidase specific to O-linked glycan, endo-alpha-N-acetylgalactosaminidase, had no visible effect on the isolated MOMP. Carbohydrate was detected in the MOMP by p-phenylenediamine staining of the protein band in the gel following SDS-PAGE. Autoradiograms of proteins of chlamydial organisms metabolically labeled with [3H]galactose or [3H]glucosamine and separated by SDS-PAGE revealed the MOMP band. The isolated MOMP was shown to bind specifically to concanavalin A, wheat germ agglutinin, and Dolichos biflorus agglutinin in the lectin binding assay. No binding was observed with Ulex europaeus agglutinin I, soybean agglutinin, or Ricinus communis agglutinin.

Prevalence of antibody to Chlamydia pneumoniae TWAR in japan

Chlamydia pneumoniae TWAR is a newly recognized Chlamydia species that is a pathogen of respiratory tract infection. To clarify the endemic status of C. pneumoniae in Japan, we evaluated the incidence of C. pneumoniae antibody in 1,330 serum samples (660 from outpatients, 600 from normal individuals, and 70 from cord blood). The antibody titer was determined by a microimmunofluorescence test by using the elementary body of C. pneumoniae TW-183 as the antigen. Immunoglobulin G antibody titers of 1:32 or higher were regarded as evidence of past infection. The detection rate of C. pneumoniae antibody rapidly increased in subjects between the ages of 4 and 7 years, reached 44% in subjects between the ages of 8 and 11 years, and was about 50% in older subjects. The rate did not differ between healthy subjects and outpatients. These results suggest that C. pneumoniae infection is highly endemic in Japan as it is in Western countries. However, the antibody prevalence was high in the low age groups in Japan compared with that in Western countries.

Interaction of chlamydiae and host cells in vitro

The obligately intracellular bacteria of the genus Chlamydia, which is only remotely related to other eubacterial genera, cause many diseases of humans, nonhuman mammals, and birds. Interaction of chlamydiae with host cells in vitro has been studied as a model of infection in natural hosts and as an example of the adaptation of an organism to an unusual environment, the inside of another living cell. Among the novel adaptations made by chlamydiae have been the substitution of disulfide-bond-cross-linked polypeptides for peptidoglycans and the use of host-generated nucleotide triphosphates as sources of metabolic energy. The effect of contact between chlamydiae and host cells in culture varies from no effect at all to rapid destruction of either chlamydiae or host cells. When successful infection occurs, it is usually followed by production of large numbers of progeny and destruction of host cells. However, host cells containing chlamydiae sometimes continue to divide, with or without overt signs of infection, and chlamydiae may persist indefinitely in cell cultures. Some of the many factors that influence the outcome of chlamydia-host cell interaction are kind of chlamydiae, kind of host cells, mode of chlamydial entry, nutritional adequacy of the culture medium, presence of antimicrobial agents, and presence of immune cells and soluble immune factors. General characteristics of chlamydial multiplication in cells of their natural hosts are reproduced in established cell lines, but reproduction in vitro of the subtle differences in chlamydial behavior responsible for the individuality of the different chlamydial diseases will require better in vitro models.

Characterisation of Chlamydia psittaci isolated from a horse

This paper describes the isolation and characterisation of a strain of Chlamydia psittaci obtained from a nasal swab taken from a horse with serous nasal discharge. Initial isolation was achieved in cycloheximide-treated McCoy cell monolayers. Chlamydial inclusions stained by immunofluorescence either with a rabbit antiserum raised against C. psittaci or with a monoclonal antibody directed against the genus-specific lipopolysaccharide antigen were single and compact. They did not stain with iodine or with a monoclonal antibody reactive against Chlamydia trachomatis. The agent was re-isolated in the yolk sacs of embryonated hens eggs and designated N16. Identification of the agent was confirmed by electron microscopy. Unique plasmid DNA was prepared from a purified suspension of chlamydial elementary bodies (EBs), and analysed by electrophoresis through 1.0% agarose gels stained by ethidium bromide. This strain of C. psittaci grew relatively slowly in cycloheximide-treated McCoy cells, and the yield of elementary bodies during the course of one growth cycle was relatively low.

Use of HL cells for improved isolation and passage of Chlamydia pneumoniae

We compared growth of the recently discovered respiratory pathogen Chlamydia pneumoniae in McCoy, HeLa 229, BHK-21, and HL cells. When cells were not pretreated with DEAE-dextran, HL cells had significantly higher mean numbers of inclusion-forming units (IFUs) on initial inoculation than the other cell lines. When cells were pretreated with DEAE-dextran, HeLa 229 and HL cells had equivalent mean numbers of IFUs on initial inoculation. HL cells had strikingly higher mean numbers of IFUs in passage than HeLa 229, BHK-21, or McCoy cells. In addition, HL cells did not require pretreatment with DEAE-dextran and could be used from 2 to 4 days after seeding. We conclude that HL cells are an excellent cell culture system for laboratory propagation of C. pneumoniae and may be a more sensitive cell line for initial isolation.

Mixed infection of Rickettsiella phytoseiuli and Coxiella burnetii in Dermacentor reticulatus female ticks: electron microscope study

Mixed infection of Rickettsiella phytoseiuli and Coxiella burnetii was investigated in hemolymph and organs of experimentally infected females of Dermacentor reticulatus ticks. Following intracoelomic infection, both agents, with the exception of Gene's organ, multiplied well in the cells of the tick host's organs. Two out of six developmental stages of R. phytoseiuli, i.e., crystal-forming and small dark particles, in dual infection with C. burnetii revealed marked morphological alterations. C. burnetii in the presence of R. phytoseiuli penetrated into the cortical layer of the synganglion and into the alveoli of the second and third type of salivary glands, but did not occur in the single infection.

Experimental infection with Chlamydia pneumoniae in nonhuman primates

To serially examine the immunopathogenesis and histopathology of infection with Chlamydia pneumoniae, we inoculated two cynomolgus monkeys in the conjunctival sac, nose, and nasopharynx with C. pneumoniae TWAR. After inoculation, C. pneumoniae was isolated from the inoculation sites and the rectums of both monkeys for a period of 5 weeks. After a second inoculation, C. pneumoniae was recovered from the inoculation sites and the rectums of both monkeys for 20 weeks. A third inoculation with C. pneumoniae caused very little productive infection at any site. Prior C. pneumoniae infection did not prevent subsequent C. trachomatis serovar E (Bour strain) infection. Clinical and histopathologic ocular responses to C. pneumoniae infection were mild compared with those to infection with C. trachomatis serovar E. Rectal infection, demonstrated by culture isolation and immunohistopathology, occurred without direct experimental inoculation. Both immunofluorescent staining of mucosal smears with monoclonal antibodies and tissue culture were able to detect C. pneumoniae infection. Experimental nonhuman primate infection with C. pneumoniae appears to be clinically and histopathologically mild and can occur at extrapulmonary sites.

Structural and antigenic analysis of Chlamydia pneumoniae

Several isolates of Chlamydia pneumoniae were compared with each other and to Chlamydia trachomatis and Chlamydia psittaci by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and immunoblots. Protein profiles of the C. pneumoniae isolates appeared to be the same and were distinct from the other Chlamydia species. A 39.5-kilodalton (kDa) protein, similar in molecular weight to the major outer membrane proteins (MOMP) of C. trachomatis and C. psittaci, was found in the Sarkosyl-insoluble fraction, demonstrating its association with the outer membrane complex. In the outer membrane complex, the MOMP was shown to exist in disulfide-linked protein complexes. Electron microscopy of the Sarkosyl-extracted elementary bodies showed that the structural rigidity and pear-shaped morphology remained intact. Rabbit immune sera prepared against C. pneumoniae demonstrated immunoreactive proteins of 98-, 77-, 75-, 66-, 60-, 39.5-, 28-, and 17.5-kDa proteins. Cross-reactivity experiments revealed that most of the antigenic reactivities shared between C. psittaci and C. trachomatis extend to C. pneumoniae and that the 98-kDa protein recognition appeared to be C. pneumoniae specific. In contrast to the other Chlamydia spp., the recognition of the C. pneumoniae MOMP by homologous immune sera was weak and was cross-reactive with the MOMPs of the other Chlamydia species. These results suggest that the C. pneumoniae MOMP is less immunogenic and antigenically complex than are the MOMPs of C. trachomatis and C. psittaci.

Chlamydia pneumoniae, strain TWAR, as the cause of an outbreak in a boys' school previously called psittacosis

Sera from an outbreak of acute respiratory illness in a boys boarding school originally thought to have been due to psittacosis (1) have been re-examined and evidence is presented that suggests that the outbreak was caused by Chlamydia pneumoniae, strain TWAR (2).

Chlamydia species strain TWAR

The chlamydia have long been recognized as ubiquitous pathogens capable of producing a wide spectrum of disease both in children and in adults. Common infections caused by this pathogen include pneumonia in infants, trachoma in children, and genital tract disease in adults. While neonatal chlamydial pneumonia is commonly described, chlamydial pneumonia in adults is less commonly recognized and was originally associated only with exposure to psittacine birds. Instances of person-to-person transmission of a chlamydial pneumonia were first identified in San Francisco in 1941. The organism isolated was a chlamydia-like agent with glycogen-staining characteristics unlike those of the well-studied avian chlamydia but much more difficult to maintain in culture. This finding lapsed into obscurity until 1965, when a chlamydial organism again demonstrating aChlamydia psittaci-likestaining pattern was isolated from a Taiwanese child in a trachoma study. This isolate was eventually named TW183. It was not until 1983, however, when a patient with atypical pneumonia was found to be infected with a similar pathogen, dubbed AR39, that the question of prevalence was raised. As the behavior of these isolates was characterized in Grayston's laboratory, it became apparent that they represented a novel human pathogen and the name TWAR (Taiwan acute respiratory agent) was adopted. Subsequent epidemiologic studies of this agent have shown broad exposure over a wide geographic distribution with almost 40% of tested populations showing serologic evidence of exposure.

Laboratory diagnosis of human chlamydial infections

Chlamydia trachomatis is a human pathogen that causes ocular disease (trachoma and inclusion conjunctivitis), genital disease (cervicitis, urethritis, salpingitis, and lymphogranuloma venereum), and respiratory disease (infant pneumonitis). Respiratory chlamydioses also occur with infection by avian strains of C. psittaci or infection by the newly described TWAR agent. Diagnosis of most acute C. trachomatis infections relies on detection of the infecting agent by cell culture, fluorescent antibody, immunoassay, cytopathologic, or nucleic acid hybridization methods. Individual non-culture tests for C. trachomatis are less sensitive and specific than the best chlamydial cell culture system but offer the advantages of reduced technology and simple transport of clinical specimens. Currently available nonculture tests for C. trachomatis perform adequately as screening tests in populations in which the prevalence of infection is greater than 10%. A negative culture or nonculture test for C. trachomatis does not, however, exclude infection. The predictive value of a positive nonculture test may be unsatisfactory when populations of low infection prevalence are tested. Tests that detect antibody responses to chlamydial infection have limited utility in diagnosis of acute chlamydial infection because of the high prevalence of persistent antibody in healthy adults and the cross-reactivity due to infection by the highly prevalent C. trachomatis and TWAR agents. Assays for changes in antibody titer to the chlamydial genus antigen are used for the diagnosis of respiratory chlamydioses. A single serum sample that is negative for chlamydial antibody excludes the diagnosis of lymphogranuloma venereum.

Current knowledge on Chlamydia pneumoniae, strain TWAR, an important cause of pneumonia and other acute respiratory diseases

This article reviews current knowledge of Chlamydia pneumoniae strain TWAR, a newly recognized Chlamydia organism that causes acute respiratory infection, especially atypical pneumonia. Information is included on the microbiology, classification and laboratory diagnosis of the organism. Details of a series of studies of both endemic and epidemic respiratory infections are reviewed to present information on both the clinical and epidemiological characteristics of infection with strain TWAR. Laboratory studies of antibiotic sensitivity and recommendations for treatment are presented.

Isolation of a gene encoding a Chlamydia sp. strain TWAR protein that is recognized during infection of humans

Chlamydia sp. strain TWAR is a unique Chlamydia sp. that causes acute respiratory disease. A gene bank consisting of TWAR isolate AR-39 DNA in pUC19 was screened with anti-AR-39 rabbit immune sera. Two positive clones were isolated that contained 7.3-kilobase (pLC1) and 14.9-kilobase (pLC2) plasmids. Restriction mapping and hybridization studies showed that both pLC1 and pLC2 contained a common 4.2-kilobase PstI fragment. Plasmids were used as templates of in vitro transcription-translation. All three plasmids had a novel protein product of ca. 75 kilodaltons not found in the vector alone. Western blots showed that this protein reacted with anti-TWAR rabbit immune sera and with human immune serum from an individual who had proven TWAR infection. Whole-cell lysates of TWAR demonstrated a protein having the same molecular weight and immunoreactivity as the recombinant gene product. This protein was also recognized by rabbit immune serum against Chlamydia psittaci or Chlamydia trachomatis. Southern hybridizations with the cloned fragment as a probe of digests of other Chlamydia spp. showed weakly hybridizing fragments. These results suggest that we have isolated a gene encoding a protein recognized during human TWAR infection that contains some sequences shared among Chlamydia spp.