Publications by authors named "Konrad Sachse"

119 Publications

Comparative Genome Analysis of 33 Strains Reveals Characteristic Features of and Closely Related Species.

Pathogens 2020 Oct 28;9(11). Epub 2020 Oct 28.

RNA Bioinformatics and High-Throughput Analysis, Friedrich-Schiller-Universität Jena, 07743 Jena, Germany.

To identify genome-based features characteristic of the avian and human pathogen and related chlamydiae, we analyzed whole-genome sequences of 33 strains belonging to 12 species. Using a novel genome analysis tool termed Roary ILP Bacterial Annotation Pipeline (RIBAP), this panel of strains was shown to share a large core genome comprising 784 genes and representing approximately 80% of individual genomes. Analyzing the most variable genomic sites, we identified a set of features of that in its entirety is characteristic of this species: (i) a relatively short plasticity zone of less than 30,000 nt without a tryptophan operon (also in ), (ii) a characteristic set of of Inc proteins comprising IncA, B, C, V, X, Y (with homologs in and as closest relatives), (iii) a 502-aa SinC protein, the largest among spp., and (iv) an elevated number of Pmp proteins of subtype G (14 in 14 in C. ibidis). In combination with future functional studies, the common and distinctive criteria revealed in this study provide important clues for understanding the complexity of host-specific behavior of individual spp.
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http://dx.doi.org/10.3390/pathogens9110899DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7694038PMC
October 2020

EpiDope: a deep neural network for linear B-cell epitope prediction.

Bioinformatics 2021 May;37(4):448-455

RNA Bioinformatics /High Throughput Analysis, Faculty of Mathematics and Computer Science.

Motivation: By binding to specific structures on antigenic proteins, the so-called epitopes, B-cell antibodies can neutralize pathogens. The identification of B-cell epitopes is of great value for the development of specific serodiagnostic assays and the optimization of medical therapy. However, identifying diagnostically or therapeutically relevant epitopes is a challenging task that usually involves extensive laboratory work. In this study, we show that the time, cost and labor-intensive process of epitope detection in the lab can be significantly reduced using in silico prediction.

Results: Here, we present EpiDope, a python tool which uses a deep neural network to detect linear B-cell epitope regions on individual protein sequences. With an area under the curve between 0.67 ± 0.07 in the receiver operating characteristic curve, EpiDope exceeds all other currently used linear B-cell epitope prediction tools. Our software is shown to reliably predict linear B-cell epitopes of a given protein sequence, thus contributing to a significant reduction of laboratory experiments and costs required for the conventional approach.

Availabilityand Implementation: EpiDope is available on GitHub (http://github.com/mcollatz/EpiDope).

Supplementary Information: Supplementary data are available at Bioinformatics online.
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http://dx.doi.org/10.1093/bioinformatics/btaa773DOI Listing
May 2021

Occurrence of in Raptors and Crows in Switzerland.

Pathogens 2020 Sep 2;9(9). Epub 2020 Sep 2.

Vetsuisse Faculty, Institute for Food Safety and Hygiene, National Reference Center for Poultry and Rabbit Diseases, University of Zurich, 8057 Zurich, Switzerland.

Bacteria of the family are globally disseminated and able to infect many bird species. So far, 11 species of have been detected in wild birds, and several studies found chlamydial strains classified as genetically intermediate between (.) and . Recently, a group of these intermediate strains was shown to form a separate species, i.e., . In the present study, 1128 samples from 341 raptors of 16 bird species and 253 corvids representing six species were examined using a stepwise diagnostic approach. DNA was detected in 23.7% of the corvids and 5.9% of the raptors. In corvids, the most frequently detected species was of outer membrane protein A () genotype 1V, which is known to have a host preference for corvids. The most frequently detected genotype in raptors was M56. Furthermore, one of the raptors harbored 1V, and two others carried genotype A. was not detected in the bird population investigated, so it remains unknown whether this species occurs in Switzerland. The infection rate of in corvids was high compared to rates reported in other wild bird species, but neither -positive corvids nor raptors showed overt signs of disease. Since the of both, raptors and crows were identified as and all genotypes are considered to be zoonotic, it can be suggested that raptors and crows pose a potential hazard to the health of their handlers.
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http://dx.doi.org/10.3390/pathogens9090724DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7558692PMC
September 2020

Development of a Plasmid Shuttle Vector System for Genetic Manipulation of Chlamydia psittaci.

mSphere 2020 08 26;5(4). Epub 2020 Aug 26.

Department of Infectious Diseases and Microbiology, University of Lübeck, Lübeck, Germany.

The obligate intracellular bacterium is a known avian pathogen causing psittacosis in birds and is capable of zoonotic transmission. In human pulmonary infections, can cause pneumonia associated with significant mortality if inadequately diagnosed and treated. Although intracellular manipulates host cell organelles for its replication and survival, it has been difficult to demonstrate host-pathogen interactions in infection due to the lack of easy-to-handle genetic manipulation tools. Here, we show the genetic transformation of using a plasmid shuttle vector that contains a controllable gene induction system. The 7,553-bp plasmid p01DC12 was prepared from the nonavian strain 01DC12. We constructed the shuttle vector pCps-Tet-mCherry using the full sequence of p01DC12 and the 4,449-bp fragment of shuttle vector pBOMB4-Tet-mCherry. pCps-Tet-mCherry includes genes encoding the green fluorescent protein (GFP), mCherry, and ampicillin resistance (AmpR). Target genes can be inserted at a multiple cloning site (MCS). Importantly, these genes can be regulated by a tetracycline-inducible (tet) promoter. Using the pCps-Tet-mCherry plasmid shuttle vector, we show the expression of GFP, as well as the induction of mCherry expression, in strain 02DC15, which belongs to the avian 6BC clade. Furthermore, we demonstrated that pCps-Tet-mCherry was stably retained in transformants. Thus, our plasmid shuttle vector system represents a novel targeted approach that enables the elucidation of host-pathogen interactions. Psittacosis, caused by avian , has a major economic impact in the poultry industry worldwide and represents a significant risk for zoonotic transmission to humans. In the past decade, the tools of genetic manipulation have been improved for chlamydial molecular studies. While several genetic tools have been mainly developed in , a stable gene-inducible shuttle vector system has not to date been available for In this study, we adapted a plasmid shuttle vector system to We constructed a plasmid backbone shuttle vector called pCps-Tet-mCherry. The construct expresses GFP in Importantly, exogeneous genes can be inserted at an MCS and are regulated by a tet promoter. The application of the pCps-Tet-mCherry shuttle vector system enables a promising new approach to investigate unknown gene functions of this pathogen.
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http://dx.doi.org/10.1128/mSphere.00787-20DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7449628PMC
August 2020

Regeneration of Pulmonary Tissue in a Calf Model of Fibrinonecrotic Bronchopneumonia Induced by Experimental Infection with .

Int J Mol Sci 2020 Apr 17;21(8). Epub 2020 Apr 17.

Institute for Molecular Pathogenesis, Friedrich-Loeffler-Institut, Federal Research Institute for Animal Health, Naumburgerstr. 96a, 07743 Jena, Germany.

Pneumonia is a cause of high morbidity and mortality in humans. Animal models are indispensable to investigate the complex cellular interactions during lung injury and repair in vivo. The time sequence of lesion development and regeneration is described after endobronchial inoculation of calves with Calves were necropsied 2-37 days after inoculation (dpi). Lesions and presence of were investigated using histology and immunohistochemistry. Calves developed bronchopneumonia at the sites of inoculation. Initially, replicated in type 1 alveolar epithelial cells followed by an influx of neutrophils, vascular leakage, fibrinous exudation, thrombosis and lobular pulmonary necrosis. Lesions were most extensive at 4 dpi. Beginning at 7 dpi, the number of chlamydial inclusions declined and proliferation of cuboidal alveolar epithelial cells and sprouting of capillaries were seen at the periphery of necrotic tissue. At 14 dpi, most of the necrosis had been replaced with alveoli lined with cuboidal epithelial cells resembling type 2 alveolar epithelial cells and mild fibrosis, and hyperplasia of organized lymphoid tissue were observed. At 37 dpi, regeneration of pulmonary tissue was nearly complete and only small foci of remodeling remained. The well-defined time course of development and regeneration of necrotizing pneumonia allows correlation of morphological findings with clinical data or treatment regimen.
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http://dx.doi.org/10.3390/ijms21082817DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7215337PMC
April 2020

The Genetic Transformation of Chlamydia pneumoniae.

mSphere 2018 10 10;3(5). Epub 2018 Oct 10.

Department of Infectious Diseases and Microbiology, University of Luebeck, Luebeck, Germany

We demonstrate the genetic transformation of using a plasmid shuttle vector system which generates stable transformants. The equine N16 isolate harbors the 7.5-kb plasmid pCpnE1. We constructed the plasmid vector pRSGFPCAT-Cpn containing a pCpnE1 backbone, plus the red-shifted green fluorescent protein (RSGFP), as well as the chloramphenicol acetyltransferase (CAT) gene used for the selection of plasmid shuttle vector-bearing transformants. Using the pRSGFPCAT-Cpn plasmid construct, expression of RSGFP in koala isolate LPCoLN was demonstrated. Furthermore, we discovered that the human cardiovascular isolate CV-6 and the human community-acquired pneumonia-associated IOL-207 could also be transformed with pRSGFPCAT-Cpn. In previous studies, it was shown that spp. cannot be transformed when the plasmid shuttle vector is constructed from a different plasmid backbone to the homologous species. Accordingly, we confirmed that pRSGFPCAT-Cpn could not cross the species barrier in plasmid-bearing and plasmid-free , , , , and However, contrary to our expectation, pRSGFPCAT-Cpn did transform Furthermore, pRSGFPCAT-Cpn did not recombine with the wild-type plasmid of Taken together, we provide for the first time an easy-to-handle transformation protocol for that results in stable transformants. In addition, the vector can cross the species barrier to , indicating the potential of horizontal pathogenic gene transfer via a plasmid. The absence of tools for the genetic manipulation of has hampered research into all aspects of its biology. In this study, we established a novel reproducible method for transformation based on a plasmid shuttle vector system. We constructed a plasmid backbone shuttle vector, pRSGFPCAT-Cpn. The construct expresses the red-shifted green fluorescent protein (RSGFP) fused to chloramphenicol acetyltransferase in transformants stably retained pRSGFPCAT-Cpn and expressed RSGFP in epithelial cells, even in the absence of chloramphenicol. The successful transformation in using pRSGFPCAT-Cpn will advance the field of chlamydial genetics and is a promising new approach to investigate gene functions in biology. In addition, we demonstrated that pRSGFPCAT-Cpn overcame the plasmid species barrier without the need for recombination with an endogenous plasmid, indicating the potential probability of horizontal chlamydial pathogenic gene transfer by plasmids between chlamydial species.
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http://dx.doi.org/10.1128/mSphere.00412-18DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6180227PMC
October 2018

Genomic evidence that the live Chlamydia abortus vaccine strain 1B is not attenuated and has the potential to cause disease.

Vaccine 2018 06;36(25):3593-3598

Infection Genomics, Wellcome Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridgeshire CB10 1SA, United Kingdom.

Background: The live, temperature-attenuated vaccine strain 1B of Chlamydia abortus, the aetiological agent of ovine enzootic abortion (OEA), has been implicated in cases of vaccine breakdown. The aim of this study was to understand the nature of this attenuation through sequencing of the vaccine parent strain (AB7) and the derived mutant strains 1B and 1H, as well as to clarify the role of the vaccine strain in causing disease through comparative whole genome analysis.

Methods: Whole genome sequencing was performed on: vaccine parent strain AB7; N-methyl-N'-nitro-N-nitrosoguanidine (NTG)-induced temperature attenuated mutant strain 1B grown from the commercial live vaccines Cevac Chlamydia and Enzovax; strain 1H a reverted NTG mutant; and 5 strains isolated from cases of OEA originating from animals from the original vaccine safety trial (2 strains) or from vaccinated ewes or ewes exposed to vaccinated animals (3 strains).

Results: We confirmed that AB7 is in a different lineage from the reference strain S26/3. The genome of vaccine strain 1B contains ten single nucleotide polymorphisms (SNPs) created by the NTG treatment, which are identical to those found in strain 1H. The strains from OEA cases also cluster phylogenetically very tightly with these vaccine strains.

Conclusions: The results show that C. abortus vaccine strain 1B has an identical genome sequence to the non-attenuated "reverted mutant" strain 1H. Thus, the protection of the 1B vaccine is unlikely to be due to the NTG induced SNPs and is more likely caused by the administration of high doses of C. abortus elementary bodies that stimulate protective immunity. Vaccine-identical strains were also isolated from cases of disease, as well as strains which had acquired 1-3 SNPs, including an animal that had not been vaccinated with either of the commercial live OEA vaccines, indicating that the 1B vaccine strain may be circulating and causing disease.
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http://dx.doi.org/10.1016/j.vaccine.2018.05.042DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6005232PMC
June 2018

A novel synthetic peptide microarray assay detects Chlamydia species-specific antibodies in animal and human sera.

Sci Rep 2018 03 16;8(1):4701. Epub 2018 Mar 16.

Alere Technologies GmbH, Jena, Germany.

Serological analysis of Chlamydia (C.) spp. infections is still mainly based on micro-immunofluorescence and ELISA. To overcome the limitations of conventional serology, we have designed a novel microarray carrying 52 synthetic peptides representing B-cell epitopes from immunodominant proteins of all 11 chlamydial species. The new assay has been validated using monospecific mouse hyperimmune sera. Subsequently, serum samples from cattle, sheep and humans with a known history of chlamydial infection were examined. For instance, the specific humoral response of sheep to treatment with a C. abortus vaccine has been visualized against a background of C. pecorum carriership. In samples from humans, dual infection with C. trachomatis and C. pneumoniae could be demonstrated. The experiments revealed that the peptide microarray assay was capable of simultaneously identifying specific antibodies to each Chlamydia spp. The actual assay represents an open platform test that can be complemented through future advances in Chlamydia proteome research. The concept of the highly parallel multi-antigen microarray proven in this study has the potential to enhance our understanding of antibody responses by defining not only a single quantitative response, but also the pattern of this response. The added value of using peptide antigens will consist in unprecedented serodiagnostic specificity.
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http://dx.doi.org/10.1038/s41598-018-23118-7DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5856796PMC
March 2018

[Detection of Chlamydia abortus in bovine reproductive losses in the province of La Pampa, Argentina].

Rev Argent Microbiol 2018 Jul - Sep;50(3):269-274. Epub 2018 Jan 17.

Cátedra de Microbiología Clínica, Departamento de Bioquímica Clínica, Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Ciudad Autónoma de Buenos Aires, Argentina. Electronic address:

Reproductive losses linked to an infectious etiology in bovine cattle are a major economic concern worldwide. In Argentina, more than 50% of abortion cases have unknown causes. Species belonging to Chlamydiaceae family are frequent etiologic agents of abortion around the world; however, there is yet no information on their prevalence in Argentina. The objective of this work was to identify Chlamydia spp., and particularly C. abortus in reproductive losses from bovine cattle in La Pampa, Argentina. Real time PCR targeting Chlamydiaceae-specific DNA fragments was performed on 251 samples obtained from bovine abortions and stillborns, and ArrayTube was used for species identification on positive samples. Chlamydiaceae DNA was detected in 12 samples of aborted fetuses (4.78%), 83.33% (10/12) accounting for abortions and 16.66% (2/12) for stillborns. C. abortus was detected by ArrayTube in 5 cases (1.99% of all samples, and 41.67% of Chlamydiaceae positive samples). This study shows the first detection of Chlamydiaceae and C. abortus DNA on reproductive losses of bovine cattle in Argentina, and the described prevalence value (4.78%) should be taken as baseline value due to the type of samples analyzed. Detection of genetic material from Chlamydiaceae not matching any of the studied species could be due to intraspecies variants or local species not yet described. Further research on Chlamydia infections in bovine cattle in Argentina is imperative to describe their range, to analyze their economic and zoonotic implications and to make recommendations about prevention and control measures.
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http://dx.doi.org/10.1016/j.ram.2017.10.002DOI Listing
February 2019

From genomes to genotypes: molecular epidemiological analysis of Chlamydia gallinacea reveals a high level of genetic diversity for this newly emerging chlamydial pathogen.

BMC Genomics 2017 Dec 6;18(1):949. Epub 2017 Dec 6.

Jiangsu Co-Innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou University College of Veterinary Medicine, Yangzhou, Jiangsu, 225009, People's Republic of China.

Background: Chlamydia (C.) gallinacea is a recently identified bacterium that mainly infects domestic chickens. Demonstration of C. gallinacea in human atypical pneumonia suggests its zoonotic potential. Its prevalence in chickens exceeds that of C. psittaci, but genetic and genomic research on C. gallinacea is still at the beginning. In this study, we conducted whole-genome sequencing of C. gallinacea strain JX-1 isolated from an asymptomatic chicken, and comparative genomic analysis between C. gallinacea strains and related chlamydial species.

Results: The genome of C. gallinacea JX-1 was sequenced by single-molecule, real-time technology and is comprised of a 1,059,522-bp circular chromosome with an overall G + C content of 37.93% and sequence similarity of 99.4% to type strain 08-1274/3. In addition, a plasmid designated pJX-1, almost identical to p1274 of the type strain, except for two point mutations, was only found in field strains from chicken, but not in other hosts. In contrast to chlamydial species with notably variable polymorphic membrane protein (pmp) genes and plasticity zone (PZ), these regions were conserved in both C. gallinacea strains. There were 15 predicted pmp genes, but only B, A, E1, H, G1 and G2 were apparently intact in both strains. In comparison to chlamydial species where the PZ may be up to 50 kbp, C. gallinacea strains displayed gene content reduction in the PZ (14 kbp), with strain JX-1 having a premature STOP codon in the cytotoxin (tox) gene, while tox gene is intact in the type strain. In multilocus sequence typing (MLST), 15 C. gallinacea STs were identified among 25 strains based on cognate MLST allelic profiles of the concatenated sequences. The type strain and all Chinese strains belong to two distinct phylogenetic clades. Clade of the Chinese strains separated into 14 genetically distinct lineages, thus revealing considerable genetic diversity of C. gallinacea strains in China.

Conclusions: In this first detailed comparative genomic analysis of C. gallinacea, we have provided evidence for substantial genetic diversity among C. gallinacea strains. How these genetic polymorphisms affect C. gallinacea biology and pathogenicity should be addressed in future studies that focus on phylogenetics and host adaption of this enigmatic bacterial agent.
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http://dx.doi.org/10.1186/s12864-017-4343-9DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5717833PMC
December 2017

A Novel Pan- Detection and Identification Assay Based on RT-qPCR and Microarray.

Biomed Res Int 2017 24;2017:4248756. Epub 2017 May 24.

Institute for Novel and Emerging Infectious Diseases, Friedrich-Loeffler-Institut (Federal Research Institute for Animal Health), Insel Riems, Greifswald, Germany.

The genus includes arthropod-borne viruses responsible for a large number of infections in humans and economically important animals. While RT-PCR protocols for specific detection of most species are available, there has been also a demand for a broad-range assay covering all members of the genus. It is particularly challenging to balance specificity at genus level with equal sensitivity towards each target species. In the present study, a novel assay combining a SYBR Green-based RT-qPCR with a low-density DNA microarray has been developed. Validation experiments confirmed that the RT-qPCR exhibited roughly equal sensitivity of detection and quantification for all flaviviruses tested. These PCR products are subjected to hybridization on a microarray carrying 84 different oligonucleotide probes that represent all known species. This assay has been used as a screening and confirmation tool for presence in laboratory and field samples, and it performed successfully in international External Quality Assessment of NAT studies. Twenty-six strains were tested with the assay, showing equivalent or superior characteristics compared with the original or even with species-specific RT-PCRs. As an example, test results on West Nile virus detection in a panel of 340 mosquito pool samples from Greece are presented.
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http://dx.doi.org/10.1155/2017/4248756DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5463098PMC
March 2018

Comprehensive global genome dynamics of show ancient diversification followed by contemporary mixing and recent lineage expansion.

Genome Res 2017 07 6;27(7):1220-1229. Epub 2017 Jun 6.

Clinical Research Department, Faculty of Infectious and Tropical Diseases, London School of Hygiene & Tropical Medicine, London WC1E 7HT, United Kingdom.

is the world's most prevalent bacterial sexually transmitted infection and leading infectious cause of blindness, yet it is one of the least understood human pathogens, in part due to the difficulties of in vitro culturing and the lack of available tools for genetic manipulation. Genome sequencing has reinvigorated this field, shedding light on the contemporary history of this pathogen. Here, we analyze 563 full genomes, 455 of which are novel, to show that the history of the species comprises two phases, and conclude that the currently circulating lineages are the result of evolution in different genomic ecotypes. Temporal analysis indicates these lineages have recently expanded in the space of thousands of years, rather than the millions of years as previously thought, a finding that dramatically changes our understanding of this pathogen's history. Finally, at a time when almost every pathogen is becoming increasingly resistant to antimicrobials, we show that there is no evidence of circulating genomic resistance in .
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http://dx.doi.org/10.1101/gr.212647.116DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5495073PMC
July 2017

Chlamydia pecorum is the endemic intestinal species in cattle while C. gallinacea, C. psittaci and C. pneumoniae associate with sporadic systemic infection.

Vet Microbiol 2016 Sep 13;193:93-9. Epub 2016 Aug 13.

Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou University College of Veterinary Medicine, Yangzhou, Jiangsu, 225009, PR China; College of Veterinary Medicine, Auburn University, Auburn, AL, USA. Electronic address:

To investigate the prevalence and diversity of bovine Chlamydia spp. in cattle, whole blood from dairy and beef cattle in 11 provinces of China (n=2003) and vaginal swabs, whole blood samples, feces, milk samples from cows in a Yangzhou dairy farm (n=108) were examined using genus- and species-specific PCRs. In cattle from 11 provinces, 2.4% (48/2003) of whole-blood samples were positive for Chlamydia spp., and four Chlamydia species (C. pneumoniae, 41.7%, 20/48; C. psittaci, 22.9%, 11/48; C. gallinacea, 20.8%, 10/48; C. pecorum, 6.3%, 3/48) were identified. In a further study on a Yangzhou dairy farm, 64.8% (70/108) of the cows were positive for Chlamydia spp. C. pecorum was the intestinal endemic species (51/51, 100%), and C. gallinacea was the most frequent species in vaginal swabs (24/27, 88.9%), whole blood buffy coats (5/8, 62.5%) and milk (4/6, 66.7%). C. psittaci and C. pneumoniae were infrequently detected. DNA sequencing of the ompA gene demonstrated the presence of multiple in-herd C. pecorum serovars and single C. gallinacea and C. psittaci serovars which were identical with those of poultry from Yangzhou. This is the first report of C. gallinacea and C. pneumoniae in cattle. Further study is required to address the transmission of Chlamydia spp., in particular of C. gallinacea and C. pneumoniae from their natural hosts, and their potential pathogenic effect on health and production of cattle.
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http://dx.doi.org/10.1016/j.vetmic.2016.08.008DOI Listing
September 2016

Whole-Genome Sequence of Chlamydia gallinacea Type Strain 08-1274/3.

Genome Announc 2016 Jul 21;4(4). Epub 2016 Jul 21.

RNA Bioinformatics and High-Throughput Analysis, Faculty of Mathematics and Computer Science, Friedrich-Schiller-Universität, Jena, Germany Institute of Molecular Pathogenesis, Friedrich-Loeffler-Institut (Federal Research Institute for Animal Health), Jena, Germany

The recently introduced bacterial species Chlamydia gallinacea is known to occur in domestic poultry and other birds. Its potential as an avian pathogen and zoonotic agent is under investigation. The whole-genome sequence of its type strain, 08-1274/3, consists of a 1,059,583-bp chromosome with 914 protein-coding sequences (CDSs) and a plasmid (p1274) comprising 7,619 bp with 9 CDSs.
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http://dx.doi.org/10.1128/genomeA.00708-16DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4956461PMC
July 2016

Comparison of multilocus sequence typing and multilocus typing microarray of Chlamydia trachomatis strains from Argentina and Chile.

J Microbiol Methods 2016 08 7;127:214-218. Epub 2016 Jun 7.

Section of Clinical Bacteriology, Department of Medical Sciences, Uppsala University, S-751 85 Uppsala, Sweden. Electronic address:

This study compared conventional ompA genotyping of Chlamydia trachomatis with multilocus sequence typing (MLST) and multilocus typing (MLT) DNA microarray. DNA extracts of 104 C. trachomatis positive specimens were analyzed by ompA sequencing and MLST and of these 76 by MLT array. Obtained MLST sequence types (STs) were compared to sequences in the database http://mlstdb.uu.se. The resolution obtained for MLST (35 STs) was 2.1 higher than for ompA sequencing (17 variants) and 1.3 higher than MLT array (27 MLT groups). Among the 104 samples the predominant genotype E could be divided into 5 ompA variants and 23 STs of which 16 had not been reported in previous studies. The most common STs, ST3 and ST56, were identified as founders and are common in several countries on a global scale. The MLST and the MLT array provided similar strain discrimination capacity and showed considerably higher resolution than conventional ompA sequencing.
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http://dx.doi.org/10.1016/j.mimet.2016.06.005DOI Listing
August 2016

Analysis of Humoral Immune Responses to Surface and Virulence-Associated Chlamydia abortus Proteins in Ovine and Human Abortions by Use of a Newly Developed Line Immunoassay.

J Clin Microbiol 2016 07 18;54(7):1883-1890. Epub 2016 May 18.

Institute of Medical Microbiology and Hygiene, University Hospital of Ulm, Ulm, Germany.

The obligate intracellular bacterium Chlamydia abortus is the causative agent of enzootic abortion of ewes and poses a significant zoonotic risk for pregnant women. Using proteomic analysis and gene expression library screening in a previous project, we identified potential virulence factors and candidates for serodiagnosis, of which nine were scrutinized here with a strip immunoassay. We have shown that aborting sheep exhibited a strong antibody response to surface (MOMP, MIP, Pmp13G) and virulence-associated (CPAF, TARP, SINC) antigens. While the latter disappeared within 18 weeks following abortion in a majority of the animals, antibodies to surface proteins persisted beyond the duration of the study. In contrast, nonaborting experimentally infected sheep developed mainly antibodies to surface antigens (MOMP, MIP, Pmp13G), all of which did not persist. We were also able to detect antibodies to these surface antigens in C abortus-infected women who had undergone septic abortion, whereas a group of shepherds and veterinarians with occupational exposure to C abortus-infected sheep revealed only sporadic immune responses to the antigens selected. The most specific antigen for the serodiagnosis of human C abortus infections was Pmp13G, which showed no cross-reactivity with other chlamydiae infecting humans. We suggest that Pmp13G-based serodiagnosis accomplished by the detection of antibodies to virulence-associated antigens such as CPAF, TARP, and SINC may improve the laboratory diagnosis of human and animal C abortus infections.
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http://dx.doi.org/10.1128/JCM.00351-16DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4922118PMC
July 2016

Inadequate Reference Datasets Biased toward Short Non-epitopes Confound B-cell Epitope Prediction.

J Biol Chem 2016 Jul 9;291(28):14585-99. Epub 2016 May 9.

From the Department of Pathobiology, Auburn University, Auburn, Alabama 36849 and

X-ray crystallography has shown that an antibody paratope typically binds 15-22 amino acids (aa) of an epitope, of which 2-5 randomly distributed amino acids contribute most of the binding energy. In contrast, researchers typically choose for B-cell epitope mapping short peptide antigens in antibody binding assays. Furthermore, short 6-11-aa epitopes, and in particular non-epitopes, are over-represented in published B-cell epitope datasets that are commonly used for development of B-cell epitope prediction approaches from protein antigen sequences. We hypothesized that such suboptimal length peptides result in weak antibody binding and cause false-negative results. We tested the influence of peptide antigen length on antibody binding by analyzing data on more than 900 peptides used for B-cell epitope mapping of immunodominant proteins of Chlamydia spp. We demonstrate that short 7-12-aa peptides of B-cell epitopes bind antibodies poorly; thus, epitope mapping with short peptide antigens falsely classifies many B-cell epitopes as non-epitopes. We also show in published datasets of confirmed epitopes and non-epitopes a direct correlation between length of peptide antigens and antibody binding. Elimination of short, ≤11-aa epitope/non-epitope sequences improved datasets for evaluation of in silico B-cell epitope prediction. Achieving up to 86% accuracy, protein disorder tendency is the best indicator of B-cell epitope regions for chlamydial and published datasets. For B-cell epitope prediction, the most effective approach is plotting disorder of protein sequences with the IUPred-L scale, followed by antibody reactivity testing of 16-30-aa peptides from peak regions. This strategy overcomes the well known inaccuracy of in silico B-cell epitope prediction from primary protein sequences.
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http://dx.doi.org/10.1074/jbc.M116.729020DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4938180PMC
July 2016

Oral Uptake of Chlamydia psittaci by Ducklings Results in Systemic Dissemination.

PLoS One 2016 11;11(5):e0154860. Epub 2016 May 11.

ANSES, Animal Health Laboratory, Bacterial Zoonoses Unit, Maisons-Alfort, France.

Enteric infections caused by Chlamydia (C.) psittaci are frequent in ducks, but mostly remain subclinical under field conditions. To emulate natural infection, we investigated the pathogenic potential of a C. psittaci field strain in orally inoculated 4-day-old ducklings. Three different challenge doses were tested and seven contact animals were also mock-inoculated with buffer in each group. Over the course of ten days, the birds were monitored for clinical symptoms and chlamydial dissemination before final examination of tissues using histopathology and immunohistochemistry. While the challenge strain disseminated systemically to all internal organs, mild signs of diarrhea were confined to ducklings inoculated with the highest dose (4.3 x 108 IFU/mL, Group 1). No other clinical symptoms or histopathological lesions were seen. The chlamydial load in internal organs as measured by PCR depended on the challenge dose and was unevenly distributed, i.e. high loads in spleen, liver, and distal small and large intestinal tract (ileum, cecum and rectum) vs. ten times lower values in lungs and proximal small intestinal tract (duodenum and jejunum). Notably, the C. psittaci infection of contact birds became evident on day 10 post-infection, with bacterial loads comparable to those of experimentally-infected animals, thus suggesting rapid bird-to-bird transmission of the challenge strain.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0154860PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4864072PMC
July 2017

High Frequency of Chlamydia trachomatis Mixed Infections Detected by Microarray Assay in South American Samples.

PLoS One 2016 15;11(4):e0153511. Epub 2016 Apr 15.

Universidad de Buenos Aires. Cátedra de Microbiología Clínica, Facultad de Farmacia y Bioquímica, Buenos Aires, Argentina.

Chlamydia trachomatis is one of the most common sexually transmitted infections worldwide. Based on sequence variation in the ompA gene encoding the major outer membrane protein, the genotyping scheme distinguishes 17 recognized genotypes, i.e. A, B, Ba, C, D, Da, E, F, G, H, I, Ia, J, K, L1, L2, and L3. Genotyping is an important tool for epidemiological tracking of C. trachomatis infections, including the revelation of transmission pathways and association with tissue tropism and pathogenicity. Moreover, genotyping can be useful for clinicians to establish the correct treatment when LGV strains are detected. Recently a microarray assay was described that offers several advantages, such as rapidity, ease of standardization and detection of mixed infections. The aim of this study was to evaluate the performance of the DNA microarray-based assay for C. trachomatis genotyping of clinical samples already typed by PCR-RFLP from South America. The agreement between both typing techniques was 90.05% and the overall genotype distribution obtained with both techniques was similar. Detection of mixed-genotype infections was significantly higher using the microarray assay (8.4% of cases) compared to PCR-RFLP (0.5%). Among 178 samples, the microarray assay identified 10 ompA genotypes, i.e. D, Da, E, F, G, H, I, J, K and L2. The most predominant type was genotype E, followed by D and F.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0153511PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4833370PMC
August 2016

Detection of atypical Chlamydiaceae in roe deer (Capreolus capreolus).

Vet Microbiol 2015 Dec 7;181(3-4):318-22. Epub 2015 Nov 7.

University Paris-Est, Anses, Animal Health Laboratory, Bacterial Zoonoses Unit, Maisons-Alfort, France. Electronic address:

Investigations on fecal samples, vaginal swabs and sera from roe deer (Capreolus capreolus) in south-western France led to the detection of a non-classified Chlamydiaceae strain. A total of 85 vaginal swabs were sampled from roe deer that had been captured in 2012 (n=42) and 2013 (n=43). Using a Chlamydiaceae family-specific real-time PCR, only one vaginal swab out of the 42 samples done in 2012 tested positive and was subsequently identified as Chlamydia (C.) psittaci. In contrast, 6/43 vaginal swab samples were positive in 2013. Four of these positive samples came from a single group of roe deer, captured in the Fabas plain. Fecal samples from this group of 9 females were subsequently analyzed, with 6 of them testing positive with the Chlamydiaceae-specific PCR. All positive samples collected in 2013 were negative when re-tested with C. abortus-, C. pecorum- and C. suis-specific real-time PCR assays. Sera from this group of 9 females were analyzed with two immunoassays (recomLine and ELISA). Whereas intense positive reactions with C. pneumoniae antigens were observed for all sera when tested with the recomLine test, none was positive with the C. abortus specific ELISA test. Comparative sequence analysis of the 16S, 23S rRNA and ompA gene sequences from 3 animals, as well as the MLST analysis from 2 animals, showed that this roe deer group likely harbored the same bacterium related to members of the family Chlamydiaceae. Notably, the roe deer strain formed a separate entity different from the currently recognized chlamydial species, with C. trachomatis, C. suis and C. muridarum appearing as its closest relatives.
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http://dx.doi.org/10.1016/j.vetmic.2015.10.018DOI Listing
December 2015

Kinetics of Local and Systemic Leucocyte and Cytokine Reaction of Calves to Intrabronchial Infection with Chlamydia psittaci.

PLoS One 2015 7;10(8):e0135161. Epub 2015 Aug 7.

Institute of Molecular Pathogenesis at 'Friedrich-Loeffler-Institut' (Federal Research Institute for Animal Health), Jena, Germany.

Infection of cattle with chlamydiae is ubiquitous and, even in the absence of clinical sequeleae, has a quantifiable negative impact on livestock productivity. Despite recent progress, our knowledge about immune response mechanisms capable of counteracting the infection and preventing its detrimental effects is still limited. A well-established model of bovine acute respiratory Chlamydia (C.) psittaci infection was used here to characterize the kinetics of the local and systemic immune reactions in calves. In the course of two weeks following inoculation, leukocyte surface marker expression was monitored by flow cytometry in blood and bronchoalveolar lavage fluid (BALF). Immune-related protein and receptor transcription were determined by quantitative real-time reverse transcription PCR in blood, BALF and lung tissue. An early increase of IL2RA, IL10 and HSPA1A mRNA expressions was followed by a rise of lymphocytes, monocytes, and granulocytes exhibiting activated phenotypes in blood. Monocytes showed elevated expression rates of CD11b, CD14 and MHC class II. The rates of CD62L expression on CD8hi T cells in blood and on CD4+ T cells in BALF were also augmented and peaked between 2 and 4 dpi. Notably, CD25 antigen expression was significantly elevated, not only on CD8dim/CD62L+ and CD8-/CD62L+ cells in blood, but also on granulocytes in blood and BALF between 2-3 dpi. From 4 dpi onwards, changes declined and the calves recovered from the infection until 10 dpi. The findings highlight the effectiveness of rapid local and systemic immune reaction and indicate activated T cells, monocytes and granulocytes being essential for rapid eradication of the C. psittaci infection.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0135161PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4529195PMC
May 2016

Draft Genome Sequence of the First Human Isolate of the Ruminant Pathogen Mycoplasma capricolum subsp. capricolum.

Genome Announc 2015 Jun 18;3(3). Epub 2015 Jun 18.

Centre for GeoGenetics, Natural History Museum of Denmark, University of Copenhagen, Copenhagen, Denmark.

Mycoplasma capricolum subsp. capricolum is a well-known pathogen of small ruminants. A recent human case of septicemia involving this agent raised the question of its potential pathogenicity to humans. We present the first draft genome sequence of a human Mycoplasma capricolum subsp. capricolum isolate.
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http://dx.doi.org/10.1128/genomeA.00583-15DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4472885PMC
June 2015

Diversification and Distribution of Ruminant Chlamydia abortus Clones Assessed by MLST and MLVA.

PLoS One 2015 22;10(5):e0126433. Epub 2015 May 22.

Anses, Animal Health Laboratory, Bacterial Zoonoses Unit, University Paris-Est, Maisons-Alfort, France.

Chlamydia abortus, an obligate intracellular bacterium, is the most common infectious cause of abortion in small ruminants worldwide and has zoonotic potential. We applied multilocus sequence typing (MLST) together with multiple-locus variable-number tandem repeat analysis (MLVA) to genotype 94 ruminant C. abortus strains, field isolates and samples collected from 1950 to 2011 in diverse geographic locations, with the aim of delineating C. abortus lineages and clones. MLST revealed the previously identified sequence types (STs) ST19, ST25, ST29 and ST30, plus ST86, a recently-assigned type on the Chlamydiales MLST website and ST87, a novel type harbouring the hemN_21 allele, whereas MLVA recognized seven types (MT1 to MT7). Minimum-spanning-tree analysis suggested that all STs but one (ST30) belonged to a single clonal complex, possibly reflecting the short evolutionary timescale over which the predicted ancestor (ST19) has diversified into three single-locus variants (ST86, ST87 and ST29) and further, through ST86 diversification, into one double-locus variant (ST25). ST descendants have probably arisen through a point mutation evolution mode. Interestingly, MLVA showed that in the ST19 population there was a greater genetic diversity than in other STs, most of which exhibited the same MT over time and geographical distribution. However, the evolutionary pathways of C. abortus STs seem to be diverse across geographic distances with individual STs restricted to particular geographic locations. The ST30 singleton clone displaying geographic specificity and represented by the Greek strains LLG and POS was effectively distinguished from the clonal complex lineage, supporting the notion that possibly two separate host adaptations and hence independent bottlenecks of C. abortus have occurred through time. The combination of MLST and MLVA assays provides an additional level of C. abortus discrimination and may prove useful for the investigation and surveillance of emergent C. abortus clonal populations.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0126433PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4441495PMC
April 2016

Two more species of Chlamydia-does it make a difference?

Pathog Dis 2015 Feb 4;73(1):1-3. Epub 2014 Dec 4.

University Paris-Est, Anses, Animal Health Laboratory, Bacterial Zoonoses Unit 23, avenue du général de Gaulle, 94706 Maisons-Alfort, France.

The recent description of Chlamydia (C.) avium and C. gallinacea as new species of the reunited genus Chlamydia can be expected to have implications on the perception of avian chlamydiosis. We discuss possible effects on epidemiology, diagnosis and our understanding of aetiopathogenesis resulting from this discovery.
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http://dx.doi.org/10.1093/femspd/ftu008DOI Listing
February 2015

Chlamydia psittaci: update on an underestimated zoonotic agent.

Pathog Dis 2015 Feb 4;73(1):1-15. Epub 2014 Dec 4.

Institute of Molecular Pathogenesis, Friedrich-Loeffler-Institut, 07743 Jena, Germany

Chlamydia (C.) psittaci is an economically relevant pathogen in poultry and pet birds, where it causes psittacosis/ornithosis, and also a human pathogen causing atypical pneumonia after zoonotic transmission. Despite its well-documented prevalence, the agent has received less attention by researchers than other Chlamydia spp. in the last decades. In the present paper, we review recently published data on C. psittaci infection and attempt to single out characteristic features distinguishing it from related chlamydial agents. It is remarkable that C. psittaci is particularly efficient in disseminating in the host organism causing systemic disease, which occasionally can take a fulminant course. At the cellular level, the pathogen's broad host cell spectrum (from epithelial cells to macrophages), its rapid entry and fast replication, proficient use of intracellular transport routes to mitochondria and the Golgi apparatus, the pronounced physical association of chlamydial inclusions with energy-providing cell compartments, as well as the subversive regulation of host cell survival during productive and persistent states facilitate the characteristic efficient growth and successful host-to-host spread of C. psittaci. At the molecular level, the pathogen was shown to upregulate essential chlamydial genes when facing the host immune response. We hypothesize that this capacity, in concert with expression of specific effectors of the type III secretion system and efficient suppression of selected host defense signals, contributes to successful establishment of the infection in the host. Concerning the immunology of host-pathogen interactions, C. psittaci has been shown to distinguish itself by coping more efficiently than other chlamydiae with pro-inflammatory mediators during early host response, which can, to some extent, explain the effective evasion and adaptation strategies of this bacterium. We conclude that thorough analysis of the large number of whole-genome sequences already available will be essential to identify genetic markers of the species-specific features and trigger more in-depth studies in cellular and animal models to address such vital topics as treatment and vaccination.
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http://dx.doi.org/10.1093/femspd/ftu007DOI Listing
February 2015

Enrofloxacin and macrolides alone or in combination with rifampicin as antimicrobial treatment in a bovine model of acute Chlamydia psittaci infection.

PLoS One 2015 13;10(3):e0119736. Epub 2015 Mar 13.

Institute of Molecular Pathogenesis at Friedrich-Loeffler-Institut (Federal Research Institute for Animal Health), Naumburger Str. 96a, 07743 Jena, Germany.

Chlamydia psittaci is a zoonotic bacterium with a wide host range that can cause respiratory disease in humans and cattle. In the present study, effects of treatment with macrolides and quinolones applied alone or in combination with rifampicin were tested in a previously established bovine model of respiratory C. psittaci infection. Fifty animals were inoculated intrabronchially at the age of 6-8 weeks. Seven served as untreated controls, the others were assigned to seven treatment groups: (i) rifampicin, (ii) enrofloxacin, (iii) enrofloxacin + rifampicin, (iv) azithromycin, (v) azithromycin + rifampicin, (vi) erythromycin, and (vii) erythromycin + rifampicin. Treatment started 30 hours after inoculation and continued until 14 days after inoculation (dpi), when all animals were necropsied. The infection was successful in all animals and sufficient antibiotic levels were detected in blood plasma and tissue of the treated animals. Reisolation of the pathogen was achieved more often from untreated animals than from other groups. Nevertheless, pathogen detection by PCR was possible to the same extent in all animals and there were no significant differences between treated and untreated animals in terms of local (i.e., cell count and differentiation of BALF-cells) and systemic inflammation (i.e. white blood cells and concentration of acute phase protein LBP), clinical signs, and pathological findings at necropsy. Regardless of the reduced reisolation rate in treated animals, the treatment of experimentally induced respiratory C. psittaci infection with enrofloxacin, azithromycin or erythromycin alone or in combination with rifampicin was without obvious benefit for the host, since no significant differences in clinical and pathological findings or inflammatory parameters were detected and all animals recovered clinically within two weeks.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0119736PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4358964PMC
January 2016

Defining species-specific immunodominant B cell epitopes for molecular serology of Chlamydia species.

Clin Vaccine Immunol 2015 May 11;22(5):539-52. Epub 2015 Mar 11.

Department of Pathobiology, Auburn University, Auburn, Alabama, USA

Urgently needed species-specific enzyme-linked immunosorbent assays (ELISAs) for the detection of antibodies against Chlamydia spp. have been elusive due to high cross-reactivity of chlamydial antigens. To identify Chlamydia species-specific B cell epitopes for such assays, we ranked the potential epitopes of immunodominant chlamydial proteins that are polymorphic among all Chlamydia species. High-scoring peptides were synthesized with N-terminal biotin, followed by a serine-glycine-serine-glycine spacer, immobilized onto streptavidin-coated microtiter plates, and tested with mono-specific mouse hyperimmune sera against each Chlamydia species in chemiluminescent ELISAs. For each of nine Chlamydia species, three to nine dominant polymorphic B cell epitope regions were identified on OmpA, CT618, PmpD, IncA, CT529, CT442, IncG, Omp2, TarP, and IncE proteins. Peptides corresponding to 16- to 40-amino-acid species-specific sequences of these epitopes reacted highly and with absolute specificity with homologous, but not heterologous, Chlamydia monospecies-specific sera. Host-independent reactivity of such epitopes was confirmed by testing of six C. pecorum-specific peptides from five proteins with C. pecorum-reactive sera from cattle, the natural host of C. pecorum. The probability of cross-reactivity of peptide antigens from closely related chlamydial species or strains correlated with percent sequence identity and declined to zero at <50% sequence identity. Thus, phylograms of B cell epitope regions predict the specificity of peptide antigens for rational use in the genus-, species-, or serovar-specific molecular serology of Chlamydia spp. We anticipate that these peptide antigens will improve chlamydial serology by providing easily accessible assays to nonspecialist laboratories. Our approach also lends itself to the identification of relevant epitopes of other microbial pathogens.
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http://dx.doi.org/10.1128/CVI.00102-15DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4412952PMC
May 2015

Mycoplasma pneumoniae and Chlamydia spp. infection in community-acquired pneumonia, Germany, 2011-2012.

Emerg Infect Dis 2015 Mar;21(3):426-34

Mycoplasma pneumoniae and Chlamydia spp., which are associated with community-acquired pneumonia (CAP), are difficult to propagate, and can cause clinically indistinguishable disease patterns. During 2011-2012, we used molecular methods to test adult patients in Germany with confirmed CAP for infection with these 2 pathogens. Overall, 12.3% (96/783) of samples were positive for M. pneumoniae and 3.9% (31/794) were positive for Chlamydia spp.; C. psittaci (2.1%) was detected more frequently than C. pneumoniae (1.4%). M. pneumoniae P1 type 1 predominated, and levels of macrolide resistance were low (3.1%). Quarterly rates of M. pneumoniae-positive samples ranged from 1.5% to 27.3%, showing a strong epidemic peak for these infections, but of Chlamydia spp. detection was consistent throughout the year. M. pneumoniae-positive patients were younger and more frequently female, had fewer co-occurring conditions, and experienced milder disease than did patients who tested negative. Clinicians should be aware of the epidemiology of these pathogens in CAP.
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http://dx.doi.org/10.3201/eid2103.140927DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4344269PMC
March 2015

Host preference and zoonotic potential of Chlamydia psittaci and C. gallinacea in poultry.

Pathog Dis 2015 Feb 6;73(1):1-11. Epub 2015 Feb 6.

Paris-Est University, Anses, Animal Health Laboratory, Bacterial Zoonoses Unit, 94701 Maisons-Alfort, France

Chlamydia psittaci and C. gallinacea are obligate intracellular bacteria infecting poultry. We conducted a survey in two poultry slaughterhouses that were processing either exclusively ducks (A) or various poultry species except ducks (B). Cloacal swabs were collected from all incoming poultry flocks in the course of a week, and blood samples and pharyngeal swabs were taken from workers. Swabs were examined using PCR and sera were analyzed with two immunoassays. PCR testing revealed the presence of C. psittaci in 9/38 duck flocks and the complete absence of C. gallinacea in these flocks (slaughterhouse A), whereas 16/33 Chlamydiaceae-positive poultry flocks handled in slaughterhouse B harbored C. gallinacea only. In an episode of psittacosis in slaughterhouse A, where one PCR-positive worker presented clinical signs, seroconversions were detected in 10 workers. In contrast, serological responses of slaughterhouse B workers to C. psittaci were generally low. This is in line with the almost complete absence of C. psittaci in handled flocks, where in additional sampling campaigns the agent was detected only once in the course of a year. Our study indicates that C. psittaci has a certain preference for ducks, whereas C. gallinacea was the predominant chlamydial agent in chickens and guinea fowl flocks.
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http://dx.doi.org/10.1093/femspd/ftv005DOI Listing
February 2015

Host-pathogen interactions in specific pathogen-free chickens following aerogenous infection with Chlamydia psittaci and Chlamydia abortus.

Vet Immunol Immunopathol 2015 Mar 10;164(1-2):30-9. Epub 2015 Jan 10.

Department of Molecular Biotechnology and Immunology, Ghent University, Belgium.

Although Chlamydia (C.) psittaci infections are recognized as an important factor causing economic losses and impairing animal welfare in poultry production, the specific mechanisms leading to severe clinical outcomes are poorly understood. In the present study, we comparatively investigated pathology and host immune response, as well as systemic dissemination and expression of essential chlamydial genes in the course of experimental aerogeneous infection with C. psittaci and the closely related C. abortus, respectively, in specific pathogen-free chicks. Clinical signs appeared sooner and were more severe in the C. psittaci-infected group. Compared to C. abortus infection, more intense systemic dissemination of C. psittaci correlated with higher and faster infiltration of immune cells, as well as more macroscopic lesions and epithelial pathology, such as hyperplasia and erosion. In thoracic air sac tissue, mRNA expression of immunologically relevant factors, such as IFN-γ, IL-1β, IL-6, IL-17, IL-22, LITAF and iNOS was significantly stronger up-regulated in C. psittaci- than in C. abortus-infected birds between 3 and 14 days post-infection. Likewise, transcription rates of the chlamydial genes groEL, cpaf and ftsW were consistently higher in C. psittaci during the acute phase. These findings illustrate that the stronger replication of C. psittaci in its natural host also evoked a more intense immune response than in the case of C. abortus infection.
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http://dx.doi.org/10.1016/j.vetimm.2014.12.014DOI Listing
March 2015