Phylogenetic analyses of Chlamydia psittaci strains from birds based on 16S rRNA gene sequence

The nucleotide sequences of 16S ribosomal DNA (rDNA) were determined for 39 strains of Chlamydia psittaci (34 from birds and 5 from mammals) and for 4 Chlamydia pecorum strains. The sequences were compared phylogenetically with the gene sequences of nine Chlamydia strains (covering four species of the genus) retrieved from nucleotide databases. In the neighbor-joining tree, C. psittaci strains were more closely related to each other than to the other Chlamydia species, although a feline pneumonitis strain was distinct (983 to 98.6% similarity to other strains) and appeared to form the deepest subline within the species of C. psittaci (bootstrap value, 99%). The other strains of C. psittaci exhibiting similarity values of more than 99% were branched into several subgroups. Two pigeon strains and one turkey strain formed a distinct clade recovered in 97% of the bootstrapped trees. The other pigeon strains seemed to be distinct from the strains from psittacine birds, with 88% of bootstrap value. In the cluster of psittacine strains, three parakeet strains and an ovine abortion strain exhibited a specific association (level of sequence similarity, 99.9% or more; bootstrap value, 95%). These suggest that at least four groups of strains exist within the species C. psittaci. The 16S rDNA sequence is a valuable phylogenetic marker for the taxonomy of chlamydiae, and its analysis is a reliable tool for identification of the organisms.

Chlamydiae in porcine abortion

Formalin-fixed, paraffin-embedded fetal livers and lungs from 139 cases of swine abortion were investigated retrospectively for chlamydiae by means of immunohistochemistry. Using a genus-specific antibody, chlamydial antigen was found in eight livers obtained from five (3.6%) abortion cases from different herds. All lung sections were negative. Chlamydiae were also labeled in five of the eight positive livers using a monoclonal antibody against immunotype 1 of Chlamydia psittaci; the remaining three livers were negative. No reactivity was seen using an antibody specific for C. trachomatis. Chlamydiae should be considered a cause of abortion in sows in Switzerland. Porcine abortigenic strains identified in this study differed immunologically from intestinal strains (known to be mainly C. trachomatis) but shared similarities with abortigenic chlamydiae of ruminants.

Chlamydiosis in a fishing cat (Felis viverrina)

A fishing cat (Felis viverrina) died overnight, within 12 hr of peracute onset of depression, slight tremors, pallor, and icterus. Necropsy showed widespread hemorrhage and hematomata in the heart, stomach, and kidneys. The lungs were hyperemic and edematous. The liver was swollen and yellowish green. The spleen was very large and hyperemic. Histologic changes consisted of pneumonia, hepatic necrosis, and renal hemorrhage with glomerular fibrin clots. Chlamydia antigen was detected in liver and kidney using a direct immunofluorescence assay, and Chlamydia were cultured.

Polymerase chain reaction (PCR) detection of porcine Chlamydia trachomatis and ruminant Chlamydia psittaci serovar 1 DNA in formalin-fixed intestinal specimens from swine

In previous studies chlamydiae were detected immunohistologically in the gut of 66 out of 311 pigs. The aim of the present investigation was the classification of these intestinal porcine chlamydiae. For the study, DNA extracted from 52 paraffin-embedded intestinal tissues was amplified in nested polymerase chain reactions (PCRs) with Chlamydia omp1 genus- and species-specific primers. Some of the amplification products were cloned and sequenced. In 45 cases DNA could be amplified with genus-specific primers. Species-specific PCR and sequencing showed that in 42 cases the chlamydial omp1 genotype was Chlamydia trachomatis. Sequenced DNA fragments were 95-99% identical with the porcine strain S45. In three further cases sequencing analysis provided DNA sequences which were 100% identical with Chlamydia psittaci B577 (serovar 1) omp1 genotype. So far as the authors are aware this is the first report on the occurrence of C. psittaci serovar 1 in pigs.

In vitro and in vivo antichlamydial activities of HSR-903, a new fluoroquinolone antibiotic

The in vitro and in vivo antichlamydial activities of HSR-903 were investigated. The MICs of HSR-903 for different species of chlamydia were 0.016 to 0.063 microg/ml, which were superior to those of conventional fluoroquinolones. The therapeutic effect of HSR-903 in experimental mouse Chlamydia psittaci pneumonia was also excellent and almost equal to that of minocycline and superior to that of ofloxacin. These results indicate that HSR-903 may be useful in the treatment of respiratory infections caused by chlamydiae.

Comparison of Chlamydia psittaci from cats with upper respiratory tract disease by polymerase chain reaction analysis of the ompA gene

Conjunctival swabs were taken from 168 cats with clinical signs of acute or chronic upper respiratory tract disease and tested for Chlamydia psittaci by the polymerase chain reaction (PCR) to amplify the ompA gene coding region. Twenty-two (13 per cent) were positive for C psittaci. The PCR products from positive samples were subjected to restriction endonuclease analysis with the restriction enzymes Alu I and Mse I. The fragments of DNA were detected on silver-stained polyacrylamide gels and the results were compared with the results obtained from chlamydial isolates from cats in Japan, France, the USA and the UK. All the strains had identical restriction patterns. When PCR is used as an epidemiological tool, feline chlamydial strains worldwide appear very similar.

Heparin-mediated inhibition of Chlamydia psittaci adherence to HeLa cells

The adherence of human strains of Chlamydia trachomatis has been recently shown to be inhibitable by heparin and heparitinase, leading to the proposal that Chlamydia binding to host cells may be mediated by a glycosaminoglycan (GAG)-dependent mechanism. We here describe the adherence of the guinea-pig pathogen, Chlamydia psittaci GPIC, to HeLa cells, which was measured by cytofluorometry with chlamydiae whose DNA was fluorescently labelled. Adherence could be inhibited by heat or trypsin pretreatment of the bacteria, and binding was much faster at 37 degrees C (reaching a plateau within 1 h) than 4 degrees C. Little binding remained when host cells were pre-fixed with paraformaldehyde, suggesting that host cell receptor mobility may be required for effective adherence. Visualization by confocal microscopy confirmed that the bacteria were at or near the host cell surface during the entire time-course of these experiments. Adherence increased as a function of pH between pH 6 and pH 8.0-8.5. Both adherence and infection of HeLa cells could be inhibited with heparin when the adherence step was performed at 4 degrees C, but only infection was inhibited when the adherence step was performed at 37 degrees C, even though heparitinase could block adherence at either 4 degrees C or 37 degrees C. Even at 4 degrees C, heparin-mediated inhibition was significantly lower at pH 8 than pH 7.4, suggesting that GAG-independent mechanisms may play a role in the higher adherence observed at basic pH. These results therefore demonstrate that a GAG-dependent adherence step may be operative in C. psittaci, and raise the possibility that other adherence mechanisms may also contribute to binding by this chlamydial strain. Furthermore, they suggest that there may not be a strict correlation between C. psittaci adherence and the ability to cause productive infections.

Virulence of feline Chlamydia psittaci in mice is not a function of the major outer membrane protein (MOMP)

The virulent strain of feline Chlamydia psittaci, the Cello strain, produces conjunctivitis and upper respiratory disease in cats. This same strain produces a lethal disease in mice when inoculated intraperitoneally (i.p.). In this study we have shown that the Baker strain of feline C. psittaci is attenuated in the mouse model system. Intraperitoneal inoculation of mice with the Baker strain produced no disease but did stimulate an immune response that protected the mice from subsequent produced i.p. inoculation with the virulent Cello strain. To determine if the difference between these two strains was in the major outer membrane protein (MOMP), the omp1 gene which codes for this protein was sequenced for both the Baker and Cello strains. The MOMP was chosen to study because in Chlamydia trachomatis this protein has been shown to contain neutralizing epitopes and has been shown to play a role in cell attachment. These functions make it a likely structural component capable of mutating and causing altered cell tropism and virulence. The DNA sequence of the omp1 was determined by amplifying the gene with PCR, cloning the PCR product into the pCR-II cloning vector and determining the DNA sequence of the inserted gene using primers to sites in the plasmid vector. From the DNA sequence, the deduced amino acid sequence of MOMP was determined for both the attenuated Baker and the virulent Cello strains of feline C. Psittaci. The results indicated that the omp1 gene of both strains contained 1179 base pairs which coded for a protein 392 amino acids. The DNA sequences of the omp1 gene of the two strains differed by only two base pairs which resulted in two amino acid changes in the MOMP. The Baker strain had a serine instead of a tryptophan at amino acid 7 and a tyrosine instead of an aspartic acid at amino acid 125 of the uncleaved protein. Neither amino acid change was in an area of the MOMP which could logically account for the difference in biological activity. Amino acid 7 was in the leader sequence which is cleaved from the authentic MOMP and is not present in the infectious elementary body. Amino acid 125 was in a conserved hydrophobic area of one of the constant regions of the protein. A change at this location was not likely surface exposed and thus could not affect cell adhesion, tissue tropism or neutralizing epitopes. Therefore, the differences in the primary structure of the MOMP from the Baker and Cello strains of feline C. psittaci could not account for the attenuation of the Baker strain for mice. The molecular basis of their difference is yet to be determined.

Localization of chronic Chlamydia psittaci infection in the reproductive tract of sheep

Twelve sheep experimentally infected with Chlamydia psittaci during pregnancy either aborted or gave birth to weak, low-birth-weight lambs as a result of uteroplacental infection. Subsequently, these ewes excreted chlamydial antigen from their reproductive tracts during estrus. About 1 year after pregnancy failure, immunohistochemistry and polymerase chain reaction were used to examine sections of vagina, uterus, and oviduct for evidence of C. psittaci. Four noninfected control ewes were similarly examined. C. psittaci antigen or DNA was detected in vagina, uterus, and oviduct samples from chronically infected ewes. Endometrial cells in the basal stroma were the predominant site of infection. There was no obvious evidence of pathology associated with persistent infection, but increased numbers of plasma cells and intraepithelial lymphocytes were detected in the uterus. C. psittaci is a naturally occurring reproductive infection in sheep that persists following primary infection. Therefore, sheep provide an excellent model to study the host-parasite interactions that occur during natural infection and subsequent persistence.

Seroepidemiology of feline chlamydiosis by microimmunofluorescence assay with multiple strains as antigens

The prevalence of anti-chlamydia antibodies was examined in 232 cat sera collected in 1985 and from 1993 to 1995 from laboratories and veterinary hospitals located in 11 prefectures of Japan. The antibodies were determined by an indirect microimmunofluorescence test using six strains of feline Chlamydia: one strain each of avian- and guinea pig-derived C. psittaci and one strain each of C.pecorum, C.pneumoniae and C.trachomatis. Positive rates of IgG antibodies to chlamydiae were 34.4% in 1985 and 16.5-21.4% from 1993 to 1995. Positive rates of IgM antibodies to chlamydiae were 8.2% in 1985 and 6.6-14.3% from 1993 to 1995. Variations in antibody reactivity to the different feline strains were observed. The results suggest the wide prevalence of chlamydial infection in cats in Japan, and antigenic diversity in the feline strains of C.psittaci.

Murine granulated metrial gland cells are susceptible to Chlamydia psittaci infection in vivo

Granulated metrial gland (GMG) cells are the most numerous lymphoid cells in the uteroplacental unit in rodent pregnancy. In an experimental murine model of abortion-causing infection, we have studied the responses of GMG cells to Chlamydia psittaci. Chlamydial inclusions have been found within GMG cells, both in apparently healthy cells and in cells with degenerative changes. Establishing the existence of GMG cells infected by C. psittaci opens a new and interesting chapter in the study of these cells.

Pathogenesis of Chlamydia psittaci infection in sheep: detection of the organism in a serial study of the lymph node

Sixteen sheep were inoculated subcutaneously over the left prefemoral lymph node with an abortifacient strain of Chlamydia psittaci. Groups of four animals were killed after 3, 6, 12 and 18 days. Four of eight sheep which received a control inoculum were killed on day 6 and four on day 18. The left and right prefemoral lymph nodes were removed and weighed and portions taken from each for examination by the polymerase chain reaction (PCR), by culture, and by histopathological and immunohistochemical methods. The left prefemoral lymph nodes enlarged after the injection of C. psittaci, with the group mean weight on day 6 being the greatest and that on day 18 being normal. Examination by "nested" PCR showed samples from these nodes to be positive, except for one animal killed on day 3 and one on day 12. Live organisms, however, were not cultured from any of the samples collected. C. psittaci antigen was detected immunohistochemically in three of four nodes on day 3, in each of four on day 6, and in two of four on both days 12 and 18. Nodes from the contralateral side remained normal, as did those from unchallenged control sheep, and no antigen or DNA was detected in them.

[Hepatic psittacosis: a case of liver abnormality diagnosed by ultrasonography]

Psittacosis marked by liver and spleen involvement and minimal pericarditis was observed in an 18-year-old patient hospitalized for fever of 1 month duration. At admission, there was no other clinical manifestation and the chest X-ray showed no sign of pulmonary involvement. Liver tests revealed cholestasis. Ultrasonography of the abdomen revealed multiple nodular formations in the liver and spleen, images confirmed on computed tomography. Liver biopsy showed granulomatous with hyperplasia of the Kupffer cells surrounded by healthy tissue. Complement fixation to psittacosis antigen was positive and increased significantly over a 15-day interval. Treatment with tetracycline led to rapid remission of the fever and normalization of the liver tests and hepatic images. Liver involvement in psittacosis is not uncommon, but this is apparently the first case reporting echographic anomalies. The absence of pulmonary involvement has been reported earlier in a few cases. The diagnosis is usually suggested on the basis of epidemiologic criteria and confirmed by complement fixation.

[Avian Chlamydia psittaci phyla and their pathogenic significance for turkeys]

The present study demonstrates that Chlamydia psittaci is an important cause of respiratory disease in turkeys in Europe. The serotyping of isolates revealed that European turkeys frequently become infected with Chlamydia psittaci serovar D strains, but also can become infected with serovar A and B strains. In turkeys, differences in pathogenicity were observed not only between strains belonging to the serovars A (strain 84/55), serovar B (strain 89/1326) and serovar D (Texas Turkey strain and strain 92/1293), but also between two strains belonging to the same serovar D (Texas Turkey strain and strain 92/1293). In order to find an explanation for these differences in pathogenicity, the pathogenesis of the infection was studied in specific pathogen free turkeys. However, for all three serovars examined a similar pathogenetic sequence of events was deduced. In order to try and elucidate the observed differences in pathogenicity between different Chlamydia psittaci strains, the bacterium-host cell interaction was studied in BGM cell culture using transmission electron microscopy and immuno electron microscopy. Strains most pathogenic for turkeys, namely the serovar A strain and strain 92/1293 (serovar D) produced significantly larger inclusions with more numerous infectious organisms, produced the most severe degenerative changes in the host cell an also replicated freely in the cytoplasm of the host cell.

Detection of Chlamydia psittaci in enteric subclinical infections in adult sheep, through cell culture isolation

Ovine chlamydiasis is a well known disease in countries with a good practice of breeding sheep herds, not so in Mexico. Aiming to determine Chlamydia psittaci presence in sheep herds in Mexico, we sampled 10 different farmlands in 5 geographical zones on the highlands, gathering a total of 267 viable samples from adult ewes in SPG (92 of them were obtained in a second sampling carried out in five randomly chosen farms). Samples were treated and inoculated on L-929 cells grown in Iscove's supplemented medium; identification of the characteristic intracytoplasmic inclusions was performed by Giemsa stain, and indirect immunofluorescence in suspected samples. Isolation was successful in 92.88% of the trials. No significant differences were observed among the studied herds nor between the two samplings. This high incidence leads to consider seriously the possible pathogenic role of C. psittaci in Mexico.

[An adult case of pneumonia due to Mycoplasma pneumoniae and Chlamydia psittaci]

A 18-year-old male was admitted to another hospital complaining of his chest X-ray. After transfer to our hospital, increased serum antibody titers to simultaneous M. pneumoniae and C. psittaci were noted. These antibody titers decreased after about four months. Positive results for M. pneumoniae was obtained by Polymerase chain reaction in the right pleural effusion. Based on these findings, this case was diagnosed as M. pneumoniae and C. psittaci pneumonia. A transbronchial lung biopsy and a bronchial biopsy revealed rare histological findings, including histiocytic intra-alveolar pneumonia with palisaded granuloma and small foci of necrosis in the left upper lobe and eosinophilic bronchitis in the right middle bronchus. His chest X-ray and chest CT showed a nodular shadow, obstructive pneumonia and pleural effusion which are rare in M. pneumoniae and C., psittaci pneumonia.

Chlamydiae as pathogens: new species and new issues

The recognition of genital chlamydial infection as an important public health problem was made first by the recognition of its role in acute clinical syndromes, as well as in serious reproductive and ocular complications, and secondly by our awareness of its prevalence when diagnostic tests became widely accessible. The recent availability of effective single dose oral antimicrobial therapy and sensitive molecular amplification tests that allow the use of noninvasive specimens for diagnosis and screening is expected to have a major impact in reducing the prevalence of disease in the next decade. Clinical manifestations associated with Chlamydia pneumoniae infection continue to emerge beyond respiratory illness. In particular, its association with atherosclerosis deserves further investigation. Chlamydia pecorum, a pathogen of ruminants, was recently recognized as a new species. The continued application of molecular techniques will likely elucidate an expanding role for chlamydiae in human and animal diseases, delineate the phylogenetic relationships among chlamydial species and within the eubacteria domain, and provide tools for detection and control of chlamydial infections.

Epizootic bovine abortion in a dairy herd: characterization of a Chlamydia psittaci isolate and antibody response

A chlamydial agent was recovered from the placental cotyledons of an aborting cow from a 100-cow dairy herd in Cumbria. Immunoblotting analysis of purified elementary bodies of the isolate revealed a reactivity pattern typical of serotype I Chlamydia psittaci strains. Nucleotide sequencing of the major outer membrane protein (MOMP) gene further confirmed the isolate, BA1, as a serotype I strain. The sequence was identical to that of the type strain of ovine enzootic abortion, B577. In both the antigenic and MOMP sequencing analyses BA1 was distinguishable from serotype II C. pecorum strains. A sequential series of sera obtained from the aborting cow, from which BA1 was recovered, was analysed by immunoblotting against the homologous isolate, and demonstrated reactivity to major chlamydial antigens over a 110-day period. Close contact between ruminant species on the farm suggested that the C. psittaci strain may have been transmitted to cattle from infected sheep.

Experimental infections of pregnant sows with ovine Chlamydia psittaci strains

Four sows were experimentally inoculated at 42 days pregnancy, with the BS isolate of Chlamydia psittaci from aborted ewes. Their body temperature and health were monitored until 30 days after farrowing. The sows seroconverted but their reproductive performance was not impaired. Chlamydiae were identified in the afterbirths from two sows with normal litters using stained smears, "Clearview" and "IDEIA" ELISA antigen detection tests. The presence of inclusion bodies was detected in sections of the infected fetal membranes after staining with haematoxylin and eosin, methylene blue and Streptavidin-Biotin using an anti-Chlamydia monoclonal antibody.

Detection of Chlamydia psittaci (ovis) antigen in tissue sections and McCoy cells using streptavidin-biotin and the IMAGEN staining method

Two procedures for identifying chlamydial antigen in infected McCoy cells and tissue sections are described. Both the streptavidin-biotin method and the IMAGEN test clearly detected chlamydial antigen in ovine placental tissue sections and in infected McCoy cells before they could be detected by conventional stains. The streptavidin-biotin method is lengthy, but specific and sensitive, and the slides can be kept indefinitely for later examination. By contrast, the IMAGEN test is a single step procedure which requires fluorescent microscopy and slides can only be kept for up to 1 week before examination.

Monoclonal antibody to a major outer membrane protein of feline Chlamydia psittaci: antibody specificity and anti-idiotype antibody production

A murine monoclonal antibody, F1-8, was developed against the purified major outer membrane protein (MOMP) of Chlamydia psittaci feline pneumonitis (FPn). F1-8 showed a serotype-specific activity against intact Fpn elementary bodies in a micro-immunofluorescence assay. In immunoblot, F1-8 reacted only with the Fpn MOMP but did not react with the MOMPs from other strains of C. psittaci and C. trachomatis. F1-8 neutralized Fpn infectivity in L929 cell culture in a dose-dependent and complement independent fashion. These results suggested that the monoclonal antibody (mAb) binds with an epitope on the MOMP region that is exposed at the cell surface and plays an important role in FPn infection. Polyclonal anti-idiotype (anti-Id) antibodies to mAb F1-8 were elicited by F1-8 coupled to keyhole limpet hemocyanin. These anti-Id antibodies inhibited F1-8 binding to FPn MOMP.