Evaluation of five immunoassays for detection of Chlamydia psittaci in cloacal and conjunctival specimens from turkeys

Five commercially available immunoassays were evaluated for the detection of Chlamydia psittaci in cloacal and conjunctival swabs from industrially raised turkeys: IMAGEN (DAKO Diagnostics, Ely, Cambridgeshire, United Kingdom), Chlamydia CEL-VET IF (Cellabs, Brookvale, Australia), IDEIA (DAKO Diagnostics), CELISA (Cellabs), and CLEARVIEW (Unipath, Bedford, United Kingdom). Results were compared with isolation in Buffalo Green Monkey cells as a reference method. For the conjunctival samples, the sensitivities of the IMAGEN test, the Chlamydia CEL-VET IF test, the IDEIA, the CELISA, and the CLEARVIEW test were found to be 100, 66, 0, 0, and 0%, respectively, as compared to the reference test. Also for the conjunctival samples, the specificities of the IMAGEN test, the Chlamydia CEL-VET IF test, and the IDEIA were found to be 100, 11, and 92.8%, respectively. For the cloacal specimens, the sensitivities of the IMAGEN test, the Chlamydia CEL-VET IF test, the IDEIA, the CELISA, and the CLEARVIEW test were found to be 100, 93.3, 26.6, 0, and 53.3%, respectively. Also for the cloacal specimens, the specificities of the IMAGEN test, the Chlamydia CEL-VET IF test, the IDEIA, and the CLEARVIEW test were found to be 92, 12, 100, and 88%, respectively. The IMAGEN test was the most sensitive and specific direct chlamydia antigen detection test for cloacal and conjunctival samples from turkeys.

Enzyme immunoassay with enhanced specificity for detection of antibodies to Chlamydia trachomatis

Two different methods for preventing the binding of cross-reacting antibodies to the genus-reactive chlamydial lipopolysaccharide (LPS) were used to improve the specificity of an enzyme immunoassay for the determination of antibodies to Chlamydia trachomatis. Coated elementary bodies were treated with either sodium periodate, to oxidize the antigenic sites of the LPS, or Triton X-100, to extract the LPS. By using these new enzyme immunoassays, the standard enzyme immunoassay, and the whole inclusion fluorescence (WIF) assay, antibodies to C. trachomatis were determined in sera from different groups of patients and controls. Paired serum samples from patients with culture-proven urogenital C. trachomatis infections showed similar responses in all three assays. Paired serum samples from patients with Chlamydia psittaci infections showed similar responses in the WIF assay and the standard enzyme immunoassay, whereas significantly reduced titers were obtained in the enzyme immunoassays with treated antigen, especially in the convalescent-phase serum samples. Serum samples from patients with symptoms suggestive of infection with C. trachomatis, pregnant women, and blood donors were evaluated by all three types of assays. Eighty percent of the significant reductions in immunoglobulin G (IgG), IgA, and IgM titers were observed in sera with WIF assay titers in the lower classes (IgG, 1: < or = 256; IgA, 1: < or = 32; IgM, 1: < or = 16). From these results we conclude that oxidation of the antigen by sodium periodate is a simple and effective method of producing an enzyme immunoassay with enhanced specificity that could be useful for diagnostic purposes and seroepidemiological studies.

Clinical aspects of Chlamydia psittaci infection in cats infected with feline immunodeficiency virus

Two groups of six cats were established, one a control group and one infected with feline immunodeficiency virus (FIV) 18 months previously. The cats in both groups were inoculated with Chlamydia psittaci and the clinical progression of the infection was monitored by means of a clinical scoring system for 10 months. Haematological, serological and viral and chlamydial isolation studies were also made. The response of the FIV infected group to treatment with oxytetracycline was monitored in the 11th and 12th months. The FIV infection prolonged the duration of the clinical signs resulting from the infection with C psittaci and led to the development of chronic conjunctivitis. The haematological and antibody responses to C psittaci were comparable in the two groups. However, it was possible to isolate C psittaci from the FIV-infected cats up to day 270, when the treatment began, but only up to day 70 in the control group. In addition, it appeared that the infection with a secondary pathogen may have accelerated the clinical progression of the FIV infection.

The importance of interferon-gamma in an early infection of Chlamydia psittaci in mice

Athymic mice (nu/nu) and their hairy littermates (nu/+) were infected experimentally with Chlamydia psittaci and the role of endogenous interferon-gamma (IFN-gamma) on the resolution of the infection was studied. The pathological changes produced in the spleen, liver and lung were exacerbated by administration of a monoclonal antibody (mAb) to IFN-gamma and an increased number of viable chlamydiae were recovered from the tissues of both nu/+ and nu/nu mice treated in this way.

Chlamydia psittaci infections in birds: a review on the pathogenesis and histopathological features

In this review the literature on the pathogenesis and histopathological features of Chlamydia psittaci infections in birds and their significance for psittacosis/ornithosis in humans is summarized. Models of experimental infections to elucidate the pathogenicity of avian strains are discussed briefly.

The role of Branhamella ovis, Mycoplasma conjunctivae and Chlamydia psittaci in conjunctivitis of sheep

Smooth (S) and rough (R) types of Branhamella ovis were used alone and in conjunction with Mycoplasma conjunctivae and Chlamydia psittaci in attempts to produce conjunctivitis in lambs. This was only successful with one S-type previously isolated from a clinical case of conjunctivitis. In experimental mixed infection, B. ovis contributed to the severity of ovine keratoconjunctivitis attributable to infection with Mycoplasma conjunctivae. When B. ovis and C. psittaci were inoculated into the conjunctival sac mild conjunctivitis was produced but C. psittaci could not be re-isolated.

Primary pathogenicity of an European isolate of Chlamydia psittaci from turkey poults

Chlamydia psittaci was isolated as the sole pathogenic agent from a severe outbreak of respiratory disease in a commercial broiler turkey farm in the Netherlands. The mortality rate in the flocks was 65%. Clinical signs included conjunctivitis, swelling of the sinus infraorbitalis and sneezing. Cloacal excretion of chlamydia was demonstrated in twelve out of fifteen birds examined by a direct immunofluorescence test. In all the fifteen birds antibodies against Chlamydia psittaci were detected in the sera by a competitive ELISA. At necropsy sinusitis, rhinitis, airsacculitis, pneumonia, pericarditis and enlargement of the liver and spleen were found. Chlamydiae were demonstrated in the sinus material of all and in conjunctival smears of eight of the fifteen examined birds. Chlamydiae were isolated from all the examined birds after one to three passages on Buffalo Green Monkey (BGM) cell cultures using samples taken from lung, liver and spleen. No other pathogens were isolated. The chlamydia isolate was typed using a panel of serovar-specific monoclonal antibodies in a micro-immunofluorescence test. The isolate belonged to the avian Chlamydia psittaci serovar D. Experimental inoculation with this isolate of 7-day-old specific pathogen free (SPF) turkeys resulted in severe clinical signs, with mortality and extensive pathological lesions, similar to those seen in turkeys from the examined broiler turkey farm. From the data it was concluded that this Chlamydia psittaci isolate can cause severe disease in turkeys.

Comparison of type I and type II Chlamydia psittaci strains infecting koalas (Phascolarctos cinereus)

The native Australian marsupial Phascolarctos cinereus, otherwise known as the koala, is prone to infection by the obligate intracellular parasite Chlamydia psittaci, which causes ocular 'pink eye' and urogenital 'dirty tail' diseases. Several chlamydial DNA probes to both chromosomal and plasmid sequences were used to type by Southern blot analysis 51 samples taken from wild and captive koalas from habitats on the eastern seaboard of Australia as far apart as Queensland and Victoria. Two types of C. psittaci were observed and called types I and II. Type II was found more frequently than type I and occurred in both ocular and urogenital samples, while type I showed a strong but not absolute preference for ocular sites. Cross-hybridization analyses indicated that type I and type II had about 10% DNA sequence identity to each other. DNA analyses showed that type II was very closely related to some ovine and bovine chlamydiae but type I could not be related to any other C. psittaci strain available. Light and electron microscopic analyses of infected BGM monolayers revealed that the two strains were similar in morphological characteristics. The type I strain was considerably more infectious than the type II strain in BGM cells and in the yolk sacs of embryonated eggs. A PCR based assay detected both type I and type II koala chlamydiae in samples that had been negative by Southern blot and tissue culture and provided the first evidence that both types can occur simultaneously at the one site of infection.

Endometritis in cattle experimentally induced by Chlamydia psittaci

On the day of estrus, eight virgin heifers received intrauterine inoculations of yolk sac propagated Chlamydia psittaci strain BovEnd 11/88 isolated from the uterus of a slaughter cow. All heifers developed purulent vaginal discharge which persisted for 3 to 7 weeks. Chlamydiae or chlamydial antigen were detected in vaginal and uterine discharges of infected animals by culture or Capture ELISA, while other bacterial pathogens were not found. In sera of the chlamydia-infected heifers marked increases in antibody titres against the chlamydial genus-specific LPS-antigen were found by ELISA and complement fixation test. Six heifers were artificially inseminated in 5 successive cycles beginning at the first estrus following intrauterine inoculation. In two of the infected heifers spontaneous healing of endometritis occurred after 5 estrus cycles. Only these animals conceived after the 5th breeding, whereas in the remaining four animals a chlamydia-associated chronic endometritis was recognized as the cause of infertility in the 19th and 26th week p.i. at slaughter. Two control heifers which remained clinically normal after intrauterine exposure to sterile yolk sac-suspensions conceived at the 1st and 2nd service, respectively.

[Intestinal Chlamydia psittaci infection of cattle: frequency and technical aspects of the cultural detection of the agent]

With the purpose to evaluate the prevalence of latent chlamydial infections in cattle, 190 animals were examined for fecal shedding of chlamydiae. From the feces of 42 animals (22.1%) Chlamydia (C.) psittaci was grown either in the yolk sac of chicken embryos and/or in coverslip cultures of BGM-cells. The cell culture proved to be of lower susceptibility to chlamydial infections. In comparison with the chicken egg technique a sixfold quantity of chlamydial particles was required to initiate detectable intracellular growth. With the chicken embryo technique as a standard cell culture with a sensitivity range of 31.6% was not satisfactory for isolating chlamydiae from bovine feces. Attempts to recover chlamydiae from feces of two experimentally infected heifers in embryonated chicken eggs provided evidence that at least four randomly subsequent isolation trials are required to detect asymptomatic chlamydial infections of the bovine gut with a 95% confident level. Based on this fact, the positivity rate of 22.1% obtained by single fecal specimen examination indicates a wide spread occurrence of chlamydial infections in cattle.

Comparison of ovine abortion and non-abortion isolates of Chlamydia psittaci using inclusion morphology, polyacrylamide gel electrophoresis, restriction endonuclease analysis and reactivity with monoclonal antibodies

Twelve reference and four Northern Ireland ovine Chlamydia psittaci isolates including ovine abortion, faecal, conjunctivitis and arthritis isolates were compared. Inclusion morphology was shown to provide a useful means of differentiating the abortion and the non-abortion isolates studied. Identical SDS-PAGE polypeptide profiles were produced by the ovine abortion isolates. The polypeptide profiles of the non-abortion isolates were similar to one another and clearly distinct from the abortion isolate profiles. The restriction endonuclease profiles of the abortion isolates were remarkably similar whereas different profiles were produced by most of the non-abortion isolates. Monoclonal antibodies were prepared and characterized. A number of these reacted with all the isolates of chlamydia tested. Three mAbs reacted exclusively with the ovine abortion isolates while four mAbs reacted exclusively with a number of the faecal isolates.

Antibody prevalence and isolation of Chlamydia psittaci from pigeons (Columba livia)

The isolation of Chlamydia psittaci and serological detection of Chlamydia-specific antibodies in racing pigeons and pigeons from public parks is described. Several serological methods (complement fixation test, indirect microimmunofluorescence test, and enzyme-linked immunosorbent assay) were compared with bacteriological techniques (isolation both in embryonated eggs and McCoy cell monolayers). Tests confirmed that 28.6%, 33.5%, and 35.9% of the pigeons, respectively, were seropositive by the tests mentioned above. Chlamydiae were isolated from 13% of the fecal specimens in ovocultures and from 18% of the fecal specimens in cell cultures. No significant differences between the two groups of pigeons were found (at a 95% confidence level, alpha = 0.05) using the hypothesis test of the difference between proportions of two populations. The serological and bacteriological techniques used are compared and discussed.

Transmission of antibodies to Chlamydia psittaci and Coxiella burnetii through eggs and "crop milk" in pigeons

Young semi-domesticated pigeons captured or hatched from eggs gathered in Bratislava during 1989-1991 were examined for complement fixing antibodies to Chlamydia psittaci and agglutinating antibodies to Coxiella burnetii. Antibodies to Ch. psittaci were present in 76% of birds younger than 24 h, in 47.7% between 1 and 10 days of age and in 12% of nestlings over 10 days old. Antibodies to Ch. psittaci were also detected in "crop milk" of 4.1% of 1 to 10 day old birds and in 4.5% of specimens older than 10 days. Antibodies to C. burnetii were not found in juvenile birds under 24 h old, but antibodies against this agent were present in 16.4% birds between 1 and 10 days old and in 18% over 10 days old. Antibodies to C. burnetii were also detected in "crop milk" collected from crops of 2% of the young birds between 1 and 10 days.

Serotyping of European isolates of Chlamydia psittaci from poultry and other birds

A panel of five serovar-specific monoclonal antibodies which distinguish the five known avian serovars of Chlamydia psittaci was used to serotype 45 European avian Chlamydia psittaci isolates. Chlamydial antigen was grown in Buffalo green monkey (BGM) cells or in embryonated chicken eggs and was then inoculated into BGM cells. Serotyping was performed in an indirect immunofluorescence test. The 45 European isolates included 22 isolates from the order Psittaciformes, 9 isolates from the order Columbiformes, 6 isolates from the order Galliformes, 5 isolates from the order Passeriformes, and 3 isolates from the order Anseriformes. All of these were successfully serotyped. No additional serovars were found. One isolate from a duck and two isolates from psittacine birds gave positive immunofluorescences with two monoclonal antibodies considered to be specific for two different serovars. These three isolates were cloned by an agar overlay method. Serotyping of the clones demonstrated that the duck and one psittacine bird each were infected with two different serovars. After cloning, one isolate from a psittacine bird reacted only with serovar A. From these results it was concluded that this serotyping system allows the classification of all isolates tested so far. The results show that similar serovars are prevalent in avian species in Europe and the United States. The results also indicate that birds from a certain order are more susceptible to a distinct serovar. The use of a panel of serovar-specific monoclonal antibodies in the immunofluorescence test provides a reliable method for serotyping avian isolates. Monoclonal antibodies to new avian isolate serovars can easily be added to the panel, which makes the system useful for epidemiological studies.

Evaluation of the polymerase chain reaction (PCR) for detection of Chlamydia psittaci in abortion material from ewes

The polymerase chain reaction (PCR) was evaluated as a diagnostic tool for detection of Chlamydia (C.) psittaci in abortion material from 40 ewes. For this purpose, PCR results of 87 samples were compared with direct microscopic identification after chemical staining, cell culture isolation and a commercially available enzyme-linked immunosorbent assay (ELISA). The value for sensitivity as compared to cell culture was 97.7% whereas the specificity-value was calculated to be 84.1%.

Biological properties and genetic analysis of the ompA locus in chlamydiae isolated from swine

Eight strains of Chlamydia psittaci isolated from swine with pneumonia, pleuritis, pericarditis, and enteritis were characterized through analysis of the major outer membrane protein gene ompA by a two-step polymerase chain reaction, by their interactions with cells in culture, and by the morphologic features and ultrastructure of intracellular inclusions. Amplified chlamydial ompA DNA fragments were differentiated by restriction endonuclease digestion. Chlamydial isolates were separated into 2 types on the basis of ompA restriction fragment length polymorphism. Strains of type L71 had finely granular inclusions, whereas those of type 1710S contained pleomorphic reticulate bodies (RB) in the inclusions, which are characteristic of aberrant chlamydial developmental forms. Chlamydial types L71 and 1710S required centrifuge-assisted inoculation for efficient infection of cell cultures. Cultivation in cell culture medium containing cycloheximide increased the numbers of chlamydial inclusions about 1.5-fold. These strains formed few elementary bodies in yolk sac cells of chicken embryos. Ultrastructurally, unique doublet RB were observed, particularly in strains of the ompA type L71. These doublets consisted of 2 RB, bounded by a cytoplasmic membrane, contained within a common cell wall and an extended periplasmic space. Ultrastructural examination of strains of the ompA type 1710S confirmed the aberrant chlamydial developmental forms, but evidence of viral infection of the RB as a cause of these aberrant forms was not found. The strain S45 isolated from intestinal sites of swine was a trachoma restriction fragment length polymorphism type. With the mouse biotype, it represented the second isolate from animals of Chlamydia trachomatis.

Pneumonia due to Legionella bozemanii and Chlamydia psittaci/TWAR following renal transplantation

Chlamydia and Legionella are recognized causes of atypical pneumonia. A case of pneumonia due to Chlamydia psittaci/TWAR and Legionella bozemanii following renal transplantation is described. Legionella bozemanii infection was diagnosed by a rise in antibodies and by isolation of the organism from bronchoscopy specimens. It is unusual to find pneumonia caused concomitantly by two such agents. This case, despite the fatal outcome, emphasises the necessity for a comprehensive approach to the diagnosis of atypical pneumonia, including culture for Legionella, especially in immunocompromised patients.

Restriction endonuclease analysis of DNA from ruminant Chlamydia psittaci and its relation to mouse virulence

DNA from 20 pathogenic or non-pathogenic ruminant strains of Chlamydia psittaci was compared by restriction endonuclease analysis. The strains could be easily differentiated according to their invasiveness for mouse, whatever their pathological origin. DNA patterns of invasive strains were similar, whereas those of non-invasive strains were distributed in two groups.