Chlamydia abortus OmcB protein is essential for adhesion to host cells.

Chlamydia abortus (C. abortus) is one of the most important zoonotic pathogens, causing a number of serious diseases. The adhesion of C. abortus to host cells is the first and crucial step in the process of infection. Outer membrane protein 2 (OmcB) is the second most abundant outer membrane protein. It has been shown to be an important adhesin of Chlamydia trachomatis and Chlamydia pneumoniae. In the present study, the OmcB gene of C. abortus was cloned and expressed in Escherichia coli, and the recombinant OmcB protein with His-tag was used to prepare polyclonal antibodies. Infectivity inhibition assays carried out with C. abortus in the presence of recombinant OmcB showed a considerable reduction (∼50%) in infectivity. Using anti-OmcB serum in infectivity inhibition assays resulted in a 30% reduction in infectivity. Anti-OmcB serum and recombinant OmcB protein in infection inhibition assays showed that OmcB is a surface-exposed protein that functions as an adhesin. The constructed deletion variant of the OmcB motif for infection inhibition assays showed that the first XBBXBX motif of the C. abortus OmcB protein is essential for binding to host cells.

Seroprevalence and associated risk factors for chlamydiosis, coxiellosis and brucellosis in sheep and goats in Borana pastoral area, southern Ethiopia.

BACKGROUND: Abortion is considered an important disease problem of small ruminants in Borana pastoral area. A cross-sectional study was conducted to estimate the prevalence and risk factors of chlamydiosis, coxiellosis (Q-fever) and brucellosis in small ruminants in selected districts of Borana zone. RESULTS: A total of 506 sheep and goats were tested using serological tests. Fifty (9.88%; 95% CI: 7.42, 12.82), 144 (28.46%; 95% CI: 24.56, 32.61) and none (0.00%; 95% CI: 0.00, 0.59) of them were positive for chlamydiosis, coxiellosis and brucellosis, respectively. History of abortion was recorded in 136 (32.00%; CI: 27.59, 36.67) of sheep and goats in the study area. The logistic regression analysis, however, showed that statistically significant difference ccurred among districts and between the species of small ruminants. The prevalence odd of antibodies against C. abortus was significantly lower in Miyo, Dire and Teltelle districts compared to Dillo. The odd of infection with this bacterium was lower in sheep than goats. Similarly the odd of infection with C. burnettii was significantly higher in Dillo district than the rest of the districts studied, higher in goats than sheep and higher in adult animals than young ones. CONCLUSION: High prevalence of abortion is observed in sheep and goats in the study area. High seropositivity of C. burnetii and C. abortus in both sheep and goats tested implies risks of human infection by both diseases. Thus, attention needs to be paid to further study of both diseases in animals and humans in the area.

The serostatus of Brucella spp., Chlamydia abortus, Coxiella burnetii and Neospora caninum in cattle in three cantons in Bosnia and Herzegovina.

BACKGROUND: Dairy production in Bosnia and Herzegovina exhibits limited productivity, which may partly, be explained by extensive reproductive problems of non-infectious and infectious origin. Brucella spp., Chlamydia abortus, Coxiella burnetii and Neospora caninum are common infectious causes of decreased reproductive outcomes in cattle worldwide. Little is, however, known about the disease status of herds with reduced reproductive performances. A cross-sectional study was designed to document the status of these pathogens in dairy cattle in Bosnia and Herzegovina. A total of 1970 serum samples were collected from cattle in farms located in three cantons (regions). Enzyme linked immunosorbent assays were used to screen for seropositivity against four selected pathogens. RESULTS: The overall seroprevalence was estimated at both the herd level and at individual level for each pathogen. At the individual animal level, the prevalence for C. abortus, C. burnetii, N. caninum and Brucella spp. was 52.1% (95% CI: 41.2-62.7), 8.8% (95% CI: 5.3-14.2), 9.2% (95% CI: 6.0-12.3 and 0.2% (95% CI: 0.1-0.5), respectively. The corresponding estimates for herd level were 87.9% (95% CI: 82.6-91.8), 19.6% (95% CI: 14.6-25.8), 35.2% (95% CI: 28.8-42.1), and 1.5% (95% CI: 0.5-4.6). A substantial overlap was observed in the presence of N. caninum, C. abortus and C. burnetii at individual and herd level. CONCLUSION: Our study demonstrated a high level of antibodies to Chlamydia abortus. Considering the association of this agent with reproductive disorders in cattle, future studies should be directed to the epidemiological traits of this infection. Additionally, the relatively high levels of exposure to C. burnetii and N. caninum found in this study highlights the need for targeted control of infectious causes of reproductive disorders in dairy cattle of the studied areas. Given the low seroprevalence, Brucella spp. does not seem to represent a problem in the reproductive health of cattle in the studied areas.

Whole Genome Sequencing and Comparative Genome Analyses of Chlamydia abortus Strains of Avian Origin Suggests That Chlamydia abortus Species Should Be Expanded to Include Avian and Mammalian Subgroups.

A variety of Chlamydia species belonging to the Chlamydiaceae family have been reported in birds. Until recently, C. psittaci was considered to be the most common avian species, although found in both birds and mammals, while C. abortus has only been found in mammals. Recently, a new group of avian C. abortus strains with worldwide distribution in various wild bird families has been described. In this study, whole genome sequencing (WGS) of three of these strains (15-70d24, 15-49d3 and 15-58d44, representing genotypes G1, G2 and 1V, respectively) that were isolated from wild birds were analysed. Genome assemblies based on both short-read Illumina and long-read Nanopore data indicate that these avian C. abortus strains show features characteristic of both C. abortus and C. psittaci species, although phylogenetic analyses demonstrate a closer relationship with classical C. abortus strains. Currently, species classification established by the ICSP Subcommittee on the taxonomy of Chlamydiae, determines that these avian C. abortus strains 15-70d24, 15-49d3 and 15-58d44 should be classified as C. abortus. However, the authors of this study conclude that the current taxonomic definition of C. abortus is outdated and should be amended to include two subgroups, mammalian and avian, the latter of which would include all isolates so far referred to as atypical C. psittaci or C. psittaci/C. abortus intermediates.

First report of Chlamydophila abortus infection in the dromedary camel (Camelus dromedarius) population in eastern Algeria.

Chlamydiosis is caused by an obligate intracellular gram-negative bacterium of the genus Chlamydophila which is a zoonotic pathogen. The objectives of the study were to identify the seroprevalence of antibodies against Chlamydophila abortus in dromedary camel herds from four districts in eastern Algeria, as well as to estimate the association between seroprevalence and certain factors present at the animal and herd levels. Blood samples were collected from a random sample of animals within each of 82 camel herds. Serum samples were subjected to a C. abortus ELISA test, and association between the presence of antibodies and potential risk factors was estimated. Animal and herd seroprevalence were 2.5 % and 15.8 %, respectively, indicating substantial exposure of camels to C. abortus in the four districts studied. Age, breed, and sex did not influence seroprevalence in tested animals. Based on the univariate analysis, contact with sheep and goats, contact with other camel herds, and histories of abortion were major risk factors for infection. By using multivariate analysis, contact of camels with sheep and goats and with others camel herds, through shared grazing or watering points, were important factors for transmission of chlamydiosis with an odds ratio of 3.3 and 9.4, respectively. At the herd level the introduction of purchased animals was the major risk factor. This baseline information will be highly useful for launching C. abortus control programs in the region and potentially elsewhere.

Seroprevalence of some viral and bacterial zoonoses in domestic ruminants in Medina.

OBJECTIVE: The study aimed to explore the seroprevalence of some bacterial (Brucella spp., Chlamydia abortus) and viral [Rift Valley fever virus (RVFV), foot and mouth disease virus (FMDV)] zoonoses in domestic ruminants in Medina. MATERIALS AND METHODS: A total of 1,000 blood samples from 665 sheep, 228 goats, and 107 camels were collected from the central slaughterhouse, private farms, and veterinary clinics affiliated to the Ministry of Agriculture. The samples were screened using the Enzyme-Linked Immunosorbent Assay (ELISA). The results were statistically analyzed using Statistical Package for the Social Sciences version 20. RESULTS: Brucella was found in 7.7%, 8.8%, and 6.5% of sheep, goats, and camel's sera, respectively. In humans, Brucella abortus and Brucella melitensis had higher frequencies in males (61.3%, 59.8%) than in females (38.7%, 40.2%). Chlamydia abortus was reported only in sheep at a rate of 0.75%. RVFV was prevalent in sheep (10.7%) and goats (17.9%). FMDV was reported in 27.8% of sheep and 7.9% of goats. There was a highly statistical significance between Brucella, RVFV, and FMDV seropositivity and locally bred animals (p < 0.01). Multiple seropositivities have been reported among sheep and goats. Brucella was commonly observed in mixed infection with other bacterial and viral agents under study. CONCLUSION: The surveyed viral and bacterial agents were prevalent in ruminants in the Medina region. Since Medina is an important destination for pilgrims from all over the world, therefore, an integrated approach involving strict control measures and routine vaccination programs should be adopted to reduce the possibility of global epidemics.

Seroprevalence of Five Zoonotic Pathogens in Wild Ruminants in Xinjiang, Northwest China.

Wild ruminants are at risk for zoonotic pathogen infection as a result of interactions with domestic animals and humans. One way to assess the level of a wild ruminant disease in a population is to determine the seroprevalence of the pathogen of interest. The objective of this study was to determine the seroprevalence of five zoonotic pathogens in wild ruminants in Xinjiang, Northwest China. In 2009 and 2011-2015, 258 wild ruminant sera samples were collected from various species. Samples were obtained from 30 Siberian ibexes, 94 goitered gazelles, 6 Tibetan antelopes, 32 argali sheep, 16 roe deer, 20 blue sheep, 56 red deer, and 4 wild yaks, in 10 regions of Xinjiang. Samples were tested using antibodies against Brucella spp., Chlamydophila abortus, Coxiella burnetii, Toxoplasma gondii, and West Nile virus. Seropositivity was detected for all five pathogens, with detection rates of Brucella spp., C. abortus, C. burnetii, T. gondii, and West Nile virus of 2.3% (95% confidence interval [CI], 0.5-4.2%), 6.2% (95% CI, 3.3-9.1%), 7.8% (95% CI, 4.5-11.0%), 2.3% (95% CI, 0.5-4.2%), and 0.8% (95% CI, 0-1.8%), respectively. The level of pathogens differed for different species and different regions. The results indicate that seropositivity to zoonotic pathogens is common among wild ruminants in Xinjiang, Northwest China, with C. burnetii and C. abortus detected at the highest levels. This study provides a baseline for future assessment of spillover events.

Occurrence of Chlamydiaceae in Raptors and Crows in Switzerland.

Bacteria of the family Chlamydiaceae are globally disseminated and able to infect many bird species. So far, 11 species of Chlamydia have been detected in wild birds, and several studies found chlamydial strains classified as genetically intermediate between Chlamydia (C.) psittaci and C.abortus. Recently, a group of these intermediate strains was shown to form a separate species, i.e., C.buteonis. 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. Chlamydiaceae DNA was detected in 23.7% of the corvids and 5.9% of the raptors. In corvids, the most frequently detected Chlamydia species was C.psittaci of outer membrane protein A (ompA) genotype 1V, which is known to have a host preference for corvids. The most frequently detected ompA genotype in raptors was M56. Furthermore, one of the raptors harbored C.psittaci 1V, and two others carried genotype A. C.buteonis was not detected in the bird population investigated, so it remains unknown whether this species occurs in Switzerland. The infection rate of Chlamydiaceae in corvids was high compared to rates reported in other wild bird species, but neither Chlamydiaceae-positive corvids nor raptors showed overt signs of disease. Since the Chlamydiaceae of both, raptors and crows were identified as C.psittaci and all C.psittaci genotypes are considered to be zoonotic, it can be suggested that raptors and crows pose a potential hazard to the health of their handlers.

Can Chlamydia abortus be transmitted by embryo transfer in goats?

The objectives of this study were to determine (i) whether Chlamydia abortus would adhere to or penetrate the intact zona pellucida (ZP-intact) of early in vivo-derived caprine embryos, after in vitro infection; and (ii) the efficacy of the International Embryo Transfer Society (IETS) washing protocol for bovine embryos. Fifty-two ZP-intact embryos (8-16 cells), obtained from 14 donors were used in this experiment. The embryos were randomly divided into 12 batches. Nine batches (ZP-intact) of five embryos were incubated in a medium containing 4 × 10(7)Chlamydia/mL of AB7 strain. After incubation for 18 hours at 37 °C in an atmosphere of 5% CO2, the embryos were washed in batches in 10 successive baths of a phosphate buffer saline and 5% fetal calf serum solution in accordance with IETS guidelines. In parallel, three batches of ZP-intact embryos were used as controls by being subjected to similar procedures but without exposure to C. abortus. The 10 wash baths were collected separately and centrifuged for 1 hour at 13,000 × g. The washed embryos and the pellets of the 10 centrifuged wash baths were frozen at -20 °C before examination for evidence of C. abortus using polymerase chain reaction. C. abortus DNA was found in all of the infected batches of ZP-intact embryos (9/9) after 10 successive washes. It was also detected in the 10th wash fluid for seven batches of embryos, whereas for the two other batches, the last positive wash bath was the eighth and the ninth, respectively. In contrast, none of the embryos or their washing fluids in the control batches were DNA positive. These results report that C. abortus adheres to and/or penetrates the ZP of in vivo caprine embryos after in vitro infection, and that the standard washing protocol recommended by the IETS for bovine embryos, failed to remove it. The persistence of these bacteria after washing makes the embryo a potential means of transmission of the bacterium during embryo transfer from infected donor goats to healthy recipients and/or their offspring. Nevertheless, the detection of C. abortus DNA by polymerase chain reaction does not prove that the bacteria found was infectious. Further studies are required to investigate whether enzymatic and/or antibiotic treatment of caprine embryos infected by C. abortus would eliminate the bacteria from the ZP.