High prevalence of natural Chlamydophila species infection in calves

Investigation of Chlamydia pecorum in livestock from Switzerland reveals a high degree of diversity in bovine strains

Chlamydia pecorum is a widespread veterinary chlamydial species causing endemic infections in livestock, such as ruminants and pigs, globally. However, there is limited contemporary knowledge on infecting strain diversity in various hosts. This study aimed to evaluate the genetic diversity of C. pecorum strains infecting Swiss livestock through C. pecorum genotyping and phylogenetic analyses in comparison to the global population, while also assessing chlamydial strains for plasmid carriage. A total of 263 C. pecorum positive samples from clinically healthy ruminant and pig herds (Bovines = 216, sheep = 25, pigs = 14) as well as placentae from eight C. pecorum positive ruminant abortion cases from other Swiss herds were investigated. The ompA and Multi-Locus sequence typing revealed novel C. pecorum genotypes, and bovine strains exhibited considerable genetic diversity, contrasting with lower diversity in sheep and pig strains. C. pecorum plasmid was detected in 100.0% of sheep (41/41) and pig (255/255) samples, and in 69.4% of bovine samples (150/216). In contrast, no plasmid was detected in the eight C. pecorum-positive ruminant abortion cases either representing plasmid-less strains or possibly escaping PCR detection due to autolysis of the placenta. This study supports the genetic diversity of C. pecorum strains, particularly in bovines, and identifies novel sequence types in Swiss livestock.

Sporadic bovine encephalopathy caused by Chlamydia pecorum secondary to bovine viral diarrhoea virus infection in calves in South Australia

BACKGROUND

Despite bovine viral diarrhoea virus and Chlamydia pecorum being important endemic diseases of cattle, there are limited reports of theirco-occurrence.

CASE REPORT

Several 12-18-week-old, weaned Hereford calves presented with ill-thriftiness and neurological signs on a mixed cattle and sheep farm in South Australia in July 2021. Immune suppression resulting from transient infection with bovine viral diarrhoea virus (BVDV) is implicated in predisposing to infection with Chlamydia pecorum, the causative agent of sporadic bovine encephalopathy (SBE). Chlamydia spp. are difficult to culture in vitro or definitively identify based on current standard molecular based tests. In this case, diagnosis was confirmed by immunohistochemistry.

CONCLUSION

To the authors' knowledge, this case report is the first to document BVDV transient infection occurring in conjunction with SBE. Given the current high prevalence of BVDV on Australian farms, such co-infections may have significant future clinical relevance. This case also highlights the need for appropriate tests, such as immunohistochemistry to demonstrate the causative organism in histological lesions and thus reduce the occurrence of false negative diagnosis.

Longitudinal study of Chlamydia pecorum in a healthy Swiss cattle population

Chlamydia pecorum is a globally endemic livestock pathogen but prevalence data from Switzerland has so far been limited. The present longitudinal study aimed to get an insight into the C. pecorum prevalence in Swiss cattle and investigated infection dynamics. The study population consisted of a bovine herd (n = 308) located on a farm in the north-eastern part of Switzerland. The herd comprised dairy cows, beef cattle and calves all sampled up to five times over a one-year period. At each sampling timepoint, rectal and conjunctival swabs were collected resulting in 782 samples per sampled area (total n = 1564). Chlamydiaceae screening was performed initially, followed by C. pecorum-specific real-time qPCR on all samples. For C. pecorum-positive samples, bacterial loads were determined. In this study, C. pecorum was the only chlamydial species found. Animal prevalences were determined to be 5.2-11.4%, 38.1-61.5% and 55-100% in dairy cows, beef cattle and calves, respectively. In all categories, the number of C. pecorum-positive samples was higher in conjunctival (n = 151) compared to rectal samples (n = 65), however, the average rectal load was higher. At a younger age, the chlamydial prevalence and the mean bacterial loads were significantly higher. Of all sampled bovines, only 9.4% (29/308) were high shedders (number of copies per μl >1,000). Calves, which tested positive multiple times, either failed to eliminate the pathogen between sampling timepoints or were reinfected, whereas dairy cows were mostly only positive at one timepoint. In conclusion, C. pecorum was found in healthy Swiss cattle. Our observations suggested that infection takes place at an early age and immunity might develop over time. Although the gastrointestinal tract is supposed to be the main infection site, C. pecorum was not present in rectal samples from dairy cows.

Seroprevalence and Risk Factors of Chlamydia Infection in Cattle in Shanxi Province, North China

The information on Chlamydia infection in cattle is limited in Shanxi Province, north China. This study aimed to investigate the seroprevalence and risk factors of Chlamydia and Chlamydia abortus infection in cattle in Shanxi Province. In November 2020, a large-scale investigation of Chlamydia seroprevalence was conducted on 981 cattle serum samples collected from 40 cattle farms in 11 cities of Shanxi Province. The seroprevalence of Chlamydia and C. abortus was examined by indirect hemagglutination assay (IHA) and enzyme-linked immunosorbent assay (ELISA), respectively. The seroprevalence of Chlamydia and C. abortus was 52.29% (513/981) and 2.96% (29/981), respectively, in cattle in Shanxi Province. Location was identified as a risk factor for Chlamydia and C. abortus infection (p < 0.05). Under different management patterns, the seroprevalence of Chlamydia and C. abortus in large-scale animal farming companies was higher than that in household animal farms and animal farming cooperatives, and only the seroprevalence of Chlamydia was significantly different in different management patterns (p < 0.01). The results showed that there was higher seroprevalence of Chlamydia in cattle in Shanxi Province, while C. abortus was not the dominant species. This study provided baseline information on Chlamydia infection in cattle in Shanxi Province, which constitutes valuable data for monitoring livestock health and preventing potential zoonoses.

Comparative analysis of two genomes of Chlamydia pecorum isolates from an Alpine chamois and a water buffalo

Background

To date, whole genome sequencing has been performed mainly for isolates of Chlamydia trachomatis, C. pneumoniae, C. psittaci and C. abortus, but only a few isolates of C. pecorum have been entirely sequenced and this makes it difficult to understand its diversity and population structure. In this study the genome of two C. pecorum strains isolated from the lung of an Alpine chamois affected with pneumonia (isolate PV7855) and the brain of a water buffalo affected with meningoencephalomyelitis (isolate PV6959), were completely sequenced with MiSeq system (Illumina) and analyzed in their most polymorphic regions.

Results

The genome length and GC content of the two isolates were found to be consistent with other C. pecorum isolates and the gene content of polymorphic membrane proteins and plasticity zone was found to be very similar. Some differences were observed in the phospholipase genes for both isolates and in the number of genes in the plasticity zone, such as the presence of some hypothetical proteins in PV6959, not present in any other genomes analyzed in this study. Interestingly, PV6959 possesses an extra pmp and has an incomplete tryptophan biosynthesis operon. Plasmids were detected in both isolates.

Conclusions

Genome sequencing of the two C. pecorum strains did not reveal differences in length and GC content despite the origin from different animal species with different clinical disease. In the plasticity zone, the differences in the genes pattern might be related to the onset of specific symptoms or infection of specific hosts. The absence of a tryptophan biosynthesis pathway in PV6959 may suggest a strict relationship between C. pecorum and its host.

A Meta-Analysis of Bovine Chlamydia Prevalence in Cattle in China from 1989 to 2020

Chlamydia bovis is a widespread infection disease caused by the mixed infection of Chlamydia psittaci, Chlamydia pecorum, Chlamydia abortus, and Chlamydia suis in cattle. Although many studies have investigated Chlamydia infection in cattle, there is no nationwide study on the prevalence of Chlamydia infection in cattle of China. We constructed the first meta-analysis to assess the infection rate and infection risk factors of Chlamydia in cattle in China, and we searched PubMed, ScienceDirect, Chinese Web of Knowledge, Wanfang, and VIP Chinese journal database for studies reporting Chlamydia infection in cattle from April 29, 2020. We collected a total of 563 publications from 1989 to 2019, and finally, 78 studies were eligible, which included 152,364 cattle from 27 provinces across the country. We estimated the pooled prevalence of Chlamydia in cattle was 14.2% (95% confidence interval [CI]: 12.2 to 16.4). The prevalence of bovine Chlamydia in China collected before 2000 (14.8%, 95% CI: 5.6 to 27.3) showed the highest prevalence rate. The highest prevalence was found in Central China (22.6%, 95% CI: 12.8 to 34.2). The prevalence of Chlamydia spp. between abortion cattle (39.1%, 95% CI: 24.6 to 54.6) and healthy cattle (8.3%, 95% CI: 3.1 to 15.2) showed significant variation (p < 0.05). In detection methods subgroup, enzyme-linked immunosorbent assay (30.5%, 95% CI: 21.5 to 40.3) showed the highest prevalence. In the age subgroup, the prevalence rate of age >1 year (16.6%, 95% CI: 12.6 to 20.9) was higher compared with age ≤1 year (9.8%, 95% CI: 6.7 to 13.3). Yaks (17.8%, 95% CI: 13.3 to 22.8) showed the highest Chlamydia prevalence among the varieties of bovine. We also estimated the potential risk factors such as feeding model, sample classification, sampling seasons, bovine gender, parity, and quality level of included studies. Our findings suggested that Chlamydia was prevalent in cattle in China. So we should pay attention to bovine Chlamydia and take necessary measures to prevent it.

Identification of Parachlamydiaceae DNA in nasal and rectal passages of healthy dairy cattle

AIMS

The order Chlamydiales comprises a broad range of bacterial pathogens and endosymbionts, which infect a wide variety of host species. Within this order, members of the family Parachlamydiaceae, which includes Parachlamydia and Neochlamydia species, have been particularly associated with infections in both humans and cattle, including having a potential pathogenic role in cases of bovine abortion. While the route of transmission has yet to be defined, it has been hypothesised that asymptomatic carriage and contamination of the immediate environment may be a route of inter-animal transmission. We investigated the asymptomatic carriage of Chlamydia-related organisms in healthy cattle.

METHODS & RESULTS

DNA was isolated from nasal and rectal swabs obtained from 38 healthy dairy heifers. A Chlamydiales sp. 16S rRNA qPCR was performed on each sample. A total of 18/38 nasal samples and all 38/38 rectal samples were identified as positive for Chlamydiales sp. Each positive sample was sequenced confirming the presence of DNA belonging to the Parachlamydiaceae.

CONCLUSIONS

The presence of Parachlamydiaceae DNA in nasal and rectal swab samples of healthy cattle provides evidence for the asymptomatic carriage of parachlamydial organisms within cattle.

SIGNIFICANCE & IMPACT OF THE STUDY

The study provides evidence of potential routes of environmental contamination that could provide a route for inter-animal and animal transmission of Parachlamydiaceae.

Seroprevalence of Seven Reproductive Diseases in Beef and Dairy Cows from Three Provinces in Indonesia

Bovine reproductive diseases are endemic in Indonesia, but comprehensive information about their infectious causes is not available. Therefore, our aim for this study was to detect several infectious agents that cause reproductive diseases in Indonesian beef and dairy cows. A total of 152 cow serum samples collected by Faculty of Veterinary Medicine of Brawijaya University and Veterinary Disease Investigation Centre as a part of the mandatory and regularly surveillance system from three provinces during 2019–2020 were used. The samples were then sent to Indonesian Research Centre for Veterinary Science (IRCVS) for further detection of seven reproductive diseases by enzyme-linked immunosorbent assay (ELISA). Seven reproductive diseases to be tested in parallel are neosporosis, chlamydiosis, brucellosis, Q fever, bovine viral diarrhea (BVD), infectious bovine rhinotracheitis (IBR), and BHV-4 infection. The dominant reproductive diseases in Indonesian cows were BVD (45.69%), chlamydiosis (31.58%), IBR (20.53%), neosporosis (11.84%), and BHV-4 infection (10.53%). The seroprevalence of IBR, BHV-4 infection, neosporosis, and brucellosis varied significantly (P < 0.05) between dairy and beef cattle. The most dominant reproductive diseases in aborted cows were chlamydiosis (45%), BVD (41%), and neosporosis (10%). The conclusion drawn from this study is that the dominant reproductive diseases in Indonesian cows are BVD, chlamydiosis, IBR, neosporosis, and BHV-4 infection. Chlamydiosis, BVD, and neosporosis are common among aborted cow. Chlamydiosis, neosporosis, and BHV-4 infection should be included in the national priority list in Indonesia. Control and preventive measures should be focused on high-risk areas and animals like stray cat and dog.

Phylogenetic and molecular analysis based on genes 16S-rRNA, OMPA and POMP to identify Chlamydia abortus infection occurrence at the milk samples of goats and sheep in west Azerbaijan of Iran

Background and Objectives:

Enzootic abortion in sheep and goats, also called ovine enzootic abortion (OEA) or enzootic abortion of ewes (EAE), is caused by Chlamydia abortus. The disease has a major economic impact as it represents the most important cause of lamb loss in sheep in parts of Europe, North America and Africa. This serious and potentially life-threatening zoonosis can also affect pregnant women after contact with lambing ewes, leading to severe febrile illness in pregnancy and loss of the foetus.

Materials and Methods:

The present study was conducted to the Phylogenetic and Molecular Analysis based on Genes 16S-rRNA, OmpA and POMP of C. abortus in milk samples collected from sheep and goats in West Azerbaijan province, Iran. During 2018, a total number of 360 milk samples were collected from sheep (n = 180) and goats (n = 180) of different regions of the province. All milk samples were subjected to DNA extraction and examined by PCR.

Results:

Among 360 milk samples collected from sheep and goats, 31 (8.611%; 95% CI=6.13–11.96) were positive for Chlamydia spp. The helicase, 16S-rRNA and ompA genes were examined and resulted in 8, 31, 31 of positive samples respectively. The accession numbers have been deposited in GenBank (NCBI) (MT367602 and MT367603).

Conclusion:

Phylogenetic analysis based on the gene of helicase showed that most of the isolates shared similarity > 99.97%.

Component Causes of Infectious Bovine Keratoconjunctivitis-Non-Moraxella Organisms in the Epidemiology of Infectious Bovine Keratoconjunctivitis

Infectious bovine keratoconjunctivitis (IBK) is a multifactorial disease complex caused by opportunistic pathogens, classically those members of the genus Moraxella. However, IBK in some situations is associated with other potentially pathogenic agents, which include Mycoplasma bovoculi, Mycoplasma bovis, Ureaplasma diversum, bovine herpesviruses, and Chlamydia sp. Ocular infections that may resemble IBK are also caused by Listeria monocytogenes. These agents and their association with IBK are reviewed in this article.

Meningoencephalitis, Vasculitis, and Abortions Caused by Chlamydia pecorum in a Herd of Cattle

A cow dairy (n = 2000) in close proximity to a sheep flock had third-trimester abortions and fatalities in cows and calves over a 14-month period. Eighteen of 33 aborted fetuses (55%) had multifocal random suppurative or mononuclear meningoencephalitis with vasculitis. Seventeen of these affected fetuses had intracytoplasmic bacteria in endothelial cells, and 1 fetus with pericarditis had similar bacteria within mesothelial cells or macrophages. Immunohistochemistry for Chlamydia spp. or polymerase chain reaction (PCR) for Chlamydia pecorum or both, performed on brain or pooled tissue, were positive in all 14 tested fetuses that had meningoencephalitis and in 4/4 calves and in 3/4 tested cows that had meningoencephalitis and thrombotic vasculitis. In 1 calf and 11/11 fetuses, C. pecorum PCR amplicon sequences were 100% homologous to published C. pecorum sequences. Enzootic chlamydiosis due to C. pecorum was the identified cause of the late term abortions and the vasculitis and meningoencephalitis in fetuses, calves, and cows. C. pecorum, an uncommon bovine abortogenic agent, is a differential diagnosis in late-term aborted fetuses with meningoencephalitis, vasculitis, and polyserositis.

Peptide ELISA and FRET-qPCR Identified a Significantly Higher Prevalence of Chlamydia suis in Domestic Pigs Than in Feral Swine from the State of Alabama, USA

Chlamydia suis is an important, highly prevalent, and diverse obligate intracellular pathogen infecting pigs. In order to investigate the prevalence and diversity of C. suis in the U.S., 276 whole blood samples from feral swine were collected as well as 109 fecal swabs and 60 whole blood samples from domestic pigs. C. suis-specific peptide ELISA identified anti-C. suis antibodies in 13.0% of the blood of feral swine (26/276) and 80.0% of the domestic pigs (48/60). FRET-qPCR and DNA sequencing found C. suis DNA in 99.1% of the fecal swabs (108/109) and 21.7% of the whole blood (13/60) of the domestic pigs, but not in any of the assayed blood samples (0/267) in feral swine. Phylogenetic comparison of partial C. suis ompA gene sequences and C. suis-specific multilocus sequencing typing (MLST) revealed significant genetic diversity of the C. suis identified in this study. Highly genetically diverse C. suis strains are prevalent in domestic pigs in the USA. As crowding strongly enhances the frequency and intensity of highly prevalent Chlamydia infections in animals, less population density in feral swine than in domestic pigs may explain the significantly lower C. suis prevalence in feral swine. A future study is warranted to obtain C. suis DNA from feral swine to perform genetic diversity of C. suis between commercial and feral pigs.

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.

Chlamydial infection and on-farm risk factors in dairy cattle herds in South East Queensland

Chlamydial infections in dairy cattle are common and have been sporadically associated with reduced performance and severe disease manifestations. While chlamydial infections are well described in sheep, very little is known about the epidemiology of these infections in dairy cattle in Australia. In this study, we screened for chlamydial infections and assessed on-farm risks in dairy cattle herds from Southeast Queensland (SE Qld) region of Australia. In total, 228 paired vaginal and rectal swabs were collected from 114 visually healthy dairy cows from four farms in SE Qld. Risk factors were rated by observational study and included: hygiene and cleanliness of cows, walkway and parlour, incidence of perinatal mortality, external replacements, mode of breeding, calving pen management, heat reduction strategies, and feed ration usage. Testing for chlamydial pathogens (Chlamydia pecorum, Chlamydia psittaci and Chlamydia abortus) was done using species-specific quantitative polymerase chain reaction (qPCR) assays. Detected rates of chlamydial infection were evaluated against the on-farm risk factors. C. pecorum infection was widespread in all four farms, with 56.1% (64/114) of individual animals shedding this organism from vaginal and rectal, or both sites. C. abortus and C. psittaci were not detected in any animals. No association was found to exist with risk factors and C. pecorum infection rates in our study, however the number of Chlamydia positive animals was statistically different between the herds. This study suggests that subclinical chlamydial infections may impact on dairy herd health at the production level rather than affecting individual animal.

In vitro analysis of genetically distinct Chlamydia pecorum isolates reveals key growth differences in mammalian epithelial and immune cells

Chlamydia (C.) pecorum is an obligate intracellular bacterium that infects and causes disease in a broad range of animal hosts. Molecular studies have revealed that this pathogen is genetically diverse with certain isolates linked to different disease outcomes. Limited in vitro or in vivo data exist to support these observations, further hampering efforts to improve our understanding of C. pecorum pathogenesis. In this study, we evaluated whether genetically distinct C. pecorum isolates (IPA, E58, 1710S, W73, JP-1-751) display different in vitro growth phenotypes in different mammalian epithelial and immune cells. In McCoy cells, shorter lag phases were observed for W73 and JP-1-751 isolates. Significantly smaller inclusions were observed for the naturally plasmid-free E58 isolate. C. pecorum isolates of bovine (E58) and ovine origin (IPA, W73, JP-1-751) grew faster in bovine cells compared to a porcine isolate (1710S). C. pecorum isolates could infect but appear not able to complete their developmental cycle in bovine peripheral neutrophil granulocytes. All isolates, except 1710S, could multiply in bovine monocyte-derived macrophages. These results reveal potentially important phenotypic differences that will help to understand the pathogenesis of C. pecorum in vivo and to identify C. pecorum virulence factors.

Risk of Chlamydia abortus transmission via embryo transfer using in vitro produced early bovine embryos

The objectives of this study were to determine (i) whether Chlamydia (C.) abortus would adhere to the intact zona pellucida (ZP-intact) of early in vitro produced bovine embryos; (ii) whether the bacteria would adhere to the embryos (ZP-free) after in vitro infection; and (iii) the efficacy of the International Embryo Transfer Society (IETS) washing protocol. The experimentation was made twice. For each replicate 100 (8-16-cell) bovine embryos produced in vitro were randomly divided into 10 batches. Height batches (4 ZP-intact and 4 ZP-free) of 10 embryos were incubated in a medium containing 4 × 10⁷Chlamydia/ml of AB7 strain. After incubation for 18 h at 37 °C in an atmosphere of 5% CO₂, the embryos were washed in accordance with the IETS guidelines. In parallel, two batches (1 ZP-intact and 1 ZP-free) of 10 embryos were subjected to similar procedures but without exposure to C. abortus as a control group. The 10 washing fluids from each batch were collected and centrifuged for 1 h at 13,000×g. Each batch of washed embryos and each wash pellets were tested using PCR. C. abortus DNA was found in all ZP-intact and ZP-free batches of 10 embryos after 10 successive washes. For ZP-intact infected embryos, Chlamydia-DNA was also detected in all 10 wash baths for two batches (2/8) of embryos, whereas for ZP-free infected embryos, Chlamydia-DNA was detected in all 10 wash baths for 6/8 batches of embryos. In contrast, none of the embryos or their washing fluids in the control batches was DNA positive. The bacterial load for batches of 10 embryos after the 10 wash baths was significantly higher for batches of ZP-free embryos (20.7 ± 9 × 10³ bacteria/mL) than for batches of ZP-intact embryos (0.47 ± 0.19 × 10³ bacteria/mL). These results demonstrate that C. abortus adheres to the ZP as well as the early embryonic cells of in vitro produced bovine embryos after in vitro infection, and that the standard washing protocol recommended by the IETS fails to remove it.

Understanding the health and production impacts of endemic Chlamydia pecorum infections in lambs

Lamydia pecorum is a globally recognised livestock pathogen that is capable of causing severe and economically significant diseases such as arthritis in sheep and cattle. Relatively little information is available on the clinical progression of disease and the long-term effects of asymptomatic and symptomatic chlamydiosis in sheep. Recent studies in calves indicate that endemic C. pecorum infections may reduce growth rates. To investigate the clinical health parameters and production impacts of endemic C. pecorum infection in an Australian commercial lamb flock, we performed bimonthly sampling and clinical health assessments on 105 Border Leicester lambs from two to ten months of age. Chlamydial status was investigated via serology and species-specific quantitative PCR. Throughout the study period, conjunctivitis remained a persistent clinical feature while signs of arthritis (e.g. palpable synovial joint effusions) resolved in a subset of lambs while persisting in others. Clinical disease and C. pecorum infection were highest at six months of age (weaning). As previously reported, peak seroconversion tends to occur two months after the onset of clinical symptoms (6 months of age), with lambs clearing chlamydial infection by 10 months of age, despite ongoing disease still being present at this time. Notably, the presence of chlamydial infection did not affect lamb mass or growth rates throughout the study. At necropsy, C. pecorum was not detected within the joints of lambs with chronic arthritis. Molecular analysis of the strains in this flock suggest that the infecting strains circulating in this flock are clonal C. pecorum pathotypes, denoted ST 23, commonly associated with conjunctivitis and polyarthritis in Australian sheep. This study provides a platform for further research in the epidemiology and disease transmission dynamics of C. pecorum infections in sheep.

Sero-prevalence of chlamydiosis in cattle and selected wildlife species at a wildlife/livestock interface area of Zimbabwe

A study was conducted to investigate the seroprevalence and associated risk factors of Chlamydia abortus infection in cattle and some selected wildlife species at selected interface areas at the periphery of the Great Limpopo Transfrontier Conservation Area in Zimbabwe. Three study sites were selected based on the type of livestock-wildlife interface, porous livestock-wildlife interface (unrestricted), non-porous livestock-wildlife interface (restricted by fencing), and livestock-wildlife non-interface (totally absent or control). Sera were collected from cattle aged ≥ 2 years representing both female and intact male. Sera were also collected from selected wild ungulates from Mabalauta (porous interface) and Chipinda Pools (non-interface) areas of the Gonarezhou National Park. Sera were tested for antibodies to Chlamydia abortus using a CFT. A X ² test was used to assess differences between categories and p < 0.05 was considered as significant. In cattle, the overall seroprevalence was 32.7% (327/1011; 95% CI 29.5-35.3). A significantly lower seroprevalence was recorded for the porous interface (24.2%) compared to the non-porous (42.5%) (p < 0.0001) and the non-interface (36.2%) (p = 0.001). Overall, the wet season recorded a significantly (p = 0.015) higher seroprevalence than the dry season. In wildlife, antibodies were detected in buffaloes (47.7%) and impalas (43.8%) but not in kudus. Buffaloes from Chipinda Pools (53.4%) had a significantly (p = 0.036) higher seroprevalence than those from Mabalauta (26.1%). The results established the presence of chlamydiosis in cattle and selected wildlife and that independent infections may be maintained in buffalo populations. Further studies are required to clarify chlamydiae circulating between cattle and wildlife.

Chlamydia pecorum: fetal and placental lesions in sporadic caprine abortion

Chlamydial abortion in small ruminants is usually associated with Chlamydia abortus infection. Although Chlamydia pecorum has been detected in aborted ruminants and epidemiological data suggests that C. pecorum is abortigenic in these species, published descriptions of lesions in fetuses are lacking. This work describes fetoplacental lesions in a caprine abortion with C. pecorum infection, and further supports the abortigenic role of C. pecorum in ruminants. A 16-month-old Boer goat aborted twin fetuses at ~130 days of gestation. Both fetuses (A and B) and the placenta of fetus A were submitted for postmortem examination and diagnostic workup. At autopsy, the fetuses had moderate anasarca, intermuscular edema in the hindquarters (A), and brachygnathia and palatoschisis (B). In the placenta, the cotyledons were covered by yellow fibrinosuppurative exudate that extended into the adjacent intercotyledonary areas. Histologically, there was severe suppurative and necrotizing placentitis with vasculitis (arteriolitis) and thrombosis, multifocal lymphohistiocytic and neutrophilic hepatitis (A), and fibrinosuppurative enteritis in both fetuses. Chlamydia antigen was detected in the placenta by the direct fluorescent antibody test and in fetal intestines by immunohistochemistry. Nested polymerase chain reaction of DNA extracted from formalin-fixed, paraffin-embedded sections of placenta and intestine amplified 400 bp of the Chlamydia 16S rRNA gene that was sequenced and found to be 99% identical to C. pecorum by BLAST analysis. Other known abortigenic infectious agents were ruled out by specific testing. It is concluded that C. pecorum infection is associated with fetoplacental lesions and sporadic abortion in goats.

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

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.

First report and histological features of Chlamydia pecorum encephalitis in calves in New Zealand

CASE HISTORY

Between September and October 2013, 40 of 150 crossbred Friesian dairy calves on a farm in the Manawatu region of New Zealand developed neurological signs when between 1 and 3 months of age. Calves were grazed in multiple mobs and calves from each mob were affected. A variable response was observed to initial treatment with thiamine, fluoroquinolone antibiotics and non-steroidal anti-inflammatory drugs.

CLINICAL AND PATHOLOGICAL FINDINGS

Affected calves exhibited a range of neurological signs that included generalised depression, hind limb ataxia with a stiff gait, and knuckling of the fetlocks. In advanced cases, calves became recumbent with opisthotonous. Over a 4-week period, 13 calves died or were subject to euthanasia and a thorough necropsy was performed on three of these calves. Necropsy findings included fibrinous peritonitis, pleuritis and pericarditis, with no gross abnormalities visible in the brain or joints. Histology of the brain was possible in seven of the affected calves, with lesions ranging from lymphocytic and histiocytic vasculitis and meningoencephalitis, to extensive thrombosis and neutrophilic inflammation. Immunohistochemistry using an anti-chlamydial lipopolysaccharide antibody revealed positive immuno-staining in all seven cases, with no brain samples exhibiting immunostaining for Histophilus somni. DNA was extracted from a sample of fresh brain from one case and chlamydial DNA sequences were amplified by PCR and found to be identical to Chlamydia pecorum. PCR was also performed on formalin-fixed brain tissue from three of the other cases, but no chlamydial DNA was amplified.

DIAGNOSIS

Chlamydia pecorum meningoencephalomyelitis (sporadic bovine encephalomyelitis).

CLINICAL RELEVANCE

This is the first time that C. pecorum has been confirmed as a cause of clinical disease in New Zealand. Practitioners should be aware of this disease as a differential in calves with neurological signs, and submit samples of formalin-fixed brain as well as fresh brain to enable confirmation of suspected cases using PCR analysis. Furthermore, these cases illustrate that the histological lesions in the brains of calves with C. pecorum are more variable than previously reported, and pathologists should be aware that histological features may overlap with those traditionally ascribed to other organisms, such as H. somni.

Chlamydia pecorum infections in sheep and cattle: A common and under-recognised infectious disease with significant impact on animal health

There is a growing recognition that infections of livestock by the obligate intracellular bacterium, Chlamydia pecorum, are more widespread than was previously thought. A range of diseases have been associated with this pathogen, with the most important manifestations including infectious arthritis, infertility, enteritis, reduced growth rates, mastitis, and pneumonia. C. pecorum infections have also been associated with sub-clinical disease, highlighting our lack of knowledge about its true economic impact on livestock producers. Diagnosis of C. pecorum infection is based on clinical findings, serology and histopathology, which are not necessarily implemented in subclinical or early stages of infection, thus potentially contributing to under-diagnosis and under-reporting of infections associated with this bacterium. Recent molecular epidemiology studies have revealed that C. pecorum is genetically diverse and that there may be an association between certain strains and disease in sheep and cattle. Antimicrobial treatment of affected animals has questionable efficacy, justifying development of chlamydia vaccines for livestock. This review summarises current knowledge of the prevalence and impact of C. pecorum infections in sheep and cattle and provides an update on attempts to improve detection, management and treatment of infections by this important obligate intracellular pathogen.

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

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 CD8^hi 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 CD8d^im/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.

Prevalence of antibodies to Chlamydiaceae in pet dogs in Shenzhen, Guangdong Province, China

The prevalence of chlamydiosis in pet dogs was surveyed in Shenzhen, Guangdong Province, China. A total of 442 serum samples were collected from three districts of Shenzhen, namely the Futian, Nanshan, and Luohu Districts, and assayed for Chlamydiaceae antibodies by indirect haemagglutination assay. The results showed that the mean positive rate was 6.11%, and the positive rate for the Futian District was the highest (9.52%), followed by the Nanshan District (7.08%), and the Luohu District (4.02%). The positive rate for male dogs was 6.08%, and for female dogs 6.16%. Out of all the 38 breeds of dogs examined, 14 breeds were positive. The positive rate for the Cocker Spaniel dog was the highest (14.2%), followed by the Pekinese dog (10.71%), and the Border Collie dog (10.34%). This is the first time that the seroprevalence of Chlamydiaceae infection in pet dogs in Shenzhen, Guangdong province, China was reported, and the results indicated that pet dogs may be an important source for human infection by Chlamydiaceae in Shenzhen and other areas of China.

Culture-independent genome sequencing of clinical samples reveals an unexpected heterogeneity of infections by Chlamydia pecorum

Chlamydia pecorum is an important global pathogen of livestock, and it is also a significant threat to the long-term survival of Australia's koala populations. This study employed a culture-independent DNA capture approach to sequence C. pecorum genomes directly from clinical swab samples collected from koalas with chlamydial disease as well as from sheep with arthritis and conjunctivitis. Investigations into single-nucleotide polymorphisms within each of the swab samples revealed that a portion of the reads in each sample belonged to separate C. pecorum strains, suggesting that all of the clinical samples analyzed contained mixed populations of genetically distinct C. pecorum isolates. This observation was independent of the anatomical site sampled and the host species. Using the genomes of strains identified in each of these samples, whole-genome phylogenetic analysis revealed that a clade containing a bovine and a koala isolate is distinct from other clades comprised of livestock or koala C. pecorum strains. Providing additional evidence to support exposure of koalas to Australian livestock strains, two minor strains assembled from the koala swab samples clustered with livestock strains rather than koala strains. Culture-independent probe-based genome capture and sequencing of clinical samples provides the strongest evidence yet to suggest that naturally occurring chlamydial infections are comprised of multiple genetically distinct strains.

Comparative genomics of koala, cattle and sheep strains of Chlamydia pecorum

BACKGROUND

Chlamydia pecorum is an important pathogen of domesticated livestock including sheep, cattle and pigs. This pathogen is also a key factor in the decline of the koala in Australia. We sequenced the genomes of three koala C. pecorum strains, isolated from the urogenital tracts and conjunctiva of diseased koalas. The genome of the C. pecorum VR629 (IPA) strain, isolated from a sheep with polyarthritis, was also sequenced.

RESULTS

Comparisons of the draft C. pecorum genomes against the complete genomes of livestock C. pecorum isolates revealed that these strains have a conserved gene content and order, sharing a nucleotide sequence similarity > 98%. Single nucleotide polymorphisms (SNPs) appear to be key factors in understanding the adaptive process. Two regions of the chromosome were found to be accumulating a large number of SNPs within the koala strains. These regions include the Chlamydia plasticity zone, which contains two cytotoxin genes (toxA and toxB), and a 77 kbp region that codes for putative type III effector proteins. In one koala strain (MC/MarsBar), the toxB gene was truncated by a premature stop codon but is full-length in IPTaLE and DBDeUG. Another five pseudogenes were also identified, two unique to the urogenital strains C. pecorum MC/MarsBar and C. pecorum DBDeUG, respectively, while three were unique to the koala C. pecorum conjunctival isolate IPTaLE. An examination of the distribution of these pseudogenes in C. pecorum strains from a variety of koala populations, alongside a number of sheep and cattle C. pecorum positive samples from Australian livestock, confirmed the presence of four predicted pseudogenes in koala C. pecorum clinical samples. Consistent with our genomics analyses, none of these pseudogenes were observed in the livestock C. pecorum samples examined. Interestingly, three SNPs resulting in pseudogenes identified in the IPTaLE isolate were not found in any other C. pecorum strain analysed, raising questions over the origin of these point mutations.

CONCLUSIONS

The genomic data revealed that variation between C. pecorum strains were mainly due to the accumulation of SNPs, some of which cause gene inactivation. The identification of these genetic differences will provide the basis for further studies to understand the biology and evolution of this important animal pathogen.

Host adaptation of Chlamydia pecorum towards low virulence evident in co-evolution of the ompA, incA, and ORF663 Loci

Chlamydia (C.) pecorum, an obligate intracellular bacterium, may cause severe diseases in ruminants, swine and koalas, although asymptomatic infections are the norm. Recently, we identified genetic polymorphisms in the ompA, incA and ORF663 genes that potentially differentiate between high-virulence C. pecorum isolates from diseased animals and low-virulence isolates from asymptomatic animals. Here, we expand these findings by including additional ruminant, swine, and koala strains. Coding tandem repeats (CTRs) at the incA locus encoded a variable number of repeats of APA or AGA amino acid motifs. Addition of any non-APA/AGA repeat motif, such as APEVPA, APAVPA, APE, or APAPE, associated with low virulence (P<10⁻⁴), as did a high number of amino acids in all incA CTRs (P = 0.0028). In ORF663, high numbers of 15-mer CTRs correlated with low virulence (P = 0.0001). Correction for ompA phylogram position in ORF663 and incA abolished the correlation between genetic changes and virulence, demonstrating co-evolution of ompA, incA, and ORF663 towards low virulence. Pairwise divergence of ompA, incA, and ORF663 among isolates from healthy animals was significantly higher than among strains isolated from diseased animals (P≤10⁻⁵), confirming the longer evolutionary path traversed by low-virulence strains. All three markers combined identified 43 unique strains and 4 pairs of identical strains among all 57 isolates tested, demonstrating the suitability of these markers for epidemiological investigations.

Chlamydia genomics: providing novel insights into chlamydial biology

Chlamydiaceae are obligate intracellular pathogens that have successfully evolved to colonize a diverse range of hosts. There are currently 11 described species of Chlamydia, most of which have a significant impact on the health of humans or animals. Expanding chlamydial genome sequence information has revolutionized our understanding of chlamydial biology, including aspects of their unique lifecycle, host-pathogen interactions, and genetic differences between Chlamydia strains associated with different host and tissue tropisms. This review summarizes the major highlights of chlamydial genomics and reflects on the considerable impact these have had on understanding the biology of chlamydial pathogens and the changing nature of genomics tools in the 'post-genomics' era.

Longitudinal prevalence and faecal shedding of Chlamydia pecorum in sheep

The prevalence and faecal shedding of Chlamydia spp. in sheep in Australia has not been well described. Two species-specific quantitative PCRs (qPCRs) targeting the chlamydial outer membrane protein cell surface antigen gene (ompA) were validated and used to determine the prevalence and faecal shedding of C. abortus and C. pecorum from faecal samples of lambs at three sampling times (weaning, post-weaning and pre-slaughter) from eight farms in South Australia, New South Wales, Victoria and Western Australia. A total of 3412 faecal samples were collected and screened from approximately 1189 lambs across the four states. C. abortus was not detected in any of the samples screened. The overall prevalence of C. pecorum was 1027/3412 (30.1%) and median bacterial concentrations at weaning, post-weaning and pre-slaughter were 1.8 × 10(7), 1.2 × 10(7) and 9.6 × 10(5)/g faeces, respectively. A subset of C. pecorum positive samples from each farm, (n = 48) was sequenced to confirm their identity. The present study demonstrates that C. pecorum is prevalent in Australian sheep, highlighting a need for further research on the impact of this bacterium on production.

Molecular and pathological insights into Chlamydia pecorum-associated sporadic bovine encephalomyelitis (SBE) in Western Australia

Background

Despite its global recognition as a ruminant pathogen, cases of Chlamydia pecorum infection in Australian livestock are poorly documented. In this report, a C. pecorum specific Multi Locus Sequence Analysis scheme was used to characterise the C. pecorum strains implicated in two cases of sporadic bovine encephalomyelitis confirmed by necropsy, histopathology and immunohistochemistry. This report provides the first molecular evidence for the presence of mixed infections of C. pecorum strains in Australian cattle.

Case presentation

Affected animals were two markedly depressed, dehydrated and blind calves, 12 and 16 weeks old. The calves were euthanized and necropsied. In one calf, a severe fibrinous polyserositis was noted with excess joint fluid in all joints whereas in the other, no significant lesions were seen. No gross abnormalities were noted in the brain of either calf. Histopathological lesions seen in both calves included: multifocal, severe, subacute meningoencephalitis with vasculitis, fibrinocellular thrombosis and malacia; diffuse, mild, acute interstitial pneumonia; and diffuse, subacute epicarditis, severe in the calf with gross serositis. Immunohistochemical labelling of chlamydial antigen in brain, spleen and lung from the two affected calves and brain from two archived cases, localised the antigen to the cytoplasm of endothelium, mesothelium and macrophages. C. pecorum specific qPCR, showed dissemination of the pathogen to multiple organs. Phylogenetic comparisons with other C. pecorum bovine strains from Australia, Europe and the USA revealed the presence of two genetically distinct sequence types (ST). The predominant ST detected in the brain, heart, lung and liver of both calves was identical to the C. pecorum ST previously described in cases of SBE. A second ST detected in an ileal tissue sample from one of the calves, clustered with previously typed faecal bovine isolates.

Conclusion

This report provides the first data to suggest that identical C. pecorum STs may be associated with SBE in geographically separated countries and that these may be distinct from those found in the gastrointestinal tract. This report provides a platform for further investigations into SBE and for understanding the genetic relationships that exist between C. pecorum strains detected in association with other infectious diseases in livestock.

Genome sequencing and comparative analysis of three Chlamydia pecorum strains associated with different pathogenic outcomes

Background

Chlamydia pecorum is the causative agent of a number of acute diseases, but most often causes persistent, subclinical infection in ruminants, swine and birds. In this study, the genome sequences of three C. pecorum strains isolated from the faeces of a sheep with inapparent enteric infection (strain W73), from the synovial fluid of a sheep with polyarthritis (strain P787) and from a cervical swab taken from a cow with metritis (strain PV3056/3) were determined using Illumina/Solexa and Roche 454 genome sequencing.

Results

Gene order and synteny was almost identical between C. pecorum strains and C. psittaci. Differences between C. pecorum and other chlamydiae occurred at a number of loci, including the plasticity zone, which contained a MAC/perforin domain protein, two copies of a >3400 amino acid putative cytotoxin gene and four (PV3056/3) or five (P787 and W73) genes encoding phospholipase D. Chlamydia pecorum contains an almost intact tryptophan biosynthesis operon encoding trpABCDFR and has the ability to sequester kynurenine from its host, however it lacks the genes folA, folKP and folB required for folate metabolism found in other chlamydiae. A total of 15 polymorphic membrane proteins were identified, belonging to six pmp families. Strains possess an intact type III secretion system composed of 18 structural genes and accessory proteins, however a number of putative inc effector proteins widely distributed in chlamydiae are absent from C. pecorum. Two genes encoding the hypothetical protein ORF663 and IncA contain variable numbers of repeat sequences that could be associated with persistence of infection.

Conclusions

Genome sequencing of three C. pecorum strains, originating from animals with different disease manifestations, has identified differences in ORF663 and pseudogene content between strains and has identified genes and metabolic traits that may influence intracellular survival, pathogenicity and evasion of the host immune system.

Electronic supplementary material

The online version of this article (doi:10.1186/1471-2164-15-23) contains supplementary material, which is available to authorized users.

Seroprevalence of Chlamydophila abortus infection in yaks (Bos grunniens) in Qinghai, China

Chlamydophila abortus is an important amphixenosis which in a wide range of animals, associated with reproductive disorders in yaks. In order to assess the prevalence of this infection in yaks in Qinghai, China, a cross-sectional study was carried out, and a total of 674 serum samples were collected from June to October 2012 in six counties, and antibodies to C. abortus were examined by indirect hemagglutination (IHA) test. The overall seroprevalence of C. abortus in yaks was 17.66 % (119/674), and the seroprevalence of antibodies to C. abortus in yaks ranged from 11.82 to 28.43 % among the six different areas, and the difference was statistically significant (P < 0.05). The seropositivity of C. abortus infection in different age groups varied from 16.33 to 18.49 %, and prevalence in yaks of ≥3 year (18.49 %) was slightly higher than that in yaks of <3 year, but the differences among the age groups were not statistically significant (P > 0.05). The seroprevalence of C. abortus infection in male yak (16.8 %) was slightly lower than that in females (17.85 %), and the difference was not statistically significant (P > 0.05). So far, this is the first systematic and comprehensive investigation of C. abortus infectionin in yaks in this area.

Multilocus sequence analysis provides insights into molecular epidemiology of Chlamydia pecorum infections in Australian sheep, cattle, and koalas

Chlamydia pecorum is a significant pathogen of domestic livestock and wildlife. We have developed a C. pecorum-specific multilocus sequence analysis (MLSA) scheme to examine the genetic diversity of and relationships between Australian sheep, cattle, and koala isolates. An MLSA of seven concatenated housekeeping gene fragments was performed using 35 isolates, including 18 livestock isolates (11 Australian sheep, one Australian cow, and six U.S. livestock isolates) and 17 Australian koala isolates. Phylogenetic analyses showed that the koala isolates formed a distinct clade, with limited clustering with C. pecorum isolates from Australian sheep. We identified 11 MLSA sequence types (STs) among Australian C. pecorum isolates, 10 of them novel, with koala and sheep sharing at least one identical ST (designated ST2013Aa). ST23, previously identified in global C. pecorum livestock isolates, was observed here in a subset of Australian bovine and sheep isolates. Most notably, ST23 was found in association with multiple disease states and hosts, providing insights into the transmission of this pathogen between livestock hosts. The complexity of the epidemiology of this disease was further highlighted by the observation that at least two examples of sheep were infected with different C. pecorum STs in the eyes and gastrointestinal tract. We have demonstrated the feasibility of our MLSA scheme for understanding the host relationship that exists between Australian C. pecorum strains and provide the first molecular epidemiological data on infections in Australian livestock hosts.

Infection, disease, and transmission dynamics in calves after experimental and natural challenge with a Bovine Chlamydia psittaci isolate

Chlamydia (C.) psittaci is the causative agent of psittacosis, a zoonotic disease in birds and man. In addition, C. psittaci has been repeatedly found in domestic animals and is, at least in calves, also able to induce respiratory disease. Knowledge about transmission routes in cattle herds is still deficient, and nothing is known about differences in host response after either experimental or natural exposure to C. psittaci. Therefore, our recently developed respiratory infection model was exploited to evaluate (i) the presence of the pathogen in blood, excretions and air, (ii) the possibility of transmission and (iii) clinical symptoms, acute phase and immune response until 5 weeks after exposure. In this prospective study, intrabronchial inoculation of 10⁸ inclusion-forming units of C. psittaci (n = 21 calves) led to reproducible acute respiratory illness (of approximately one week), accompanied by a systemic inflammatory reaction with an innate immune response dominated by neutrophils. Excretion and/or exhalation of the pathogen was sufficient to transmit the infection to naïve sentinel calves (n = 3) co-housed with the infected animals. Sentinel calves developed mild to subclinical infections only. Notably, excretion of the pathogen, predominantly via feces, occurred more frequently in animals naturally exposed to C. psittaci (i.e. sentinels) as compared to experimentally-inoculated calves. The humoral immune response was generally weak, and did not emerge regularly following experimental infection; however, it was largely absent after naturally acquired infection.

Asymptomatic endemic Chlamydia pecorum infections reduce growth rates in calves by up to 48 percent

Intracellular Chlamydia (C.) bacteria cause in cattle some acute but rare diseases such as abortion, sporadic bovine encephalomyelitis, kerato-conjunctivitis, pneumonia, enteritis and polyarthritis. More frequent, essentially ubiquitous worldwide, are low-level, asymptomatic chlamydial infections in cattle. We investigated the impact of these naturally acquired infections in a cohort of 51 female Holstein and Jersey calves from birth to 15 weeks of age. In biweekly sampling, we measured blood/plasma markers of health and infection and analyzed their association with clinical appearance and growth in dependence of chlamydial infection intensity as determined by mucosal chlamydial burden or contemporaneous anti-chlamydial plasma IgM. Chlamydia 23S rRNA gene PCR and ompA genotyping identified only C. pecorum (strains 1710S, Maeda, and novel strain Smith3v8) in conjunctival and vaginal swabs. All calves acquired the infection but remained clinically asymptomatic. High chlamydial infection associated with reduction of body weight gains by up to 48% and increased conjunctival reddening (P<10⁻⁴). Simultaneously decreased plasma albumin and increased globulin (P<10⁻⁴) suggested liver injury by inflammatory mediators as mechanisms for the growth inhibition. This was confirmed by the reduction of plasma insulin like growth factor-1 at high chlamydial infection intensity (P<10⁻⁴). High anti-C. pecorum IgM associated eight weeks later with 66% increased growth (P = 0.027), indicating a potential for immune protection from C. pecorum-mediated growth depression. The worldwide prevalence of chlamydiae in livestock and their high susceptibility to common feed-additive antibiotics suggests the possibility that suppression of chlamydial infections may be a major contributor to the growth promoting effect of feed-additive antibiotics.

A bovine model of respiratory Chlamydia psittaci infection: challenge dose titration

This study aimed to establish and evaluate a bovine respiratory model of experimentally induced acute C. psittaci infection. Calves are natural hosts and pathogenesis may resemble the situation in humans. Intrabronchial inoculation of C. psittaci strain DC15 was performed in calves aged 2–3 months via bronchoscope at four different challenge doses from 10⁶ to 10⁹ inclusion-forming units (ifu) per animal. Control groups received either UV-inactivated C. psittaci or cell culture medium. While 10⁶ ifu/calf resulted in a mild respiratory infection only, the doses of 10⁷ and 10⁸ induced fever, tachypnea, dry cough, and tachycardia that became apparent 2–3 days post inoculation (dpi) and lasted for about one week. In calves exposed to 10⁹ ifu C. psittaci, the respiratory disease was accompanied by severe systemic illness (apathy, tremor, markedly reduced appetite). At the time point of most pronounced clinical signs (3 dpi) the extent of lung lesions was below 10% of pulmonary tissue in calves inoculated with 10⁶ and 10⁷ ifu, about 15% in calves inoculated with 10⁸ and more than 30% in calves inoculated with 10⁹ ifu C. psittaci. Beside clinical signs and pathologic lesions, the bacterial load of lung tissue and markers of pulmonary inflammation (i.e., cell counts, concentration of proteins and eicosanoids in broncho-alveolar lavage fluid) were positively associated with ifu of viable C. psittaci. While any effect of endotoxin has been ruled out, all effects could be attributed to infection by the replicating bacteria. In conclusion, the calf represents a suitable model of respiratory chlamydial infection. Dose titration revealed that both clinically latent and clinically manifest infection can be reproduced experimentally by either 10⁶ or 10⁸ ifu/calf of C. psittaci DC15 while doses above 10⁸ ifu C. psittaci cannot be recommended for further studies for ethical reasons. This defined model of different clinical expressions of chlamydial infection allows studying host-pathogen interactions.

Chlamydiaceae in cattle: commensals, trigger organisms, or pathogens?

Epidemiological data indicate that infection of cattle with chlamydiae such as Chlamydophila (C.) pecorum, C. abortus, C. psittaci and Chlamydia suis, is ubiquitous with mixed infections occurring frequently. The apparent lack of association between infection and clinical disease has resulted in debate as to the pathogenic significance of these organisms, and their tendency to sub-clinical and/or persistent infection presents a challenge to the study of their potential effects. However, recent evidence indicates that chlamydial infections have a substantial and quantifiable impact on livestock productivity with chronic, recurrent infections associated with pulmonary disease in calves and with infertility and sub-clinical mastitis in dairy cows. Data also suggest these infections manifest clinically when they coincide with a number of epidemiological risk factors. Future research should: (1) use relevant animal models to clarify the pathogenesis of bovine chlamydioses; (2) quantify the impact of chlamydial infection at a herd level and identify strategies for its control, including sub-unit vaccine development; and (3) evaluate the zoonotic risk of bovine chlamydial infections which will require the development of species-specific serodiagnostics.

Recent advances in the understanding of Chlamydophila pecorum infections, sixteen years after it was named as the fourth species of the Chlamydiaceae family

Chlamydophila pecorum found in the intestine and vaginal mucus of asymptomatic ruminants has also been associated with different pathological conditions in ruminants, swine and koalas. Some endangered species such as water buffalos and bandicoots have also been found to be infected by C. pecorum. The persistence of C. pecorum strains in the intestine and vaginal mucus of ruminants could cause long-term sub-clinical infection affecting the animal’s health. C. pecorum strains present many genetic and antigenic variations, but coding tandem repeats have recently been found in some C. pecorum genes, allowing C. pecorum strains isolated from sick animals to be differentiated from those isolated from asymptomatic animals. This review provides an update on C. pecorum infections in different animal hosts and the implications for animal health. The taxonomy, typing and genetic aspects of C. pecorum are also reviewed.

Recombinant 35-kDa inclusion membrane protein IncA as a candidate antigen for serodiagnosis of Chlamydophila pecorum

Chlamydophila pecorum strains are commonly found in the intestine and vaginal mucus of asymptomatic ruminants and may therefore induce a positive serological response when the animals are tested for C. abortus. They have also been associated with different pathological diseases in ruminants, swine and koala. The aim of this study was to identify specific C. pecorum immunodominant antigens which could be used in ELISA tests allowing to distinguish between animals infected with C. pecorum and those infected with other chlamydial species. A gene encoding 35-kDa inclusion membrane protein incA of C. pecorum was isolated by immunoscreening of the C. pecorum DNA library using ovine anti-C. pecorum antibodies. The recombinant IncA protein did not react with a murine serum directed against C. abortus but did react with a specific monoclonal antibody of C. pecorum and toward several ovine serum samples obtained after experimental infection with different C. pecorum strains. This protein could be a good candidate for specific diagnosis of C. pecorum infection.

Simultaneous differential detection of Chlamydophila abortus, Chlamydophila pecorum and Coxiella burnetii from aborted ruminant's clinical samples using multiplex PCR

Background

Chlamydiosis and Q fever, two zoonosis, are important causes of ruminants' abortion around the world. They are caused respectively by strictly intracellular and Gram negative bacterium Chlamydophila abortus (Cp. abortus) and Coxiella burnetii (C. burnetii). Chlamydophila pecorum (Cp. pecorum) is commonly isolated from the digestive tract of clinically inconspicuous ruminants but the abortive and zoonotic impact of this bacterium is still unknown because Cp. pecorum is rarely suspected in abortion cases of small ruminants. We have developed a multiplex PCR (m-PCR) for rapid simultaneous differential detection of Cp. abortus, Cp. pecorum and C. burnetii in clinical samples taken from infected animals.

Results

Specific PCR primers were designed and a sensitive and specific m-PCR was developed to detect simultaneously, in one tube reaction, three specific fragments of 821, 526 and 687-bp long for Cp. abortus, Cp. pecorum and C. burnetii respectively. This m-PCR assay was performed on 253 clinical samples taken from infected ruminant's flocks that have showed problems of abortion diseases. Thus, 67 samples were infected by either one of the three pathogens: 16 (13 vaginal swabs and 3 placentas) were positive for Cp. abortus, 2 were positive for Cp. pecorum (1 vaginal swab and 1 placenta) and 49 samples (33 vaginal swabs, 11 raw milks, 4 faeces and 1 placenta) were positive for C. burnetii. Two vaginal swabs were m-PCR positive of both Cp. abortus and C. burnetii and none of the tested samples was shown to be infected simultaneously with the three pathogens.

Conclusion

We have successfully developed a rapid multiplex PCR that can detect and differentiate Cp. abortus, Cp. pecorum and C. burnetii; with a good sensitivity and specificity. The diagnosis of chlamydiosis and Q fever may be greatly simplified and performed at low cost. In addition, the improvement in diagnostic techniques will enhance our knowledge regarding the prevalence and the pathogenetic significance of Q fever and chlamydiosis.

Characterization of Chlamydiaceae species using PCR and high resolution melt curve analysis of the 16S rRNA gene

AIM

To design a rapid diagnostic test to differentiate species belonging to the family Chlamydiaceae.

METHODS AND RESULTS

Five oligonucleotide sets each targeting various conserved regions of the genome of six species (Chlamydia muridarum, C. suis, C. trachomatis, Chlamydophila felis, Cp. pneumoniae and Cp. psittaci) belonging to the family Chlamydiaceae were tested for their suitability for polymerase chain reaction (PCR) and high resolution melt (HRM) curve analysis to differentiate Chlamydiaceae species. Three of the oligonucleotide sets were able to detect all six reference species used in this study, but only one set (16SG) could clearly differentiate between them by HRM curve analysis. The PCR-HRM curve analysis confidence percentages correlated strongly with the nucleotide sequence identities. Clinical specimens from a number of animal species suspected of chlamydiosis were tested with the newly developed 16SG PCR-HRM curve analysis and sequenced to confirm the infecting species. It was demonstrated that PCR-HRM using the 16SG oligonucleotide set could relate the infecting Chlamydiaceae species to the most similar (based on 16S rRNA gene nucleotide sequence) reference species tested. Although Cp. pecorum was not included initially as a reference species in this assay, inclusion of a field isolate of Cp. pecorum as a reference allowed two koala specimens to be correctly identified.

CONCLUSION

PCR-HRM analysis using the oligonucleotide set 16SG is a robust, simple and rapid technique for differentiation of at least the Chlamydiaceae species used in this study.

SIGNIFICANCE AND IMPACT OF THE STUDY

This technique allowed for the rapid detection and identification of the six Chlamydiaceae reference species and may be useful for identification of uncharacterized Chlamydiaceae species or for use in animal species where occurrence of the disease has not been fully investigated.

Zoonotic potential of Chlamydophila

The purpose of this article is to present the diseases induced in humans and animals by the different species of Chlamydophila, after providing an overview on the history of these infectious agents and their taxonomy. The route of transmission and the available methods for prevention and control in the different animal species are reviewed.

Investigation of Chlamydophila spp. in dairy cows with reproductive disorders

Background

Reports worldwide indicate high prevalence of Chlamydophila spp. infection in cattle. To assess the prevalence in Sweden, 525 cows in 70 dairy herds with reproductive disorders was investigated.

Methods

To detect antibodies two commercially available kits were used. Moreover, 107 specimens, including vaginal swabs, organ tissues and milk were analysed by Polymerase Chain Reaction (PCR).

Results

Two (0.4%) cows were seropositive in the Pourquier Cp. abortus ELISA. The seroprevalence with the Chekit ELISA was 28% with no difference between cases and controls. Five specimens were positive in real-time PCR and further analysed by nested PCR. Cp. pecorum was confirmed by partial omp1 DNA sequencing of the nested PCR product of vaginal swabs from control cows.

Conclusion

The results suggest that Cp. abortus infection is absent or rare in Swedish cows whereas Cp. pecorum is probably more spread. They also suggest that Chlamydophila spp. are not related to reproduction disorders in Swedish cattle.

Recent developments in the laboratory diagnosis of chlamydial infections

There are two main approaches to diagnosing infections by Chlamydia and Chlamydophila spp. in mammals and birds. The first involves the direct detection of the agent in tissue or swab samples, while the second involves the serological screening of blood samples for the presence of anti-chlamydial antibodies. Ultimately, the test that is used is dependent on the types of samples that are submitted to the diagnostic laboratory for analysis. The present paper gives an overview on methodologies and technologies used currently in diagnosis of chlamydial infections with emphasis on recently developed tests. The performance characteristics of individual methods, such as the detection of antigen in smears and in pathological samples, the isolation of the pathogen, various antibody detection tests and DNA-based methods utilising conventional and real-time PCR, as well as DNA microarray technology are assessed, and specific advantages and drawbacks are discussed. Further, a combination of a specific real-time PCR assay and a microarray test for chlamydiae is proposed as an alternative reference standard to isolation by cell culture.

OmpA and antigenic diversity of bovine Chlamydophila pecorum strains

Infections with the intracellular bacterium Chlamydophila (C.) pecorum are highly prevalent worldwide in cattle. These infections cause significant diseases such as polyarthritis, pneumonia, enteritis, genital infections and fertility disorders, and occasionally sporadic bovine encephalomyelitis. Subclinical respiratory infections of calves with C. pecorum have been associated with airway obstruction, pulmonary inflammation, and reduced weight gains. This investigation examined four chlamydial strains with biological properties of C. pecorum isolated from feces of clinically normal cattle, from calves with pneumonia, and from bulls with posthitis. The objective was to characterize the evolutionary relationships of these bovine chlamydial isolates to other chlamydiae by genetic analysis of the ompA gene, and by the immunological cross-reactivities in Western immunoblot analysis. PCR typing of the ompA gene identified these isolates as C. pecorum. The OmpA-deduced amino acid dissimilarities between these four strains spanned 10-20%. In phylogenetic analysis, the four isolates clustered with C. pecorum ruminant, porcine, and koala strains of different geographic origins rather than with each other. All four isolates showed different patterns of Western immunoblot reactivity with antiserum against bovine C. pecorum strain LW63, and, interestingly, no cross-reactivity of the OmpA proteins with the anti-LW613 OmpA antibodies. These data underscore the polyphyletic population structure of C. pecorum and suggest that the spectrum of C. pecorum OmpA proteins in a host species can occupy the entire evolutionary bandwidth within C. pecorum. The variant immunoblot reactivities support the notion of considerable genomic plasticity of C. pecorum.