Isolation and characterisation of local strains of Chlamydophila abortus (Chlamydia psittaci serotype 1) from Tunisia

Prospective cohort study reveals unexpected aetiologies of livestock abortion in northern Tanzania

Livestock abortion is an important cause of productivity losses worldwide and many infectious causes of abortion are zoonotic pathogens that impact on human health. Little is known about the relative importance of infectious causes of livestock abortion in Africa, including in subsistence farming communities that are critically dependent on livestock for food, income, and wellbeing. We conducted a prospective cohort study of livestock abortion, supported by cross-sectional serosurveillance, to determine aetiologies of livestock abortions in livestock in Tanzania. This approach generated several important findings including detection of a Rift Valley fever virus outbreak in cattle; high prevalence of C. burnetii infection in livestock; and the first report of Neospora caninum, Toxoplasma gondii, and pestiviruses associated with livestock abortion in Tanzania. Our approach provides a model for abortion surveillance in resource-limited settings. Our findings add substantially to current knowledge in sub-Saharan Africa, providing important evidence from which to prioritise disease interventions.

Seroprevalence and associated risk factors of Chlamydia abortus infection in ewes in Tunisia

Enzootic abortion of ewes (EAE) caused by Chlamydia abortus is a disease of ruminants that results in serious economic losses in livestock industry. The zoonotic potential of the pathogen adds a public health concern on the efforts to control the disease. We report herein a cross-sectional study that was conducted during the lambing season (June and July) in Tunisia to estimate the seroprevalence of C. abortus infection in large sheep herds with abortion history. A total of 803 ewes were sampled and tested using indirect enzyme linked immunosorbent assay (iELISA). The overall apparent seroprevalence at herd and individual levels were 58 % (95 %CI = 39-74.5 %) and 6.6 % (95 %CI = 4.9-8.3 %), respectively. Significant risk factors investigated using univariate and multivariate analyses were history of infertility (OR = 5.7; 95 %CI = 3.05-10.66), the number of reproductive ewes (OR = 2.1; 95 %CI = 1.12-3.94), the control of new animals at introduction (OR = 4.35; 95 %CI = 2.46-7.68), the sharing of drinking water (OR = 2.18; 95 %CI = 1.22-3.9), the exchange of breeding males (OR = 2.56; 95 %CI = 1.003-6.54), the disposal of abortion materials without precaution (OR = 4.36; 95 %CI = 2.42-7.87), the lack of lambing barn (OR = 2.39; 95 %CI = 1.13-5.04), the non-application of hygienic post-abortion measures (OR = 10.35; 95 %CI = 5.28-20.26) and the manure management (OR = 11.35; 95 %CI = 3.26-39.48). To the best of our knowledge, this is the first sero-epidemiological survey conducted on an abortive disease in Tunisian ewes that investigated the risk factors of C. abortus infection.

In silico functional elucidation of uncharacterized proteins of Chlamydia abortus strain LLG

AIM

This study reports structural modeling, molecular dynamics profiling of hypothetical proteins in Chlamydia abortus genome database.

METHODOLOGY

The hypothetical protein sequences were extracted from C. abortus LLG Genome Database for functional elucidation using in silico methods.

RESULTS

Fifty-one proteins with their roles in defense, binding and transporting other biomolecules were unraveled. Forty-five proteins were found to be nonhomologous to proteins present in hosts infected by C. abortus. Of these, 31 proteins were related to virulence. The structural modeling of two proteins, first, WP_006344020.1 (phosphorylase) and second, WP_006344325.1 (chlamydial protease/proteasome-like activity factor) were accomplished. The conserved active sites necessary for the catalytic function were analyzed.

CONCLUSION

The finally concluded proteins are envisioned as possible targets for developing drugs to curtail chlamydial infections, however, and should be validated by molecular biological methods.

Detection and genotyping of Chlamydia species responsible for reproductive disorders in Algerian small ruminants

Chlamydiosis in small ruminants is a zoonotic disease mainly related to Chlamydia abortus. This bacterium is responsible for abortions and reproductive disorders in sheep and goats. Stillbirth and infertility, leading to important economic losses, are also associated with this pathology. In Algeria, abortion cases are frequently reported by veterinarians but, except for brucellosis which is a notifiable disease in this country, abortive diseases are in general poorly studied. In order to detect and genotype Chlamydia species in small ruminants in different areas of Algeria, a study was conducted on samples collected from females (164 blood samples and 199 vaginal swabs) between October 2011 and March 2013. Serum samples were tested with a C. abortus-specific indirect ELISA test. Fourteen samples (8.5 %), from six farms (6/20, 30 %) were tested positive. Vaginal swabs were analysed with a real-time PCR targeting all Chlamydiaceae spp. Thirty samples (15 %) were diagnosed positive in 16 farms (16/25, 64 %). Positive samples were all re-tested with a C. abortus- and a C. pecorum-specific real-time PCR. Finally, 13/30 (43.3 %) and 6/30 (20 %) were identified as C. abortus and C. pecorum, respectively. Enough concentrated C. abortus samples were genotyped by multi-loci variable number of tandem repeat (VNTR) analysis (MLVA), and all were related to the genotype [2] group which mainly includes French C. abortus isolates. C. pecorum-positive samples were genotyped by multi-locus sequence typing (MLST). Interestingly, two of them were successfully genotyped and showed identical MLST sequences to VB2, AB10, E58 and SBE, a group which includes C. pecorum isolates considered as highly pathogenic. These findings suggest a possible role of C. abortus and C. pecorum strains in the aetiology of abortion in Algerian small ruminants.

Seroprevalence and risk factors of Chlamydia abortus infection in Tibetan sheep in Gansu province, northwest China

Chlamydia abortus, an important pathogen in a variety of animals, is associated with abortion in sheep. In the present study, 1732 blood samples, collected from Tibetan sheep between June 2013 and April 2014, were examined by the indirect hemagglutination (IHA) test, aiming to evaluate the seroprevalence and risk factors of C. abortus infection in Tibetan sheep. 323 of 1732 (18.65%) samples were seropositive for C. abortus antibodies at the cut-off of 1:16. A multivariate logistic regression analysis was used to evaluate the risk factors associated with seroprevalence, which could provide foundation to prevent and control C. abortus infection in Tibetan sheep. Gender of Tibetan sheep was left out of the final model because it is not significant in the logistic regression analysis (P > 0.05). Region, season, and age were considered as major risk factors associated with C. abortus infection in Tibetan sheep. Our study revealed a widespread and high prevalence of C. abortus infection in Tibetan sheep in Gansu province, northwest China, with higher exposure risk in different seasons and ages and distinct geographical distribution.

Prevalence and molecular identification of Chlamydia abortus in commercial dairy goat farms in a hot region in Mexico

The aim of this study was to determine the seroprevalence and presence of Chlamydia abortus in Saanen breed female goats from commercial dairy goat farms under intensive production in the municipality of Guanajuato, Mexico. Sera were collected to determine the prevalence of anti-C. abortus IgG antibodies using recombinant enzyme-linked immunosorbent assay (rELISA) and cell culture. Polymerase chain reaction (PCR) was used to prove the presence of the pathogen in swab samples collected from the vagina and rectum of selected animals. Additionally, foetal tissue samples from a sudden abortion were collected. C. abortus prevalence in female goats of commercial milking farms sampled in Guanajuato, Mexico, was 4.87% (n = 246). Seropositive animals were found in six out of nine (66.6%) dairy goat farms sampled, and prevalence among animals in individual farms ranged between 3.44 and 13.51%. C. abortus was detected using PCR in spleen tissue from the aborted foetus. PCR-based detection, as well as isolation from vaginal and rectal swabs, was not possible in the present study. Isolation through cell culture was also unsuccessful from aborted foetal tissue samples. In conclusion, the results from rELISA and PCR show that C. abortus is present in dairy goat farms in the state of Guanajuato, Mexico.

High frequency of chlamydial co-infections in clinically healthy sheep flocks

Background

The epidemiological situation of ovine chlamydial infections in continental Europe, especially Germany is poorly characterised. Using the German state of Thuringia as a model example, the chlamydial sero- and antigen prevalence was estimated in thirty-two randomly selected sheep flocks with an average abortion rate lower than 1%. Seven vaccinated flocks were reviewed separately.

Results

A wide range of samples from 32 flocks were examined. Assumption of a seroprevalence of 10% (CI 95%) at flock level, revealed that 94% of the tested flocks were serologically positive with ongoing infection (i.e. animals with seroconversion) in nearly half (47%) of the flocks. On the basis of an estimated 25% antigen prevalence (CI 95%), PCR and DNA microarray testing, together with sequencing revealed the presence of chlamydiae in 78% of the flocks. The species most frequently found was Chlamydophila (C.) abortus (50%) followed by C. pecorum (47%) and C. psittaci genotype A (25%). Mixed infections occurred in 25% of the tested flocks. Samples obtained from the vaccinated flocks revealed the presence of C. abortus field samples in 4/7 flocks. C. pecorum was isolated from 2/7 flocks and the presence of seroconversion was determined in 3/7 flocks.

Conclusions

The results imply that chlamydial infections occur frequently in German sheep flocks, even in the absence of elevated abortion rates. The fact that C. pecorum and the potentially zoonotic C. psittaci were found alongside the classical abortifacient agent C. abortus, raise questions about the significance of this reservoir for animal and human health and underline the necessity for regular monitoring. Further studies are needed to identify the possible role of C. psittaci infections in sheep.