Abortion and various associated risk factors in dairy cow and sheep in Ili, China

Knowledge, attitudes and practices of sheep owners regarding abortion in Northern Tunisia

BACKGROUND

Abortion in ewes causes high economic losses and represents a threat for human health due to abortive zoonotic pathogens.

OBJECTIVE

The present study aimed to assess the knowledge, attitudes and practices (KAP) among sheep owners in the northern Tunisia regarding ewes' abortions.

METHODS

Between February 2021 and May 2022, a structured questionnaire containing both close and open-ended questions was applied to 120 sheep owners in northern Tunisia. The data collected were analysed by chi-square test using Epi info 6 software.

RESULTS

The majority (75%) of participants reported a history of abortion in their sheep flocks. Sheep owners thought that the most frequent cause of abortion was physical factors, such as trauma, climate and stress (60% ± 5.5%; 48/80), followed by toxicity (15% ± 4%; 12/80), metabolic and nutritional conditions (12.5% ± 3.7%; 10/80), vaccination (5% ± 2.4%; 4/80) and infectious causes (7.5% ± 2.9%; 6/80) (p < 0.001). The majority of animal owners reported that abortions occurred mainly during autumn (39.6% ± 5%; 38/96), followed by summer (27% ± 4.5%; 26/96), winter (23% ± 4.3%; 22/96) and spring (10.4% ± 3.1%; 10/96) (p < 0.001). Approximately, half (45.8% ± 5%; 55/120) of interviewed farmers would not take any action if an abortion occurred. Half of the interviewed farmers (50.5% ± 5.1%; 48/95) did not apply any preventive measures when manipulating aborted ewes, and most of the sheep owners (77.3% ± 3.8%; 92/119) did not know that aborted ewes could transmit zoonotic pathogens.

CONCLUSIONS

Our survey concluded that sheep owners in Northern Tunisia had poor knowledge and attitudes as well as applied limited actions concerning several health aspects related to abortion. Education programmes should be established in order to improve Tunisian sheep owners' KAP regarding abortion.

Molecular detection of bacterial zoonotic abortive agents from ruminants in Turkey

Abortions in cattle and sheep are one of the major causes of economic losses worldwide. Brucella spp. are the most common infectious agent associated with these abortions. However, abortions caused by bacteria such as Listeria spp., Leptospira spp., Campylobacter spp. and Mycoplasma spp. are usually overlooked due to their sporadic nature and their status as non-priority abortion agents. In our study, we investigated the bacteria associated with abortion cases in cattle and sheep using PCR. For this purpose, we collected vaginal swab samples (n: 110) of aborted cattle and sheep, as well as stomach content samples (n: 69) of aborted calves and lambs from various cities in Turkey. The samples were analysed by bacteria-specific PCR to detect Campylobacter fetus, Leptospira spp., Listeria spp., Mycoplasma spp., and Yersinia spp. PCR analyses revealed that the investigated bacterial agents were present in 18.85% and 19.3% of the cattle and sheep samples, respectively, with an overall percentage of 18.99%. While the overall positivity rate for C. fetus, Leptospira spp., and Mycoplasma spp. was 2.79%, 10.06%, and 4.47%, respectively, the positivity rate for co-infection with Leptospira spp. and C. fetus was 1.68%. All samples were found to be negative for Yersinia spp. and Listeria spp. The high C. fetus positivity rate detected in sheep and in the stomach contents was statistically significant (p < 0.05). However, the difference in positivity rates between the cities, hosts, co-infections and causative agents was statistically insignificant (p > 0.05). This study provides preliminary data on the significant involvement of C. fetus, Leptospira spp. and Mycoplasma spp. in cattle and sheep abortions in Turkey indicating that they should not be overlooked in diagnosis. In addition, further research is needed to investigate the zoonotic potential of these pathogens for public health in Turkey.

Risk Factors for the Spread of Brucellosis in Sheep and Goats in the Campania Region in the Years 2015-2020

Brucella is a Gram-negative facultative intracellular pathogen that causes infection in sheep and goats (B. melitensis.); B. melitensis can also infect other animals. Sheep and goat brucellosis is still present in some regions of Italy, including Campania, and causes considerable economic losses and health threats. The aim of this study was to evaluate the possible risk factors influencing the spread of brucellosis among sheep and goat farms in the Campania region in order to provide the local veterinary services with practical support in evaluating and planning diagnostic, preventive and control interventions. The results of official controls for brucellosis carried out from 2015 to 2020 in the sheep and goat farms of the Campania Region were analyzed. Data were extracted from the National Veterinary Information Systems and the Laboratory Management System of the Experimental Zooprophylactic Institute of Southern Italy. Statistical analysis was carried out through the software R version 4.1.0; the dataset consisted of 37,442 observations, and 9 qualitative and quantitative variables were evaluated on 8487 farms, 248 of which were positive. The association between covariates and the outcome (presence/absence of the disease) was evaluated (Fisher and Wilcoxon tests). A logistic regression model with mixed effects was carried out. This study confirmed that brucellosis in sheep and goats in the Campania region mostly occurs through contact with infected animals imported from other farms (OR = 3.41-IC 95% [1.82-6.41]). Farms with a greater number of animals were seen to be at the greatest risk of infection (OR = 1.04-IC 95% [1.03-1.05]); previous suspension of healthy status also proved to be a risk factor (OR = 55.8-IC 95% [26.7-117]).

Bovine infectious abortion: a systematic review and meta-analysis

The aim of the present systematic review and meta-analysis was to identify the main infectious agents related to bovine abortion worldwide in the period between 2000 and 2022. First, we investigated the global prevalence of infectious agents related to bovine abortion. For this analysis, only 27 articles detected of a wide panel of agents were included. The random effects model revealed that the estimated prevalence of the abortifacient agents in bovine abortion was 45.7%. The heterogeneity among studies was high, but Egger's test showed that there was no publication bias, even though the total number of samples analyzed in these articles was variable. There was no significant effect of the year of the study publication on the estimated prevalence, although an increasing trend was observed over time, possibly due to the implementation of new diagnostic techniques. Then, we analyzed the prevalence of the main transmissible agents in bovine abortion. For this analysis, 76 studies that analyzed 19,070 cases were included. Some infectious agent was detected in 7,319 specimens, and a final diagnosis was reached in 3,977 of these, when both the infectious agent and compatible histopathological changes were detected. We found that Neospora caninum was the most detected agent (22.2%), followed by opportunistic bacteria (21.4%), Chlamydiaceae family (10.9%) and Coxiella burnetii (9.5%). Regarding viral agents, bovine herpes virus type 1 and bovine viral diarrhea displayed similar prevalence rates (approximately 5%). After considering the description of specific histopathological changes, our analyzes showed that N. caninum was a confirmed cause of abortion in 16.7% of the analyzed cases, followed by opportunistic bacteria (12.6%) and Chlamydia spp. (6.8%); however, C. burnetii was only confirmed as a cause of abortion in 1.1% of the cases. For all agents, the heterogeneity among studies was high, and the subgroup analyzes discarded the diagnostic method as the cause of such heterogeneity. This study provides knowledge about the global prevalence of the different infectious agents related to bovine abortion, the most coming of which is N. caninum. In addition, this review reveals the existing deficiencies in the diagnosis of bovine abortion that must be addressed in the future.

Scanning iron response regulator binding sites using Dap-seq in the Brucella genome

Iron is an essential element required for all organisms. Iron response regulator (Irr) is a crucial transcriptional regulator and can affect the growth and iron uptake of Brucella. The growth rate of Brucella melitensis M5-90 irr mutant was significantly lower than that of B. melitensis M5-90 under normal or iron-sufficient conditions, however, the growth rate of the B. melitensis M5-90 irr mutant was significantly higher than that of B. melitensis M5-90 under iron-limited conditions. In addition, irr mutation significantly reduced iron uptake under iron-limited conditions. Previous studies suggested that the Irr protein has multiple target genes in the Brucella genome that are involved in iron metabolism. Therefore, in the present study, a Dap-seq approach was used to investigate the other iron metabolism genes that are also regulated by the Irr protein in Brucella. A total of seven genes were identified as target genes for Irr in this study and the expression levels of these seven genes was identified using qRT-PCR. The electrophoretic mobility shift assay confirmed that six out of the seven genes, namely rirA (BME_RS13665), membrane protein (BME_RS01725), hypothetical protein (BME_RS09560), ftrA (BME_RS14525), cation-transporting P-type ATPase (zntA) (BME_RS10660), and 2Fe-2S binding protein (BME_RS13655), interact with the Irr protein. Furthermore, the iron utilization and growth assay experiments confirmed that rirA was involve in iron metabolism and growth of Brucella. In summary, our results identified six genes regulated by the Irr protein that may participate in iron metabolism, and the rirA was identified as a regulon of Irr and it also plays a role in iron metabolism of Brucella. Collectively, these results provide valuable insights for the exploration of Brucella iron metabolism.

The Seroprevalence of Chlamydia Infection in Sheep in Shanxi Province, China

Chlamydia, an obligate intracellular bacterium, can cause chlamydiosis in humans and animals worldwide and also leads to serious economic losses to the sheep industry. However, the information on Chlamydia infection in sheep was limited in Shanxi Province, northern China. In the present study, a total of 984 serum samples of sheep were collected from 11 regions in Shanxi Province, northern China in the autumn of 2020. The antibodies against Chlamydia and Chlamydia abortus were examined by the indirect hemagglutination assay (IHA) and indirect enzyme-linked immunosorbent assay (ELISA), respectively. The result showed that 351 (35.67%, 95% CI 32.68-38.66) of 984 serum samples were positive for Chlamydia, and the seroprevalence ranged from 6.67% to 70.79% among the different regions. In addition, antibodies to C. abortus infection were detected in 78 (7.93%, 95% CI 6.24-9.61) of 984 serum samples, and the seroprevalence ranged from 6.24% to 14.81% among the different regions. This is the first report on the seroprevalence of Chlamydia and C. abortus in sheep in Shanxi province, northern China. The findings provide baseline information for preventing and controlling Chlamydia infection in sheep in Shanxi Province, China.

Using a Relative Quantitative Proteomic Method to Identify Differentially Abundant Proteins in Brucella melitensis Biovar 3 and Brucella melitensis M5-90

Brucellosis, caused by Brucella spp., is one of the most widespread bacterial zoonoses worldwide. Vaccination is still considered the best way to control brucellosis. An investigation into the differential proteome expression patterns of wild and vaccine strains may help researchers and clinicians differentiate between the strains to diagnose and better understand the mechanism(s) underlying differences in virulence. In the present study, a mass spectrometry-based, label-free relative quantitative proteomics approach was used to investigate the proteins expressed by the wild strain, B. melitensis biovar 3 and compare it with those expressed by B. melitensis M5-90. The higher level of virulence for B. melitensis biovar 3 compared to B. melitensis M5-90 was validated in vitro and in vivo. A total of 2133 proteins, encompassing 68% of the theoretical proteome, were identified and quantified by proteomic analysis, resulting in broad coverage of the B. melitensis proteome. A total of 147 proteins were identified as differentially expressed (DE) between these two strains. In addition, 9 proteins and 30 proteins were identified as unique to B. melitensis M5-90 and B. melitensis biovar 3, respectively. Pathway analysis revealed that the majority of the DE proteins were involved in iron uptake, quorum sensing, pyrimidine metabolism, glycine betaine biosynthetic and metabolic processes, thiamine-containing compound metabolism and ABC transporters. The expression of BtpA and VjbR proteins (two well-known virulence factors) in B. melitensis biovar 3 was 8-fold and 2-fold higher than in B. melitensis M5-90. In summary, our results identified many unique proteins that could be selected as candidate markers for differentiating vaccinated animals from animals with wild-type infections. BtpA and VjbR proteins might be responsible for the residual virulence of B. melitensis M5-90, while ABC transporters and thiamine metabolism associated proteins may be newly identified Brucella virulence factors. All of the identified DE proteins provide valuable information for the development of vaccines and the discovery of novel therapeutic targets.

A Retrospective Survey of the Abortion Outbreak Event Caused by Brucellosis at a Blue Fox Breeding Farm in Heilongjiang Province, China

Brucellosis is a common zoonosis in China, resulting in abortion in animals. Outbreaks of abortion in blue foxes caused by Brucella infection have rarely been reported. In the present study, 3-5 mL blood samples collected from the femoral veins of 10 abortuses of blue foxes were assessed by RBPT (Rose Bengal plate test) and SAT (serum tube agglutination test) to preliminarily investigate the source of infection for the clustering of abortion events at a blue fox farm in Heilongjiang Province. Screening experiments showed that all 10 blood samples were positive in the RBPT, while only eight blood samples out of the 10 were positive in the SAT. Subsequently, 10 tissue samples (spleen, lungs, stomach contents, and afterbirth) from the same 10 foxes were assessed using AMOS (acronym for B. abortus, melitensis, ovis, and suis)-PCR (polymerase chain reaction), and sequencing analysis was performed on amplification products to verify the results of the serology survey. Results showed a spectral band of ~731 bp in these samples. BLAST showed sequences of AMOS-PCR products in this study to be 100% similar (E = 0.0) to sequences in B. melitensis strain from GenBank. These data preliminarily indicated that the blue fox's outbreak of abortion events was caused by brucellosis via the B. melitensis strain. Then 726 serum samples were tested by RBPT and SAT to determine the prevalence of brucellosis on the farm. A comprehensive epidemiological and reproductive status survey of the infected blue fox population was performed. The seropositive rate was found to be 67.90% (493/726) by RBPT and 41.32% (300/726) by SAT. The technicians had stopped feeding the foxes with chicken carcasses and instead fed them raw ground sheep organs (lungs, tracheae, placentae, and dead sheep fetuses) infected by B. meliteneis strains, and that this change in diet caused the outbreak of abortion events. The high abortion rate (55%) and low cub survival rate (65%) were the most distinctive features of the outbreak; these factors led to severe economic losses. Feeding cooked sheep/goat offal and strict breeding management is necessary for disease prevention.

Evaluation and Differential Diagnosis of a Genetic Marked Brucella Vaccine A19ΔvirB12 for Cattle

Brucella abortus is an important zoonotic pathogen that causes severe economic loss to husbandry and poses a threat to human health. The B. abortus A19 live vaccine has been extensively used to prevent bovine brucellosis in China. However, it is difficult to distinguish the serological response induced by A19 from that induced by natural infection. In this study, a novel genetically marked vaccine, A19ΔvirB12, was generated and evaluated. The results indicated that A19ΔvirB12 was able to provide effective protection against B. abortus 2308 (S2308) challenge in mice. Furthermore, the safety and protective efficacy of A19ΔvirB12 have been confirmed in natural host cattle. Additionally, the VirB12 protein allowed for serological differentiation between the S2308 challenge/natural infection and A19ΔvirB12 vaccination. However, previous studies have found that the accuracy of the serological detection based on VirB12 needs to be improved. Therefore, we attempted to identify potential supplementary antigens with differential diagnostic functions by combining label-free quantitative proteomics and protein chip technology. Twenty-six proteins identified only in S2308 were screened; among them, five proteins were considered as potential supplementary antigens. Thus, the accuracy of the differential diagnosis between A19ΔvirB12 immunization and field infection may be improved through multi-antigen detection. In addition, we explored the possible attenuation factors of Brucella vaccine strain. Nine virulence factors were downregulated in A19ΔvirB12. The downregulation pathways of A19ΔvirB12 were significantly enriched in quorum sensing, ATP-binding cassette transporter, and metabolism. Several proteins related to cell division were significantly downregulated, while some proteins involved in transcription were upregulated in S2308. In conclusion, our results contribute to the control and eradication of brucellosis and provide insights into the mechanisms underlying the attenuation of A19ΔvirB12.