BMC Veterinary Research最新文献

Background: Toxoplasma gondii is a globally distributed zoonotic parasite that affects both humans and animals, with significant implications for public health and livestock production. The current research aims to update the information on the present prevalence of T. gondii and the risk factors associated with the infection in domestic ruminants in Aswan, Egypt, from August 2024 to January 2025, using serological, histopathological, and molecular approaches.

Methods: The blood of 387 domestic ruminants collected during the antemortem examination from four central abattoirs in the Aswan governorate, Upper Egypt, was inspected for the occurrence of anti-T. gondii antibodies through a modified agglutination technique. Data were confirmed by a nested polymerase chain reaction that targeted T. gondii DNA (B1 gene). Tissue specimens (heart and diaphragm) from seropositive animals were collected during postmortem examination and subjected to a histopathological and immunohistochemical approach.

Results: The overall occurrence of T. gondii was 29.5% (114/387), with seropositivity of 33.5% (52/155), 28.2% (22/78), 23.6% (21/89), and 29.2% (19/65) in cattle, buffalo, sheep, and goats, respectively. The studied risk factors (age, gender, breed, body condition, and location) in this study were detected to be significantly related to the presence of T. gondii infection (p ˂ 0.05). Histopathological examination detected tissue cysts in 38 out of 114 cardiac muscles of seropositive animals and failed to detect any cysts in the diaphragm tissue, indicated by encased, circular to elongated, basophilic cysts with many bradyzoites entrenched in muscle fibers by H&E staining, while showing intense brown granule staining of lymphoblastic cells by immunohistochemistry assay. Nested PCR confirmed the presence of the B1 gene of T. gondii in blood samples of all seropositive animals (100%).

Conclusions: The combined use of serology, PCR, and IHC demonstrates that T. gondii is present in slaughtered ruminants in Aswan and that viable tissue cysts are present in edible tissues. These findings highlight a potential risk of zoonotic transmission through the consumption of undercooked meat and emphasize the need for monitoring and control measures to reduce the burden of foodborne toxoplasmosis in Egypt.

Avian infectious bronchitis virus (IBV) is a major pathogen impacting the global poultry industry. The QX genotype (GI-19 lineage) of IBV has rapidly spread worldwide and is now the dominant genotype in Asia and Europe. In this study, three QX-type field strains (JS/773, JS/774, and SD/783) were isolated from diseased chicken flocks in eastern China, which had been vaccinated with IBV live attenuated vaccines (H120 or QXL87) between December 2024 and January 2025. Notably, the JS/773 strain showed an H536P mutation at the S protein cleavage site, marking the first identification of a PRRRR cleavage motif in this lineage and highlighting the diversity of cleavage sites among QX-type strains. Recombination analysis showed that these isolates are recombinant variants from vaccine strains 4/91, H120, and QXL87, as well as circulating field strains, with recombination occurring in the ORF1a/ORF1b, ORF5a/ORF5b and M regions. Pathogenicity testing in SPF chickens demonstrated that the isolates induced marked lesions in the respiratory and urinary systems; however, JS/773 caused the most severe tissue damage and resulted in the highest mortality rate among the groups. Cross-neutralization assays revealed substantial antigenic differences between the isolates and the H120 strain, and with reduced antigenic relatedness to the QXL87 strain. Seven amino acid mutations occurred in the isolates S1 subunit neutralizing epitope region, altering protein conformation and potentially contributing to antigenic variation and immune evasion. In conclusion, the genetic traits and pathogenicity of these isolates highlight the evolving QX-type strains in China, that offers new insights into the molecular evolution of QX-type IBV antigenicity.

Background: Bovine viral diarrhea (BVD) is an economically significant disease affecting both domestic and wild ruminant species. The causative agent is bovine viral diarrhea virus (BVDV) of the genus Pestivirus within the family Flaviviridae. In Ethiopia, information on the disease to initiate prevention and control measures is scarce. Hence, this study aimed to assess the prevalence of BVD and persistently infected cattle and identify the associated risk factors in dairy farms situated in urban and peri-urban areas.

Methodology: An Enzyme-Linked Immunosorbent Assay (ELISA) technique was used to test serum samples collected from 1634 dairy cattle in 180 herds. Univariate analysis was conducted to assess the association between independent and outcome variables, and those with a significant association with the outcome variables were considered for a multivariable binary logistic regression model to identify potential risk factors.

Results: The study revealed an overall antibody and antigen prevalence of 28.4% (95% confidence interval (CI): 26.2-30.6%) and 1.5% (95% confidence interval: 1.04-2.3%), respectively. The true within- and between-herd- sero-prevalence of BVD was 49.1% and 67.8%, respectively. The study also revealed a 0.94% (95% confidence interval (CI): 0.53-1.77) animal level and 6.4% (95% CI: 0.53-10.9) herd level prevalence of persistently infected animals. The study location, body condition score (BCS), diarrhea, herd size, origin of animals, and calf congenital anomalies were significantly associated with the prevalence of BVD (P < 0.05). Location, BCS, herd size, and origin of the animals were identified as potential risk factors (p < 0.05).

Conclusions: Our study revealed that BVD is well established in commercial dairy farms, suggesting the need to design strong prevention and control measures. Future studies should be encouraged to determine the genetic diversity of the viruses in the country.

African Swine fever (ASF) is an acute, hemorrhagic infectious disease caused by the African swine fever virus (ASFV), posing a major threat to the global pig farming industry. ASFV is a complex DNA virus. Its non-structural protein, A151R, is a thioredoxin crucial for the replication and morphogenesis of ASFV. In this study, a monoclonal antibody (mAb) 3E5D6 against pA151R (A151R Protein) was prepared using cell fusion technology to gain deeper insight into the function of A151R during ASFV infection. Immunolabeling of pA151R with 3E5D6 mAb revealed its involvement in viral factory formation and its characteristic early expression during infection. However, the antibody exhibited no detectable neutralizing activity. Subsequently, the antigenic epitope ⁸⁴KIWSGEPR⁹¹ of 3E5D6 was identified using bioinformatic analysis and molecular biology techniques. Homology and structural analyses indicated that this amino acid sequence was highly conserved across pA151R of different strains and was located on the surface of the protein. Furthermore, the 87 S residue is a key site for 3E5D6 recognition of pA151R. This antibody will allow us to better characterize host-virus interactions and further our understanding of the pathophysiology of ASFV infection.

Background: Osteosarcoma is the most common primary bone tumor in cats, yet it is typically diagnosed in older animals and rarely metastasizes. Among its histological variants, the fibroblastic subtype-defined by spindle-shaped osteogenic cells that generate osteoid-is infrequently reported in young cats.

Case presentation: A one-year-old intact female domestic shorthair (DSH) cat was referred to the Veterinary Teaching Hospital of Ferdowsi University of Mashhad with a one-month history of progressive lameness and a firm swelling on the right hindlimb. Radiographs revealed an aggressive osteolytic lesion of the fourth metatarsal bone with a Codman's triangle periosteal reaction, as well as a pulmonary mass consistent with metastasis. Fine-needle aspiration cytology demonstrated pleomorphic osteoblasts with anisokaryosis, multinucleated giant cells, and osteoid material, suggesting osteosarcoma. Following humane euthanasia, necropsy revealed extensive bone destruction and metastatic foci in the lung and popliteal lymph node. Histopathology showed a mixture of spindle-shaped and pleomorphic osteogenic cells producing eosinophilic osteoid matrix, confirming a diagnosis of fibroblastic osteosarcoma. Immunohistochemistry showed strong nuclear positivity for SATB2, confirming osteoblastic lineage. Hepatic and splenic changes were reactive and non-metastatic.

Conclusions: This report describes an exceptionally early-onset fibroblastic osteosarcoma in a one-year-old cat, accompanied by both pulmonary and lymphatic metastasis, a presentation rarely reported in feline patients. Recognition of such atypical presentations broadens the understanding of feline osteosarcoma behavior and underscores the value of integrating radiologic, cytologic, histopathologic, and immunohistochemical findings for accurate diagnosis.

Background: Mycoplasma infections pose a significant economic burden and represent a serious health and welfare concern for the livestock sector. Their control often requires repeated antimicrobial treatments. Antimicrobial susceptibility testing (AST) procedures for veterinary mycoplasmas lack standardization. Furthermore, clinical breakpoints (CBPs) are not available to interpret AST data (i.e., Minimum Inhibitory Concentration, MIC values) and categorize isolates as susceptible, resistant, or intermediate to the different antimicrobials used in livestock, nor epidemiological cut-offs (ECOFFs), which are a prerequisite to define CBPs. In 2023, the MyMIC network - a consortium of 22 laboratories specializing in veterinary mycoplasmas- was established to support efforts in standardizing diagnostics and AST, including clinical interpretation. Its initial goals were to (i) review routine diagnostic practices in frontline laboratories and examine veterinarians' prescribing habits and (ii) assess practices for culture, identification and AST used in expert laboratories and how these practices may affect MIC results as collected for five major livestock pathogens (M. bovis, M. gallisepticum, M. synoviae, M. hyopneumoniae and M. hyorhinis).

Results: A first survey targeting veterinarians from the avian, porcine, and ruminant livestock sectors provided 468 complete responses from 39 countries worldwide, giving an account of current trends in the treatment and first-line diagnosis of veterinary mycoplasmoses. Macrolides, tetracyclines, pleuromutilins, florfenicol and fluoroquinolones were the most frequently administered antimicrobials, with usage varying by livestock sector. Veterinarians reported requesting diagnostic in 40-75% of clinical cases, but only one-third requested AST regularly. A separate survey within the consortium highlighted significant variability in the media and methods used by specialized laboratories, particularly for MIC determination, which relied mostly on in-house broth dilution techniques. This methodological diversity limited our ability to aggregate collected MIC data for establishing ECOFFs.

Conclusions: Several concerns regarding best practices for antimicrobial treatments of mycoplasma infections may be linked to the lack of AST in frontline laboratories. Based on information collected in expert laboratories, we identified multiple sources contributing to inconsistent MIC results. The next step will be to establish consensus gold-standard AST methods tailored to specific mycoplasma-antimicrobial combinations to generate reliable MIC data for defining ECOFFs. Subsequently, the development of ready-to-use commercial MIC plates for use in frontline laboratory will support veterinarians in selecting appropriate treatments.

Background: Porcine epidemic diarrhea virus (PEDV) is a highly virulent enterovirus that is responsible for severe diarrhea in neonatal piglets. For no effective vaccine or specific treatment are available, rapid and accurate diagnosis is crucial for the prevention and control of disease. The nucleocapsid (N) protein is conserved with strong immunogenicity, making it an important target for developing serological approaches.

Results: In this study, soluble PEDV N protein was expressed, purified, and then used to produce monoclonal antibodies (mAbs). Three mAbs, named 8G2, 6F3, and 3E1, against PEDV N protein were generated. These mAbs were identified as IgG1 isotypes with κ light chains, exhibited high specificity for PEDV, and showed no cross-reactivity with transmissible gastroenteritis virus (TGEV) or porcine deltacoronavirus (PDCoV). Epitope mapping revealed 8G2 specifically recognized a novel linear B-cell epitope at 274-DLKDIPEWR-282 of viral N protein by using a serious of truncated overlapping peptides. Homology analysis showed that the epitope of 8G2 was highly conserved (100%) among different PEDV strains. Structural assay suggested that the identified epitope was located on the surface of PEDV N protein. Functional analysis demonstrated 8G2 could be used in indirect immunofluorescence assay, western blot, flow cytometry, and immunohistochemistry.

Conclusions: These mAbs help us better understanding the antigenicity of PEDV N protein, and serve as robust tools for serological diagnosis and vaccine development.

Background: High containment facilities provide limited environmental stimuli for cattle. Adding environmental enrichment can reduce frustration and stereotyping, improving overall animal welfare and benefitting scientific output. Current research into environmental enrichment for indoor housed cattle is lacking despite such facilities facing unique challenges to maintain high welfare standards. This study compared four different environmental enrichment items in the aim to help inform high containment facilities on the most effective enrichment items for cattle. Five pens holding four 18-month-old Hereford-Holstein cattle were equipped with control enrichment (broom head and salt lick) and one trial enrichment item. The test items were a hay net filled with hay, rope, empty chemical drum, and ball. Items were rotated weekly over a three week period. Interactions between the cattle and enrichment were recorded daily via CCTV, data collected using continuous all-occurrence sampling with three point samples per day, and analysed using negative binomial regression models.

Results: The hay net elicited the highest interactive frequency and duration. It was also the least affected by habituation, possibly due to the nutritional incentive and novelty created when refilled. A similar level of interaction was seen between the ball and drum and both items were interacted with more than control items. The rope was interacted with less frequently than control items.

Conclusion: Although the hay net appeared most engaging, all items declined in popularity over time indicating that several different items rotated sporadically may maximise the benefit of enrichment by maintaining the cattle's interest.