Journal of Veterinary Medical Science最新文献

Glaesserella parasuis, the causative agent responsible for Glässer's disease in swine, leads to severe polyserositis, meningitis, and arthritis, posing a significant threat to swine production. The LuxS/AI-2 quorum sensing system is crucial for G. parasuis growth, biofilm formation, and pathogenicity. Quorum sensing inhibitors, such as paeoniflorin (PF), offer a potential strategy to mitigate antibiotic resistance. This study evaluated PF's effects, alone and combined with antibiotics, on quorum sensing, biofilm formation, and virulence gene expression of drug-resistant G. parasuis. PF significantly reduced AI-2 production, biofilm formation, and virulence genes expression in vitro. A viable model for G. parasuis infection was established using KM mice, and demonstrated that a low-dose combination of PF and lincomycin effectively mitigated organ damage, reduced bacterial load in the liver, and improved survival rates compared to individual treatments in vivo. These findings suggest PF as a promising quorum sensing and virulence inhibitor for controlling G. parasuis infections. Further research is warranted to optimize its clinical application.

Bovine leukemia virus (BLV), a retrovirus that is widespread worldwide, causes enzootic bovine leukosis (EBL), a B-cell leukemia/lymphoma with a poor prognosis that ultimately results in death. In Japan, the number of cattle infected with this virus is increasing, and it is estimated more than 35% of cattle are currently infected. Since no vaccines or treatments against BLV infection are currently available, it is important to establish a method of early diagnosis for EBL to reduce economic losses caused by the disposal of EBL cattle in Japan, where a large number of expensive beef cattle are raised. We previously developed Rapid Amplification of the Integration Site without Interference by Genomic DNA Contamination (RAISING), a cost-effective, rapid, and sensitive method for the clonality analysis of BLV-infected cells. Despite its usefulness for the early diagnosis of EBL, RAISING had drawbacks preventing its practical application. Here, we report the development of an improved method, RAISING ver.2, and its performance. Compared to BLV clonality analysis using the previous method, RAISING ver.2 was found to maintain high accuracy and reproducibility despite its simplification. Moreover, its performance was also validated in a multicenter validation study. Taken together, our results strongly suggest that RAISING ver.2 can be fully utilized in clinical practice. Successful commercialization of a RAISING test kit could overcome the concerns of livestock farmers suffering from EBL, thereby promoting a stable supply of Japanese beef, both domestically and internationally.

Meningothelial proliferative diseases can rarely occur in extracranial sites, but there is limited information about them in veterinary medicine. This study investigated cutaneous meningothelial proliferative disease in eleven cats. Five cases were microscopically diagnosed with cutaneous meningioma and six cases with meningothelial hamartoma. Three of the former cases were subclassified as fibrous type and two as meningothelial type. The proliferating cells were positive for vimentin and E-cadherin, partially positive for cytokeratin, and negative for S100. All the lesions were located in the midline of the parietal skin and occurred at a young age. These facts suggest that both diseases in cats may be a congenital disease caused by ectopic meningothelial remnants during the fetal period.

This is the first report of paroxysmal atrioventricular block with Wenckebach cycles in a dog exhibiting syncope. The patient was a 1-year-old female Shiba Inu referred to our hospital with chief complaints of exercise intolerance, dizziness during walking, and tongue discoloration. Pacemaker implantation was performed based on the clinical presentation and Holter electrocardiogram findings. In this case, long-term management was successfully achieved for 13 years and 3 months (Age 15 years old) after the placement of pacemaker. A histopathological examination revealed that no abnormalities in the conduction system were detected that could explain the arrhythmia. Consequently, the arrhythmia was suspected to have been caused by vagus nerve stimulation.

Porcine circovirus type 2 (PCV2) induces wasting and immunosuppression in pigs and is widely transmitted in pig farms worldwide. Classical swine fever (CSF) is a particularly important contagious disease in pigs. In CSF-endemic areas, such as Japan, thorough vaccination is performed, and effective use of the CSF vaccine is important to prevent outbreaks. This study investigated the impact of PCV2 infection on the immune response to CSF vaccines in field farms. The mortality rate of fattening pigs on the farm was investigated, and pig sera were used to measure the PCV2 viral load and neutralizing antibody titer of CSF as indicators of CSF vaccine efficacy. Results indicated a sharp increase in mortality rate, PCV2 detection rate reaching 100%, and high viral load, whereas CSF antibody titers were significantly lower in the fattening pig herd. After PCV2 inactivated vaccination was initiated, the mortality rate, PCV2 detection rate, and viral load in fattening pigs decreased, and CSF antibody titers also improved. Furthermore, there was a correlation between higher PCV2 viral load and lower CSF antibody titers in this farm. In contrast, other PCV2-vaccinated farms had higher CSF antibody levels. These results indicate that PCV2 infection negatively affects the efficacy of CSF vaccines, and the control of PCV2 in field farms is important.

Streptococcus uberis, a Gram-positive bacterium commonly found in dairy cows, causes mastitis and decreases milk production quality. While usually non-pathogenic in humans, rare cases of infections such as endocarditis and abscesses have been reported. This paper presents the first documented case of Streptococcus uberis infection in a whooper swan, leading to systemic illness. The swan exhibited hepatic necrosis, spleen congestion, and heart abnormalities, with bacterial presence confirmed through microbiological methods. The source of infection remains to be elucidated but is possibly linked to exposure to wild animals or environmental factors in the zoo habitat.

Human epidermal growth factor receptor 2 (HER2) is a known therapeutic target in canine osteosarcoma (OSA); however, the efficacy of anti-HER2 antibody drugs remains unclear. This study aimed to investigate the effects of the anti-HER2 antibody drugs including trastuzumab and trastuzumab emtansine (T-DM1) on canine OSA cell lines in vitro and in vivo. Four canine OSA cell lines (HMPOS, POS, OOS, and HOS) were used. Western blotting revealed HER2 protein expression in all the cell lines. Although water-soluble tetrazolium salt assays showed growth inhibitory activity of trastuzumab and T-DM1 against all the cell lines in vitro, the activity of T-DM1 was significantly stronger than that of trastuzumab. Flow cytometric analysis of the canine OSA cell line (HMPOS) revealed that T-DM1, but not trastuzumab, significantly increased the sub-G1 phase fraction in cell cycle analyses and the percentage of early and late apoptotic cells in annexin V apoptotic assays. For in vivo experiments, canine OSA cells (HMPOS) were subcutaneously injected into nude mice. Six days after inoculation, trastuzumab, T-DM1, or the vehicle control was administered intraperitoneally once per week. Survival until the tumor volume in the canine OSA-engrafted mice reached mean final tumor volume in the T-DM1 group was significantly longer in the T-DM1 group, but not in the trastuzumab group, compared to the vehicle control group. These findings indicated that T-DM1 exerts antitumor effects on canine OSA cells in vitro and in vivo, possibly by inducing apoptosis due to DM1.

Live vaccination is the most protective method against bovine neosporosis, which is the major cause of bovine abortion globally. Here, the Neospora caninum parenteral strain Nc1 and NcGRA7-deficient N. caninum (NcGRA7KO), which is less virulent in mice, were evaluated as potential live vaccines. BALB/c mice were subcutaneously inoculated with high (1 × 10⁵) or low (1 × 10⁴) doses of tachyzoites. At high doses, Nc1-inoculated female mice presented decreased body weight gain and increased clinical signs and died before challenge infection with green fluorescent protein (GFP)-expressing Nc1 (Nc1-GFP), whereas NcGRA7KO-inoculated animals exhibited increased survival before and after challenge infection. Although inoculation of female mice with Nc1 or NcGRA7KO resulted in a lower brain parasite number of challenged Nc1-GFP than in noninoculated animals, the total brain parasite burden in NcGRA7KO-infected mice decreased compared with that in Nc1-infetced animals. At low dose of NcGRA7KO, increased survival rates of mice and lower total brain parasite number were observed compared with high dose of NcGRA7KO. In male mice, a significant lower brain parasite burden of Nc1-GFP was observed in both high and low doses of NcGRA7-inoculated mice, and the total parasite number in the brains of low dose of NcGRA7KO-inoculated animals was lower than that in the brains of high dose of NcGRA7KO-inoculated or noninoculated animals. In conclusion, these results suggest that NcGRA7KO parasites have potential for use as a live vaccine against N. caninum infection.

There is a clinical challenge in decision-making regarding prophylactic glaucoma treatment based solely on intraocular pressure (IOP) trends for long-term cataract management or before phacoemulsification surgery in canines. This study aimed to compare IOP and ultrasound biomicroscopy (UBM) parameters with cataract maturity in small dog breeds. We conducted a retrospective review of medical records pertaining to ophthalmic examinations and UBM assessments of small breed dogs diagnosed with cataracts at the Veterinary Medical Teaching Hospital of Seoul National University from January 2020 to August 2024. UBM images obtained under topical anesthesia were analyzed to quantify various parameters. Subsequently, the 47 eyes examined were classified into four groups according to cataract maturity. The ciliary cleft area (CCA), ciliary cleft length (CCL) and width (CCW), and iridocorneal angle (ICA) were measured. The measured values were compared to determine their degree of correlation with cataract maturity. Statistical analyses of patient demographics were also performed. Both CCA (P=0.0024) and CCL (P=0.0004) decreased significantly with increasing cataract maturity. However, IOP, CCW, and ICA were not significantly associated with cataract maturity. Age and sex did not have significant effects on any dependent variable. Among the UBM parameters, CCA and CCL demonstrated a significant correlation with cataract maturity, indicating structural alterations in the ICA might develop in association with cataracts, independent of direct IOP effects. These findings underscore the importance of considering prophylactic glaucoma management in patients with advanced cataracts to mitigate potential complications.

Although velogenic Newcastle disease viruses (NDVs) generally show low pathogenicity in waterfowl such as ducks, lethal infection by NDVs has been reported sporadically. A previous study revealed that a serially-passaged NDV isolate showed increased virulence in ducks, and that the viral proteins harbored a total of 11 amino acid substitutions. Among them, the fusion protein (F), matrix protein (M), and hemagglutinin-neuraminidase (HN) were suspected to be involved in enhanced virulence. The present study aimed to clarify the association between genetic mutations in NDVs and pathogenicity in ducks by comparing histopathological findings in ducks inoculated with three recombinant (r)NDVs: rM44 (Q44R substitution in M), rF142 (I142M substitution in F), and rM+F+HN (Q44R, N123D, and D342N substitutions in M; I142M and E304K substitutions in F; and G538R substitution in HN; three viral proteins compatible with amino acid sequences from passaged NDV). Seven-day-old ducks were intranasally inoculated with rM44, rF142, or rM+F+HN. Gross and histopathological lesions in the heart, thymus, brain, and pancreas were more severe in ducks inoculated with rM+F+HN than in ducks inoculated with rM44 or rF142. In particular, myocarditis associated with NDV antigens and mixed inflammatory cells was prominent in rM+F+HN-inoculated ducks. Therefore, the increased virulence of NDV in ducks is not due to a single amino acid substitution in one protein, but rather to the synergistic effects of multiple mutations in three viral proteins.