BMC Veterinary Research最新文献

Aeromonas dhakensis, an increasingly prevalent pathogen in tropical areas, presents significant risks to public health and the aquaculture industry. This research evaluates the virulence effects of ugd and phoB gene deletions. The double gene deletion mutant strain ΔugdΔphoB was obtained by further knocking out the ugd gene in the previously constructed single mutant strain ΔphoB. Phenotypic analyses under phosphate-deficient conditions showed marked decreases in both growth and motility for the Δugd and ΔugdΔphoB mutants compared to the wild type. Conversely, under phosphate-rich conditions, growth remained stable, although motility variations were noted. The mutants ΔugdΔphoB and Δugd exhibited diminished resistance to H₂O₂, ECPase activity, and antimicrobial peptide resistance, alongside reduced adherence to EPC cells. However, the Δugd mutant displayed enhanced biofilm formation. The immunoprotection experiment showed that the protection rate (relative percent survival, RPS) of the Δugd mutant strain was 63.3%, which was significantly higher than the 40.0% of the ΔugdΔphoB mutant strain. Consistently, the Δugd mutant strain also exhibited a more significant degree of virulence attenuation (median lethal dose, LD₅₀ = 2.87 × 10⁸ CFU/mL); in contrast, the LD₅₀ of the ΔugdΔphoB mutant strain was 1.23 × 10⁸ CFU/mL. This indicates that the Δugd mutant strain has greater potential as an attenuated live vaccine candidate due to its stronger immunoprotective efficacy and lower residual virulence.

Background: Animal African trypanosomiasis (AAT) poses a significant impediment to livestock production and economic progress in sub-Saharan Africa. To reduce the burden of AAT in Uganda and contribute to the AAT progressive control pathway, there is a need to develop effective AAT and tsetse control measures. In this study, we assessed a combination of chemotherapy and Restricted Insecticide Application Protocol (RAP) as a last mile control option for the progressive control of AAT and acute sleeping sickness in south- eastern Uganda.

Methods: Cattle from fourteen AAT endemic villages in south-eastern Uganda were treated with two doses of diminazene acecurate 40 days apart and sprayed with deltamethrin once monthly for 6 months following chemotherapy. Both cattle and tsetse flies were screened for trypanosomes before and 6 months into the interventions using ITS1-PCR. Tsetse flies trapped per day per trap were counted and the apparent tsetse fly density [Flies/Trap/Day-FTD] determined and mapped. The effect of chemotherapy and RAP on (1) FTD and (2) trypanosome infection in both cattle and tsetse flies was determined using mixed effects regression models.

Results: RAP and chemotherapy were associated with significantly lower odds of trypanosome infections in cattle (OR = 0.43, 95% CI; 0.35-0.54) and tsetse flies (OR = 0.06, 95% CI; 0.03-0.10). RAP and chemotherapy reduced Trypanosoma species prevalence from 23.38% to 12.70% among cattle and 73.33% to 21.76% in tsetse flies. Additionally, treatment was significantly associated (P = 0.04) with a reduction in FTD by 1.02. Unlike T. vivax, both T. congolense and T. brucei infections were reduced by RAP and chemotherapy. There was a single infection with Trypanosoma brucei rhodesiense detected in the cattle and none in tsetse flies.

Conclusion: Combination of RAP and chemotherapy offers promising approach to control AAT in endemic areas and can support last mile acute sleeping sickness elimination efforts when combined with other available tsetse and AAT control methods. A singular infection with T. b. rhodesiense indicates that there is still a risk of acute sleeping sickness resurgence in south-eastern Uganda unless tsetse and trypanosomiasis control and surveillance efforts are maintained.

Background: This case study reports testicular asymmetry in entire male (EM) and immunocastrated pigs (IC), specifically focusing on histomorphometric and transcriptomic characteristics of testicular and epididymal tissue in three IC with pronounced unilateral testicular atrophy.

Case presentations: During post-mortem assessment of genital tract, three IC were identified with marked testicular asymmetry. Testes and cauda epididymides were collected from these animals for histomorphometric analysis and quantitative polymerase chain reaction (qPCR). In addition, percentage of testicular asymmetry was calculated in a broader cohort of EM and IC pigs to assess prevalence and degree of asymmetry.

Conclusion: The observed cases of severe unilateral atrophy did not appear to be systematically related to immunocastration, based on available data. In atrophic testes, there were distinct histological differences in testes and cauda epididymides, along with molecular changes, including downregulation of gonadotropin-releasing hormone receptor II (GnRHRII), estrogen receptor 1 (ESR1) and betaine homocysteine S-methyltransferase (BHMT), but no marked differences in plasma testosterone concentrations nor immunocastration efficacy. Although based on a limited number of cases, these findings provided the first combined histological and molecular characterization of unilateral testicular atrophy in immunocastrated boars.

The purpose of this study was to investigate how growing rabbit bucks responded to stress induced by dexamethasone (DEX). Sixteen New Zealand White male rabbits (4-5 months old, 2.75 ± 0.07 kg) were randomly assigned to four groups. After a one-week preliminary period under the same management, three groups received intramuscular DEX injections for seven consecutive days at doses of 1, 2, and 3 mg/kg body weight (D01, D02, and D03, respectively), while the control group (D00) received saline. Reproductive, behavioral, and physiological stress indicators were assessed throughout the preliminary, treatment, and two- weeks recovery periods. DEX administration induced dose-dependent adverse effects. Significant reductions in body weight gain, testosterone levels, sexual behavior, and semen quality were observed. High doses of DEX produced a great increase in anxiety-related responses in the open field test, and also in the novel object recognition test, they produced a great decrease in chin marking frequencies during the third 5 min habituation, discrimination ratio (RI), and primary object recognition response (PORR); and altered discrimination ratio for both RI and PORR. Physiological stress markers, including triiodothyronine levels, rectal temperature, and pulse rate, increased significantly, particularly in higher dose groups. The neutrophil-to-lymphocyte ratio also rose in a dose-dependent manner, with only partial recovery post-treatment. In conclusion, high-dose DEX administration in growing rabbit bucks negatively affects semen quality, behavior, growth, and hormonal balance, even over short durations. Therefore, glucocorticoids must be used carefully when breeding animals, particularly during sensitive developmental stages.

Background: Universal vaccine against Streptococcus suis (S. suis) remains a challenge due to the high number of serotypes/strains, the absence of cross-protection among them and the existence of different immune escape strategies. In this study, the immunomodulatory potential of live and inactivated porcine derived Bacillus Calmette-Guérin (dpB) in combination with specific immunogenic proteins S. suis is evaluated in murine model.

Results: Results revealed different immune responses depending on dpB formulation. Live-dpB administered intravenously induced consistent results with trained immunity, including elevated proinflammatory cytokines and enhanced phagocytosis activity, reflecting stronger innate immune activation. However, inactivated dpB administered intravenously twice, enhanced adaptive responses post-S. suis vaccination showing increased IFN-γ levels in plasma and higher spot forming units in splenic ELISpot assays.

Discussion: These findings suggest complementary roles for live and inactivated dpB in innate and adaptive immunity. This approach may represent an initial step towards improving vaccine efficacy against S. suis, combining targeted innate with adaptive immunity. Further research is needed to optimize combinations of immunomodulators with traditional S. suis antigens.