农林科学最新文献

Salmonellosis is a major food safety challenge in poultry production, requiring effective antibiotic alternatives. We isolated a polyvalent Tequintavirus, vB_SalS_KY05, from a Taiwanese poultry farm and evaluated its biological properties and in vivo efficacy against Salmonella enterica serovars Typhimurium and Enteritidis, and Escherichia coli. The objective of this study was to comprehensively characterize vB_SalS_KY05 and assess its potential as a biocontrol agent for poultry farming. Genome analysis confirmed a lytic lifestyle with no detectable virulence or antimicrobial resistance genes. The phage remained stable at pH 4-10, at 41 °C, and in water for 7 days. For improved biosafety, large-scale amplification was achieved by switching the propagation host to non-pathogenic E. coli K12. In vivo, SPF chickens challenged with S. Typhimurium received low-dose (10⁵ PFU/mL) or high-dose (10⁸ PFU/mL) phage via drinking water. Low-dose treatment reduced splenic Salmonella, improved albumin-to-globulin ratios, and enriched beneficial taxa like Lactobacillus crispatus and Blautia coccoides. In contrast, high-dose treatment resulted in phage-bacteria coexistence and increased potentially harmful taxa including Erysipelatoclostridium. Overall, cecal microbiota composition remained largely unchanged. These findings indicate vB_SalS_KY05 is a promising biocontrol candidate, highlighting the importance of dose optimization to enhance pathogen control while preserving gut microbiota stability in poultry production.

Vaccination is routinely used in industrial poultry to control infectious diseases. Vaccines based on mRNA and self-amplifying RNA (saRNA) are approved for human use, but research on their application in poultry is limited. In this study the saRNA vaccine platform is evaluated in poultry. First, a luciferase-encoding saRNA (luc-saRNA) was tested as a model vaccine across different administration routes and doses in broilers. High luciferase expression, and anti-luciferase antibodies were observed after intramuscular (IM), subcutaneous (SC), and in ovo (IO) administration. After a second Luc-saRNA injection, seroconversion rates and antibody titers increased in the IM and SC group to almost 100%. Higher doses of Luc-saRNA increased luciferase production. However, they did not linearly increase antibody production, as all tested doses (0.20-5.0 µg) elicited an equipotent immune response. A vaccination experiment with saRNA encoding the hemagglutinin head-domain (HA-HD) of H5N1 avian influenza showed hemagglutinin inhibition (HI) titers that are indicative for protection after a single injection and these titers remained above the protective threshold during 6 weeks without boosting. When boosted, the HI titers increased four-fold. This study confirms effective protein translation and immune response induction in chickens with IM or SC administered saRNA-LNPs, even at the lowest dose of 0.20 µg.

Staphylococcus aureus (S. aureus) evades host immunity by modulating macrophage functions, including immune regulation and phagocytosis, ultimately contributing to bovine mastitis. This study aimed to elucidate the molecular mechanisms of S. aureus-induced bovine mastitis from both host and pathogen perspectives, focusing on prostaglandin E₂ (PGE₂) as a key regulator. During bovine mastitis, macrophages were recruited into the mammary gland with elevated inflammatory mediators. S. aureus lipoproteins amplified inflammation by activating MAPK and NF-κB pathways via TLR2, TLR4, and NLRP3, leading to elevated secretion of mediators, including PGE₂, in bBMMs. Inhibition of TLR2, TLR4, or NLRP3 decreased COX-2 and mPGES-1 expression, suppressing PGE₂ synthesis, while inhibition of COX-2 or mPGES-1 can regulate the expression of TLR2 and NLRP3, as well as the activation of MAPKs and NF-κB signaling pathways. Excess PGE₂ can regulate inflammation and phagocytosis mediated by TLR2, TLR4, and NLRP3. S. aureus lipoproteins promote PGE₂ synthesis via TLR2, TLR4, and NLRP3 signaling, while PGE₂, in turn, modulates receptor activity, inflammation, and phagocytosis. These findings reveal crucial functional cross-talk between PGE₂ and innate immune receptors in S. aureus-induced mastitis, suggesting that targeting this interaction may provide novel therapeutic strategies.

Feline calicivirus (FCV) infection causes nasal discharge, oral mucosa inflammation, ulcerations, gingivitis, and conjunctivitis, often progressing to chronic gingivostomatitis, severe pneumonia, and fatal systemic infections. With no antivirals currently available, poly(sodium 4-styrene sulfonate) (PSSNa) was identified in 2019 as a safe inhibitor in vitro. In this preliminary single-center, randomized, double-blind, placebo-controlled field study, we further characterized the PSSNa's safety profile and tested its efficacy in cats after topical oral application. Twenty-eight cats were enrolled in the study, and they were initially treated with standard dental therapy, followed by adjuvant local oral application of PSSNa or placebo. After 4 weeks, PSSNa demonstrated a favorable safety profile with no adverse effects. The treatment group showed a significant decrease in viral load (p = 0.001) compared to placebo (p = 0.012). Disease symptoms improved significantly, though the oral health index remained unchanged. Additionally, PSSNa showed activity against multiple genetically diverse isolates, indicating a potential, exploratory link between genetic background and treatment outcome. Summarizing, this study presents initial data on the efficacy and tolerability of PSSNa treatment for FCV infections in cats. Nevertheless, several significant limitations should be acknowledged, including inconsistent drug administration by owners, non-sterile housing, sample size, variable oral disease severity, and concurrent treatments.

Herein, we present novel quantitative loop-mediated isothermal amplification (qLAMP) and reverse-transcription qLAMP (RT-qLAMP) assays for the detection of five viruses implicated with the onset and progression of bovine respiratory disease (BRD): Bovine Alphaherpesvirus Type 1 (BHV-1), Bovine Adenovirus Type 3 (BAV-3), Bovine Respiratory Syncytial Virus (BRSV), Bovine Viral Diarrhea Virus Type 1 (BVDV-1), and Bovine Parainfluenza Virus Type 3 (BPIV-3). Using contrived samples spiked with whole viruses, our extraction-free assays have limits of detection between 30 and 1,057 copies per reaction (1.8% final sample concentration) with minimal sample processing. Using dual-tipped swabs and 1.4 mL resuspension volumes, limits of detection are on the order of 2 × 10⁵ copies per swab for BAV-3 and BHV-1 and between 6.31 × 10⁶ to 8.22 × 10⁶ copies per swab for BPIV-3, BRSV, and BVDV-1. Analytical sensitivities ranged from 73 - 100% and analytical specificities ranged from 90 - 100%. Additionally, we introduced a streamlined pipeline to minimize the experimental workload to design, screen, select, and characterize LAMP performance for developing assays. Our assays support the development of colorimetric LAMP assays that enable the sensitive and specific detection of these viruses' chute side to aid in diagnosing and treating BRD. The associated pipeline enables more rapid development of LAMP-based diagnostic tools targeting emerging pathogens.

Managing fat accumulation is a critical goal in the poultry industry, with the liver being the primary site for lipid metabolism in chickens. This study used non-targeted metabolomics to investigate dynamic changes in metabolite composition in chicken liver across five physiological stages. A total of 1121 metabolites were identified, with 749 and 372 detected in positive- and negative-ion modes, respectively. The regulation of hepatic lipolysis involves numerous metabolic pathways, making it a complex process. We performed trend analysis of lipid, carbohydrate and amino acid-related metabolites. Age exerted major effects on hepatic metabolism, significantly enriching pathways including alpha-linolenic acid metabolism, linoleic acid metabolism, steroid hormone biosynthesis, 2-oxocarboxylic acid metabolism and nicotinate and nicotinamide metabolism. Transcriptomic analysis identified 12 lipid-metabolism-related genes, showing a tendency of continuously increase. Potential functional genes influencing lipid metabolism-related pathways were identified through a comprehensive analysis of differential lipid-related metabolites and genes, including fatty acid desaturase 2 (FADS2), acetyl-CoA acetyltransferase 2 (ACAT2), apovitellenin 1 (APOV1), vitellogenin 1 (VTG1), membrane-bound O-acyltransferase domain-containing protein 2 (MBOAT2) and ELOVL fatty acid elongase 1 (ELOVL1). These findings could help improve understanding of hepatic metabolism during different physiological stages and identify valuable biomarkers for specific metabolite accumulation.

Diagnostic ultrasound (US) is a noninvasive, cost-effective imaging modality widely used for evaluating the gastrointestinal (GI) tract in companion animals. It provides information on wall thickness and layer differentiation, allowing assessment of normal anatomy and pathological changes. Despite its diagnostic relevance, ultrasonographic reference values for the GI tract in dogs and cats remain inconsistent across publications. This study reviewed ultrasonographic characteristics of the normal GI wall in dogs and cats and compiled a consensus-based reference table for overall wall thickness and individual layer proportions to enhance clinical interpretation. A literature search of PubMed and Scopus identified studies assessing the ultrasonographic features of normal GI segments, from stomach to colon, in healthy dogs and cats. Twelve studies met the inclusion criteria: six focused on dogs and six on cats. Reference values for GI wall thickness and its layers were reported in both species. However, discrepancies were noted in weight-based classifications for dogs, and the stomach of adult dogs remains poorly studied. Moreover, evaluation of gastric rugal and inter-rugal folds remains limited in this species. US is valuable for GI assessment, but dispersion of reference values across studies may hinder accessibility. Establishing standardized ultrasonographic parameters could improve diagnostic accuracy and clinical decision-making.

While thyroid physiology has been studied in domestic ruminants, many uncertainties remain. In fact, this metabolism is rarely assessed in routine veterinary practice, and diseases of the thyroid gland or its metabolism are poorly documented in domestic ruminants. This scoping review aims to summarize current knowledge in anatomy, physiology, diseases, and diagnostic methods related to thyroid function in domestic ruminants. A structured research methodology was followed using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) extension for scoping reviews. Four databases were used: CAB Abstracts, Embase, PubMed and Scopus. Selection and screening process of the identified studies, as well as data extraction, were managed using Covidence software. Finally, 206 studies were included. Most studies involved cattle (n = 104), followed by sheep (n = 65) and goats (n = 28). The main study topic was on thyroid physiology (n = 127), followed by diseases (n = 48), diagnostic methods (n = 22) and histology (n = 9). Although many studies addressed the anatomy and physiology of the thyroid gland, few confirmed the euthyroid status (having a normally functioning thyroid gland) of these animals, warranting cautious interpretation of the results. Hypothyroidism is the most documented thyroid disease in ruminants, predominantly caused by iodine deficiency. The physiology of the thyroid gland has been extensively studied in relation to heat stress, reproduction, animal production and nutrition. However, there is much less literature available on diseases described in domestic ruminants and their diagnostic methods. Diagnostic tools for assessing thyroid metabolism in ruminants include assays for total thyroxine, total triiodothyronine, bovine thyroid stimulating hormone, total serum iodine, milk iodine, urine iodine, and plasmatic inorganic iodine.

Canine mammary tumors (CMTs) are the most common neoplasms in intact female dogs, yet early detection remains challenging due to the lack of clinically validated, noninvasive biomarkers. This study aimed to develop a noninvasive diagnostic model for CMT detection by integrating serum autoantibody biomarkers with machine learning. Serum samples from 154 dogs with mammary tumors (31 benign, 123 malignant) and 39 healthy controls were analyzed using a custom multiplex immunoassay detecting autoantibodies against AGR2, HAPLN1, IGFBP5, and TYMS, normalized to anti-BSA levels. Median fluorescence intensity (MFI), standardized autoantibody ratios, and their combination, together with clinical variables, were used to train random forest classifiers. The model based on standardized autoantibody ratios achieved the best performance, with an AUC of 0.79 (sensitivity 75.3%, specificity 74.4%) for overall CMT detection; 0.78 (92.7%, 61.5%) for malignant CMTs; and 0.77 (82.2%, 71.8%) for early-stagemalignancies. Assuming a CMT prevalence of 0.5 in the hospital-referred population, the positive and negative predictive values ranged from 0.74-0.75 and 0.75-0.91, respectively. This proof-of-concept study demonstrates that a machine learning-assisted multiplex autoantibody assay offers a feasible noninvasive approach for CMT detection. Further validation in larger, independent cohorts is warranted to support clinical translation in veterinary oncology.

The genus Listeria is heterogeneous and contains pathogenic and nonpathogenic species. Pathogenic L. monocytogenes and L. ivanovii have different environmental distributions, infect different hosts, and cause distinct syndromes. Here, we evaluated whether responses of different Listeria species to diverse host niches contribute to virulence heterogeneity and influence their environmental distribution. We assessed resistance to gastric and intestinal fluids, gut and uterus microbiota, and semen. L. monocytogenes was more resistant than L. ivanovii in gastric fluid, whilst L. seeligeri and L. valentina showed an intermediate phenotype. All the tested Listeria species resisted the intestinal fluid. Gut microbial communities outcompeted and eliminated L. ivanovii and L. valentina. However, L. monocytogenes and L. seeligeri outcompeted intestinal commensal bacteria. Our findings suggest that, unlike L. monocytogenes and L. seeligeri, the tested L. ivanovii are unlikely to colonize the gastrointestinal tract of ruminants, which would reduce replication, fecal shedding, and environmental distribution. However, the ability of L. ivanovii to survive within uterine microbiota and semen suggests that the tested clones could persist in the urogenital tract of ruminants. Then venereal transmission could be more probable than the oral route, which could explain why L. ivanovii is associated with abortion outbreaks and not encephalitic cases.