Veterinary microbiology最新文献

Escherichia (E.) coli inhabits the pig's microbiota, and some strains can cause a range of diseases when carrying specific virulence factors. Although molecular diagnostics are used to detect these virulence factors, the strength of their detection with clinical disease remains incompletely quantified under field conditions. This systematic review and meta-analysis aimed to estimate the prevalence ratio (PR) of E. coli virulence factor detection in isolates from clinically affected (i.e., enteric disease characterized by diarrhea) versus non-affected pigs. The search was conducted in February 2025 using PubMed and CAB Abstracts to identify articles reporting PCR-based detection of E. coli virulence factors in isolates from pigs with and without clinical signs (i.e., diarrhea). Meta-analyses of each virulence factor detected in two or more studies were conducted using a random-effect model. From 2575 records initially identified, 31 studies met the inclusion criteria, spanning data from 22 countries, with studies from 1998 to 2024. Eighteen virulence factors were analyzed by age category, of which seven were detected more frequently in clinically affected pigs. The F18 (PR = 2.24, 95 % CI = 1.13-4.46), STb (PR = 1.53, 95 % CI = 1.11-2.11), Stx1 (PR = 1.72, 95 % CI = 1.26-2.35), and Stx2 (PR = 1.76, 95 % CI = 1.16-2.67) had a higher frequency of detection in clinically affected pigs over all age categories. When investigating only suckling piglets, F4 (PR = 5.29, 95 % CI = 1.84-15.19), F18 (PR = 2.44, 95 % CI = 1.3-4.6), AIDA (PR = 5.32, 95 % CI = 1.45-19.51), EAST1 (PR = 1.53, 95 % CI = 1.03-2.28), STb (PR = 2.04, 95 % CI = 1.26-3.32) were detected more frequently in clinically affected piglets. The Stx2 was also more frequently detected in clinically affected pigs in the nursery phase (PR = 2.90, 95 % CI = 1.30-6.48). High heterogeneity was present in most analyses, highlighting variability in detection patterns across studies. Several traditionally tested virulence factors, such as F5, F6, and Stx2e, did not show differences between clinically affected and non-affected pigs. These findings support the role of molecular diagnostics in the characterization of pathogenic E. coli and underscore the importance of interpreting virulence factors results in conjunction with clinical signs for a more accurate diagnostic.

Leptospirosis is a zoonotic disease caused by spirochetes of the genus Leptospira. Equine genital leptospirosis (EGL) has been described as a chronic and silent syndrome, presenting reproductive alterations such as abortion, stillbirth, placentitis, embryonic loss, repeat breeding syndrome, and subfertility. This study aimed to investigate the genital Leptospira infection in naturally infected mares with poor reproductive performance, as well as to genetically characterize the agents. A total of 41 mares with a history of poor reproductive performance were selected. Sera were collected for serology by Microscopic Agglutination Test (MAT), while urine, uterine mucus, and uterine fragment samples were collected for a lipL32-PCR screening. Samples positive at lipL32-PCR were submitted to secY gene sequencing. Considering MAT, 17/41 mares were seroreactive (41.5 %). The most frequent serogroup was Australis, detected in 13 animals (76.5 % of the reactive). Out of the 41 mares, 25 (61.0 %) were positive in lipL32-PCR and, of these, 21 (84.0 %) showed positive in at least one genital sample. Regarding secY nested-PCR, only six samples, all from the uterine fragment, were amplified, and all were characterized as Leptospira interrogans with ≥ 99 % of similarity with isolates of serovar Bratislava, from the Australis serogroup. Our results confirmed the diagnosis of EGL and highlighted the high detection rate of Leptospira DNA in genital samples of mares with poor reproductive performance.

Swine enteric coronaviruses (SECoVs), including porcine epidemic diarrhea virus (PEDV), transmissible gastroenteritis virus (TGEV), and porcine deltacoronavirus (PDCoV), pose a major threat to global swine production, with current control measures remaining suboptimal. These infections are often characterized by mixed infections, highlighting the urgent need for anti-SECoV drugs. This study elucidates the potential of luteolin as a broad-spectrum antiviral agent targeting the 3 C like protease (3CLpro). Molecular docking and dynamics simulations indicated a stable and high-affinity interaction between luteolin and PEDV 3CLpro, which was confirmed by molecular layer interferometry, showing direct binding with a high affinity (KD = 236 nM). In vitro, luteolin significantly inhibited 3CLpro enzymatic activity (IC₅₀ = 18.74 µM) and potently suppressed PEDV replication. In a piglet model, both prophylactic and therapeutic administration of luteolin achieved a 75 % protection rate (3/4), significantly alleviated diarrhea, mitigated intestinal tissue damage, and reduced the viral load in the jejunum and cecum following PEDV challenge. Furthermore, luteolin exhibited direct binding to TGEV and PDCoV 3CLpro with high affinities (KD = 342 nM and 282 nM, respectively). Consistent with this, it demonstrated broad-spectrum antiviral activity in vitro, the half-effective concentrations (EC₅₀) for TGEV and PDCoV were 13.14 μM and 4.10 μM, respectively. Collectively, our findings not only validate luteolin as an effective PEDV inhibitor but also highlight its promise as a broad-spectrum agent against SECoVs, providing a crucial foundation for developing novel anti-coronavirus therapeutics.

Mycoplasma bovis (M. bovis) is an emerging major bovine pathogen, causing economic losses worldwide in the dairy and beef industry. In this study, whole-genome sequencing was performed on 47 representative isolates collected from 11 provinces in China between 2018 and 2023, and the data were compared with 86 global reference genomes. Core SNP phylogeny and core genome multilocus sequence typing (cgMLST) showed that Chinese isolates were mainly attributed to type I spectrum, ST-52 was the dominant type (87.5 %), with high overall homology and geographical clustering. Annotation of virulence factors identified six categories of functional genes, while Chinese isolates displayed varying degrees of deletions within the vsp family and the adhesion-immune modulation region (Mbov_0723-Mbov_0735). Functional validation using representative strains-PZJS01 (complete), PZNX02 (partially undetected), and PZHLJ02 (large-fragment undetected)-demonstrated that PZJS01, which harbors an intact pathogenicity island, exhibited stronger invasiveness and significantly induced host cell apoptosis (∼28 %). These findings indicate that this structural region may play a critical role in the pathogenic process. Antimicrobial susceptibility testing revealed that Chinese isolates were generally resistant to erythromycin (97.9 %) and tylosin (59.6 %), and all strains were non-susceptible to oxytetracycline, showing a pattern of multidrug resistance. In contrast, doxycycline and tiamulin exhibited favorable in vitro activity based on MIC testing. This study systematically elucidates the clonal dissemination patterns, virulence evolution, and antimicrobial resistance risks of M. bovis in China, providing scientific evidence for the development of control strategies and vaccine design.