A combined molecular strategy was developed to accurately differentiate wild-type and vaccine strains of Bacillus anthracis. This approach integrates a multiplex TaqMan qPCR assay targeting the BclA, sap, and cap genes with conventional PCR analysis of BclA fragment length polymorphism. The qPCR assay demonstrated high specificity, with no cross-reactivity against other common pathogens, and exhibited a consistent limit of detection of 2.11 × 101 copies/μL (Cq < 35) for all three targets. Excellent repeatability was confirmed, with intra- and inter-assay coefficients of variation below 1.96% and 3.06%, respectively. Validation using 19 wild-type strains revealed two distinct qPCR profiles, and all wild-type strains were conclusively differentiated from the capsule-producing Chinese vaccine strain II and the acapsular Sterne strain by their characteristic BclA amplicon sizes. Through simulation PCR validation of common global canSNP genotyping (groups A, B, and C), it is possible to distinguish between wild-type and vaccine strains in China. This integrated "multiplex qPCR-BclA length analysis" protocol provides a reliable, sensitive, and specific tool for the precise detection and differentiation of B. anthracis strains in China.IMPORTANCEAnthrax, which is caused by the bacterium B. anthracis, remains a serious zoonotic disease. Its effective surveillance relies on precise strain identification. Currently, it is challenging to rapidly and accurately distinguish wild-type strains from vaccine strains, which hinders outbreak investigation and response. This study develops a novel molecular strategy combining multiple genetic targets to solve this critical diagnostic problem. The new method provides a reliable tool for strain differentiation, directly supporting accurate source tracing and informed decision-making during anthrax outbreaks. By improving diagnostic precision, this work contributes to strengthening public and veterinary health defenses against this persistent threat.

In recent years, the inappropriate use of antibiotics has led to the widespread emergence of multidrug-resistant Klebsiella pneumoniae (MDR-K. pneumoniae), resulting in infections that are increasingly challenging to manage clinically. Bacteriophages (phages) are emerging as promising alternatives to antibiotics. This study aimed to isolate and characterize lytic phages targeting MDR-K. pneumoniae, providing biological resources and experimental data for phage-based control of MDR-K. pneumoniae infections. A lytic phage, designated vB_KpnA_Pkp-1 (Pkp-1), was successfully isolated. TEM revealed that Pkp-1 belongs to the Caudoviricetes class, featuring an icosahedral head (62 ± 2 nm) and a short tail (17 ± 1 nm), with plaques displaying clear centers and translucent halos. Pkp-1 exhibited strict specificity for porcine-derived ST967 K. pneumoniae isolates. Its optimal MOI was 0.00001, with a latent period of 25 min and a burst size of 108 PFU/cell. Pkp-1 demonstrated high stability at 40 °C–60 °C and pH 4.0–11.0, effectively inhibiting planktonic bacteria and suppressing/eradicating biofilms. Genomic analysis revealed a 38,455 bp dsDNA genome with 48 open reading frames (ORFs), functions of 30 proteins were predicted (e.g., DNA polymerase, tail fiber), while the remaining 18 proteins were annotated as hypothetical. Genomic analysis confirmed the absence of virulence, lysogeny-related, and antibiotic resistance genes. Pkp-1 shared high identity with phages phi1_146013 (98.71

Proteus mirabilis (P. mirabilis) is frequently detected in the food supply chain, particularly in meat and fresh produce. It carries antibiotic resistance genes (ARGs) and virulence factors, which pose significant risks to food safety and public health. Phages are considered a promising natural antimicrobial agent capable of effectively eliminating multidrug-resistant (MDR) pathogens. However, the application of phages to control MDR P. mirabilis in the food supply chain remains relatively limited. In this study, the P. mirabilis isolate carried seven virulence factors, one class 1 integron, and four ARGs, showing resistance to 94.74% (18/19) of the tested antibiotics. We isolated and characterized a lytic P. mirabilis phage, vB_PMG_YP1. Genomic analyses revealed that vB_PMG_YP1 belongs to the genus Privateervirus. vB_PMG_YP1 encodes tRNA genes and lacks genes associated with antibiotic resistance, virulence, or lysogeny. vB_PMG_YP1 maintained activity from 4 to 60 °C and across pH 3-11. The optimal multiplicity of infection (MOI) was 0.1, with a burst size of 240 phages per cell. The spot assay (60.87%, 14/23) and EOP test showed that vB_PMG_YP1 possesses a moderate lytic spectrum against P. mirabilis. vB_PMG_YP1 provided sustained suppression of P. mirabilis on chicken breast, pork tenderloin, and lettuce at 4 °C, whereas at 25 °C it achieved more rapid and robust inhibition. Under both 4 °C and 25 °C conditions, phage treatment did not significantly affect the color, texture, odor, or overall acceptability of any food matrix. These findings suggest vB_PMG_YP1 as a potential biocontrol candidate for reducing MDR P. mirabilis on food matrices.

Streptococcus suis serotype 9 is an emerging zoonotic pathogen threatening pig production and public health. Here, we combined comparative genomics of 16 strains, including clinical isolate SS2401, to elucidate the role of prophages in shaping genomic plasticity and virulence evolution. The pan-genome was open (α = 0.375), highlighting extensive genetic diversity. Prophages were prevalent (56.25% of strains), significantly correlated with larger genomes, and exhibited two integration modes: direct insertion as genomic islands and integration at recombination hotspots associated with large-scale inversions. Phylogenetic analysis of the terminase large subunit (TerL) and whole-genome sequences revealed multiple independent acquisitions, with three prophages in SS2401 originating from distinct lineages ("one strain, multiple sources"). Recombination analysis detected 1,432 events across the core genome, indicating frequent horizontal gene exchange. The virulence gene sly (suilysin) was carried as a gene cassette within prophage Phi2401a. Notably, we identified integrase-deficient but otherwise intact prophages that may function as "gene prisons," stably fixing virulence traits. These findings demonstrate that prophages act as dual drivers of genomic architecture and as dynamic reservoirs for virulence genes, providing a framework for understanding bacterial adaptation and informing surveillance strategies in the swine industry.IMPORTANCEStreptococcus suis serotype 9 poses a significant threat to pig farming and public health worldwide. This study reveals that prophages are not passive passengers but active architects of genomic plasticity and virulence evolution in this pathogen. We demonstrate that prophages contribute to genome expansion, facilitate large-scale chromosomal rearrangements, and carry key virulence genes such as sly. The discovery of a "one strain, multiple sources" acquisition pattern and the "gene prison" model explains how virulence traits can be stably maintained and disseminated. These findings redefine prophages as dual drivers of bacterial evolution, providing new insights for surveillance and intervention strategies in the swine industry.

Multidrug-resistant Staphylococcus aureus, including methicillin-resistant strains (MRSA) pose an increasing risk to animal health and are a known zoonotic risk in the One Health paradigm. The use of bacteriophage cocktails (combinations of two or more lytic phages) have gained interest for expanding host range, inhibiting phage-resistant mutants, and disrupting biofilms, a growing challenge in conventional antibiotic therapy. This review aims to summarise the existing literature on phage cocktails against MDR S. aureus in three different animal populations: pets, livestock and wild animals. For livestock, particularly dairy cattle, a number of cocktails have advanced from in vitro characterization and murine mastitis models to pilot field trials, with one randomized study showing an 81.3% bacteriological cure rate for naturally occurring S. aureus mastitis. Companion animal research is in the intermediate phase, and polyvalent phages against both S. pseudintermedius and S. aureus have been shown to be effective in canine pyoderma and otitis, with a recent study of a canine fracture-related infection showing efficacy comparable to prolonged antibiotic treatment. However, there are no specific studies on wild animals and this is a gap in knowledge. Some of the ongoing problems are the development of phage resistance, the instability of biological matrices like milk and serum, anti-phage immune responses, and the lack of harmonized regulatory guidelines for veterinary phage products. New technologies such as liposomal encapsulation, hydrogel delivery, and phage-antibiotic synergy are promising. A recent EU approval of a phage feed additive for poultry is a regulatory milestone. Although they show promise, phage cocktails are still in the investigational stages. They have a significant clinical and public health potential that must be confirmed by increasing multicenter field trials in livestock, well-controlled studies in companion animals, systematic investigations of wildlife reservoirs, standardized dosing, extensive safety testing and regulatory harmonization prior to recommending their routine use in veterinary medicine.

(1) Background: In recent years, the increasing emergence of multidrug-resistant pathogens in pig farms has begun to pose a severe threat to animal welfare and, by extension, public health. In this study, we aimed to explore the biological characteristics and genomic features of bacteriophages that are capable of lysing porcine multidrug-resistant E. coli, which was isolated from sewage. In doing so, we provided a reference for phage therapies that can be used to treat multidrug-resistant strains. (2) Method: Using the multidrug-resistant E. coli isolate sq-1 as the host bacterium, bacteriophages were isolated and purified from fecal samples using a double-layer agar plate method. The morphology was observed using a transmission electron microscope, and its host range, optimal multiplicity of infection (MOI), one-step growth curve, thermal stability, acid–base tolerance, and in vitro antibacterial ability were tested. Genomic features were analyzed using whole-genome sequencing. (3) Results: A lytic phage named vB_EcoS_Psq-1 (abbreviated as Psq-1) was successfully isolated. Electron microscopy revealed that Psq-1 belongs to the family of long-tailed phages, possessing clear and transparent plaques of approximately 1 mm in diameter. Psq-1 only lyses the host bacterium and does not affect other E. coli strains or other species of bacteria. The optimal MOI for phage Psq-1 was 0.1, with a latent period of 25 min, an exponential growth period of 25 min, and a lysis yield of 44.21 PFU/cell. Its activity remains stable at temperatures between 40 °C and 60 °C and from pH 4.0 to pH 13.0. Psq-1 exhibited a significant inhibitory effect on E. coli in liquid culture medium. The nucleic acid type of phage Psq-1 was dsDNA, with a total genome length of 44,183 bp and a GC content of 52.16%. No known resistance, lysogenic, or virulence-related genes were detected. The whole genome contains 55 open reading frames (ORFs). (4) Conclusions: This study isolated a bacteriophage that is capable of lysing multidrug-resistant E. coli. Characterized by a narrow E. coli lysis range, a long latent period, limited lytic ability, and stable biological properties, this bacteriophage can serve as a reference isolate for E. coli phages and can provide biological materials and data to support research on bacteriophages that are effective against multidrug-resistant porcine E. coli.

Nontuberculous mycobacteria (NTM) are environmental organisms that can cause opportunistic infections in humans and animals. Mycobacterium abscessus (Mab) is a rapidly growing Mycobacterium known for its resistance to multiple antibiotics and ability to cause respiratory, skin, and mucosal infections. Understanding the distribution and prevalence of NTM, particularly Mab, in cattle farms and slaughterhouses is crucial for developing effective prevention and control measures. We collected environmental swabs from various surfaces (e.g., feed troughs, sinks, walls, floors, feces, and padding) in cattle farms and slaughterhouses across multiple provinces. High-throughput sequencing technology was utilized to analyze the 16S rDNA V3-V4 region of bacterial DNA extracted from the samples, and qPCR methods were employed to detect and quantify Mycobacterium abscessus in the collected samples. Bioinformatics analysis was performed to identify and classify the NTM species present in the samples. This study compared the abundance and diversity of NTM in different environments and assessed the potential zoonotic risk. A total of 1648 environmental swabs were collected from cattle farms and slaughterhouses in 12 provinces of China in 2023, of which 12 samples tested positive for Mab qPCR detection, yielding a detection rate of 0.73% (12/1648). Among them, the detection rate of environmental samples from cattle farms and slaughterhouses was 0.42% (3/720) and 0.87% (9/928), respectively. This study provides valuable information on the epidemiology of NTM in cattle farms and slaughterhouses, contributing to developing effective strategies for preventing and controlling NTM infections. It also enhances our understanding of the zoonotic potential of Mycobacterium abscessus and other NTM species.

The emergence of multidrug-resistant (MDR) Proteus mirabilis poses a significant threat in porcine farming and public health, highlighting the need for alternative biocontrol agents. This study aimed to isolate and characterize a lytic bacteriophage with therapeutic potential against MDR P. mirabilis. Using the clinical MDR P. mirabilis strain Pm 07 as host, a bacteriophage, vB_Pmc_P-07 (P-07), was successfully isolated from fecal and sewage samples via an enrichment protocol. Phage P-07 forms plaques surrounded by a distinct translucent “halo,” suggesting the production of depolymerase. It achieved high titers of up to 1.40 × 108 PFU/mL and exhibited a narrow host range, high stability across a broad range of temperatures (40–60 °C) and pH (4–12), as well as considerable anti-biofilm activity. An optimal multiplicity of infection (MOI) of 0.001 was determined. Whole-genome sequencing revealed a linear double-stranded DNA genome of 58,582 bp with a GC content of 46.91%, encoding 63 open reading frames. Crucially, no virulence or antibiotic resistance genes were detected, supporting its safety profile. Phylogenetic analysis classified P-07 within the Casjensviridae family, closely related to phages PM87 and pPM01. These findings indicate that phage P-07 is a novel, safe, and effective lytic phage with strong potential as a biocontrol agent against biofilm-forming MDR P. mirabilis in swine.

Enterococcus faecalis is a prevalent opportunistic pathogen associated with chicken embryonic and neonatal chick mortality, posing a significant challenge in poultry farming. In the current study, E. faecalis strain EF6, isolated from a recent hatchery outbreak, served as the host bacterium for the isolation of a novel phage EFP6, capable of lysing E. faecalis. Transmission electron microscopy revealed a hexagonal head and a short tail, classifying EFP6 as a member of the Autographiviridae family. EFP6 showed sensitivity to ultraviolet radiation and resistance to chloroform. The lytic cycle duration of EFP6 was determined to be 50 min, highlighting its efficacy in host eradication. With an optimal multiplicity of infection of 0.001, EFP6 exhibited a narrow lysis spectrum and strong specificity towards host strains. Additionally, EFP6 demonstrated optimal growth conditions at 40 °C and pH 8.0. Whole genome sequencing unveiled a genome length of 18,147 bp, characterized by a GC concentration of 33.21% and comprising 25 open reading frames. Comparative genomic assessment underscored its collinearity with related phages, notably devoid of lysogenic genes, thus ensuring genetic stability. This in-depth characterization forms the basis for understanding the biological attributes of EFP6 and its potential utilization in phage therapy, offering promising prospects for mitigating E. faecalis-associated poultry infections.

为初步了解新疆地区滑液囊支原体的发病及流行情况,对新疆地区某疑似感染滑液囊支原体(My-coplasma synoviae,MS)的肉鸡场的病鸡进行剖检观察、病原菌分离培养和基因测序,并对其16S rRNA测序结果进行遗传进化分析.通过病原分离培养、16S rRNA基因序列测序比对,结果表明该病例为MS感染.将分离所得菌株命名为XJMS-yb1,对XJMS-yb1的遗传进化分析显示,其与现已分离得到的MS菌株同源性较高.本试验为新疆地区MS的进一步研究提供了科学依据.

为了解2021年新疆部分地区规模化猪场的猪瘟病毒(CSFV)抗体水平,本试验采用间接酶联免疫吸附试验(ELISA)对来自新疆6个地区13个规模化猪场的513份血清样品进行猪瘟病毒抗体水平检测.结果显示,CSFV抗体平均阳性率为73.88％(379/513),高于国家规定标准(70％);除1号和3号地区外,其余4个地区的CSFV抗体平均阳性率均达到国家规定标准;61.5％(8/13)规模化猪场的CSFV抗体阳性率高于国家规定水平,有3个养殖场CSFV抗体阳性率较低,且抗体离散度较大.表明新疆部分地区规模化猪场的CSFV整体免疫效果较好,不同地区及不同养殖场间CSFV抗体水平存在明显差异,个别地区和养殖场的CSF发病风险高,需对现有的免疫程序进行调整和完善.本试验可为新疆部分地区的CSFV防控工作提供一定的参考.

为了分离一株裂解性鸡白痢沙门氏菌噬菌体,对抗多重耐药细菌,试验从健康鸡粪便中分离富集噬菌体,采用双层琼脂平板法纯化、增殖,超速离心法浓缩,利用透射电镜观察噬菌体形态,通过提取噬菌体基因组、酶切、电泳确定核酸类型,同时测定噬菌体的宿主谱、最佳感染复数、一步生长曲线、酸碱及热稳定性等生物学特性.结果表明:从鸡粪中分离得到1株裂解性噬菌体,命名为PSP2-22.该噬菌体头部直径为(60±5)nm,尾部长为(130±5)nm,为长尾噬菌体科;核酸类型为双链DNA.该噬菌体不仅能裂解鸡白痢沙门氏菌,还可裂解鼠伤寒沙门氏菌和奇异变形杆菌;最佳感染复数为0.1;平均裂解量约为136pfu/cell,效价最高可达9.83 lg pfu/mL;在pH值6～11时相对稳定,70℃作用60 min之后仍具有一定活性.说明噬菌体PSP2-22是一株对不同温度和pH值有较强适应能力的双链DNA噬菌体,宿主谱相对较宽,具有潜在的应用价值.

根据母源抗体衰减规律确定仔猪猪瘟合理的首免时间.检测21、28、35、38日龄仔猪体内母源猪瘟抗体的水平;分析21日龄进行猪瘟首免的免疫效果.21、28、35日龄仔猪体内母源猪瘟抗体阻断率分别为79.44％、73.63％、62.25％,猪瘟抗体合格率分别为100％(34/34)、100％(34/34)、94％(32/34).仔猪21日龄进行猪瘟首免,在首免后17天,猪瘟抗体平均阻断率为48.22％,猪瘟抗体合格率为64％(9/14),未达到农业部规定的猪瘟抗体合格率70％的最低要求.根据试验结果,建议仔猪猪瘟首免时间为35～40日龄.

为了解2021年新疆部分地区猪群中伪狂犬病病毒(PRV)野毒感染情况和免疫抗体水平,试验应用PRV-gE和PRV-gB蛋白抗体检测试剂盒对新疆5个地区9个规模化养猪场的580份血清样品分别进行了PRV-gE和PRV-gB两种蛋白的抗体检测.结果发现,2021年新疆部分地区猪群PRV-gE抗体平均阳性率为28.28％(164/580),不同地区之间、不同猪场之间的PRV-gE抗体平均阳性率差异较大;PRV平均免疫抗体阳性率为61.9％(359/580),低于国家规定标准(70％),仅有22.22％(2/9)猪场的免疫抗体阳性率达到了国家规定标准,不同地区之间、不同猪场之间的PRV免疫抗体阳性率差异较大.结果表明,2021年新疆部分地区猪群PRV野毒感染率仍处于较高水平,免疫合格率相对较低,需要重视该病的防控工作.

以实验室保存的奶牛乳房炎源金黄色葡萄球菌为宿主菌,从新疆石河子地区奶牛场粪便和污水中分离纯化裂解性噬菌体,并对其生物学特性进行分析,为奶牛乳房炎的噬菌体防治提供材料,并通过噬菌斑、透射电子显微镜观察,测定其最佳感染复数、噬菌谱、热稳定性、pH稳定性、生长曲线等特性进行分析.结果显示:分离到1株裂解性噬菌体P42,噬菌斑呈透亮无晕环的圆形,透射电镜观察形态为短尾噬菌体;目前此噬菌体只能裂解其宿主菌,最佳感染复数为0.001;60℃20 min时活性丧失,且在pH4.0～9.0时,噬菌体P42的活性没有明显的变化;感染宿主菌的潜伏期是10 min,暴发期为140 min,裂解量约为126 PFU/cell.本研究分离筛选到的噬菌体P42是一株裂解性短尾科噬菌体,其裂解效果较好,繁殖迅速,为奶牛乳房炎的噬菌体防治及其制剂的研发提供了参考.

研究黄羽肉鸡新城疫病毒(NDV)、H5、H7、H9亚型禽流感病毒(AIV)的母源抗体消长规律,为规模化养鸡场制定科学合理的免疫程序提供依据.采用血凝试验和血凝抑制试验对1—38日龄的黄羽肉鸡进行NDV和H5、H7、H9亚型AIV母源抗体水平的检测.NDV、AIV母源抗体均在1日龄时达到峰值,随日龄的增加,母源抗体水平呈逐渐下降趋势.H9亚型AIV母源抗体水平最高,且维持在保护水平之上的时间最长,NDV、H5、H7亚型AIV母源抗体水平相对较低.推荐参试规模化鸡场黄麻鸡新城疫(ND)、H5N1亚型禽流感(AI)和H7N9亚型AI、H9亚型AI首次免疫时间分别为7日龄、14—17日龄、17—21日龄.

为了解2018—2020年新疆地区哺乳仔猪主要疫病的抗体水平,采用酶联免疫吸附试验(ELISA)对采集的270份血清进行了猪瘟病毒(CSFV)、伪狂犬病gB蛋白(PRV-gB)、伪狂犬病gE蛋白(PRV-gE)、圆环病毒2型(PCV2)、蓝耳病病毒(PRRSV)抗体检测.结果显示,CSFV抗体阳性率为77.35％(140/181)、PRV-gB抗体阳性率为90.29％(158/175)、PRV-gE抗体阳性率为26.26％(52/198)、PRRSV抗体阳性率为76.30％(206/270)、PCV2抗体阳性率为57.30％(106/185),其中PCV2抗体水平低于国家规定的70％,可通过提高母源抗体水平来提高PCV2的抗体阳性率.试验结果可为该地区哺乳仔猪主要猪病流行病学调查提供参考,也可为免疫程序的调整提供帮助.

奶牛乳房炎对奶牛产业的影响严重,传统抗菌疗法面临细菌耐药和药物残留的问题,因此急需研发一种能解决现有抗菌药物弊端与危害的新型疗法.论文以奶牛乳房炎源链球菌为宿主菌,分离获得裂解性噬菌体,对其进行生物学特性分析,为奶牛乳房炎无抗防治提供生物学材料.试验采用常规方法分离、纯化噬菌体,通过双层琼脂平板法观察噬菌斑的形态并测定其生物学特性,在透射电镜下观察噬菌体的形态特征.结果显示,分离出一株裂解性链球菌噬菌体,将其命名为SM-P21,噬菌斑呈无色透明的圆形,SM-P21头部为20面体,呈蝌蚪形,具有尾鞘等结构,核酸类型为双链DNA.噬菌谱检测结果显示,该噬菌体只对宿主菌株具备裂解能力而对其他菌株无裂解能力.SM-P21的最佳感染复数为10、潜伏期约15 min、暴发期为95 min、裂解量约为249 PFU/cell.在60℃环境下,SM-P21滴度大幅度下降.SM-P21对pH的耐受范围较广,在pH 4.0～11.0之间其活性没有明显下降.说明噬菌体SM-P21裂解性能较强,适应性好,具有很好的应用前景.

奶牛子宫炎是奶牛不孕症的重要原因之一,严重危害奶牛养殖业的健康发展.奶牛子宫炎可分为子宫炎和子宫内膜炎,子宫炎又可分为产褥期子宫炎和临床型子宫炎,而子宫内膜炎又可分为临床型子宫内膜炎、亚临床型子宫内膜炎.国内外对奶牛子宫炎的诊断方法很多,可概括为现场诊断技术和实验室诊断技术两大类.论文概述了临床诊断、超声诊断、Metricheck装置评估、AHMS、细胞学诊断、生物标志物、免疫细胞、病原学诊断等方法,对其优缺点进行了比较,并介绍这些方法的实际应用情况,以期能为快速准确地诊断不同类型的奶牛子宫炎,早期防治该病提供参考.