Staphylococcus aureus is a common pathogen that can cause pneumonia and a variety of skin diseases. Skin injuries have a high risk of colonization by S. aureus , which increases morbidity and mortality. Due to the emergence of multidrug-resistant strains, antimicrobial peptides are considered to be among the best alternatives to antibiotics due to their unique mechanism of action and other characteristics. MPX is an antibacterial peptide extracted from wasp venom that has antibacterial activity against a variety of bacteria. This study revealed that MPX has good bactericidal activity against S. aureus and that its minimum inhibitory concentration (MIC) is 0.08 μM. MPX (4×MIC) can kill 99.9% of bacteria within 1 h, and MPX has good stability. The research on the bactericidal mechanism found that MPX could destroy the membrane integrity, increase the membrane permeability, change the membrane electromotive force, and cause cellular content leakage, resulting in bactericidal activity. Results from a mouse scratch model experiment results show that MPX can inhibit colonization by S. aureus , which reduces the wound size, decreases inflammation, and promotes wound healing. This study reports the activity of MPX against S. aureus and its mechanism and reveals the ability of MPX to treat S. aureus infection in mice, laying the foundation for the development of new drugs for bacterial infections.

为了分析禽腺病毒(Fowl adenovirus,FAdV)在河南省新乡市的流行和变异情况,于2020年从新乡市周边养鸡场采集15份疑似FAdV感染的肝脏样品,通过PCR扩增获得病毒Hexon基因部分核酸序列,对获得的核酸序列进行同源性分析,并通过动物回归试验进一步评价其毒力.结果显示,15份样品中有12份扩增出约300 bp的目的条带,占采集样品的80％;进一步测序证实,分离毒株为同一毒株,命名为XX株.扩增片段经BLAST比对,分离毒株与FAdV-4型同源性大于95％,而与FAdV-1和鸭FAdV-I同源性较低.动物回归试验结果显示,XX株对3周龄SPF鸡致病性较强,死亡率可达60％;剖检可见典型的心包积液和肝脏质脆、出血,与FAdV-4感染所致病变一致.表明本次分离的毒株具有较强的致病力.

旨在建立一种可视化、操作简便的猪链球菌快速检测技术.针对猪链球菌种特异性基因谷氨酸脱氢酶(gdh)序列设计特异性引物,建立可同时检测出所有血清型的重组酶聚合酶扩增结合侧流层析试纸条(RPA-LFD)检测技术,优化反应温度与反应时间,评价其特异性与灵敏度,同时利用该法对45例疑似猪链球菌感染标本进行检测.结果 显示:猪链球菌RPA-LFD法检测灵敏度可达100拷贝·μL-1,优于常规PCR方法,且不与其他常见病原菌发生交叉反应.扩增反应可在较宽温度范围(30～45℃)内高效进行,20～30 min可完成检测.利用临床45例疑似猪链球菌感染样本对检测体系进行评估,其检出率高于细菌分离与常规PCR方法,具有较强的实用性.本研究建立的猪链球菌RPA-LFD检测方法具有强特异性、高灵敏度、易于操作的特点,同时不依赖于仪器、专业操作人员,适用于野外及现场检测.

新型冠状病毒(SARS-CoV-2)的全球传播引发人们对动物冠状病毒的高度关注.猪肠道冠状病毒(swine en-teric coronavirus,SECoV)是一类能够引起猪腹泻、呕吐等症状的猪肠道病原体.本文就猪传染性胃肠炎病毒、猪流行性腹泻病毒、猪德尔塔冠状病毒和猪急性腹泻综合症病毒四种SECoV检测技术的研究进展进行综述,为更好地做好SECoV防控提供参考依据.

Escherichia coli can cause intestinal diseases in humans and livestock, destroy the intestinal barrier, exacerbate systemic inflammation, and seriously threaten human health and animal husbandry development. The aim of this study was to investigate whether the antimicrobial peptide mastoparan X (MPX) was effective against E. coli infection. BALB/c mice infected with E. coli by intraperitoneal injection, which represents a sepsis model. In this study, MPX exhibited no toxicity in IPEC-J2 cells and notably suppressed the levels of interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-α), myeloperoxidase (MPO), and lactate dehydrogenase (LDH) released by E. coli. In addition, MPX improved the expression of ZO-1, occludin, and claudin and enhanced the wound healing of IPEC-J2 cells. The therapeutic effect of MPX was evaluated in a murine model, revealing that it protected mice from lethal E. coli infection. Furthermore, MPX increased the length of villi and reduced the infiltration of inflammatory cells into the jejunum. SEM and TEM analyses showed that MPX effectively ameliorated the jejunum damage caused by E. coli and increased the number and length of microvilli. In addition, MPX decreased the expression of IL-2, IL-6, TNF-α, p-p38, and p-p65 in the jejunum and colon. Moreover, MPX increased the expression of ZO-1, occludin, and MUC2 in the jejunum and colon, improved the function of the intestinal barrier, and promoted the absorption of nutrients. This study suggests that MPX is an effective therapeutic agent for E. coli infection and other intestinal diseases, laying the foundation for the development of new drugs for bacterial infections.

To prepare broad-spectrum and specific monoclonal antibodies (mAb) against deoxynivalenol (DON), DON-BSA was synthesised by the carbonyl diimidazole method as an artificial antigen to immunise Balb/C mice, and the coated DON-OVA was synthesised by the carbodiimide method to detect anti-DON antibodies. Monoclonal antibodies were screened by indirect ELISA and indirect competitive ELISA. A hybridoma cell line (4F3) capable of stably secreting DON antibody was obtained. The titre of antibody in the culture supernatant was 1:1.28 × 103, and the titre of the ascites antibody was 1:3.2 × 105. The monoclonal antibody homology was IgG1/λ. The half inhibitory concentration (IC50) of DON was 9.84 ng/mL. The cross-reaction rates with 3-Ac-DON and 15-Ac-DON were 60.44% and 52.04%, respectively, but no cross-reaction with other mycotoxins was observed. The results showed that the anti-DON monoclonal antibodies prepared in this experiment could recognise not only DON but also 3-Ac-DON and 15-Ac-DON, which could provide materials for the next step to establish a method to detect DON and its similar compounds.Highlights This study demonstrated that an artificial antigen was synthesised by carbonyl diimidazole method, and a novel broad-spectrum, high affinity monoclonal antibody was developed. The anti-DON mAb developed in this study has better sensitivity, moreover the antibody was sensitive to DON and its derivatives. Therefore, it could be used for simultaneous monitoring of three mycotoxins. Results of this study will further lay the foundation for the establishment of immunological assays for the total amount of similar compounds.

INTRODUCTION:Classical swine fever virus (CSFV) causes an economically important and highly contagious disease of pigs, leading to economic losses around the world. Attenuated live vaccines with CSFV antigens have played an important role in the prevention and control of the disease. Porcine kidney 15 (PK15) cells have been widely used for the propagation of CSFV, but this cell line is not efficient or homogeneously susceptible to viral infection. MATERIAL AND METHODS:To achieve a homogeneous PK15 cell line which enabled high titre replication of CSFV, we used the limiting dilution cell cloning method. RESULTS:We developed two cell clones, PK15-1A6 and PK15-3B1, which respectively have high- and low-permissive phenotypes to CSFV infection. The PK15-1A6, PK15-3B1, and PK15 parent cells showed different characteristics in cell proliferation rate, susceptibility to CSFV infection, and CSFV production. The mean virus titres per millilitre reflected by TCID50 values in PK15-1A6, PK15-3B1, and PK15 parent cells were 106.85, 103.63, and 104.74, respectively. CONCLUSION:The PK15-1A6 cell clone is more permissive to CSFV infection than the PK15 parent cells. The screened high-permissive cells will be useful for CSFV propagation and vaccine development in vitro, and facilitate research on the pathogenicity of CSFV.

Aflatoxin (AF) contamination is a major concern in the food and feed industry because of its prevalence and toxicity. Improved aflatoxin detection methods are still needed. Immunoassays are an important method for total aflatoxin (TAF) analysis in food due to its technical advantages such as high specificity, sensitivity, and simplicity, but require high-quality antibodies. Here, we first review the three ways to prepare high-quality antibodies for TAF immunoassay, second, compare the advantages and disadvantages of antigen synthesis methods for B-group and G-group aflatoxins, and third, describe the status of novel genetic engineering antibodies. This review can provide new methods and ideas for the development of TAF immunoassays.

玉米赤霉烯酮(ZEN)是由玉米赤霉菌等真菌产生的一种甾体霉菌毒素,可以代谢成许多次级衍生物,并通过多种途径进入人类食物链,对食品或环境造成一定的危害,威胁人体健康.国际粮农组织报道,全球约有25％的粮食受到ZEN及其他霉菌毒素的影响,降低或丧失了使用价值.文章综述了ZEN的理化性质、毒性作用、临床危害和检测技术,并就降低饲料中ZEN的危害提出建议,综述了免疫学检测方法.

Currently, corona virus disease 2019 (COVID-19) caused by SARS-CoV-2 is still raging worldwide, which attracts great concern about coronavirus originated from animal Porcine deltacoronavirus (PDCoV) and swine acute diarrhea syndrome coronavirus (SADS-CoV) are newly discovered porcine coronaviruses in recent years, they not only damage pig industry severely but also pose potential threats to public health This article reviews the literature concerning the etiology, origin and evolution, pathogenicity, and diagnostics of PDCoV and SADS-CoV, presenting the prospect of research work We aim to expand understanding on SARS-CoV-2 and provide references for subsequent research on PDCoV and SADS-CoV

This study was conducted to develop a self-assembled direct competitive enzyme-linked immunosorbent assay (dcELISA) kit for the detection of deoxynivalenol (DON) in food and feed grains. Based on the preparation of anti-DON monoclonal antibodies, we established a standard curve with dcELISA and optimized the detection conditions. The performance of the kit was evaluated by comparison with high-performance liquid chromatography (HPLC). The minimum detection limit of DON with the kit was 0.62 ng/mL, the linear range was from 1.0 to 113.24 ng/mL and the half-maximal inhibition concentration (IC50) was 6.61 ng/mL in the working buffer; there was a limit of detection (LOD) of 62 ng/g, and the detection range was from 100 to 11324 ng/g in authentic agricultural samples. We examined four samples of wheat bran, wheat flour, corn flour and corn for DON recovery. The average recovery was in the range of 77.1% to 107.0%, and the relative standard deviation (RSD) ranged from 4.2% to 11.9%. In addition, the kit has the advantages of high specificity, good stability, a long effective life and negligible sample matrix interference. Finally, wheat samples from farms in the six provinces of Henan, Anhui, Hebei, Shandong, Jiangsu and Gansu in China were analyzed by the kit. A total of 30 samples were randomly checked (five samples in each province), and the results were in good agreement with the standardized HPLC method. These tests showed that the dcELISA kit had good performance and met relevant technical requirements, and it had the characteristics of accuracy, reliability, convenience and high-throughput screening for DON detection. Therefore, the developed kit is suitable for rapid screening of DON in marketed products.

Infectious bursal disease virus (IBDV) is still a vital etiological agent in poultry farms. IBDV outbreaks occasionally occur due to the presence of very virulent, reassortment or variant strains. Vaccine immunization has played crucial roles in IBD control for decades. However, survival pressure of IBDV from the vaccine immunization also increases the reassortments of circulating viruses. In this study, an IBDV strain was isolated from several broiler farms in Henan Province, central part of China, and named IBDV HN strain. Based on the results of RT-PCR, sequencing and phylogenic analyses of VP1 and VP2 genes, the IBDV HN strain is a novel reassortment strain in the Henan region. Segment A of this strain appears to originate from the very virulent IBDV strain, while segment B comes from the other field reassortment strains. This may be the result of natural reassortant of virus circulating in the field. About 60% (6/10) of experimentally infected specific pathogen-free chickens died after 3 to 5 d post-infection with typical symptom and pathological lesions. The IBDV HN strain was prone to horizontal transmission, which poses a serious threat to the chicken industry. Further investigation on the prevalence, virulence, and evolution of HN strain IBDV will provide a foundation for the prevention and control of the disease in this region.

猪流行性腹泻病毒(porcine epidemic diarrhea virus,PEDV)对我国养猪业造成了持续性影响.为了弄清河南省新乡地区猪流行性腹泻的发病规律,对2018年1—12月期间采自新乡地区延津县、封丘县、原阳县、获嘉县、长垣县5个县55个猪场的351份病料进行了RT-PCR检测.结果表明:PEDV的猪场阳性率和样品阳性率分别为41.3％(19/55)和35.2％(125/351);其中以延津县的样品阳性率最高,为58.33％,封丘县最低,为23.6％;不同季节均有PED发病,冬季较高,阳性率为55.2％,春、秋季较低,阳性率分别为15.0％和32.9％;PEDV与传染性胃肠炎病毒(TGEV)、轮状病毒(RV)和圆环病毒2型(PCV2)存在不同程度的混合感染.研究结果为新乡地区PEDV的防控提供了参考.

This study was conducted to develop a self?assembled blocking indirect competitive ELISA ( icELISA) kit for the detection of deoxynivalenol in feed. Based on the preparation of anti?DON monoclonal antibodies, we established the standard curve of icELISA and optimized the detection conditions, which was used to examine the performance of the kit, then the determination results were compared with the high?per?formance liquid chromatography ( HPLC) method. The results showed that the minimum detectable concentra?tion of the kit for DON was 1.147 ng／mL, with the detection range of 1.50 to 130.31 ng／mL, and the 50%inhibiting concentration ( IC50) of 9.84 ng／mL. The recovery experiment by adding standard samples was car?ried out for four samples of wheat, corn, pig feed and chicken feed. The recovery was in the range of 77.1%to 113.2%, and the relative standard deviation ( RSD) ranged from 4.2% to 12.6%. Besides, the kit had the advantages of high specificity, good stability, long effective life and negligible sample matrix interference. Fi?nally, twenty blind samples were determined by the kit, and the results were in good agreement with the HPLC method. These results indicate that the icELISA kit developed in this experiment has good performance to meet the relevant technical requirements, and with the characteristics of accuracy, reliability, convenience and high throughput screening to detect DON. Therefore, it is suitable for rapid screening of DON for the market.[ Chi?nese Journal of Animal Nutrition, 2019, 31(11) :5229?5237]

氟虫腈是含氟吡唑类广谱性杀虫剂,活性高且应用范围广,但是其生物毒性对环境会产生危害.论文综述了目前国内外氟虫腈残留危害及其检测方面的研究方法和成果,用于氟虫腈药物残留检测的方法主要有气相色谱法、液相色谱-串联质谱法、高效液相色谱法、电子捕获和质谱检测的气相色谱法、酶联免疫吸附测定法等,在此基础上进行了合理的展望,以期为今后研究和开发新型氟虫腈药物残留检测方法提供参考.

Pyroptosis, a type of programmed cell death mediated by gasdermin, is characterized by the swelling and rupture of cells, release of cellular contents and a strong inflammatory response, which is critical for controlling microbial infection. Pattern recognition receptors recognize the intracellular and extracellular pathogenic microbial components and stimulate the organism's inflammatory response by activating the pyroptosis signaling pathway and releasing interleukin-1β (IL-1β), IL-18, and other inflammatory factors to promote pathogen clearance and prevent infection. In the process of continuous evolution, pathogens have developed multiple strategies to modulate the occurrence of pyroptosis and thus enhance their ability to induce disease; that is, the competition between host cells and pathogens controls the occurrence of pyroptosis. Competition can directly affect tissue inflammation outbreaks and even alter cell survival. Studies have shown that various bacterial infections, including Shigella flexneri, Salmonella, Listeria monocytogenes, and Legionella pneumophila, can lead to pyroptosis. Pyroptosis is associated with the occurrence and development of various diseases caused by microbial infection, and the identification of molecules related to the pyroptosis signaling pathway may provide new drug targets for the treatment of related diseases. This study reviews the molecular mechanisms of pyroptosis and the role of pyroptosis in microbial infection-related diseases.

为了研究羊结肠小袋纤毛虫滋养体对理化因素的抵抗力,在体外环境条件下进行了温度、光照、干燥、培养基含水量等理化因素对滋养体存活的影响试验.结果表明:滋养体对低温耐受性强,对光照非常敏感,干燥可杀死全部滋养体,培养基中充足的含水量是该虫体存活的前提条件.说明理化因素对滋养体存活有重要影响.

为进一步精确定位猪瘟病毒(CSFV)E2蛋白配体表位信息,利用DNASIS(Ver.2.5)软件分析设计合成7条多肽,主要覆盖E2蛋白,分别命名为SE21、SE22、SE231、SE232、SE241、SE242、SE03,同时设计合成1条无关多肽CP,均标记FITC.将PK-15细胞作为靶细胞,通过多肽与PK-15细胞结合试验、多肽抑制CSFV感染PK-15细胞试验和CSFV阻断多肽与PK-15细胞结合试验,筛选和鉴定E2蛋白配体表位.结果 表明,多肽SE241、SE242与PK-15细胞结合的平均荧光强度分别为74.43±4.59和83.60士3.11,显著高于其他多肽,抑制CSFV感染PK-15细胞的感染抑制率也显著高于其他多肽,同时这2条多肽与PK-15细胞的结合被CSFV有效阻断.证实SE241、SE242多肽为CSFV与靶细胞PK-15细胞结合的配体表位,并能抑制CSFV感染PK-15细胞.本试验为CSFV新型多肽疫苗或免疫佐剂的研制提供依据.

The marigold (Tagetes erecta L.) flower is rich in lutein ester with many health-promoting activities. In this study, the effects of vegetable oil type and extracting the temperature on the extraction efficiency of lutein ester in the marigold flower were evaluated. Then, the structuring of the lutein ester-loaded sunflower oil with the addition of different amounts of monostearin and cooling temperatures (4 and 20°C) was investigated. The XRD analysis suggested that these oleogels were stabilized by the network formed by monostearin crystals in the sunflower oil. The textural properties (firmness, cohesiveness, and hardness) of oleogels were positively related to the monostearin dosage, but negatively related to the cooling temperature. According to the rheological results, the oleogels belonged to the pseudoplastic gel and their gelation temperature (Tg ) was only related to the concentration of monostearin. The light stability of lutein ester in the oleogels was also significantly improved in a monostearin dosage-dependent manner. PRACTICAL APPLICATIONS: The edible lutein ester-loaded oleogel for foods developed by structuring the sunflower oil with monostearin is introduced in this study. Its texture and rheological properties can be adjusted to cater to different requirements in the food industry by changing the monostearin dosage and cooling temperature. This study provides a reference for the development of other liposoluble nutraceuticals.