Mycoplasma gallisepticum (MG) and Mycoplasma synoviae (MS) are regarded as the most clinically and economically important avian Mycoplasma species, posing significant challenges to the poultry industry worldwide. In this study, MG and MS antibodies were detected by ELISA in 857 unvaccinated Chinese native chickens from 21 breeder flocks on four multi-age farms. The overall seropositive rates were 86.3% for MG and 98.4% for MS. Offspring from an infected breeder flock were reared under different environmental conditions, and serological monitoring was conducted over a 68-week production cycle. The antibody titers and seropositive rates of both mycoplasmas in birds reared in an isolation room were significantly lower than those in birds reared on the farm after maternal antibodies vanished. By adopting strict biosecurity measures, MG and MS infections were effectively controlled in an offspring flock derived from infected breeders, as evidenced by a substantial decrease in seropositive rates. The results suggested that MG and MS infections were prevalent in the breeder flocks of Chinese native chickens. Horizontal rather than vertical infection was the primary cause of high flock infection levels under field conditions. Strict biosecurity measures could be adopted to initially control MG and MS infections in offspring from the breeder flocks with high infection levels.

Newcastle disease (ND), caused by virulent Newcastle disease virus (NDV), still remains one of the most important avian diseases affecting the poultry industry worldwide, despite intensive vaccination programs have been implemented in many countries. All NDV isolates characterized to date are of one serotype and classified into classes I and II, with class II being further divided into twenty-one genotypes. Antigenic and genetic diversity is observed among the different genotypes. Current commercially available vaccines belonging to genotypes I and II are genetically divergent from strains that caused ND outbreaks worldwide in the last two decades. Reports of vaccination failures on their insufficient ability to inhibit infection or virus shedding have created renewed interest in developing vaccines homologous to virulent NDV circulating in the field. In this study, after vaccination with the most widely used LaSota vaccine (genotype II), chickens with different hemagglutination inhibition (HI) antibody levels were challenged with heterologous virulent NDV strains of genotypes VII and IX to evaluate how antibody levels relate to clinical protection and infection or virus shedding. Under the experimental condition, LaSota vaccine could fully protect birds from morbidity and mortality, but higher antibody levels were required to inhibit virus shedding. The number of birds shedding virus generally tended to decrease as the HI antibody titers increase in vaccinated birds. When the HI antibody titers reached ≥ 13 log2 and ≥ 10 log2, the virus shedding from JSC0804 strain (genotype VII) and F48E8 strain (genotype IX) could be completely inhibited, respectively, but it may be difficult to ensure that all individuals reach and maintain those levels in chicken flocks vaccinated according to routine procedure. Furthermore, the virus shedding in vaccinated birds was correlated with the amino acid similarity between the vaccine and challenge strains; more similarity, less virus shedding. The results obtained highlight that stringent biosecurity measures combined with vaccination are crucial for chicken farms to maintain a virulent NDV-free status.

Newcastle disease (ND), caused by the virulent Newcastle disease virus (NDV), is an acute, highly contagious, and economically significant avian disease worldwide. Vaccination is the most effective measure for controlling ND. In recent years, vaccines matched with the prevalent strains of genotype VII have been developed and are now commercially available. These vaccines can provide full protection for chickens against clinical disease and mortality after challenges with genotype VII viruses and significantly decrease virus shedding compared to conventional vaccines belonging to genotypes I and II. Vaccinated hens can transfer antibodies to their offspring through the egg yolk. Maternally derived antibodies can provide passive protection against diseases but can also interfere with vaccination efficacy early in life. This study was conducted on chicks hatched from hens vaccinated with a commercial genotype VII NDV-matched vaccine to investigate the correlation between hemagglutination inhibition (HI) antibody levels in chicks and hens and the decaying pattern of maternally derived HI antibodies, and to evaluate the protective efficacy of different levels of maternally derived HI antibodies against challenge with a virulent NDV strain of genotype VII based on survivability and virus shedding. The HI antibody titers in chicks at hatching were about 1.3 log2 lower than those in hens, indicating an antibody transfer rate of approximately 41.52%. The estimated half-life of these antibodies was about 3.2 days. The protective efficacy of maternally derived HI antibodies was positively correlated with the titer. These antibodies could effectively protect chicks against mortality when the titer was 7 log2 or higher, but they were unable to prevent virus shedding or infection even at a high titer of 11 log2. The obtained results will greatly assist producers in determining the immune status of chicks and formulating appropriate vaccination schedules against ND.

为确定某鸽场送检的病死鸽病因,试验对病死鸽进行剖检,并无菌采集组织病料进行菌株的分离鉴定以及耐药性检测.根据病死鸽临床症状、剖检病变、革兰染色镜检以及16S rRNA的扩增与测序,判定该发病鸽群为大肠杆菌感染.从病料中共分离获得12株大肠杆菌,药敏试验结果显示:大肠杆菌分离株均具有不同程度的耐药情况,对链霉素、四环素、萘啶酸、氨苄西林、大观霉素、氟苯尼考、复方新诺明和恩诺沙星等药物的耐药率高于75％,甚至达100％;对阿米卡星、多粘菌素B和氨曲南和部分头孢类药物较为敏感;83.33％的分离株可对3类以上药物产生耐药性,其中1株最多可耐8类药物;以耐6类药物的菌株数量最多,占比达41.67％,其多重耐药谱为磺胺类/喹诺酮类/β-内酰胺类/氨基糖苷类/四环素类/酰胺醇类.

为了解江苏省肉种鸡场生物安全体系建设现状,并为今后的疫病防控工作提供参考和依据,本研究对江苏省内肉鸡养殖集中区的56家肉种鸡场的生物安全措施进行了调研.结果显示,能严格做到种鸡引进隔离的场有54家,占比96.4％;饲料和兽药等投入品妥善处置的场有50家,占比89.3％;有完善的消毒防疫措施的场有48家,占比85.7％;能定期开展疫病监测的场有54家,占比96.4％;有完善的疫病净化措施,并定期实施净化的场有44家,占比78.6％;有独立的养殖废弃物处理区,并进行鸡粪和病死鸡无害化处理的场有56家,占比100.0％;生产记录及台账资料齐全的场有45家,占比80.4％.结果表明,江苏省肉种鸡场生物安全体系建设总体情况良好,但仍有少数场存在消毒防疫漏洞、台账资料不全和疫病监测与净化措施不力等诸多问题,需要进一步重视加强生物安全体系建设,整体提升本省肉种鸡场疫病防控水平,实现产业高质量发展.

试验旨在从免疫遗传学的角度初步探讨藏鸡(TC)和隐性白羽鸡(RWC)对柔嫩艾美耳球虫(Eimeria tenella)易感性差异的分子机制,分别用1×105个柔嫩艾美耳球虫孢子化卵囊感染对球虫具有抗性的藏鸡和易感的隐性白羽鸡.应用实时荧光定量PCR检测藏鸡和隐性白羽鸡感染前0 d和感染后第2、4、6和8天脾脏、盲肠、胸腺、法氏囊中γ-干扰素(IFN-γ)、白细胞介素-2(IL-2)、IL-16、Toll样受体(TLR3)和TLR15免疫相关基因的转录水平变化.结果显示,藏鸡脾脏IFN-γ、IL-2、IL-16及TLR3、TLR15免疫相关基因转录水平于感染后第4和8天明显上调,隐性白羽鸡则无明显变化.藏鸡盲肠IFN-γ转录水平在感染后第2天显著上调(P<0.05),TLR3在感染后第4天起显著上调(P<0.05),其余免疫相关基因变化幅度不大;隐性白羽鸡盲肠IFN-γ转录水平在感染后第8天显著上调(P<0.05),IL-2在感染后第2天起显著上调(P<0.05),IL-16在感染后第6天起显著上调(P<0.05),TLR3在感染后第2和8天显著上调(P<0.05),TLR15变化幅度不大.各免疫相关基因在2个品种鸡胸腺和法氏囊中均出现上调或下调,但除藏鸡法氏囊TLR3和TLR15转录水平变化幅度相对较大外,其余免疫相关基因与感染前相比变化幅度不大.以上结果显示,球虫感染主要导致藏鸡和隐性白羽鸡脾脏和盲肠中的各免疫相关基因出现显著变化,表明宿主的遗传背景在一定程度上可影响球虫感染的免疫应答.

为了解江苏某种鸡场鸡白痢沙门菌分离株的药敏性及其与耐药基因的相关性,采用K-B法测定96株鸡白痢沙门菌分离株对9类21种抗菌药物的敏感性,通过PCR方法检测分离株的6类药物的10种耐药基因,并对分离株的药敏性与耐药基因的相关性进行分析.结果 表明:所有鸡白痢沙门菌分离株均有不同程度的耐药现象,其中对萘啶酸(95.83％)、氨苄西林(55.21％)和链霉素(39.58％)的耐药率较高,且56.25％的分离株呈多重耐药.36.46％的分离株可检出耐药基因,共检出7种耐药基因,分别为aadA1 (26.04％)、blaCMY-2 (11.46％)、sul2 (11.46％)、blaTEM-1 (9.38％)、tetA (4.17％)、strA (3.13％)和qnr (3.13％).与药敏性符合率较高的耐药基因依次为cat1 (93.75％)、tetA(73.96％)、tetC (71.88％)、sul2 (68.75％)和sul1 (67.71％).这一研究提示该种鸡场鸡白痢沙门菌耐药情况较为严重,但耐药基因携带率较低,且耐药基因检测结果与药敏性并不完全符合.

为了解江苏省某种鸡场重要疫病感染和免疫状况,从绿壳蛋鸡核心群采集了290日龄鸡的血清样品进行了禽白血病(AL)、网状内皮组织增生症(RE)、沙门菌病、新城疫(ND)和高致病性禽流感(HPAI)血清学调查.562份样品进行鸡白痢和鸡伤寒沙门菌(SP/SG)、新城疫病毒(NDV)和高致病性禽流感病毒(HPAIV)抗体检测,取460份样品检测A亚群和B亚群禽白血病病毒(ALV-A/B)、J亚群禽白血病病毒(ALV-J)和网状内皮组织增生症病毒(REV)抗体.结果 显示:种鸡群ALV-A/B、ALV-J、REV以及SP/SG抗体阳性率分别为10.00％(46/460)、6.92％(32/460)、27.39％ (126/460)和26.16％ (147/562).公鸡ALV-A/B、ALV-J和SP/SG抗体阳性率显著低于母鸡,但其REV抗体阳性率则显著高于母鸡.在同时检测ALV-MB、ALV-J、REV和SP/SG抗体的鸡中,有54.78％(252/460)呈抗体阳性,其中,单抗体阳性、2种抗体阳性和3种抗体阳性的鸡数分别占74.21％(187/252)、22.22％(56/252)和3.57％(9/252).结果 提示种鸡群存在不同程度的ALV-A/B、ALV-J、REV和SP感染,以REV和SP感染较为严重,且多重感染现象较为普遍.ND和HPAI免疫抗体检测结果显示,NDV、H5亚型AIV Re-11株、Re-12株和H7亚型AIV平均血凝抑制(HI)抗体效价分别为(10.85±0.95) log2、(8.14±1.31) log2、(7.76±1.23) log2和(8.96±1.03) log2,表明鸡群ND和HPAI免疫效果良好.以上研究结果可以为鸡群重要疫病的防控和净化工作提供依据.

为进一步明确柔嫩艾美耳球虫对球虫易感性差异鸡种的致病性,本研究以1×105个柔嫩艾美耳球虫孢子化卵囊的剂量分别感染对球虫具有抗性的藏鸡和易感的隐性白羽鸡,接种后观察记录各组鸡的临床表征、血便记分、死亡率、增重、盲肠病变记分、卵囊产量,并于感染前和感染后3、6和8d每个品种分别随机选择5只鸡采集抗凝血,应用流式细胞仪(FCAS)检测外周血CD4+T和CD8+T淋巴细胞亚群数量.结果 显示,柔嫩艾美耳球虫感染后藏鸡相对增重率高于隐性白羽鸡,死亡率、血便记分和盲肠病变记分均低于隐性白羽鸡,但卵囊产量高于隐性白羽鸡.外周血T淋巴细胞亚群变化方面,感染前,藏鸡CD4+T淋巴细胞数及CD4+/CD8+比值均高于隐性白羽鸡.感染后第3天,藏鸡CD4+、CD8+T淋巴细胞数及CD4+/CD8+比值下降,隐性白羽鸡CD8+T淋巴细胞数略有下降,CD4+T淋巴细胞数及CD4+/CD8+比值上升,但CD4+/CD8+比值仍显著低于藏鸡(P＜0.05).感染后第6天,2个品种鸡CD4+T淋巴细胞数及CD4+/CD8+比值均下降,其中藏鸡表现为显著下降(P＜0.05),而隐性白羽鸡仅CD4+/CD8+比值显著降低(P＜0.05),隐性白羽鸡CD8+T淋巴细胞数显著升高(P＜0.05).感染后第8天,2个品种鸡CD4+/CD8+比值显著下降(P＜0.05),藏鸡CD8+T淋巴细胞数显著高于隐性白羽鸡(P＜0.05),但CD4+/CD8+比值显著低于隐性白羽鸡(P＜0.05).结果 表明,球虫对藏鸡和隐性白羽鸡的致病性存在差异,这种差异与T淋巴细胞介导的免疫应答反应密切相关.

为从病理生理角度探究宿主抗球虫感染的机制,对藏鸡和隐性白羽鸡感染柔嫩艾美耳球虫(Eimeria tenella)后的血清生化指标变化进行了比较分析.26日龄藏鸡和隐性白羽鸡均设感染组和非感染对照组,每组40只.感染组每只鸡经嗉囊接种1 mL含1×105个柔嫩艾美耳球虫孢子化卵囊悬液.感染后第0、3、6、8天,分别测定感染组和对照组鸡的14项血清生化指标.结果表明:藏鸡血清球蛋白含量于感染后第3天升高,而隐性白羽鸡则显著下降(P＜0.05);藏鸡血清白蛋白含量于感染后第6天起显著降低(P＜0.05),隐性白羽鸡则在感染后第3天显著升高(P＜0.05);2个品种鸡血清碱性磷酸酶含量于感染后第6天起明显下降,其中隐性白羽鸡显著下降(P＜0.05).藏鸡血清γ-谷氨酰基转移酶含量于感染后第6天显著下降(P＜0.05),而隐性白羽鸡则表现为升高趋势;两个品种鸡血清甘油三酯含量于感染后第6天明显下降,其中藏鸡显著下降(P＜0.05);藏鸡血清尿酸含量在感染后第3天显著上升,隐性白羽鸡则在感染后第8天显著下降(P＜0.05);藏鸡和隐性白羽鸡血清P3+浓度分别于感染后第3和6天显著升高(P＜0.05);其余指标亦有升高或降低,但与对照组间无显著差异.提示鸡感染柔嫩艾美耳球虫后心、肝未受到严重损害,肾功能受到一定程度的影响,肠道受损较为严重,且隐性白羽鸡肠道受损程度较藏鸡严重.

为探讨鸡白痢沙门菌耐药基因携带情况及其与药敏性的相关性,研究采用PCR方法对已确定耐药谱的207株鸡白痢沙门茵分离株的6类药物的10种耐药基因进行了检测.结果显示:12株(5.80％)未检出耐药基因,11株(5.31％)可携带多达7种耐药基因,携带3种耐药基因的菌株数量最多,占38.16％.10种耐药基因均可检出,tetC基因检出率最高(54.11％),其次为tetA (50.24％)和blaCMY～2(49.76％).与菌株药敏性总符合率较高的基因依次为cat1(90.82％)、addA1(87.76％)、tetA(86.36％)、blaTEM-1(79.31％),但catⅠ的耐药符合率及addA1的敏感符合率均为0.blaCMY-2与tetC虽然基因检出率较高,但与药敏性的符合率均较低.研究表明:鸡白痢沙门茵分离株耐药基因携带率较高,但耐药基因与药敏性并不完全相符,耐药基因检测结果可能并不一定能反映分离菌株的实际耐药状况.

Twenty-one, 25-day-old, artificially reared, coccidia-free goslings (Anser cygnoides var. domestica) were inoculated orally with 0.5 × 104, 1 × 104, or 100 × 104 sporulated oocysts of Eimeria anseris and sacrificed at intervals from 24 to 216 h post-inoculation (HPI). Nine uninfected goslings served as negative controls. Parts of the visceral organs from goslings, including the intestines, kidneys, and liver, were fixed, sectioned, and observed microscopically. The results revealed that two generations of meronts occurred in the life cycle of E. anseris. The first generation of meronts developed at 24–96 HPI and the second generation at 90–128 HPI. Each meront contained 4–10 merozoites. Development of gamonts began at 128 HPI and mature oocysts appeared at 168 HPI. Developmental stages presented mainly in the epithelial cells of crypts and lamina propria in the posterior parts of the jejunum and ileum. Parasites localized mostly in the cytoplasm and occasionally in the nuclei of host cells. Histological lesions were pronounced in the jejunum and ileum. Desquamation and necrosis of the epithelium of intestine and crypts, infiltration of inflammatory cells, and hemorrhage and mucosal edema were associated with aggregates of endogenous stages. The infected goslings mainly showed severe diarrhea, depression, anorexia, and emaciation, suggesting that E. anseris is highly pathogenic in goslings.

采用萘啶酸、恩诺沙星、诺氟沙星、环丙沙星、加替沙星等5种喹诺酮类药物进行了鸡白痢沙门菌体外诱导耐药试验,观察和分析了细菌耐药性发展进程及药物间的交叉耐药情况.鸡白瘌沙门菌标准株C79-3以药物浓度递增法分别在5种药物的次抑菌浓度下诱导传代至30代,每10代进行药敏试验检测耐药性,并对诱导株诱导前和诱导30代后的药物最低抑菌浓度(MIC)进行测定和比较.结果:随着诱导代次增加,诱导株对诱导药物的敏感性逐渐下降,至30代时所有诱导株均对诱导药物产生耐药.不同药物诱导耐药的进程有一定程度的差异,萘啶酸最易诱导耐药,其次为恩诺沙星、环丙沙星和加替沙星,最后为诺氟沙星.环丙沙星诱导株的环丙沙星MIC增幅最大,萘啶酸诱导株的萘啶酸MIC值最高.5种药物间存在不同程度的交叉耐药现象,恩诺沙星、诺氟沙星和环丙沙星之间为双向交叉耐药,而萘啶酸与恩诺沙星、诺氟沙星、环丙沙星和加替沙星间以及加替沙星与恩诺沙星、诺氟沙星和环丙沙星间为单向交叉耐药.此外,药物间的交叉耐药与菌株的耐药水平密切相关.

从江苏省某肉鸽场发生的腹泻症状的死亡鸽中采集病料,分离出1株病原菌,通过PCR鉴定菌株,并进一步做药敏试验.结果表明,病原菌分离鉴定为鼠伤寒沙门菌,属于血清O4群,该菌对20种抗生素均敏感.

以新城疫病毒(NDV) La Sota株为模板,以P基因发生RNA编辑的编码位点为起始,扩增获得V蛋白基因C末端,经原核表达获得其融合蛋白,并制备了小鼠抗血清,Western-blot试验结果表明,该抗血清具有良好的特异性.本研究结果为NDVV蛋白生物学功能的后续研究奠定了基础.

We report here the complete genome sequence and biological characterization of a virulent Newcastle disease virus (NDV) strain, NDV/duck/Jiangsu/JSD0812/2008, isolated from laying ducks in Jiangsu Province, China. The genome is 15,192 nucleotides in length and is classified in subgenotype VIId of genotype VII, class II.

Mycoplasma gallisepticum infections impose a significant economic burden on the poultry industry. In the current study, a loop-mediated isothermal amplification (LAMP) assay was developed and optimized to detect M. gallisepticum based on a gene within the pyruvate dehydrogenase complex, the pdhA gene, which codes for the major subunit (E1α) in the complex. The reaction conditions were optimized, and the specificity was confirmed by successful amplification of several M. gallisepticum strains, while no amplification was detected with 20 other major bacterial and viral pathogens of poultry. Additionally, the LAMP assay achieved 10-fold higher sensitivity than an existing polymerase chain reaction (PCR) method. The LAMP assay was applied to swab samples collected from poultry farms and compared with PCR. The positive detection rate was 20.2% (37/183) by LAMP and 13.1% (24/183) by PCR. The LAMP assay could provide a cost-effective, quick, and sensitive method for the detection of M. gallisepticum.

禽流感主要是由A型流感病毒引起的一种禽的烈性传染病,采用疫苗免疫是防控高致病性禽流感的最有效方法.本试验采用水禽用重组禽流感病毒灭活疫苗(H5N1亚型,Re-6株)和重组禽流感病毒H5亚型二价灭活疫苗(Re-6株+Re-4株)进行了鹅的免疫试验,对鹅免疫后抗体消长情况进行跟踪监测,旨在为鹅的禽流感免疫程序的制定提供依据.

采用重组禽流感病毒灭活疫苗(H5N1亚型,Re-6株)和重组禽流感病毒H5亚型二价灭活疫苗(Re-6株+Re-4株)进行蛋鸭免疫试验,监测免疫鸭的抗体消长动态,旨在为鸭禽流感免疫程序的制定提供理论依据.基于试验结果,提出鸭禽流感免疫程序:2周龄首免,4～5周龄二免,开产前2～3周三免,此后每隔4～5个月加强免疫一次.