Humoral immune response of the duck to duck hepatitis virus: virus-neutralizing vs. virus-precipitating antibodies

Ducks were induced to develop high-level duck hepatitis virus (DHV)-neutralizing antibodies by inculation with a chicken-embryo-adapted DHV via subcutaneous, intramuscular, and intratracheal routes. Administration of the DHV orally in a gelatin capsule failed to stimulate immune response in the ducks. Contact controls of these ducks also remained negative for anti-DHV antibodies. These observations indicated that the DHV administered orally, in gelatin capsule, failed to infect the ducks. None of numerous duck anti-DHV immune sera, with virus-neutralizing activity in the range of 1.8 to 5.57 log10 median- embryo-infective-dose (EID50) neutralization index, developed precipitin lines against a variety of DHV preparations tested in low- and high-ionic-strength agar. The results suggest that the agar-gel immunodiffusion test is unsuitable for serologic testing of duck sera for anti-DHV antibody activity. Virus-neutralizing activity was revealed in both immunoglobulin M (IgM) and IgG classes of sera of actively immunized ducks. Immunodiffusion tests of Sephadex G-200 fractions of 1-day-old duckling sera with monospecific rabbit anti-duck IgM (DIgM) serum failed to detect DIgM. These results demonstrated that the IgM is not being transferred from the dam to the newly hatched ducklings. Seven- and 14-day-old ducks had DIgM in their sera. However, this IgM had no DHV-neutralizing activity, indicating that it was newly developed by the ducklings, which had no active DHV immune response, not having been exposed to DHV.     

A teratoma in a duck infected congenitally with duck hepatitis B virus

A teratoma was diagnosed in an 8-month-old pekin duck based on the presence of tissue derived from embryonic ectoderm, mesoderm, and endoderm in the neoplasm. The neoplasm was examined for the presence of duck hepatitis B virus, because the duck was congenitally infected with the virus, a member of the hepadnavirus family that is associated with hepatic neoplasms in hepadnavirus-infected mammals. Persistent infection occurred in the liver, but no evidence of viral infection was found in the neoplasm.     

Superinfection in ducks persistently infected with duck plague virus

Superinfections with homologous or heterologous strains of duck plague virus resulted in the deaths of birds persistently infected with duck plague virus. Not all birds that were superinfected died. Protection against mortality depended on the route of exposure, strain of the initial duck plague virus, and strain of the superinfecting virus.     

A sequential histologic and immunohistochemical study of duck hepatitis B virus infection in Pekin ducks

Twenty-nine Pekin ducks were inoculated with duck hepatitis B virus (DHBV), DHBV-free serum, or saline at 1 day of age. Congenitally DHBV-infected ducks were also studied. Ducks were killed periodically during a 92-week study and examined histologically and immunohistochemically to assess liver and extrahepatic inflammation and to detect and characterize DHBV core antigen tissue distribution. DHBV infection produced an asymptomatic but persistent DHBV viremia in all ducks associated with a mild to moderate transient hepatic inflammation apparent at 3 to 6 weeks post-inoculation and waning afterwards. DHBV core antigen was detected in hepatocyte cytoplasm at 1 week post-inoculation, and by 3 weeks post-inoculation scattered pancreatic acinar and islet cells also contained viral antigen. Small numbers of mononuclear cells in the splenic white pulp also contained viral antigen. Viral antigen persisted in all of these tissues throughout the duration of the experiment. No inflammation or tissue injury was detected in any of the extrahepatic tissues during the course of DHBV infection. One DHBV-injected duck developed a hepatocellular carcinoma at 88 weeks of age. Isolated patches of neoplastic hepatocytes contained cytoplasmic DHBV core antigen. The results of this study indicate that DHBV, like mammalian hepadnavirus, is capable of producing a persistent infection of the liver and several extrahepatic tissues and suggest that persistent infection may be associated with the development of hepatocellular carcinoma.     

中药茜草对鸭肠炎病毒感染鸭免疫器官病理损伤的影响

为探究中药茜草对鸭肠炎病毒感染所致鸭免疫器官组织病理损伤的影响,将30日龄健康三穗麻鸭随机分成给药组(中药干预)、模型组(病毒感染组)和对照组,经相应处理后于处理66、90和114 h时扑杀,采集相关组织和血清样本进行病原核酸PCR扩增、免疫器官指数测定、血清生化指标检测和病理组织切片观察.结果 显示:与模型组相比,给...     

Expression and immunohistochemical distribution of duck plague virus glycoprotein gE in infected ducks

To determine the distribution of duck plague virus (DPV) gE protein in paraformaldehyde-fixed, paraffin-embedded tissues of experimentally DPV-infected ducks, an indirect immunoperoxidase assay was established to detect glycoprotein E (gE) protein for the first time. The rabbit anti-His-gE serum, raised against the recombinant His-gE fusion protein expressed in Escherichia coli BL21 (DE3), was prepared and purified. Western blotting and indirect immunofluorescence analysis showed that the anti-His-gE serum had a high level of reactivity and specificity and could be used as the first antibody for further experiments to study the distribution of DPV gE protein in DPV-infected tissues. A number of DPV gE proteins were distributed in the bursa of Fabricius, thymus, spleen, liver, esophagus, duodenum, jejunum, ileum, and kidney of DPV-infected ducks and a few DPV gE were distributed in the Harders glands, myocardium, cerebrum, and lung, whereas the gE was not seen in the skin, muscle, and pancreas. Moreover, DPV gE was expressed abundantly in the cytoplasm of lymphocytes, reticulum cells, macrophages, epithelial cells, and hepatocytes. The present study may be useful not only for describing the characteristics of gE expression and distribution in infected ducks but also for understanding the pathogenesis of DPV.     

感染RA和DVHV雏鸭免疫功能动态变化研究

为深入探讨鸭免疫器官指数、T淋巴细胞和细胞因子动态变化与病毒性肝炎和传染性浆膜炎发生与发展的相互关系,并比较分析缙云麻鸭与绍兴鸭免疫功能与抗病性能,为蛋鸭抗性选育提供依据,试验分别以鸭疫里默杆菌(RA)和肝炎病毒(DVHV)人工感染3日龄缙云麻鸭与绍兴鸭,分析在不同的感染期脾脏、胸腺和法氏囊指数以及外周血淋巴细胞ANAE 阳性率和细胞因子的动态变化.结果表明:缙云麻鸭和绍兴鸭攻毒感染RA与DVHV后的死亡时间与脾脏指数、胸腺指数、法氏囊指数、外周血液淋巴细胞ANAE 阳性率及IFN-γ水平均呈现正相关(P＜0.01或P＞0.1);绍兴鸭感染DVHV后的死亡时间与IL-2也呈正相关(P＜0.1),但缙云麻鸭和绍兴鸭攻毒感染RA以及缙云麻鸭感染DVHV后的死亡时间与IL-2呈负相关(P＜0.1或P＞0.1).说明雏鸭感染RA和DVHV后的死亡时间与脾脏指数、胸腺指数、法氏囊指数、外周血液淋巴细胞ANAE 阳性率及IFN-γ水平动态变化相关,而与血清IL-2水平的相关性还有待进一步研究.     

Thermostability of duck hepatitis virus.

The comparative thermostability of 4 duck hepatitis (DH) viruses were tested at various temperatures for different times. Titer of duckling-passaged, pathogenic DH virus decreased from 10(4.50) to 10(2.33) and 10(2.20) median infective doses (ID50/0.1 ml, respectively, in 2 tests; titer of chicken embryo-passaged, nonpathogenic, but embryo-lethal, DH virus decreased from 10(6.00) to 10(0.46) and from 10(6.62) to 10(0.63) ID50/0.1 ml, respectively; duck embryo fibroblast culture-passaged and duck embryo liver cell culture-passaged, chicken ebryo-infective, but nonlethal, DH viruses were completely inactivated or nearly so after being kept at 56 C for 30 minutes. Duckling-passaged DH virus was not detected on day 21, whereas 10(0.62) ID50 of chicken embryo-passaged DH virus per 0.1 ml remained on day 32 when being kept at 37 C. Titer of chicken embryo-passaged DH virus decreased from 10(7.00) to 10(1.16) ID50/0.1 ml after being kept at room at room temperature for 150 days, to 10(5.17) ID50/0.1 ml after being kept at 4 C for 70 weeks, to 10(6.17) ID50/0.1 ml after being kept at -20 C for 70 weeks, and to 10(6.38) ID50/0.1 ml after being kept at -60 C for 1 year.     

Assessment of the immune response to duck plague vaccinations

An experiment was conducted to assess the immune responses of ducks to duck plague (DP) vaccinations employing one commercial and one laboratory-adapted (LA) DP vaccines. Virus neutralisation and leucocyte migration-inhibition tests were conducted at regular intervals before and after vaccinations. Similarly, ducks in vaccinated and control groups were subjected to challenge infection with virulent DP virus.The commercial vaccine yielded a poor immune response and partial protection on challenge whereas satisfactory responses were obtained in ducks receiving two doses of LA vaccine. The humoral as well as cellular factors were stimulated indicating possible involvement of both the immune responses in the protection from duck plague.     

河南省樱桃谷鸭乙型肝炎病毒全基因组克隆与序列分析

对河南省樱桃谷鸭主产区信阳、新郑、焦作三地628份樱桃谷鸭血清样本应用PCR技术进行鸭乙型肝炎病毒（DHBV）检测,并将三地DHBV阳性样本各挑选1份进行DHBV全基因的扩增、克隆、测序及序列分析。结果显示,信阳、新郑、焦作三地樱桃谷鸭DHBV自然携带率分别为10.5%、8.9%、17.6%;3株DHBV基因组全长分别为3 021、3 027、3 024bp,均含有编码P、S和C蛋白的3个开放阅读框,各开放阅读框氨基酸同源性比较显示差异显著的区域位于P蛋白。序列分析显示,3株DHBV河南株核苷酸同源性为89.8%~93.9%,与参考株为89.4%~99.5%。遗传进化分析及P蛋白关键位点分析结果表明,信阳分离株为西方基因型,其余2株为中国基因型。本试验掌握了河南省樱桃谷鸭主产区DHBV自然感染情况,并成功克隆了3株樱桃谷鸭DHBV全基因序列,为该病毒的进一步研究提供了有益信息。     

鸭病毒性肝炎诊断与防治

鸭病毒性肝炎（DVH，duck virus hepatitis)是雏鸭多发的一种严重的病毒性传染病。该病传播迅速，具有高度致死性。本病主要感染35d以内的小鸭，尤以14d以内的小鸭最易感染，常在出现角弓反张症状后迅速死去。病毒以肝脏肿大并伴有出血点为主要特征。该病常与其它疾病混合感染，发病初期死亡率达90%以上。该病一旦发生常给养鸭业生产带来很严重的经济损失，因此，实际生产中应引起足够的重视。本针对鸭病毒性肝炎的发病情况、临床症状、临床诊断、疗效试验及防治作了简要概述。     

水鸭类病毒性肝炎的诊治

1　发病情况　 1 999年 9月至 1 0月 ,广东南海一水鸭养殖户温某在饲养肉水鸭的过程中 ,连续 3批雏鸭 (每批 2 50 0只 ) ,均从第 4天开始发生急性传染病。这 3批雏鸭均是经鸭肝炎疫苗免疫母鸭的后代 ,先后出现严重的发病和死亡。第 3批雏水鸭是从 1 0月 1 6号进苗 ,2 0号发现小鸭突然死亡 1 3 2只 ,禽主立即采用鸭肝炎蛋黄抗体作紧急被动免疫 ,分点肌肉注射 1 .1 ml/只 ,第 2天发现鸭子死亡 1 56只 ,第3天死亡 1 3 8只 ,那天晚上 ,禽主又使用鸭肝炎蛋黄抗体作紧急免疫 ,方法同上 ,一直到第 1 0天 ,每天仍死亡 1 0 0多只 ,疫情仍未能得到控制…     

鸭瘟病毒强毒株在感染鸭实质器官内的增殖与分布

鸭瘟病毒(DPV)CHv强毒株经皮下注射、滴鼻和口服3种途径分别感染20日龄天府肉鸭,于攻毒后10、30、60、90min以及4、12、48、72h和9、15d每组分别剖杀2只鸭,采集心、肝、脾、肺、肾、脑、胸腺、法氏囊、哈德氏腺等实质器官,应用TaqMan-MGB探针实时荧光定量PCR对DPV在这些器官的分布和增殖进行检测。结果表明,DPV分布到具体器官的速度与感染的途径、鸭的解剖结构密切相关,其中皮下注射是DPV分布到各实质器官速度最快的途径。30min于皮下感染鸭的肝、脾、胸腺、法氏囊、哈德氏腺、肺、脑、肾,口服感染鸭的肺和法氏囊,滴鼻感染鸭的心脏和哈德氏腺均检测到DPV-DNA;90min所有受检样品中检测到DPV-DNA。鸭抗DPV感染的免疫器官的重要性依次是脾、胸腺、法氏囊和哈德氏腺,30min内DPV-DNA分布到脾、胸腺、法氏囊的速度和数量决定了DPV感染的潜伏期和疾病的严重程度。不同途经感染鸭的相同器官在同一时间内的DPV-DNA拷贝数大多以皮下感染鸭为最高。DPV致死鸭的法氏囊和肾是DPV-DNA含量最高的实质器官。