DHBV感染鸭特异免疫应答比较

目的 研究嗜肝病毒感染病毒清除向慢性化转变的免疫机理。方法 通过接种不同龄鸭、不同感染方案建立DHBV急性、慢性感染组及免疫组模型,并检测各组病毒复制及特异体液和细胞介导免疫反应。结果 成年鸭接种DHBV导致一过性病毒血症的形成,感染后抗－DHBs和抗-DHBc的水平比慢性感染组高（P＜0．05）,而免疫组抗－DHBs、抗－DHBc的水平又比急感染组高（P＜0．01）。特异细胞介导免疫反应（CMI）的分析提示急性感染组感染后10d外周血单个核细胞（PBMC）对特异抗原的体外增殖反应强于慢性感染组,但在感染5周内快速下降。而免疫组CMI与急性感染组比差异无显著意义。结论 感染宿主免疫应答特别是特异免疫反应是决定感染转归的重要因素。     

广西麻鸭乙型肝炎感染病毒动物模型的实验研究

目的探讨广西麻鸭作为乙型肝炎病毒感染动物模型的可能性。方法应用广西1 d龄雏麻鸭经腹腔感染鸭乙型肝炎病毒(DHBV),13 d后采用实时荧光定量PCR法检测麻鸭血清DHBV含量,筛选出DHBV强阳性鸭。结果共检测148份麻鸭血清标本,其中DHBV阳性标本136份,阳性率为91.9%。结论广西麻鸭可作为乙型肝炎病毒感染动物模型。实时荧光定量PCR法检测DHBV敏感性较高,重复性好,可用于DHBV检测。     

小分子肽抗乙型肝炎病毒的实验研究

目的:应用2.2.15细胞株和鸭乙型肝炎病毒(DHBV)感染模型,评价小分子肽CMS 017抗乙肝病毒作用.方法:①CMS 017以倍比稀释浓度加入2.2.15细胞培养中,作用8天后吸取培养上清,PCR法检测HBVDNA.②建立DHBV感染模型,CMS017以60、200、600μg/kg·d-13个剂量腹腔注射给药28天,检测用药前、后血清DHBV DNA、DHBsAg变化.结果:①CMS 017体外抑制DHBV呈量效关系,IC50为2.3μg/ml.②鸭体内实验中,CMS 017中、高剂量组用药7天、14天开始出现血清DHBV DNA降低(P＜0.01,P＜0.05),持续至停药后7天.CMS 017中剂量组用药后血清DHBsAg降低的时效关系与DHBV DNA完全一致.结论:CMS017具有抗乙肝病毒作用,其体内作用的量效关系待确定.     

鸭乙型肝炎病毒对鸭心肌细胞超微结构的影响

将鸭乙型肝炎病毒(DHBV)感染雏鸭制作的鸭乙型肝炎模型已被广泛用于研制抗乙肝病毒新药,为探索DHBV感染对雏鸭心脏有何影响,我们观察了被DHBV感染的雏鸭其心肌的超微结构,现报道如下。 1 材料与方法 1.1 动物及分组 20只1日龄武汉麻鸭(购自华中农业大学种禽厂),随机分为对照组和感染组,每组10只。 1.2 造模方法及标本制作 雏鸭喂养1周后,分成2组:感染组每只鸭自胫静脉注射DHBV阳性血清     

重庆麻鸭乙肝动物模型的建立及应用——21种中药抗鸭乙型肝炎病毒初筛研究

采用斑点杂交法检测了重庆地区263份2～3月龄麻鸭血清中的DHBV DNA,用筛选出的阳性病毒血清经腹腔感染1～2日龄的血清DHBV DNA阴性雏鸭,并用该模型进行了21种中药抗乙肝病毒初(?)。结果表明:(1)重庆地区2～3日龄麻鸭DHBV自然感染率为25.48％.(2)经腹腔感染的1～2日龄雏鸭的血清DHBV DNA阳性率1周后为82.90％,并可持续至少2个月。(3)抗乙肝病毒中药初(?)发现用广西叶下珠、苦参治疗2周可使DHBV DNA滴度下降,其余的经体外实验认为有效的抗乙肝病毒中药,动物实验并未获证实。     

鸭血清中鸭乙型肝炎病毒表面抗原与肝脏病理变化

用超速离心方法从启东鸭血清中分离和纯化了鸭乙型肝炎病毒(DHBV),提示了DHBsAg有亚型存在的可能性。纯化的DHBsAg免疫动物,制备了特异性抗血清,并用戊二醛二步法建立了检测DHBsA巴的灵敏、特异、简便的反向间接血凝法。通过对江苏启东、山东日照、广西扶绥、长春各地鸭血清中DHBsAg的检测和启东、长春鸭肝脏病理学检查,示检测血清中DHBsAg标志     

单项抗-HBe阳性患者中的隐匿性乙型肝炎病毒感染

目的 研究抗-HBe单项阳性患者中隐匿性HBV的感染情况及发生的可能原因.方法 收集HBV血清学标志物检测结果中抗HBe单项强阳性[吸光度(A)值≤0.1]的新鲜血清标本61份,采用实时定量PCR进行HBV DNA含量检测.对于HBV DNA定量阳性的标本,采用雅培试剂复测HBV血清学标志物,采用PCR扩增,并进行克隆测序.结果 61份标本中,2份HBVDNA定量阳性,HBsAg血清学漏检率为3.3％.其中l份标本经雅培试剂复测为抗-HBc单项阳性,其前S区缺失突变和前S2区起始密码子突变,并存在不同突变株混合感染;另1份标本经雅培试剂复测发现,除抗HBe强阳性外,HBsAg和抗- HBc为极弱阳性,未发现前S/S区突变.结论 抗HBe单项阳性患者中存在隐匿性HBV感染和HBsAg血清学漏检情况,后者不仅与前S/S区突变有关,而且与外周血中HBsAg低水平也有一定关系.     

肝苏颗粒浸膏粉抗鸭乙型肝炎病毒的实验研究

目的：观察肝苏颗粒浸膏粉（以下简称肝苏）体内抗鸭乙型肝炎病毒（DHBV）的作用,为临床治疗乙肝病毒感染提供实验依据,方法：采用重庆鸭乙型肝炎动物模型,用肝苏口服治疗4W,停药观察1W,检测用药前后血清的DHBVDNA,DHBsAg,转氨酶（ALT,AST）及肝组织病理变化,结果：肝苏各剂量组用药后血清DHBV DNA滴度显著降低或极显著降低（P＜0．05或P＜0．01）,停药1W后中,小剂量组血清DHBV DNA有明显回升现象,而大剂量组DHBV DNA回升现象不明显,其抗病毒效果与剂量大小有一定的关系,用药前后血清DHBsAg O,D值（490nm)的变化与DNA滴度改变相似,此外,肝脏病理学检查及治疗4W,停药1W后血清ALT,AST检查未发现该药对鸭肝组织有明显的毒性损害,结论：连续用肝苏1个月在鸭体内有抗鸭乙型肝炎病毒的作用。     

简易的Dot—ELISA法诊断耕牛和家兔日本血吸虫病

本实验用硝酸纤维膜为载体,水溶性日本血吸虫虫卵抗原为抗原,先后检测了18份实验感染黄、水牛血清、66份自然感染牛血清、84份阴性牛血清、40份实验感染兔血清和18份阴性兔血清,结果表明实验感染牛血清和兔血清都呈阳性反应,检出率达100％。自然感染牛血清的阳性检出率为93.9％(62/66),阴性牛血清的检出符合率为95.24％(80/84)。阴性兔血清都呈阴性反应。检测了4份肝片吸虫阳性兔血清和31份锥虫阳性牛血清,都不出现交叉反应。     

919糖浆抗鸭乙型肝炎病毒的实验研究

目的:研究919糖浆时鸭乙型肝炎的体内抗病毒作用。方法:以感染鸭乙型肝炎病毒(DHBV)的武汉麻鸭为实验动物模型。使1d龄武汉麻鸭感染DHBV,7d后用Dot-EIA法筛选出DHBsAg强阳性鸭。随机分组后给予919糖浆治疗14d,于感染后第7d(为用药前)、用药7d、14d及停药后3d分别采血,采用斑点杂交方法检测血清DHBVDNA。结果。用药919糖浆7d、14d鸭血清DHBV DNA OD值均明显低于给药前,有显著性差异(P<0.05,P<0.01)。停药3d后没有反跳现象。结论:919糖浆有一定的抑制DHBV DNA复制作用。     

拉米夫定联合泛昔洛韦抗鸭乙型肝炎病毒的实验研究

观察核苷酸类似物拉米夫定联合泛昔洛韦体内抗鸭乙型肝炎病毒（DHBV）的作用。方法 采用重庆麻鸭乙型肝炎动物模型,用拉米夫定联合泛昔洛韦口服治疗4周,停药观察1周,检测用药前后血清中的DHBV DNA、DHBsAg及血清转氨酶（ALT、AST）、肝组织HE染色病理。并以单用拉米夫定、泛昔洛韦、阿昔洛韦作对照。结果 拉米夫定联合泛昔洛韦用药后能使血清中DHBV DNA含量总体水平显著降低（P＜0．01）,停药1周后DHBV DNA较用药4周时DHBV DNA含量回升现象不明显。用药前后清血DHBsAg的吸光度值（490nm)的变化与DNA含量改变相似;此外,肝脏病理检查及治疗4周、停药1周后血清转氨酶检测未发现联合用药对鸭肝组织有明显的毒性损害。结论 拉米夫定联合泛昔洛韦连续用药4周在鸭体内有抗鸭乙型肝炎病毒的作用,且停药后DHBV DNA无明显“反跳”,二者用药有协同作用。     

Studies on duck hepatitis B virus: Identification and epidemiological survey in Taiwan

The presence of duck hepatitis B virus (DHBV) in domestic ducks in Taiwan was confirmed by DNA polymerase assay, Southern blot analysis and electron microscopy. To investigate the epidemiology of this virus, a total of 1274 serum samples were collected from 30 duck farms from different areas of Taiwan and studied by spot hybridization and/or DNA polymerase assay. The positive rates varied among different strains of ducks: 16% in 243 Pekin ducks, 12% in 392 Chinese common domestic ducks, 4% in 196 Muscovy, 25% in 292 Taiwan Kaiyas and 13% in 151 mule ducks. The positive rate was much higher in the younger ducks; it was highest (30.7%) in ducklings under 1 month of age, followed by ducks aged 1–12 months (11.8%), and lowest in those ducks older than 1 year (7.7%). It was concluded that the prevalence of DHBV infection in domestic ducks in Taiwan is generally high, and that the infected ducks may serve as an animal model for human hepatitis B virus infection which is also prevalent in Taiwan.     

Liver disease associated with duck hepatitis B virus infection of domestic ducks.

The liver disease associated with duck hepatitis B viremia was investigated in naturally infected ducks from Chi-tung county in China and in both naturally and experimentally infected ducks from the United States. Liver and serum specimens of adult Chinese ducks were examined for duck hepatitis B virus (DHBV) DNA by dot and gel blot hybridization. DHBV was found in serum and (in episomal form only) in livers of 6 of 11 birds exhibiting various degrees of chronic hepatitis. In 1 bird with hepatocellular carcinoma, DHBV DNA was detected at the limit of assay sensitivity and in another not at all, contrasting with findings in humans and woodchucks. In work with California Pekin and Khaki Campbell ducks, known amounts of DHBV were injected into the egg 10 days before, or into ducklings 1 day after, hatching and the livers were examined 6 weeks later. The majority of the injected ducklings had viremia detectable by hybridization 1 or 2 weeks after injection. The presence but not the amount of viremia correlated with incidence and degree of hepatitis, determined under code. The most severe instances of hepatitis, all in Pekin ducks, resembled the hepatitis in adult Chinese ducks of Chi-tung county. Severe and moderate hepatitis were found only in indoor-caged injected animals with viremia and in some uninjected birds without viremia that had been kept in outdoor flocks. The latter hepatitis, as some hepatitis in adult Chinese ducks, may not be related to DHBV. Mild and insignificant hepatitis were also found in injected and noninjected ducklings, some of which had the vertically transmitted spontaneous viremia previously described. The good correlation of experimentally induced viremia with incidence and severity of hepatitis in the Pekin duckling provides a simple, rapid, and relatively inexpensive model to study the relation of lesions to hepatitis B family infection in nonprimates.     

Protective and therapeutic effect of DNA-based immunization against hepadnavirus large envelope protein

BACKGROUND & AIMS: Studies in the murine model suggest that injection of DNA encoding hepatitis B virus structural proteins is promising for the induction of a specific immune response. We used the duck hepatitis B virus (DHBV) model to study the protective and therapeutic effects of naked DNA immunization against hepadnaviral large envelope protein. METHODS: A pCI-preS/S plasmid expressing the DHBV large protein was used for intramuscular immunization of ducks. The humoral response was tested by enzyme-linked immunosorbent assay, immunoblotting, neutralization, and in vivo protection tests. For DNA therapy, DHBV-carrier ducks received four injections of this plasmid. Viremia was monitored for 10 months; thereafter, liver biopsies were performed. RESULTS: Immunization with pCI-preS/S plasmid induced a specific, long-lasting, neutralizing, and highly protective anti-preS humoral response in uninfected animals. After pCI-preS/S treatment, a significant and sustained decrease in serum and liver DHBV DNA was observed for carrier ducks compared with the controls. CONCLUSIONS: DNA immunization against DHBV large protein results in a potent and protective anti-preS response in the duck model. The results of long-term follow-up of DNA-treated chronically infected ducks are promising and show the usefulness of this model for the study of genetic immunization in chronic hepatitis B therapy.     

Electron microscopic studies on duck hepatitis B virus particles in hepatocytes and sequential changes in various patterns of infection

To investigate the critical factors involved in the elimination of the duck hepatitis B virus (DHBV) in acute infection, the sequential changes in the number of DHBV particles in hepatocytes were studied electron microscopically in ducks experimentally infected by DHBV. Twenty Japanese white Peking ducks were infected with DHBV on the day of hatching, and on the 7th day and 14th day after hatching. Inoculation of DHBV on the day of hatching, and on the 7th and 14th day after hatching resulted in persistent viremia, transient viremia and no viremia, respectively in ducks as tested by spot hybridization assay. The number of DHBV particles in the liver correlated well with the amount of serum DHBV-DNA, DHBV particles decreased in hepatocytes without any interaction of inflammatory cells over the observation period, and the number of particles was not associated with the degree of hepatic inflammation. From these results, the elimination of the virus was thought to be induced by a reduction of viral replication in the hepatocytes and not by destruction of their host cells. There must be an age-dependent factor which strongly suppresses the viral replication.     

Electron microscopic studies on duck hepatitis B virus particles in hepatocytes and sequential changes in various patterns of infection

To investigate the critical factors involved in the elimination of the duck hepatitis B virus (DHBV) in acute infection, the sequential changes in the number of DHBV particles in hepatocytes were studied electron microscopically in ducks experimentally infected by DHBV. Twenty Japanese white Peking ducks were infected with DHBV on the day of hatching, and on the 7th day and 14th day after hatching. Inoculation of DHBV on the day of hatching, and on the 7th and 14th day after hatching resulted in persistent viremia, transient viremia and no viremia, respectively in ducks as tested by spot hybridization assay. The number of DHBV particles in the liver correlated well with the amount of serum DHBV-DNA, DHBV particles decreased in hepatocytes without any interaction of inflammatory cells over the observation period, and the number of particles was not associated with the degree of hepatic inflammation. From these results, the elimination of the virus was thought to be induced by a reduction of viral replication in the hepatocytes and not by destruction of their host cells. There must be an age-dependent factor which strongly suppresses the viral replication.     

Duck hepatitis B virus DNA in liver and serum of Chinese ducks: integration of viral DNA in a hepatocellular carcinoma.

The presence of duck hepatitis B virus (DHBV) DNA in liver and serum and its state (integrated vs. free) were studied in 23 ducks from Chi-tung county in China by spot hybridization and Southern blot hybridization, respectively. In 16 of 23 (70%), DHBV DNA was detected in serum and/or in liver tissue. These infected ducks showed a variety of pathological changes including advanced chronic disease in the liver. In contrast, none of the virus-negative ducks had advanced hepatic changes. One DHBV DNA-seropositive duck had a large hepatocellular carcinoma. Southern blot analysis demonstrated integrated DHBV DNA in neoplastic tissue and abundant episomal DHBV DNA in non-neoplastic tissue of the liver. In one noninfected duck with a small adenoma, no viral DNA was detected in tumor or non-neoplastic tissue. The detection of integrated DHBV DNA in hepatocellular carcinoma suggests that DHBV behaves like human and woodchuck hepatitis viruses in relation to chronic liver disease and hepatocarcinogenesis.