一株鸭乙型肝炎病毒DHBV全基因的克隆和序列分析

目的 从本地樱桃谷鸭血清中克隆鸭乙型肝炎病毒(DHBV)DNA,并进行序列分析。方法 用PCR扩增DHBV全基因,连接至T载体上,挑选克隆进行测序分析,与GenBank中16株DHBV全基因组进行同源性比较,并进行分子进化树分析。结果 24-18与16株DHBV基因组比较,核苷酸同源性介于89.4%~99.3%之间,各开放阅读框氨基酸同源性比较显示差异显著地方位于P区。结论 24-18属于DHBV西方基因型中的一个亚型。     

Continuous cell lines from the Muscovy duck as potential replacement for primary cells in the production of avian vaccines

Veterinary vaccines contribute to food security, interrupt zoonotic transmissions, and help to maintain overall health in livestock. Although vaccines are usually cost-effective, their adoption depends on a multitude of factors. Because poultry vaccines are usually given to birds with a short life span, very low production cost per dose is one important challenge. Other hurdles are to ensure a consistent and reliable supply of very large number of doses, and to have flexible production processes to accommodate a range of different pathogens and dosage requirements. Most poultry vaccines are currently being produced on primary avian cells derived from chicken or waterfowl embryos. This production system is associated with high costs, logistic complexities, rigid intervals between harvest and production, and supply limitations. We investigated whether the continuous cell lines Cairina retina and CR.pIX may provide a substrate independent of primary cell cultures or embryonated eggs. Viruses examined for replication in these cell lines are strains associated with, or contained in vaccines against egg drop syndrome, Marek's disease, Newcastle disease, avian influenza, infectious bursal disease and Derzsy's disease. Each of the tested viruses required the development of unique conditions for replication that are described here and can be used to generate material for in vivo efficacy studies and to accelerate transfer of the processes to larger production volumes.     

Blood flow changes in the duck during thermal panting

Carotid and sciatic blood flow have been measured in resting and panting Pekin ducks using electromagnetic flowmeters. Panting induced by high ambient temperature caused the carotid blood flow to increase from 9.6 to 26.0 ml min^-1, while the sciatic flow declined slightly from 41.6 to 38.1 ml min^-1. During panting breathing rate increased 10–20 times, but there were no significant changes in heart rate and mean arterial blood pressure. The carotid peripheral resistance was therefore greatly reduced, whereas sciatic resistance remained unchanged or increased slightly. The vascular beds perfused by the sciatic (legs) and carotid (upper respiratory tract) arteries are both important for heat dissipation. This study shows that when heat dissipation from the naked legs becomes inefficient due to high ambient temperature, blood flow in the sciatic tended to decline while conversely panting was associated with a large increase in carotid flow.     

鸭γ干扰素体外抑制鸭乙型肝炎病毒复制的实验研究

目的　在体外模型中系统研究DuIFN γ对鸭乙型肝炎病毒 (DHBV)复制的影响 ,探讨其抑制病毒复制的可能机制。方法　用重组DuIFN γ及DHBV特异抗原刺激的PBMC上清液 ,分别作用于DHBV慢性感染的原代鸭肝细胞 (PDH) ,检测PDH上清液中DHBVDNA、DHBsAg浓度和胞内病毒复制水平。结果　 1U mL、1 0U mL重组DuIFN γ可以抑制培养细胞上清液中DHBVDNA和DHBsAg的分泌 ,与慢性感染对照组比较 ,P <0 .0 5。病毒复制的抑制水平 (包括细胞内DHBV总DNA、闭合环状DNA以及上清液中病毒颗粒和DHBsAg)与DuIFN γ作用呈时间、剂量依赖性 ,但DHBV特异抗原刺激的PBMC上清液无明显抑制病毒复制的作用。结论　DuIFN γ在体外DHBV慢性感染的PDH模型中可抑制病毒复制     

Comparison of the Effect of DDE on the Ca Metabolism of the Eggshell Gland and its Subcellular Fractions of the Duck and the Domestic Fowl

Abstract: In a strain of ducks sensitive to the eggshell-thinning effect of p-p'-DDE, administration of 40 mg/kg of the compound in the food for 45 days reduced the eggshell index (EI) by 13% and the content of calcium in the fluid of the shell gland forming an eggshell by 36%, and raised the calcium content of the shell gland mucosa by 19%, compared with the control values. DDE inhibited the translocation (secretion) of calcium between the gland mucosa and the uterine cavity. The ATP-dependent binding of Ca²⁺ to the subcellular fractions of the gland mucosa was reduced in DDE-treated ducks. The Ca²⁺ binding to a microsomal subfraction (FI) rich in fragments of the plasma membrane was reduced by 16%, whereas that to a subfraction Fill which bound Ca²⁺ at a very high rate was reduced by 36%. The latter may contain calcium-secreting granules of the gland. In the mitochondrial fraction the Ca²⁺ binding was reduced by 35%. In the domestic fowl DDE did not lower EI or interfered with the translocation of calcium between the shell gland mucosa and uterine cavity. DDE administration increased the Ca²⁺ binding to FI by 26%; the binding to other subfractions was not changed significantly. DDE may interfere with the stimulus-secretion mechanism of the eggshell gland in ducks through its effect on Ca²⁺ binding.     

Duck hepatitis B photoinactivation bydimethylmethylene blue in RBC suspensions

BACKGROUND: Dimethylmethylene blue (DMMB) has been used to photoinactivate a number of model viruses, including VSV, in RBC suspensions under conditions that preserve in vitro RBC properties during storage. The relative sensitivity of duck HBV (DHBV) and VSV to photoinactivation by DMMB was investigated by performing an indirect immunofluorescence assay (IFA) using primary duck hepatocyte (PDH) cultures or a standard plaque assay for the respective viruses. STUDY DESIGN AND METHODS: DMMB was added to 45-percent Hct, WBC-reduced, oxygenated AS-3 RBCs at 10-, 1-, and 0.1-microM concentrations. Samples (1-mm thick) were illuminated with 5.4-mW per cm(2) of red light for 2 or 9 seconds. Unilluminated samples without DMMB or with 10 microM DMMB served as control. RESULTS: DHBV and VSV were rapidly photoinactivated by DMMB in a concentration and light-dose-dependent fashion. Neither virus was substantially inactivated by incubation with DMMB in the dark. For a given light exposure, DHBV required a concentration of DMMB one-one hundredth that of VSV to achieve approximately the same level of inactivation. CONCLUSION: DHBV appears to be considerably more sensitive than VSV to DMMB photoinactivation. Photoinactivation in 45-percent Hct RBCs can be achieved in seconds by using micromolar quantities of dye.     

抗体消毒法对血浆中鸭乙型肝炎病毒灭活的研究

研究发现，单抗与多抗中和法可使病毒抗原得到封闭，抑制率随剂量的增加而增加。免疫吸附法可清除血浆中的鸭乙型肝炎病毒（ＤＨＢＶ），并有剂量、时间效应关系。每毫升含ＤＨＢＶ血浆中加入５ｍｇ抗体吸附剂，反复处理４次，所测各种ＤＨＢＶ标志物均转为阴性。     

茅莓提取物体内抗乙型肝炎病毒的实验研究

目的：观察茅莓提取物（乙酸乙酯部位）体内抗乙型肝炎病毒（hepatitisBvirus,HBV）的作用。方法：采用聚合酶链反应（polymerasechain—reaction,PCR）法筛选3日龄鸭乙型肝炎病毒（duck hepatitisBvirus,DHBV）阳性麻鸭50只,将麻鸭随机分为盐水对照组、茅莓提取物高、中、低剂量组和拉米夫定组,于用药前、用药第7、14、21天及停药后第3、7天,取各组麻鸭静脉血,作鸭血清DNA斑点杂交,计算鸭血清DHBV—DNA密度,最后一次取血后取肝脏组织进行病理组织学观察。结果：体内实验显示,盐水对照组动物血清DHBV—DNA水平与用药前比较未见变化（P〉0．05）,拉米夫定组血清DHBV—DNA于用药第14天和第21天与用药前比较明显减低（P〈0．01）,与盐水对照组用药第7天、第14天和第21天血清DHBV-DNA比较明显降低（P〈0．05和0．01）。与盐水对照组比较,茅莓提取物各剂量组21d疗程各时点血清DHBV—DNA未见变化（P〉0．05）。肝脏病理检查示各组差异无显著性。结论：茅莓提取物抗HBV作用主要是通过其原形发挥作用,该原形在麻鸭体内经过代谢后,失去抗HBV的作用。     

鸭乙型肝炎病毒耐药株的慢性感染研究

目的:建立鸭乙型肝炎病毒(DHBV)耐药株的慢性感染动物模型。方法:将DHBV野生株及耐药株质粒转染细胞,培养上清接种雏鸭。连续定量检测血清DHBV DNA;印迹杂交检测肝内病毒复制中间体;观察肝组织病理变化。结果:野生株组的病毒滴度和慢性感染率均高于耐药株组;肝组织中检测到DHBV的复制中间体与cccDNA,可见轻度炎症病理改变。结论:DHBV耐药株可形成慢性感染。