鸡痘的诊断与防治技术研究

鸡痘是危害养鸡业发展的一种传染病,不分日龄大小均可发病,肉鸡和蛋鸡均可感染,发病期1-2周,雏鸡死亡率较高,可达5%～30%不等[1],近年来发病率和死亡率有上升趋势,并且免疫失败的病例时有发生[2].为了建立接种疫苗后抗体监测手段和研究感染鸡痘病毒后抗体产生规律,我们建立了间接ELISA检测鸡痘病毒抗体的方法,进一步做了中和试验和用阳性血清治疗鸡痘的试验,报告如下.     

鸡痘病毒表达载体的构建Ⅰ、鸡痘病毒282E_4株基因组PstⅠ、HindⅢ酶切片段的克隆及酶切分析

本文介绍了鸡痘病毒２８２Ｅ４株基团组ＰｓｔⅠ片段、ＨｉｎｄⅢ片段的克隆和鉴定,以及部分克隆的限制性内切酶分析。鸡痘病毒基因组经酶切、克隆分别得到３４９个、２７７个白色菌落,经质粒电泳、菌落杂交筛选分别得到２８６、２３４个重组菌落,再经酶切、斑卢、杂交鉴定,证明了所克隆的确为鸡痘病毒的ＰｓｔⅠ、ＨｉｎｄⅢ片段。最后经单、双酶切分析,得到了５个ｐＦＰ、５个ｐＦＨ克隆的物理图谱。     

传染性喉气管炎病毒gB基因和新城疫病毒F基因在重组禽痘病毒中共表达

在重组禽痘病毒中表达多个禽类病原的主要免疫原基因是构建多价基因工程疫苗的前提,但相关研究很少。在表达传染性喉气管炎病毒(ILTV)gB基因重组禽痘病毒的转移载体的基础上,构建了含有ILTV gB基因和新城疫病毒(NDV)F基因的重组禽痘病毒转移载体pSY-gB-F,采用脂质体转染禽痘病毒感染的鸡胚成纤维(CEF)细胞后,通过蓝斑试验筛选出重组禽痘病毒(rFPv-gB-F),并进行了6轮蚀斑纯化。Western-blot试验和间接免疫荧光试验证明ILTV gB基因和NBVF基因在rFPV-gB-F感染的CEF细胞中获得表达。为传染性喉气管炎、新城疫与鸡痘活载体多价疫苗的研制奠定基础。     

共表达O型口蹄疫病毒3C、P1-2A基因和猪白细胞介素18基因的重组鸡痘病毒免疫原性研究

目的 对本室已筛选到的一株共表达O型口蹄疫病毒3C基因、P1-2A基因和猪白细胞介素18基因的重组鸡痘病毒rFPV-3C-P1-2A-IL-18进行免疫原性研究。方法 分别用重组鸡痘病毒rFPV-3C-P1-2A-IL-18、rFPV-P1-2A-3C和对照组282E4株FPV、PBS对小鼠进行免疫接种,并检测各免疫组的T 淋巴细胞亚类数量、CTL杀伤活性及抗体效价。结果 重组鸡痘病毒疫苗组免疫小鼠T 淋巴细胞亚类数量,CTL杀伤活性和抗体效价均显著高于对照组,且重组鸡痘病毒rFPV-3C-P1-2A-IL-18的小鼠T 淋巴细胞亚类数量和CTL特异性杀伤活性与rFPV-P1-2A-3C相比,差异显著。结论 本实验为开发新型FMDV疫苗奠定了实验免疫基础。     

Feline panleukopenia viral infection in cats: Application of some molecular methods used for its diagnosis

Forty diseased cats and seven healthy control cats from different sex, ages and breeds had examined clinically to confirm presence or absence of clinical symptoms of Feline panleukopenia disease (FP). Several tools including ELISA, gene expression analysis (qRT-PCR), DNA fragmentation test and apoptosis assay were conducted to determine the Feline panleukopenia disease in cat tissues. Clinical symptoms in the form of depression, fever, anorexia, vomiting, diarrhea, dehydration, anaemia and leucopenia were recorded in the diseased cats while no clinical sings were observed in control healthy cats. ELISA results showed that all of diseased (n?=?40) cats were positive while control cats (n?=?7) were negative for FP viral antigen. After carrying out of ELISA assay, supportive treatment trials including fluid therapy, immunostimulant, antibiotics to overcome dehydration, restoring electrolytes imbalances, combating secondary bacterial infection were conducted but all diseased cats were died and control cats exposed to soft death. Gene expression analysis detected high levels of FP viral gene in several cat tissues in which ilium exhibited high viral expression levels compared with jejunum. Also, viral expression levels in jejunum were higher than in mesenteric lymph nodes. In addition, viral expression levels were not detected in tissues of control cats. The results of the DNA fragmentation assay observed that DNA extracted from different tissues of infected cats exhibited damaged DNA bands as compared with DNA of control cats. DNA fragmentation rates in infected tissues increased significantly (P?<?0.01), the highest rates were showed in ilium and jejunum tissue than in mesenteric lymph nodes. Determination of apoptosis in cat tissues showed that rate of apoptosis/necrosis increased significantly (P?<?0.05) in infected cats tissues in comparison to control cats. Moreover the highest apoptotic ratios of infected cats were observed in ilium and jejunum tissues compared with mesenteric lymph nodes.     

Eimeria tenella: construction of a recombinant fowlpox virus expressing rhomboid gene and its protective efficacy against homologous infection

A recombinant fowlpox virus (rFPV) expressing the Eimeria tenella rhomboid gene was constructed and its protective efficacy against homologous infection in chickens determined. Three-day-old-specific pathogen free (SPF) chickens were immunized s.c. with 10(2) plaque forming units (PFU), 10(4) PFU, or 10(6) PFU of rFPV-rhomboid, and challenged with 5x10(4) homologous sporulated oocysts 14 days post-immunization (p.i.). The specific antibody response and lymphocyte proliferation were measured 1, 2, 3 and 4 weeks p.i. Oocyst output, body weight gains and lesion scores were measured to evaluate the protective effects of immunization. rFPV-rhomboid elicited a specific humoral immune response and stimulated proliferation of peripheral blood lymphocytes. The lesion scores in groups vaccinated with rFPV-rhomboid were significantly higher than in other groups. At the same time, rFPV-rhomboid improved body weight significantly compared with other groups. Immunization with rFPV-rhomboid reduced oocyst shedding significantly, resulting in a protection rate of 39.6%, 41.1% or 41.7% given a dose of 10(2) PFU, 10(4) PFU, or 10(6) PFU of rFPV-rhomboid, respectively. These results indicated that rFPV can induce immune responses and offer partial protection of chickens against E. tenella challenge.     

Isolation of feline parvovirus from peripheral blood mononuclear cells of cats in northern Vietnam.

Feline parvovirus (FPV) was isolated rather frequently from the peripheral blood mononuclear cells (PBMCs) of cats in northern Vietnam by coculturing with MYA-1 cells (an interleukin-2-dependent feline T lymphoblastoid cell line) or Crandell feline kidney (CRFK) cells (a feline renal cell line). Efficiency of virus isolation was higher in MYA-1 cells than in CRFK cells. Interestingly, among the 17 cats from which FPV was isolated, 9 cats were positive for virus neutralizing (VN) antibody against FPV, indicating that FPV infected PBMCs and was not eliminated from PBMCs even in the presence of VN antibodies in the cats.     

Autocatalytic activation of influenza hemagglutinin

Enveloped viruses contain surface proteins that mediate fusion between the viral and target cell membranes following an activating stimulus. Acidic pH induces the influenza virus fusion protein hemagglutinin (HA) via irreversible refolding of a trimeric conformational state leading to exposure of hydrophobic fusion peptides on each trimer subunit. Herein, we show that cells expressing fowl plague virus HA demonstrate discrete switching behavior with respect to the HA conformational change. Partially activated states do not exist at the scale of the cell, activation of HA leads to aggregation of cell surface trimers, and newly synthesized HA refold spontaneously in the presence of previously activated HA. These observations imply a feedback mechanism involving self-catalyzed refolding of HA and thus suggest a mechanism similar to the autocatalytic refolding and aggregation of prions.     

Molecular events during the interaction of envelopes of myxo- and RNA-tumor viruses with cell membranes. A 270 MHz 1H nuclear magnetic resonance study

The nuclear magnetic resonance (NMR) spectra of chick embryo cells have been analyzed after exposure to Newcastle disease virus (NDV). Virions that contained the envelope glycoproteins in the cleaved form and, thus, had full biological activity have been compared to virions that had reduced infectivity due to the presence of uncleaved glycoprotein F. After exposure to infectious virus, drastic changes occurred in the signals assigned to choline and the hydrocarbon chains of fatty acids. These observations are interpreted to demonstrate alteration of the fluid lipid bilayer structure of the cell membranes. This is compatible with the concept of membrane fusion as a penetration mechanism for NDV. Virus containing uncleaved F glycoprotein did not alter the NMR spectra. This indicates that infection is blocked at the stage of penetration.Similar, though less pronounced, differences have been observed when the effects of highly infectious influenza virus containing the hemagglutinin in the cleaved form were compared to the effects of virus which had a lower infectivity due to the presence of uncleaved hemagglutinin. Thus, it appears that the hemagglutinin of influenza virus is involved in penetration and that cleavage is necessary for this function.Alterations of the NMR spectra of the membrane lipids have also been observed when susceptible chick embryo cells (C/E) were infected with Rous sarcoma virus of subgroup B. Such alterations did not occur when nonsusceptible cells (C/B) were used. Thus, infection appears to be blocked again at the stage of penetration.