Egg transmission of egg drop syndrome 1976 virus in fowl

Summary

Egg transmission of egg drop syndrome 1976 virus (BC14 virus) in fowl was demonstrated in the second and third week after experimental infection. Eggs of BC14 virus infected hens were incubated weekly after disinfection with formaline gas. After 18 days of incubation, eggs with live embryos were homogenized. This egg material was fed to adult hens, housed in isolators.

Seroconversion in these birds demonstrated egg transmission.

It is suggested that egg transmission occurs as a result of viremia.     

Egg transmission of egg drop syndrome 1976 virus in fowl

Summary Egg transmission of egg drop syndrome 1976 virus (BC14 virus) in fowl was demonstrated in the second and third week after experimental infection. Eggs of BC14 virus infected hens were incubated weekly after disinfection with formaline gas. After 18 days of incubation, eggs with live embryos were homogenized. This egg material was fed to adult hens, housed in isolators. Seroconversion in these birds demonstrated egg transmission. It is suggested that egg transmission occurs as a result of viremia.     

应用微量凝集试验检测鸡抗猪大肠杆菌抗体方法的探索

本试验建立了用微量凝集试验检测鸡抗猪大肠杆菌抗体的方法。经方阵试验，抗原最适浓度为40亿菌/ml，最佳反应温度为37℃，3～4小时观察结果为宜。本方法具有较高的敏感性和特异性，可用于监测免疫猪大肠杆菌疫苗鸡群的抗体水平。     

鸡减蛋综合征病毒Hexon基因SYBR GreenⅠ实时荧光定量PCR检测方法的建立

用PCR方法扩增出鸡减蛋综合征病毒（EDSV）Hexon基因保守片段,经琼脂糖凝胶电泳及序列测定分析扩增产物的特异性。以构建的阳性重组质粒作为标准品,建立SYBR GreenⅠ实时荧光定量PCR反应的扩增曲线和溶解曲线,并绘制标准曲线。结果表明,建立的EDSV荧光定量PCR标准曲线Ct值与1×10^1～1×10^6拷贝/μL的基因拷贝数呈现良好线性关系,灵敏度可达10拷贝,且特异性及重复性良好;说明本试验建立的SYBR GreenⅠ实时荧光定量PCR检测方法可用于EDSV的诊断及病原的定量分析。     

Outbreaks of egg drop syndrome due to EDS-76 virus in quail (Coturnix coturnix japonica).

Two outbreaks of the egg drop syndrome were observed in quail flocks maintained on a farm together with chickens. The decrease in egg production ranged from 10.6 per cent to 50.6 per cent, and the number of soft-shelled eggs increased with the decline in egg production. In both the outbreaks haemagglutination inhibiting antibodies to EDS-76 virus were detected. Fluorescent viral antigen specific to EDS-76 virus was also detected in the lining epithelial and glandular cells of the uterus.     

The chicken egg as a supply of polyclonal antibodies

Polyclonal antibodies can be isolated not only from the blood of immunized mammals but also from the egg yolk of immunized chickens. The advantages of this alternative method are: 1) Birds produce antibodies against highly conserved mammalian proteins. 2) The quantity of antigen needed for an efficient immune response is very low (20-30 micrograms). 3) The use of complete Freund's adjuvant leads to long lasting titers of yolk antibodies yielding a total amount of 65 mg specific antibodies per month. 4) The purification of antibodies is simple, inexpensive and quick. Polyethylene glycol precipitation is sufficient to obtain a purity of more than 90%. 5) Chicken antibodies are acid- and heat-resistant and might therefore be orally applied to prevent or to cure infectious intestinal diseases of young animals or humans. 6) Immunization with complete Freund's adjuvant is well tolerated and produces no inflammatory reactions and 7) collecting eggs is, in contrast to bleeding animals, non-invasive. In this review we present both, the method how to produce and to isolate yolk antibodies as well as their possible application in science, diagnosis, prophylaxis and therapy.     

减蛋综合征病毒PVⅢ蛋白基因的扩增克隆与鉴定

应用降落PCR法对减蛋综合征病毒PVⅢ蛋白基因进行了扩增，结果得到1．1kb的扩增产物。将该扩增产物克隆至pMDl8-T载体中，经酶切和PCR鉴定后，证明了目的片段的正确性，从而实现了EDSV-gDNA PVⅢ基因的克隆，这不仅为进一步阐明EDSV PVⅢ结构与功能的关系打下了基础，而且为PVⅢ基因的表达及EDS基因工程苗的研究也奠定了良好的基础。     

Serological examination and egg production of progeny of fowl experimentally infected with egg drop syndrome 1976 virus

Following EDS'76 virus (BC14 virus) infection of breeder chickens by the conjunctival route, vertical transmission occurred in the first week after infection. In the progeny which had been infected with EDS'76 virus by the vertical route, increasing haemagglutination inhibiting (HI) titres to BC14 virus and increasing numbers of birds with HI titres were observed from 3 weeks to 15 weeks of age. Sixty-one per cent of the hens and 77 per cent of the cocks had 2 log HI BC14 virus titres exceeding 4 at an age of 15 weeks. Some birds which han been serologically negative throughout the rearing period, seroconverted between 25 and 28 weeks of age. This phenomenon occurred in hens as well as in cocks. Simulation of stress twice during the laying period by injection of corticosteroid hormone did not increase the number of birds serologically positive to EDS'76 virus. EDS'76 was observed in the group of hens that was vertically infected, since egg production was significantly depressed between 28 and 34 weeks of age. Probably this was mainly the results of a production drop in the hens showing serconversion at 27 or 28 weeks of age. In this group of fowl vertically infected with EDs'76 virus, serologically positive birds appeared to be protected for the greater part to BC14 virus challenge at 50 weeks of age, while negative birds seemed to be fully susceptible. Chicks hatched from eggs collected in the third and fourth week after infection of the dams had maternal antibodies. Fertility and hatchability of apparently normally shelled eggs seemed not to be affected after BC14 virus infection of the dams. Intensive contact with contaminated faeces is probably an indispensable condition for lateral transmission of the virus.     

Detection and differentiation of Mycoplasma gallisepticum and M. synoviae antibodies in chicken serum using enzyme-linked immunosorbent assay

Affinity-purified sheep IgG anti-chicken IgG horseradish peroxidase conjugate was utilized in an enzyme-linked immunosorbent assay (ELISA) to detect Mycoplasma gallisepticum- and M. synoviae-specific antibodies in chicken sera. Antigen, conjugate and substrate concentrations, and incubation times were adjusted to provide maximum differentiation between positive and negative sera. Use of phosphate-buffered saline containing 0.05% Tween 20 for washing and diluting steps and use of normal sheep serum to make the initial 1:10 serum dilution resulted in optimal differentiation between homologous and heterologous antisera. However, sera known to contain antibodies to M. gallisepticum or M. synoviae gave higher absorbance values with the heterologous antigen than did specific-pathogen-free sera. To reduce the frequency of nonspecific reactions to less than 2%, it was necessary to adjust the threshold absorbance for each antigen according to the known infectious status of the flock. Reproducibility of the assay was maintained by using positive and negative control sera on each plate. Results from 14.2% of the plates tested were rejected, because the endpoint of the positive control serum was more than one dilution from the most common value. Of four strains of M. gallisepticum used as antigens, none was clearly superior to the others in producing maximum titers with a range of M. gallisepticum antisera. However, nonspecific absorbance tended to be less with the S6 strain. The stability of M. gallisepticum-coated plates was maintained for up to 6 months at -8 C or below, whereas M. synoviae-coated plates were stored satisfactorily for 6 months at 4 C or below.(ABSTRACT TRUNCATED AT 250 WORDS)     

上海地区野鸟和家禽中PRRSV抗体的血清学调查

2005年3～5月，采用ELISA法对来自于上海地区的208份野鸟和357份家禽的血清样品进行了猪繁殖和呼吸综合征病毒（porcine reproductive andrespiratory syndrome virus，PRRSV）抗体的血清学调查。结果表明，受检的5种家禽存有不同程度的抗体阳性率，而野鸟的阳性样品集中于绿头鸭和麻雀。     

Detection of antibodies against the virus causing viral gastroenteritis in swine using the modified autoradiography test

A modified method for autoradiographic determination of antibodies to the virus of transmissible gastroenteritis of swine was developed. It is based on the actual reaction between antigen bound in cells of the infected cell cultures and antibodies in tested sera, which is visualized, by help of rabbit antibodies marked 125J (125J RaSw IgG antibody) to porcine IgG, on a sensitive radiograph and evaluated on the basis of darkening at the point of positive immunological reaction. Specificity of the test and mutual comparability and reproducibility of the results were confirmed by examining the known positive and negative sera and by comparison with the results of the virus-neutralisation test. Out of the 36 examined porcine blood sera the antibodies were proved autoradiographically only in the samples positive also by virus-neutralisation. In experimentally infected pigs, the same dynamics of antibody production was recorded by the two tests. They were, however, demonstrated autoradiographically already by the two tests. They were, however, demonstrated autoradiographically already the eighth day after infection, while by virus neutralisation test as late as 14th day. Their level increased gradually until 35th day after infection.     

Detection of bovine leukemia virus antibodies using the cytotoxicity test in comparison with other serologic methods

In ninety-five serum samples taken in a herd of five-year to seven-year cattle that was heavily infected by bovine leukosis virus, the four serological assays were used for demonstration of the antibodies to bovine leukosis virus; cytotoxic test, immunodiffusion test in agar-agar, immunoenzymatic test and serum neutralizing test. The serum neutralizing test was found to be the most sensitive: further seven positive reagents were diagnosed in comparison with immunoenzymatic test; cytotoxic and immunodiffusion tests in agar-agar have the lowest sensitivity and the results of these tests are almost identical. It was found out in forty titrated samples that serum neutralizing test was by as much as 20 times more sensitive than immunoenzymatic test, the latter being about 50 times more sensitive than cytotoxic and immunodiffusion tests.