Proliferation of chicken lymphoblastoid cells after in vitro infection with Marek's disease virus.

Activated, thymus-derived (T) lymphoblasts were exposed to Marek's disease virus and cultivated in attempts to induce in vitro transformation. After 9 to 15 days, colonies or small clusters of proliferating lymphoblasts were observed in cultures from three of a total of 122 attempts. These developed into proliferating cell cultures that resembled conventional Marek's disease (MD) lymphoblastoid cell lines in terms of growth characteristics and morphology. All proliferative cultures were unusual in that 1) the expression of viral internal antigens consistently or periodically was very high (up to 30% of all cells) and 2) the cells deteriorated and/or proliferation ceased in all cases after culture periods of 45-176 days. The proliferative cultures were all characterized as CD2+ and CD3+, Ia-bearing T cells; one was CD4+/CD8- and TCR2+, the other two were CD4-/CD8- and TCR1+. The latter two are the only cultures of MD-infected cells known to be TCR1+.     

鸡马立克氏病病毒感染对鸡神经系统损伤的研究

为研究不同毒力的鸡马立克氏病毒(MDV)在鸡神经系统中的感染规律及其对神经系统的损伤进程,本研究选用不同毒力的血清1型MDV (MDV-1)病毒株感染4日龄的SPF鸡,在接毒后1 d、3 d、5 d、7 d、10 d、14 d、17 d、21 d、25 d、28 d和35 d动态检测病毒载量的变化,并对感染后5 d和21 d的不同病毒株感染鸡的脑部和坐骨神经进行组织病理学观察。结果显示,MDV-1强毒株在SPF鸡脑部的复制能力显著高于弱毒株(p<0.05);特超强病毒株BS在脑组织中出现的时间最早,早期复制最快。但不同毒力的MDV-1株在坐骨神经处的复制能力与其毒力无直接的关系。组织病理学观察显示,在感染早期MDV-1强毒株对SPF鸡脑组织的损伤强于弱毒株;在感染后21 d,强毒株和弱毒株造成的脑部损伤存在明显的不同;而在坐骨神经处,强毒株造成的损伤明显强于弱毒株。本研究揭示了不同MDV病毒株在SPF鸡脑和坐骨神经的复制动力学特征和组织病理学特征,为MDV-1在宿主神经系统中的感染、增殖及造成的损伤提供了实验依据。     

银杏叶多糖对雏鸡马立克HVT疫苗免疫效果影响

银杏叶提取物具有广泛的药理学作用,银杏提取物的生物活性,如免疫调节、抗肿瘤、改善心血管功能等已有报道。高媛等以S180种鼠建立模型,研究银杏叶多糖对实体瘤、腹水瘤的作用,结果证实（GBLP）可明显抑制实体瘤、腹水瘤的生长,延长荷瘤水鼠的存活时间。陈群等也对银杏叶提取物的抗肿瘤作用进行研究,结果与高嫒等的报道基本一致。     

Effect of diluting Marek's disease vaccines on the outcomes of Marek's disease virus infection when challenged with highly virulent Marek's disease viruses

Dilution of Marek's disease (MD) vaccines is a common practice in the field to reduce the cost associated with vaccination. In this study we have evaluated the effect of diluting MD vaccines on the protection against MD, vaccine and challenge MD virus (MDV) kinetics, and body weight when challenged with strains Md5 (very virulent MDV) and 648A (very virulent plus MDV) by contact at day of age. The following four vaccination protocols were evaluated in meat-type chickens: turkey herpesvirus (HVT) at manufacturer-recommended full dose; HVT diluted 1:10; HVT + SB-1 at the manufacturer-recommended full dose; and HVT + SB-1 diluted 1:10 for HVT and 1:5 for SB-1. Vaccine was administered at hatch subcutaneously. One-day-old chickens were placed in floor pens and housed together with ten 15-day-old chickens that had been previously inoculated with 500 PFU of either Md5 or 648A MDV strains. Chickens were individually identified with wing bands, and for each chicken samples of feather pulp and blood were collected at 1, 3, and 8 wk posthatch. Body weights were recorded at 8 wk for every chicken. Viral DNA load of wild-type MDV, SB-1, and HVT were evaluated by real time-PCR. Our results showed that dilution of MD vaccines can lead to reduced MD protection, reduced relative body weights, reduced vaccine DNA during the first 3 wk, and increased MDV DNA load. The detrimental effect of vaccine dilution was more evident in females than in males and was more evident when the challenge virus was 648A. However, lower relative body weights and higher MDV DNA load could be detected in chickens challenged with strain Md5, even in the absence of obvious differences in protection.     

鸡大肠杆菌与小肠球虫混合感染的诊治

广西玉林某养鸡专业户。散养三黄肉鸡5800只,免疫程序按常规进行,在56日龄发病,每天均有鸡死亡,发病率高达17％以上,死亡率则为3．68％,病程历时7天。病鸡以精神沉郁、食欲减退、腹泻、粪便带血、死亡为主要特征。当初该养殖户根据自己多年的养殖经验判断为球虫病,用磺胺药治疗,发现无法控制疫病,后拿到笔者医院诊断。经临床诊断、病理剖检及病原的实验室检验,诊断为大肠杆菌和小肠球虫混合感染。     

三氧化二砷对鸡马立克病病毒诱导鸡肝脏肿瘤中血管生长相关因子表达的影响

为了探讨三氧化二砷(As2O3)对马立克病病毒(MDV)诱导鸡肝脏肿瘤中血管生长相关因子表达的影响,构建了鸡马立克病病例模型,通过腹腔注射As2O3(3.0 mg/kg体重),于35 d,40 d与45 d观察临床症状及血管组织病理学改变,采用半定量RT-PCR法检测肝脏肿瘤中血管生长相关因子VEGF、KDR及bFGF mRNA表达水平。结果表明,MD病鸡肝脏肿瘤内VEGF、KDR及bFGF mRNA均高水平表达,As2O3能够下调肿瘤组织内VEGF、KDR与bFGF mRNA的表达水平,并呈现时间效应。揭示As2O3能够通过下调肝脏肿瘤组织中VEGF、KDR与bFGF mRNA的表达水平,减少血管的生成,进而抑制肿瘤生长,这是As2O3抗肿瘤作用机制之一。     

鸡传染性法氏囊病与球虫病混合感染的诊疗报告

广东省汕头市潮南区两英镇一养鸡户饲养的麻鸡在33日龄时,发生了以精神沉郁、闭目呆立、羽毛松乱、行动迟钝、怕冷打堆、排带有白色红色相间的水样稀便为主要症状,以法氏囊肿大,囊腔内有奶油状物、干酪状物或覆盖着果酱样粘液,两条盲肠高度肿大,肠腔内充满凝固的或新鲜的血液为主要病变的传染病。根据流行病学调查、综合临床症状、病理变化,初步诊断为鸡传染性法氏囊病与球虫病混合感染,后经实验室检查,确诊。经采取综合性治疗措施,取得良好的效果,现将诊疗情况报告如下:1发病情况广东省汕头市潮南区两英镇一黄姓养鸡户,于2004年5月14日购进…     

马立克氏病的研究进展

鸡马立克氏病(Marek'sDisease,MD)是由马立克病毒引起鸡的一种淋巴组织增生性疾病.以病鸡的外周神经、性腺、虹膜、各种内脏器官、肌肉和皮肤发生单核细胞浸润、形成淋巴肿瘤为特征.本病传播速度快,传播面积广,潜伏期长(1～6个月不等).患急性内脏型鸡马立克氏病的鸡群淘汰及死亡率高达8%一30%.严重发病的鸡群可造成全群覆灭,OIE将其列为B类疫病.     

Studies on genetic resistance to Marek's disease in the domestic chicken

Inoculation trials using the HPRS‐B14 and HPRS‐16 strains of classical and acute Marek's disease (MD) respectively, were undertaken on single sire families of commercial chickens. It was demonstrated that both sires and dams had a significant effect on the susceptibility of their progeny to Marek's disease. It is suggested that the genetic constitution of the chicken plays a rôle in controlling its susceptibility to MD. The susceptibility to MD of females was significantly greater than males.

Members of some of the single sire families used in one Marek's disease trial became naturally exposed to Marek's disease in a trial designed to examine the effect of sire families on the incidence of leukosis. There was a significant positive correlation between the incidence of Marek's disease in members of single sire families infected by inoculation and by natural exposure. There was no correlation between incidence of Marek's disease and the incidence of tumours of the leukosis/sarcoma complex.

The range in incidence of MD in single sire families suggested that there was adequate heterogeneity in the commercial lines of chicken to warrant a selection programme for resistance to Marek's disease. The absence of any significant correlation between resistance to Marek's disease and a number of production traits suggested that such a programme should have little effect on these traits.

A negative correlation between incidence of Marek's disease in single sire families and mean latent period was shown. The use of a parameter including a measure of mean latent period as well as incidence of MD resulted in greater sire variance ratios than the use of incidence alone.     

Transfection of chicken embryo fibroblasts with Marek's disease virus DNA

Total DNA from Marek's disease virus (MDV)-infected chicken embryo fibroblasts was transfected into freshly plated secondary chicken embryo fibroblasts using calcium phosphate-mediated transfection. Transfection frequencies were dose-dependent and non-linear. The maximum transfection frequencies of nine MDV DNA preparations using 8-25 micrograms total DNA ranged from 45 to 898 plaques per calcium phosphate/DNA precipitate. Approximately 100-200 plaques per 60-mm tissue-culture dish using 1-5 micrograms total DNA from MDV-infected chicken embryo fibroblasts were typically obtained. Transfection was most efficient when the pH of the HEPES buffer was 7.0, no additional carrier DNA was added to the precipitates, and the cultures were exposed for 3 minutes to 15% buffered glycerol 4 hours after the addition of the calcium phosphate/DNA precipitates.     

The early pathogenesis in chicken inoculated with non-pathogenic serotype 2 Marek's disease virus.

A newly cloned serotype 2 Marek's disease virus (MDV), strain ML-6, was inoculated via the nasal cavity in specific-pathogen-free chicks to examine early virus replication and the expression of Marek's disease (MD)-related antigens. Following inoculation, viral intracellular antigens (VIAs) were detected in lymphoid organs (bursas and spleens) between 5 and 14 days post inoculation (PI), in feather follicles between 14 and 30 days PI, and in lungs at 3 days PI by the immunohistopathological staining of avidin-biotin-peroxidase complex method. But, very few VIAs were expressed in the thymuses between 5 and 14 days PI. However, MD tumor-associated surface antigens were not detected in any organs. Viruses were isolated from separated spleen cells at 14 and 30 days PI. Fluorescent antibodies of convalescent sera were also detected after 10 days PI. As most of the VIAs were detectable in B-cells in bursas and spleens. B-cells were considered to be the main first target cells for the serotype 2 MDV infection.     

Effects of IgY antibody on the development of Marek's disease.

The effects of passive immunization with immunoglobulin Y (IgY) on the pathogenesis of Marek's disease (MD) were examined in an experimental line of White Leghorn chickens highly susceptible to MD. Purified IgY with anti-MDV antibody activity, when injected into chicks, delayed the development of MDV viremia and lesions until 9 days postinoculation (PI) with Marek's disease virus (MDV). The blastogenic response of spleen cells to concanavallin-A was depressed at 6 days PI in the birds without passive immunization, whereas it was not totally depressed until 17 days in birds passively immunized with IgY anti-MDV antibody.