B亚群禽白血病病毒与鼠伤寒沙门氏菌共感染的研究

发布时间：2019-02-08 19:32

【摘要】：在我国的鸡群中普遍存在禽白血病病毒和其它病原的共感染,造成了养禽业很大的危害和经济损失。之前的研究主要集中在禽白血病病毒的各个亚群之间,禽白血病病毒和其它一些病毒之间,很少有ALV-B和细菌性疾病共感染的文献报道。为了探讨ALV-B和鼠伤寒沙门氏菌的共感染可能具有致病作用,因此我们做了以下研究。从某鸡场病鸡的泄殖腔棉拭子中分离出一株菌,对该菌的半数致死量、致病性和凝集抗原进行研究。将120只健康1日龄SPF雏鸡随机分成A-D 4个组,分别接种该菌。每周每组分别随机抽取3只,采集法氏囊、胸腺、脾脏称重,计算免疫器官指数;观察临床症状和病理组织学变化;检测p27抗原及ALV-B抗体,血清中INF-γ、IL-2和鼠伤寒沙门氏菌的抗体。根据测序结果并与国内外参考株进行比较,发现与Typhimurium strain LT2.seq同源性最高为99.7%,最终确定为鼠伤寒沙门氏菌。鼠伤寒沙门氏菌的半数致死量为1.52×10~4CFU。鼠伤寒沙门氏菌阳性血清与自制的鼠伤寒沙门氏菌凝集抗原出现凝集现象,与鸡白痢沙门氏菌的交叉免疫学试验没有出现凝集现象。共感染组死亡率为23.33%,高于鼠伤寒沙门氏菌组(13.3%),ALV-B组(16.67%)。单感染组和共感染组的鸡都呈现一定程度生长发育迟缓的现象,其中,共感染组体重显著低于对照组(p0.05),也明显低于单感染组。鼠伤寒沙门氏菌单感染组脾脏肿大,脾脏指数升高;ALV-B单感染组和共感染组使脾脏指数下降,共感染组显著低于对照组(p0.05)。各感染组的胸腺和法氏囊免疫器官指数较对照组有不同程度的降低,并且共感染组更能加重对免疫器官的损害。单感染组和共感染组病鸡都出现了精神萎靡不振、食欲下降、瘦弱的现象。ALV-B单感染组和共感染组剖检后发现肝脏略微肿大,肉眼观察鸡的各脏器,并没有发现明显的病变。鼠伤寒沙门氏菌单感染组剖检发现有针尖状出血,出血性肠炎,肝脏肿大,脾脏肿大。在肝脏内炎性细胞浸润形成坏死灶,脾脏炎性细胞浸润形成坏死灶,淋巴细胞坏死,肾小管上皮细胞变性等一系列现象。单感染和共感染组的IL-2和干扰IFN-γ的分泌量与对照组差异显著(p0.05),并且共感染时分泌量更低。检测泄殖腔p27发现,第2周ALV-B感染组4.34%排毒;第5周ALV-B感染组50%,共感染组54.45%排毒。前4周未检测到ALV-B抗体,ALV-B抑制机体的细胞免疫和体液免疫,导致疫病的爆发。由于1日龄SPF鸡感染ALV-B很容易发生免疫耐受,导致感染鸡持续带毒排毒而不产生抗体。从检测鼠伤寒沙门氏菌抗体结果显示,共感染组第5W时阳性率最高为45.45%,表明共感染对鸡的危害性要比单感染严重。综上所述,分离得到一株鼠伤寒沙门氏菌,并制备了该菌凝集抗原。建立了ALV-B和鼠伤寒沙门氏菌感染1日龄SPF雏鸡的模型,表明ALV-B和鼠伤寒沙门氏菌共感染可能具有协同致病作用。
[Abstract]:The co-infection of avian leukemia virus and other pathogens is common in chickens in China, which causes great harm and economic loss to poultry industry. Previous studies have focused on avian leukemia virus subsets, avian leukemia virus and some other viruses. There are few reports of co-infection of ALV-B and bacterial diseases. To explore the possible pathogenicity of co-infection of ALV-B and Salmonella typhimurium, we did the following research. A strain of a bacterium was isolated from cloacal cotton swab of a chicken farm and its lethal dose pathogenicity and agglutination antigen were studied. 120 1-day-old SPF chicks were randomly divided into 4 groups and inoculated respectively. Three rats were randomly selected from each group each week to weigh the bursa of Fabricius thymus and spleen to calculate the immune organ index and to observe the changes of clinical symptoms and histopathology. P27 antigen and ALV-B antibody, serum INF- 纬, IL-2 and antibody against Salmonella typhimurium were detected. According to the results of sequencing and comparing with the reference strains at home and abroad, it was found that the highest homology with Typhimurium strain LT2.seq was 99.7%, and it was finally identified as Salmonella typhimurium. The median lethal dose of Salmonella typhimurium was 1.52 脳 10 ~ 4 CFU. The positive serum of Salmonella typhimurium was agglutinated with the self-made antigen of Salmonella typhimurium, and the cross-immunological test with Salmonella pullorum had no agglutination. The mortality of co-infection group was 23.33, higher than that of Salmonella typhimurium group (13.3%) and ALV-B group (16.67%). Both the single infection group and the co-infection group showed a certain degree of growth retardation. The body weight of the co-infected group was significantly lower than that of the control group (p0.05) and significantly lower than that of the single infection group. Splenomegaly and spleen index were increased in single infection group of Salmonella typhimurium, but decreased in single infection group and co-infection group in ALV-B group, which were significantly lower in co-infection group than in control group (p0.05). The immune organ index of thymus and bursa of each infection group was lower than that of control group, and the damage of immune organ was more serious in co-infection group. In the single infection group and co-infection group, the diseased chickens showed mental malaise, loss of appetite and weakness. The liver was slightly enlarged in the ALV-B single infection group and co-infection group, and the organs of the chicken were observed with the naked eye. No obvious lesions were found. In the single infection group of Salmonella typhimurium, needle bleeding, hemorrhagic enteritis, hepatomegaly and splenomegaly were found. In the liver, inflammatory cells infiltrate into necrotic foci, splenic inflammatory cells infiltrate into necrotic foci, lymphocyte necrosis, renal tubular epithelial cell degeneration and a series of phenomena. The secretion of IL-2 and interfering IFN- 纬 in single infection and coinfection group was significantly different from that in control group (p0.05), and the secretion was lower in co-infection group. In the second week, 4.34% of the patients were infected with ALV-B, and 54.45% in the group of ALV-B infection at the 5th week. ALV-B antibodies were not detected in the first 4 weeks, and ALV-B inhibited cellular and humoral immunity, leading to the outbreak of blight. The immune tolerance of 1 day old SPF chickens infected with ALV-B was easy to develop, which led to continuous detoxification without antibody production in infected chickens. The results of detection of Salmonella typhimurium antibody showed that the highest positive rate of co-infection was 45.45 at the 5th week, which indicated that co-infection was more harmful to chicken than to single infection. In conclusion, a strain of Salmonella typhimurium was isolated and its agglutination antigen was prepared. The model of SPF chicks infected with ALV-B and Salmonella typhimurium was established, which indicated that co-infection of ALV-B and Salmonella typhimurium might have synergistic pathogenicity.
【学位授予单位】：山东农业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：S858.31

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