【作者】 金梅花；

【导师】 郑世民；

【作者基本信息】 东北农业大学 ， 基础兽医学， 2007， 硕士

【摘要】 禽流感（avian influenza，AⅠ）是由正黏病毒科A型流感病毒——禽流感病毒（avianinfluenza virus，AⅣ）引起的主要侵害家禽呼吸系统、生殖系统和消化系统的一种急性、高度接触性传染病。不但造成各国养禽业巨大经济损失，而且对人类健康构成极大威胁，综合国内外对AⅠ的研究，主要集中在病原学、流行病学、特异性诊断、DNA序列分析和疫苗研制等方面，但对AⅣ的致病和免疫发病机制方面的研究较少。本研究采用免疫酶组织化学法、组织细胞化学法，首次对鹅源H5N1亚型AⅣ感染7和21日龄雏鸡免疫器官的细胞、体液免疫变化进行全面系统的研究，主要内容包括：免疫器官（胸腺、法氏囊、脾脏）T_ANAE⁺和CD₄⁺、CD₈⁺T细胞亚型及IgG、IgM、IgA生成细胞数量变化。旨在深入系统揭示AⅣ的免疫致病机理，为AⅠ综合防制措施的制定提供重要的科学实验依据。研究结果如下：1．无论是7日龄，还是21日龄雏鸡感染AⅣ后，其免疫器官脾脏、胸腺和法氏囊的T_ANAE⁺细胞数量于感染后3～14天明显低于对照雏鸡；感染后期T_ANAE⁺细胞数量逐渐回升。表明AⅣ感染可使雏鸡免疫器官T细胞总量下降，从而使其细胞免疫受抑制，这可能是引起雏鸡免疫力低下、死亡率增高的主要因素。2．7和21日龄雏鸡感染AⅣ后，胸腺CD₄⁺、CD₈⁺T细胞数量于感染后3～5天不同程度低于对照雏鸡；脾脏CD₄⁺T细胞数量分别于感染后5～7天及第3天明显低于对照雏鸡（p＜0.01）；CD₈⁺T细胞数量于感染后3～14天不同程度地降低；感染后期CD₄⁺、CD₈⁺T细胞数量逐渐回升。由于CD₄⁺T细胞数量迅速减少，可能导致CD₈⁺T细胞清除流感病毒的功能降低。标志着机体细胞免疫功能障碍，是AⅣ感染雏鸡后机体呈现免疫抑制的重要表现。3．7和21日龄雏鸡感染AⅣ后，免疫器官法氏囊、脾脏、胸腺的IgG、IgM、IgA生成细胞数量均于感染后3～4天不同程度低于对照雏鸡，随后上述抗体生成细胞数量开始回升，至21天接近对照雏鸡。表明AⅣ感染雏鸡后，感染初期抗体水平及抗体生成细胞数量迅速降低，机体器官机能发生衰竭，可能是造成雏鸡死亡的重要原因，但机体的康复期仍能分泌高水平抗体，从而提高了雏鸡抵御强毒攻击的能力。4．7日龄和21日龄雏鸡相比，AⅣ感染后7日龄雏鸡的临床死亡率较21日龄雏鸡高、体液免疫应答启动也较慢，抗体水平低，表明7日龄雏鸡抗AⅣ感染的能力较低。本项研究首次从禽的中枢免疫器官和外周免疫器官抗体生成细胞和T细胞数量变化，揭示AⅣ的免疫致病机理，为AⅠ的防制提供科学依据，具有重要的理论和实践意义。更多还原

【Abstract】 In this study, immunohistochemistry staining and cyto-histochemistry staining were used todiscover the changes of the contents both IgS antibody-producing cells and the quantity of CD₄⁺Tand CD₈⁺T lymphocyte subpopulation, T_ANAE⁺ cells in immune organs （thymus, bursa and spleen）of chickens infected with AIV at 7 days old and 21 days old, which were to reveal the mechanismand regularity of immunity of immune organs of chickens infected with AIV. The experimentprovided scientific evidence of experiment for the mechanism of morbidity and useful effectiveprevention in AI. The results were as follows:1. Compared with controls, the quantity of T_ANAE⁺ cells in immune issue were decreased at3～14 days post infection （P1） regardless of the chickens infected with AIV at 7 days old and 21days old at different degree; In the end of infective stage, the quantity of T_ANAE⁺ cells of twoimmune organs recovered. The observations showed that cellular immunity of chickens infectedwith AIV was critically inhibited, which was the primary element in immune subordinatechickens.2. The quantity of CD₄⁺T and CD₈⁺T lymphocyte subpopulation in thymus of chickensinfected with AIV was decreased at 3～5 days PI at different degree; the quantity of CD₄⁺T cells inspleen of infected chickens old decreased remarkably at 5～7 days and 3 days PI （p＜0.01）respectively; that of CD₈⁺T cells in spleen decreased at different degree at 3～14 days PI. In the endof infective stage, the quantities of lymphocytes of two immune organs recovered. As a result ofthe quantity of CD₄⁺T cells’ rapid reduction, possibly caused the CD₈⁺T cells’ function ofeliminating flu virus reduced. It indicated organism cellular immune functional disturbance, whichwas the important performance of chickens infected with AIV to present the immunosuppression.3. Compared with controls, the quantity of IgG, IgM, IgA antibody-producing cells in bursa,spleen and thymus of infected chickens decreased at 3～4 days PI（p＜0.05 or p＜0.01） at differentdegree. And the quantity of IgS antibody-producing cells began to ascend, approach to controls at21 days PI. In initial period of infection, the quantity of antibody-producing cells was decreasedrapidly and the physiological function in organism was exhausted, which were the importantreasons in lowing of immune function of infected chickens. But in the recovery stage, thesecretion of IgS is in high level. Thus the ability of resisting virus was raised.4. The research discovered that the clinical death rate of chickens infected at 21 days old washigh compared with chickens infected at 7 days old. And the humoral immune response wasslower, the antibody level was lower than the controls. The above results indicated: The immuneregulations in immune organs of chickens infected at 7 days old were more sensitive to AIV than that of infected chickens at 21 days old, which were full grown in immune system and could resistvirus effectively.The research revealed the immunity pathogenesis mechanism of AIV from the quantitychanges in avian center immune organ and peripheral immune organ antibody-producing cells andthe T cells for the first time. It provided the scientific basis to prevent AI, which had significantmeanings in theory and in practice.更多还原