感染传染性法氏囊病毒雏鸡对新城疫疫苗的免疫应答抑制和机理

本研究在雏鸡1日龄时感染法氏囊病毒,14日龄时点眼、滴鼻接种新城疫疫苗,检测了感染鸡ND免疫后其外周血液、泪液、气管液、肠液、胆汁中IgG,IgM,IgA含量,血液T细胞免疫功能和脾脏B细胞抗体生成功能、血清、泪液和气管液HI滴度的变化,测定了血液T,B细胞与淋巴细胞数量以及法氏囊、胸腺、脾脏、盲肠扁桃体、哈德尔腺、十二指肠粘膜、丕氏斑,支气管粘膜的浆细胞和酸性α-萘酚酯酶阳性T细胞(ANAE~+T)数量的动态变化。结果如下: 1)1日龄感染IBDV雏鸡ND免疫后,其法氏囊、脾脏、盲肠扁桃体、十二指肠粘膜固有层、丕氏斑、哈德尔腺、支气管粘膜固有层的浆细胞数量和脾脏B细胞抗体生成功能均显著降低;外周血液B细胞数量、HI滴度、血清、泪液、气管液、肠液和胆汁IgG,IgA,IgM含量较对照免疫鸡显著减少,这表明感染鸡对ND疫苗的全身和消化道、呼吸道相关局部的体液免疫应答功能显著抑制。 2)感染鸡ND免疫后,其胸腺、脾脏、法氏囊、消化道和呼吸道相关局部免疫组织的ANAE~+T细胞数量、外周血液T细胞免疫功能和T细胞数量均显著低于正常免疫鸡,这说明感染鸡对ND疫苗的全身和局部细胞免疫应答机能显著减弱。 3)ND强毒攻击后,感染鸡的ND免疫保护率明显低于健康免疫鸡,其免疫保护效应降低,与其对ND强毒的全身和消化道、呼吸道局部体液免疫和细胞免疫反应水平显著下降密切相关。

MECHANISM OF SUPPRESSION OF THE IMMUNE RESPONSE TO NEWCASTLE DISEASE VACCINE IN CHICKENS INFECTED WITH INFECTIOUS BURSAL DISEASE VIRUS

A study was carried out to determine the dynamic changes of the quantities of IgG, IgA and IgM in serum, tear, trachea washings, bile, and intestinal fluids, the immune function of T cells, the numbers of T and B cells, lymphocytes in the blood and antibody producing function of splenocytes as well as the numbers of plasmacytes and acid a-naphthyl acetate esterase positive T cells(ANAE~+T) in Bursa Fabricus, thymus, spleen, cecal tonsil, Harder gland, duodenum, peyer's Patch and primary bronchus of one-day-old chickens infected with infectious bursal disease virus and then inoculated ocularnasally with Lasota vaccine at the age of 14 days. The results are as follows. After the chickens were immunized with ND vaccine, in comparison with control ones, there was a significant decrease in plamacytes in Bursa Fabricus, spleen, cecal tonsil, Peyer's patch, Harder gland, bronchus, and the contents of IgG, IgM and IgA in the serum, tear, bile, trachea washings and intestinal fluids along with the decline of antibody producing func tion of splenocyte, so was the HI titre in serum, tear and trachea washings of the infected vaccinated chickens. Meanwhile, the immrne func-tion of T cells and the number of ANAE~+T cells were significantly lower than those of the control chickens in the peripheral blood and in the thymus, spleen, cecal tonsil, Bursa Fabricus, Peyer's patch, duodenum, Harder gland and bronchus, respectively. These suggested that both of the humoral and cellular immune responses of the infected chickens to ND vaccination were markedly suppressed in the systemic immune organs and local immune tissues of digestive and respiratory tracts. When experimental chickens were challenged with virulent ND virus(VNDV), the immune protective rate of the infected vaccinated chickens was remarkably lower than that of the vaccinated control birds. The abatement of immunity of the infected chickens against ND resulted from their significant decrease in cellular and humoral immune responses to VNDV in the systemic immune organs and local lymphoid tissues of digestive and respiratory tracts.