嗜水气单胞菌灭活疫苗免疫后大鲵外周血免疫指标的变化

摘要

以福尔马林灭活的嗜水气单胞菌(Aeromonas hydrophila)作为免疫原(F-AH)，通过腹腔注射免疫健康大鲵(Andrias davidianus)，分别于免疫后的第1、4、7、14、21、28天采集血液样品，进行大鲵外周血液的血细胞计数与白细胞组成分析，测定吞噬细胞的吞噬活性以及血清中和抗体效价，于免疫28 d后进行攻毒感染试验。结果表明，与对照组相比，在免疫后第4、7、14和第21天，免疫大鲵外周血中血细胞数量显著增加，其中，红细胞和白细胞数量均于第4天达峰值，分别为7.83×107个/mL和6.74×106个/mL；嗜中性粒细胞百分比也在第4天达峰值，为28.60%，单核细胞百分比在第7天达峰值，为10.53%；吞噬细胞活性显著提高，且吞噬百分比和吞噬指数均在第4天达到最高值，分别为34.09%和3.73。随后，淋巴细胞百分比和中和抗体效价显著增加，均在第21天达峰值，分别为75.30%和1︰426.67。攻毒感染实验结果表明，免疫组的相对免疫保护率为69.23%。由此可见， F-AH免疫原能够通过促进血细胞数量的增加、吞噬细胞吞噬活性增强以及特异性抗体的产生等方式提高大鲵的免疫保护力。%Formalin-killed Aeromonas hydrophila cells (F-AH) were used as an antigen to immunize healthy giant salamander (Andrias davidianus) via intraperitoneal injection. Peripheral blood samples were collected from im-munized and control giant salamanders at 1, 4, 7, 21 and 28 d post-immunization for the measurement of immu-neresponses by counting and classifying blood cells, determining the phagocytic percentage and index and serum agglutinating antibody titers. Compared to the control group, the number of erythrocytes and leucocytes in the peripheral blood of immunized animals increased significantly at 4, 7, 14 and 21 d post-immunization, and reached a maximum value of 7.83×107/mL and 6.74×106/mL at 4 d post-immunization, respectively. The percentage of neutrophils reached a maximum value of 28.60%at 4 d post-immunization and the number of monocytes reached a maximum value of 10.53%at 7 d post-immunization. The phagocytic percentage and phagocytic index increased significantly (P<0.01) and reached amaximum value of 34.09% and 3.73 at 4 d post-immunization, respectively. The number of lymphocyte and the serum agglutinating antibody titers increased significantly, and peaked at 75.30%and 1︰426.67 at 21 d post-immunization (P<0.01), respectively. The challenge test with live Aeromonas hydrophilaresulted in a relative percent survival in the immunized group of 69.23%. The results from this study demonst rated that F-AH enhanced the immunity of the giant salamander by increasing the number of erythrocytes and leucocytes in peripheral blood, improving the activity of phagocytes, enhancing the serum agglutinating anti-bodytiter and providing effective protection in the immunized animals.