嗜水气单胞菌3种疫苗免疫的青鱼外周血免疫指标的变化

将福尔马林灭活的嗜水气单胞菌(Aeromonas hydrophila)、菌体外膜蛋白(OMP)和菌体脂多糖(LPS)作为免疫原,分别免疫健康青鱼。在免疫1、2、4、7、14、21、28d后进行外周血的血细胞计数和白细胞分类计数,测定细胞吞噬活性和抗体效价,结果表明:3种免疫原均可诱导红细胞和白细胞数量增加,并引起各种白细胞分类百分比变化,提高吞噬活性和抗体效价;免疫应答早期(第1周)主要是红细胞、单核细胞和中性粒细胞数量明显增加,吞噬细胞的吞噬活性迅速提高,吞噬百分比(PP)和吞噬指数(PI)第4天达峰值,F-AH组、OMP组和LPS组的PP、PI值依次分别为39.84%、46.53%、41.59%及3.94、4.26、3.77;随后则是淋巴细胞大量增殖,第21天淋巴细胞数量和抗体效价达峰值,F-AH组、OMP组和LPS组的抗体效价分别为1∶426.67、1∶341.33和1∶213.33。免疫28d后活菌攻毒的结果表明,OMP组的免疫保护率为75%;LPS组为67.8%,均明显优于F-AH组(50%)。可见3种免疫原均能通过促进青鱼血细胞增殖、提高吞噬细胞的吞噬活性、产生特异性抗体等方式增强机体的免疫保护力。

Responses of immune parameters in periphery blood of black carp(Mylopharyngodon piceus) immunized with three vaccines of Aeromonas hydrophila

Black carp(Mylopharyngodon piceus)were immunized with three vaccines(formalin killed Aeromonas hydrophila:F-AH,outer membrane protein:OMP and lipopolysaccharide:LPS).Then,the blood was taken from each fish caudal vein of all groups on day 1,2,4,7,14,21 and 28 post injection to study the related responses of immune parameters.The results were as follows:the number of erythrocytes and leucocytes in peripheral blood of fish immunized by three vaccines all increased during the first 4 days post injection,peaked on day 4.The differential leucocyte count(DLC) of fish immunized by three vaccines all increased and were significantly higher than that of control group for monocytes and neutrophils from day 4 to day 7,for lymphocytes from day 14 to day 28,and peaked on day 21.The phagocytic percentage(PP) and phagocitic index(PI) of phagocytes in fish immunized by three vaccines were significantly higher than those of the non-immunized fish between day 2 and day 7,with the maximum value observed on day 4.The serum antibody titers gradually increased in fish immunized by three vaccines during the first 21 days post injection,reached the greatest value on day 21,then gradually dropped off.The result of challenging with live Aeromonas hydrophila showed that black carp immunized by three vaccines had good relative percent survival(RPS).OMP had the highest RPS,which was 75.0%,followed by LPS(67.8%) and F-AH(50%).All the results suggested that three vaccines made black carp enhance immunity against the bacterial pathogen infection.