LT粘膜佐剂对鸡新城疫疫苗的免疫增强作用研究

ENHANCEMENT OF MUCOSAL ADJUVANT LT PROTEIN ON IMMUNE RESPONSES OF NEWCASTLE DISEASE VIRUS VACCINE THROUGH DIFFERENT INOCULATION ROUTES

研究大肠杆菌热敏性肠毒素突变体蛋白(heat-labile enterotoxin,LTRG)对鸡新城疫(Newcastle disease virus,NDV)疫苗经不同途径接种效果的影响。以NDV LaSota株作为共免疫原,与LTRG重组蛋白经滴鼻、口服及肌肉注射三种途径接种雏鸡,通过血清IgG抗体、HI抗体及粘膜分泌型IgA抗体水平变化,评价不同途径接种LTRG对NDV疫苗的免疫效果的影响。结果显示:①三种途径接种,LTRG均能显著增强NDV疫苗的免疫抗体水平,免疫雏鸡血清抗体和粘膜抗体水平均高于NDV疫苗单独免疫组;②LTRG对NDV疫苗免疫增强作用,以滴鼻接种最显著:二、三免后LTRG+NDV滴鼻组与NDV组血清IgG、粘膜IgA差异均显著(P<0.01、P<0.05);LTRG+NDV口服与NDV组血清IgG差异不显著(P>0.05)、粘膜IgA差异极显著(P<0.01);LTRG+NDV肌注与NDV组IgG差异不显著(P>0.05)、粘膜IgA差异显著(P<0.05);③三种免疫途径比较:血清IgG抗体水平差异均不明显(P>0.05);滴鼻、口服免疫可诱导雏鸡产生较高的粘膜IgA抗体、血清HI抗体。由此可见:LTRG粘膜佐剂对NDV疫苗免疫增强作用,以粘膜(滴鼻、口服)途径接种效果最为显著,能诱导高水平的粘膜IgA抗体及血清抗体。

The objective of the present study was to illustrate the adjuvant effect of mutant LTRG protein on Newcastle disease virus （NDV） vaccine through different inoculation routes. The mixture of LTRG/NDV vaccine was administered to chickens with oral, intranasal and intramuscular routes. Other chickens were immunized with NDV vaccine alone via the same routes and used as controls. The local mucosal IgA and serum IgG levels were tested in ELISA. Hemagglutinin inhibition （HI） titers in serum samples were also examined. After the first immunization, lgA and IgG antibodies in all chickens were higher in LTRG/NDV groups than those of NDV vaccine alone groups. Among 3 immunization routes, the higher adjuvant effect was observed in nasal inoculation group. After 3 times of oral immunization, there was no difference of IgG between LTRG/NDV group and NDV alone group （P〉0.05） while IgA level showed significant difference （P〈0.01）. In intramuscular inoculation groups, no significant difference in IgG antibodies between LTRG/NDV and NDV alone group （P〉0.05） was observed while significant difference in IgA antibodies was detected （P〈0.05）. In addition, no difference in IgG antibodies was observed among LTRG/NDV groups with 3 routes. The delivery of LTRG/NDV mixture via oral and intranasal routes greatly enhanced mucosal IgA and HI antibodies, indicating stronger mucosal adjuvant effect. The results demonstrated that LTRG enhanced the immune response to NDV vaccines and intranasal and oral routes were more effective in inducing mucosal IgA and serum IgG antibodies.