Abstract:

In order investigate the efficacy of immunopotentiator (VA5) on bivalent vaccine in chickens, the antibody levels or the challenge protection efficacy were evaluated after the specific pathogen free chickens (SPF) and commercial layers immunized with the bivalent inactivated ND-IBD vaccines with or without VA5, respectively. The other detection way was only taking SPF chicken injected by bivalent ND-AI vaccines with or without VA5, in contrast with bivalent vaccine without VA5 groups. HI antibody level against ND antigen was achieved to 6 log2 one week early in both ND contained bivalent vaccines with VA5 groups. And HI antibody level against H9 AI antigen reached to 7 log2 one week advanced in ND-AI vaccine with VA5 group. Antibody titers of agar gel precipitation titer and serum-virus neutralization against IBD antigen were qualified one week in advance than in ND-IBD vaccine with VA5 group, and continuously high antibody titer against ND, H9 AI and IBD antigen were retained during the detection periods. Similar to the antibody level results, groups of chickens injection by bivalent vaccines with VA5 could fully protect against virulent-ND or -IBD viruses challenge based on clinical signs and (or) bursa gross lesions, and no virus shedding post H9 AI variants infection. The protective efficacy of adjuvant bivalent vaccine groups was higher than those of bivalent vaccine without VA5 groups in term of the results of the three types viruses challenge. In summary, the immune efficacy of both ND-IBD and ND-AI bivalent vaccines was improved by VA5 immunopotentiators, which had shown great application prospects in this field.

Key words: immunopotentiator, bivalent inactivated ND-IBD vaccines, bivalent inactivated ND-H9 subtype avian influenza vaccines, antibody titer

摘要：

为评价免疫增强剂（VA5）对禽用联苗的免疫增强作用，将VA5分别与市售鸡新城疫-传染性法氏囊（新法）二联苗合用免疫SPF鸡和蛋鸡、与新城疫-H9亚型禽流感（新流）二联苗合用仅免疫SPF鸡，评价免疫后的抗体效价和SPF鸡攻毒后的保护效力。结果显示，SPF鸡或蛋鸡免疫含VA5的新法二联苗、新流二联苗后，新城疫血凝抑制（HI）抗体效价比常规苗组提前1周达到6 log2，禽流感HI抗体效价比常规苗组提前1周达到7 log2，法氏囊血清琼扩抗体和中和抗体比常规苗组均提前1周合格，且3种抗体持续高于常规疫苗组。免疫含VA5疫苗组的SPF鸡对新城疫强毒攻毒，以临床症状判断，可达全保护；以囊病变和临床症状判断，对法氏囊的攻毒提供全保护；H9变异株攻毒后不排毒。对上述3种病毒的保护力均高于常规苗。上述结果表明，VA5免疫增强剂能够提高鸡新法二联苗、新流二联苗对鸡的免疫效力，具有很好的应用前景。

关键词: 免疫增强剂, 新城疫-传染性法氏囊二联灭活苗, 新城疫-H9亚型禽流感二联灭活苗, 抗体效价