H5亚型禽流感病毒A/Duck/Anhui/1/2006(Clade 2.3)密码子优化HA基因DNA疫苗的免疫保护效力研究

为了进一步评价基于HA基因的DNA疫苗的开发应用前景,本研究将表达H5亚型禽流感水禽群代表株A/Duck/Anhui/1/2006(H5N1)DKAH/1/06(H5N1)]HA基因的DNA疫苗pCAGGoAHHA的免疫保护效力进行了评估,以5μg、10μg、20μg、50μg和100μg剂量免疫3周龄SPF鸡,首次免疫后3周再加强免疫一次,加强免疫后2周用106EID50的高致病力禽流感病毒(HPAIV)A/Duck/Fujian/31/2007(H5N1)DKFJ/31/07(H5N1)]鼻腔途径进行攻毒,观察发病与死亡情况。分别于攻毒后第3d、5d、7d天采集喉头及泄殖腔拭子进行病毒分离、滴定检测攻毒鸡排毒情况,同时检测免疫及攻毒后血清HI抗体、NT抗体的动态变化。结果,20μg、50μg、100μg组的pCAGGoAHHA均可对免疫鸡产生100%完全保护(不发病、不致死、不排毒),而5μg和10μg剂量组则可对免疫鸡分别形成25%和75%的保护。结果表明,H5亚型禽流感水禽群DNA疫苗质粒pCAGGoAHHA具有良好的免疫保护性,有望成为预防H5亚型HPAIV的技术储备候选疫苗。

Protective efficacy of DNA vaccine encoding codon-optimized HA gene of H5 subtype avian influenza virus A/Duck/Anhui/1/2006(Clade 2.3)

To evaluate the efficacy of DNA vaccine pCAGGoAHHA, which encodes the hemagglutinin (HA) protein from isolate A/Duck/Anhui/1/2006(H5N1) DKAH/1/06(H5N1)]of waterfowl clade, groups of 3-week-old specific pathogen free (SPF) chickens were intramuscularly injected with 5 μg, 10 μg, 20 μg, 50 μg and 100 μg of the DNA vaccines, respectively, boosted with the same dosage aider three weeks. All chickens were nasally challenged with 10~6 EID~(50) of highly pathogenic avian influenza virus (HPAIV) A/Duck/Fujian/31/2007 (H5N1) DKFJ/31/07(H5N1)] at two weeks after the boost. Oropharyngeal and cloacal swabs were collected from all groups at 3, 5 and 7 days post the challenge for isolation of virus in embryo eggs, and the sera were collected afar vaccination and challenge to measure the titers of antibodies by hemagglutinin inhibition (HI) and neutralization (NT) tests. Results shown that a complete protection was achieved in groups with a doses as low as 20 μg of the DNA vaccine, without any clinic signs, death and virus shedding. However, partial protection of 25 % and 75 % was provided in 5 μg and 10 μg of dosage groups, respectively. Our results indicated that pCAGGoAHHA were able to induce highly protective efficacy and could be a potential H5N1 candidate vaccine against the H5 Subtype HPAIV.