Miller Darren S, Halpern Michael, Kotlarski Ieva, Jilbert Allison R
School of Molecular and Biomedical Science, The University of Adelaide, Australia.
Virology. 2006 May 10;348(2):297-308. doi: 10.1016/j.virol.2005.12.032. Epub 2006 Feb 8.
As a first step in developing immuno-therapeutic vaccines for patients with chronic hepatitis B virus infection, we examined the ability of a whole-cell vaccine, expressing the duck hepatitis B virus (DHBV) core antigen (DHBcAg), to target infected cells leading to the resolution of de novo DHBV infections. Three separate experiments were performed. In each experiment, ducks were vaccinated at 7 and 14 days of age with primary duck embryonic fibroblasts (PDEF) that had been transfected 48 h earlier with plasmid DNA expressing DHBcAg with and without the addition of anti-DHBcAg (anti-DHBc) antibodies. Control ducks were injected with either 0.7% NaCl or non-transfected PDEF. The ducks were then challenged at 18 days of age by intravenous inoculation with DHBV (5 x 10(8) viral genome equivalents). Liver biopsies obtained on day 4 post-challenge demonstrated that vaccination did not prevent infection of the liver as similar numbers of infected hepatocytes were detected in all vaccinated and control ducks. However, analysis of liver tissue obtained 9 or more days post-challenge revealed that 9 out of 11 of the PDEF-DHBcAg vaccinated ducks and 8 out of 11 ducks vaccinated with PDEF-DHBcAg plus anti-DHBc antibodies had rapidly resolved the DHBV infection with clearance of infected cells. In contrast, 10 out of 11 of the control unvaccinated ducks developed chronic DHBV infection. In conclusion, vaccination of ducks with a whole-cell PDEF vaccine expressing DHBcAg elicited immune responses that induced a rapid resolution of DHBV infection. The results establish that chronic infection can be prevented via the vaccine-mediated induction of a core-antigen-specific immune response.
作为开发慢性乙型肝炎病毒感染患者免疫治疗疫苗的第一步，我们研究了一种表达鸭乙型肝炎病毒（DHBV）核心抗原（DHBcAg）的全细胞疫苗靶向感染细胞从而解决新发DHBV感染的能力。进行了三项独立实验。在每项实验中，在7日龄和14日龄时用原代鸭胚成纤维细胞（PDEF）对鸭子进行免疫接种，这些细胞在48小时前已用表达DHBcAg的质粒DNA进行转染，且添加或不添加抗DHBcAg（抗DHBc）抗体。对照鸭注射0.7%氯化钠或未转染的PDEF。然后在18日龄时通过静脉接种DHBV（5×10⁸病毒基因组当量）对鸭子进行攻击。攻击后第4天获得的肝活检表明，接种疫苗并不能预防肝脏感染，因为在所有接种疫苗的鸭子和对照鸭中检测到的感染肝细胞数量相似。然而，对攻击后9天或更长时间获得的肝组织分析显示，11只接种PDEF-DHBcAg疫苗的鸭子中有9只，以及11只接种PDEF-DHBcAg加抗DHBc抗体的鸭子中有8只迅速解决了DHBV感染，感染细胞被清除。相比之下，11只未接种疫苗的对照鸭中有10只发生了慢性DHBV感染。总之，用表达DHBcAg的全细胞PDEF疫苗对鸭子进行接种可引发免疫反应，从而迅速解决DHBV感染。结果表明，通过疫苗介导诱导核心抗原特异性免疫反应可以预防慢性感染。
