Schödel F, Wirtz R, Peterson D, Hughes J, Warren R, Sadoff J, Milich D
Department of Bacterial Diseases, Walter Reed Army Institute of Research, Washington, DC 20307-5100.
J Exp Med. 1994 Sep 1;180(3):1037-46. doi: 10.1084/jem.180.3.1037.
The hepatitis B virus (HBV) nucleocapsid antigen (HBcAg) was investigated as a carrier moiety for the immunodominant circumsporozoite (CS) protein repeat epitopes of Plasmodium falciparum and the rodent malaria agent P. berghei. For this purpose hybrid genes coding for [NANP]4 (C75CS2) or [DP4NPN]2 (C75CS1) as internal inserts in HBcAg (between amino acids 75 and 81) were constructed and expressed in recombinant Salmonella typhimurium. The resulting hybrid HBcAg-CS polypeptides purified from S. typhimurium were particulate and displayed CS and HBc antigenicity, however, the HBc antigenicity was reduced compared to native recombinant HBcAg. Immunization of several mouse strains with HBcAg-CS1 and HBcAg-CS2 particles resulted in high titer, P.berghei- or P.falciparum-specific anti-CS antibodies representing all murine immunoglobulin G isotypes. The possible influence of carrier-specific immunosuppression was examined, and preexisting immunity to HBcAg did not significantly affect the immunogenicity of the CS epitopes within HBcAg-CS1 particles. Similarly, the choice of adjuvant did not significantly alter the immunogenicity of HBcAg-CS hybrid particles. Immunization in complete or incomplete Freund's adjuvant or alum resulted in equivalent anti-HBc and anti-CS humoral responses. Examination of T cell recognition of HBcAg-CS particles revealed that HBcAg-specific T cells were universally primed and CS-specific T cells were primed if the insert contained a CS-specific T cell recognition site. This indicates that the internal site in HBcAg is permissive for the inclusion of heterologous pathogen-specific T as well as B cell epitopes. Most importantly, 90 and 100% of BALB/c mice immunized with HBcAg-CS1 particles were protected against a P. berghei challenge infection in two independent experiments. Therefore, hybrid HBcAg-CS particles may represent a useful approach for future malaria vaccine development.
乙型肝炎病毒（HBV）核衣壳抗原（HBcAg）被研究作为恶性疟原虫和啮齿类疟原虫伯氏疟原虫免疫显性环子孢子（CS）蛋白重复表位的载体部分。为此目的，构建了编码[NANP]4（C75CS2）或[DP4NPN]2（C75CS1）作为HBcAg内部插入片段（在氨基酸75和81之间）的杂交基因，并在重组鼠伤寒沙门氏菌中表达。从鼠伤寒沙门氏菌中纯化得到的杂交HBcAg-CS多肽呈颗粒状，并表现出CS和HBc抗原性，然而，与天然重组HBcAg相比，HBc抗原性有所降低。用HBcAg-CS1和HBcAg-CS2颗粒免疫几种小鼠品系，产生了高滴度的、针对伯氏疟原虫或恶性疟原虫的特异性抗CS抗体，代表了所有小鼠免疫球蛋白G同种型。研究了载体特异性免疫抑制的可能影响，对HBcAg的预先存在的免疫并未显著影响HBcAg-CS1颗粒内CS表位的免疫原性。同样，佐剂的选择并未显著改变HBcAg-CS杂交颗粒的免疫原性。在完全或不完全弗氏佐剂或明矾中免疫产生了等效的抗HBc和抗CS体液反应。对HBcAg-CS颗粒的T细胞识别研究表明，如果插入片段包含CS特异性T细胞识别位点，HBcAg特异性T细胞会普遍被激活，CS特异性T细胞也会被激活。这表明HBcAg中的内部位点允许包含异源病原体特异性T细胞和B细胞表位。最重要的是，在两项独立实验中，用HBcAg-CS1颗粒免疫的BALB/c小鼠中有90%和100%受到保护，免受伯氏疟原虫攻击感染。因此，杂交HBcAg-CS颗粒可能是未来疟疾疫苗开发的一种有用方法。
