Fomsgaard A, Nielsen H V, Bryder K, Nielsen C, Machuca R, Bruun L, Hansen J, Buus S
Department of Virology, Statens Serum Institut, Copenhagen, Denmark.
Scand J Immunol. 1998 Apr;47(4):289-95. doi: 10.1046/j.1365-3083.1998.00323.x.
The gp120-derived V3 loop of HIV-1 is involved in co-receptor interaction, it guides cell tropism, and contains an epitope for antibody neutralization. Thus, HIV-1 V3 is an attractive vaccine candidate. The V3 of the MN strain (MN V3) contains both B- and T-cell epitopes, including a known mouse H-2d-restricted cytotoxic T lymphocyte (CTL) epitope. In an attempt to improve the immunogenicity of V3 in DNA vaccines, a plasmid expressing MN V3 as a fusion protein with the highly immunogenic middle (pre-S2 + S) surface antigen of hepatitis B virus (HBsAg) was constructed. Epidermal inoculation by gene gun was used for genetic immunization in a mouse model. Antibody and CTL responses to MN V3 and HBsAg were measured and compared with the immune responses obtained after vaccination with plasmids encoding the complete HIV-1 MN gp160 and HBsAg (pre-S2 + S), respectively. DNA vaccination with the HIV MN gp160 envelope plasmid induced a slow and low titred anti-MN V3 antibody response at 12 weeks post-inoculation (p.i.) and a late appearing (7 weeks), weak and variable CTL response. In contrast, DNA vaccination with the HBsAg-encoding plasmid induced a rapid and high titred anti-HBsAg antibody response and a uniform strong anti-HBs CTL response already 1 week p.i. in all mice. DNA vaccination with the chimeric MN V3/HBsAg plasmid elicited humoral responses against both viruses within 3-6 weeks which peaked at 6-12 weeks and remained stable for at least 25 weeks. In addition, specific CTL responses were induced in all mice against both MN V3 and HBsAg already within the first 3 weeks, lasting at least 11 weeks. Thus, HBsAg acts as a 'genetic vaccine adjuvant' augmenting and accelerating the cellular and humoral immune response against the inserted MN V3 loop. Such chimeric HIV-HBsAg plasmid constructs may be useful in DNA immunizations as a 'carrier' of protein regions or minimal epitopes which are less exposed or poorly immunogenic.
人类免疫缺陷病毒1型（HIV-1）的糖蛋白120（gp120）衍生的V3环参与共受体相互作用，引导细胞嗜性，并包含一个抗体中和表位。因此，HIV-1 V3是一个有吸引力的疫苗候选物。MN毒株的V3（MN V3）包含B细胞和T细胞表位，包括一个已知的小鼠H-2d限制性细胞毒性T淋巴细胞（CTL）表位。为了提高V3在DNA疫苗中的免疫原性，构建了一种质粒，该质粒表达的MN V3与乙型肝炎病毒（HBsAg）的高免疫原性中间（前S2+S）表面抗原融合。在小鼠模型中，通过基因枪进行表皮接种用于基因免疫。检测了对MN V3和HBsAg的抗体和CTL反应，并分别与用编码完整HIV-1 MN gp160和HBsAg（前S2+S）的质粒接种后获得的免疫反应进行比较。用HIV MN gp160包膜质粒进行DNA疫苗接种在接种后12周（p.i.）诱导出缓慢且滴度低的抗MN V3抗体反应，以及出现较晚（7周）、微弱且变化不定的CTL反应。相比之下，用编码HBsAg的质粒进行DNA疫苗接种在所有小鼠接种后1周就诱导出快速且滴度高的抗HBsAg抗体反应和一致强烈的抗HBs CTL反应。用嵌合MN V3/HBsAg质粒进行DNA疫苗接种在3至6周内引发了针对两种病毒的体液反应，在6至12周达到峰值，并至少稳定25周。此外，在所有小鼠中，在最初3周内就诱导出针对MN V3和HBsAg的特异性CTL反应，持续至少11周。因此，HBsAg作为一种“基因疫苗佐剂”，增强并加速了针对插入的MN V3环的细胞免疫和体液免疫反应。这种嵌合HIV-HBsAg质粒构建体作为蛋白质区域或暴露较少或免疫原性较差的最小表位的“载体”，可能在DNA免疫中有用。
