Division of Infectious Diseases, Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, NY, United States.
Department of Microbiology, Icahn School of Medicine at Mount Sinai, New York, NY, United States.
Front Immunol. 2024 Sep 24;15:1476924. doi: 10.3389/fimmu.2024.1476924. eCollection 2024.
HIV-1 envelope (Env) is the key target for antibodies (Abs) against the virus and thus an important HIV-1 vaccine component. Env is synthesized from a gp160 precursor with a signal peptide (SP) at its N-terminus. This study investigated the influence of the SP on Env antigenicity and immunogenicity.
Env proteins from two HIV-1 isolates, AA05 and AC02, were analyzed as gp120 and gp160 in their native wild-type (WT) forms and as chimeras with swapped SPs (AA05-02 and AC02-05). The WT and chimeric Env were assessed for antigenicity and glycosylation using monoclonal antibodies (mAbs) and glycan probes. Immunogenicity was tested in mice using three vaccine types: gp120 protein, gp120 DNA+gp120 protein, and gp120 DNA+gp160 DNA.
The recombinant AC02 gp120 protein was antigenically superior to AA05 as indicated by higher reactivity with most mAbs tested. When SPs were swapped, the antigenicity of the chimeric gp120s (AA05-02 and AC02-05) resembled that of the gp120s from which the SPs were derived; AA05-02 was similar to AC02 and vice versa. Glycan probe reactivity followed a similar pattern: AA05-02 and AC02 showed similar affinity to high-mannose specific mAbs and lectins. Interestingly, the antigenicity of gp160s showed an opposite pattern; membrane-bound gp160 expressed with the AA05 SP (AA05 and AC02-05) showed greater mAb binding than gp160 with the AC02 SP (AC02 and AA05-02). Mice immunized with gp120 protein showed that AA05-02 induced stronger cross-reactive binding Ab responses than AA05 WT, and AC02 elicited stronger responses than AC02-05, indicating AC02 SP enhanced gp120 immunogenicity. However, when DNA vaccines were included (gp120 DNA+gp120 protein and gp120 DNA+gp160 DNA), the use of heterologous SPs diminished the immunogenicity of the WT immunogens. Among the three vaccine regimens tested, only gp120 DNA+gp160 DNA immunization elicited low-level Tier 2 neutralizing Abs, with AA05 WT inducing Abs with greater neutralization capabilities than AA05-02.
These data demonstrate that the SP can significantly impact the antigenicity and immunogenicity of HIV-1 Env proteins. Hence, while SP swapping is a common practice in constructing Env immunogens, this study highlights the importance of careful consideration of the effects of replacing native SPs on the immunogenicity of Env vaccines.
HIV-1 包膜 (Env) 是针对该病毒的抗体 (Abs) 的关键靶标，因此也是 HIV-1 疫苗的重要组成部分。Env 由 gp160 前体合成，其 N 端带有信号肽 (SP)。本研究探讨了 SP 对 Env 抗原性和免疫原性的影响。
分析了来自两种 HIV-1 分离株 AA05 和 AC02 的 Env 蛋白，以其天然野生型 (WT) 形式的 gp120 和 gp160 以及具有交换 SP 的嵌合体 (AA05-02 和 AC02-05) 的形式进行分析。使用单克隆抗体 (mAbs) 和聚糖探针评估 WT 和嵌合 Env 的抗原性和糖基化。使用三种疫苗类型在小鼠中测试免疫原性：gp120 蛋白、gp120 DNA+gp120 蛋白和 gp120 DNA+gp160 DNA。
与 AA05 相比，重组 AC02 gp120 蛋白具有更高的抗原性，这表明它与大多数测试的 mAbs 反应性更高。当 SP 被交换时，嵌合 gp120s (AA05-02 和 AC02-05) 的抗原性类似于其来源的 gp120s；AA05-02 类似于 AC02，反之亦然。聚糖探针反应遵循类似的模式：AA05-02 和 AC02 对高甘露糖特异性 mAbs 和凝集素表现出相似的亲和力。有趣的是，gp160 的抗原性表现出相反的模式；表达 AA05 SP 的膜结合 gp160 (AA05 和 AC02-05) 与表达 AC02 SP 的 gp160 (AC02 和 AA05-02) 相比，具有更高的 mAb 结合。用 gp120 蛋白免疫的小鼠表明，AA05-02 诱导的交叉反应性结合 Ab 反应比 AA05 WT 更强，AC02 比 AC02-05 更强，表明 AC02 SP 增强了 gp120 的免疫原性。然而，当包含 DNA 疫苗时（gp120 DNA+gp120 蛋白和 gp120 DNA+gp160 DNA），使用异源 SP 降低了 WT 免疫原的免疫原性。在测试的三种疫苗方案中，只有 gp120 DNA+gp160 DNA 免疫诱导出低水平的 Tier 2 中和抗体，AA05 WT 诱导的抗体具有比 AA05-02 更强的中和能力。
这些数据表明，SP 可显著影响 HIV-1 Env 蛋白的抗原性和免疫原性。因此，虽然 SP 交换是构建 Env 免疫原的常见做法，但本研究强调了在替代天然 SP 对 Env 疫苗的免疫原性的影响时需要谨慎考虑的重要性。
