由于其在激活免疫系统方面的作用，Toll样受体（TLR）是癌症免疫治疗中有前景的靶点；因此，已经在临床应用中测试了多种小分子TLR激动剂。然而，TLR激动剂的临床应用受到其非特异性副作用和药代动力学差的限制。为了克服这些限制，我们使用植物病毒纳米颗粒（VNPs）和噬菌体类病毒样颗粒（VLPs）作为药物传递系统。我们将TLR3激动剂或TLR7激动剂连接到豇豆花叶病毒（CPMV）VNPs、豇豆黄化斑点病毒（CCMV）VNPs和噬菌体Qβ类VLPs上。将TLR7激动剂2-甲氧基乙氧基-8-氧代-9-（4-羧基苯甲基）腺嘌呤（1V209）与CPMV、CCMV和Qβ偶联后，能够有效激活免疫细胞并促进前炎性细胞因子白介素6的产生。我们发现，与使用游离的1V209或单纯混合1V209和病毒颗粒处理的小鼠相比，连接到CPMV、CCMV和Qβ上的1V209可以减少体内肿瘤的生长并延长小鼠的生存时间。核酸为基础的TLR3激动剂聚肌酸与聚胞嘧啶酸（poly(I:C)）也通过CPMV VNPs进行传递，从而增强了小鼠的生存率。我们的所有数据表明，耦合和共同传递是增强TLR激动剂抗肿瘤效力所需的，而仅将VLPs与激动剂简单混合不会提供生存益处。1V209或poly(I:C)偶联到VNPs/VLPs的传递，可能由于多价呈现、肿瘤滞留时间延长以及VNP/VLP载体介导的对先天免疫细胞的靶向作用增加了它们的效力。

Toll-like receptors (TLRs) are promising targets in cancer immunotherapy due to their role in activating the immune system; therefore, various small-molecule TLR agonists have been tested in clinical applications. However, the clinical use of TLR agonists is hindered by their non-specific side effects and poor pharmacokinetics. To overcome these limitations, we used plant virus nanoparticles (VNPs) and bacteriophage virus-like particles (VLPs) as drug delivery systems. We conjugated TLR3 or TLR7 agonists to cowpea mosaic virus (CPMV) VNPs, cowpea chlorotic mottle virus (CCMV) VNPs, and bacteriophage Qβ VLPs. The conjugation of TLR7 agonist, 2-methoxyethoxy-8-oxo-9-(4-carboxybenzyl)adenine (1V209), resulted in the potent activation of immune cells and promoted the production of pro-inflammatory cytokine interleukin 6. We found that 1V209 conjugated to CPMV, CCMV, and Qβ reduced tumor growth in vivo and prolonged the survival of mice compared to those treated with free 1V209 or a simple admixture of 1V209 and viral particles. Nucleic acid-based TLR3 agonist, polyinosinic acid with polycytidylic acid (poly(I:C)), was also delivered by CPMV VNPs, resulting in enhanced mice survival. All our data suggest that coupling and co-delivery are required to enhance the anti-tumor efficacy of TLR agonists and simple mixing of the VLPs with the agonists does not confer a survival benefit. The delivery of 1V209 or poly(I:C) conjugated to VNPs/VLPs probably enhances their efficacy due to the multivalent presentation, prolongation of tumor residence time, and targeting of the innate immune cells mediated by the VNP/VLP carrier.