Chemical Addressability of Ultraviolet-Inactivated Viral Nanoparticles (VNPs)

BackgroundCowpea Mosaic Virus (CPMV) is increasingly being used as a nanoparticle platform for multivalent display of molecules via chemical bioconjugation to the capsid surface. A growing variety of applications have employed the CPMV multivalent display technology including nanoblock chemistry, in vivo imaging, and materials science. CPMV nanoparticles can be inexpensively produced from experimentally infected cowpea plants at high yields and are extremely stable. Although CPMV has not been shown to replicate in mammalian cells, uptake in mammalian cells does occur in vitro and in vivo. Thus, inactivation of the virus RNA genome is important for biosafety considerations, however the surface characteristics and chemical reactivity of the particles must be maintained in order to preserve chemical and structural functionality.
Methodology/Principal FindingsShort wave (254 nm) UV irradiation was used to crosslink the RNA genome within intact particles. Lower doses of UV previously reported to inactivate CPMV infectivity inhibited symptoms on inoculated leaves but did not prohibit systemic virus spread in plants, whereas higher doses caused aggregation of the particles and an increase in chemical reactivity further indicating broken particles. Intermediate doses of 2.0–2.5 J/cm2 were shown to maintain particle structure and chemical reactivity, and cellular binding properties were similar to CPMV-WT.
ConclusionsThese studies demonstrate that it is possible to inactivate CPMV infectivity while maintaining particle structure and function, thus paving the way for further development of CPMV nanoparticles for in vivo applications.

背景：豇豆花叶病毒（Cowpea Mosaic Virus, CPMV）正日益被用作纳米颗粒平台，通过衣壳表面的化学生物偶联实现多种分子的多价展示。已有越来越多的应用场景采用CPMV多价展示技术，涵盖纳米砌块化学、体内成像以及材料科学等领域。CPMV纳米颗粒可通过实验感染的豇豆植株实现低成本、高产量制备，且具备极强的稳定性。尽管尚未有研究证实CPMV可在哺乳动物细胞中复制，但已有实验证明其确实能在体外及体内被哺乳动物细胞摄取。因此，出于生物安全考量，对病毒RNA基因组进行灭活至关重要，但同时必须保留颗粒的表面特性与化学反应活性，以维持其化学与结构功能。
方法与主要发现：本研究采用短波（254 nm）紫外线照射，对完整颗粒内的RNA基因组进行交联。此前报道的可灭活CPMV感染性的较低剂量紫外线，虽能抑制接种叶片上的症状，但无法阻止病毒在植株内的系统性传播；而更高剂量的紫外线则会引发颗粒聚集，并提升化学反应活性，进一步表明颗粒已发生破损。研究显示，2.0–2.5 J/cm²的中等剂量紫外线可维持颗粒结构与化学反应活性，且其细胞结合特性与野生型CPMV（CPMV-WT）相似。
结论：本研究证实，可在保留CPMV颗粒结构与功能的同时灭活其感染性，从而为将CPMV纳米颗粒进一步开发用于体内应用铺平了道路。