Virus Shellization And Its Applications

Viruses have received great attentions in various research fields including biology, material chemistry and medicine sciences. Nowadays, viruses are gradually accepted as potential tools or building blocks for materials fabrications, vector delivery, gene therapy, vaccine development, biological detection device and diagnosis rather than kinds of traditional pathogenic microorganism. Viruses have the characteristics of nano size effects and high symmetric structural properties, etc; they can be scaled up with biological culture, which facilitates the virus engineering and modification in large scale. However, another characteristics of viruses, such as undesirable infections and tedious and time comsuming for scale up. along with inate cellular barriers and nature traps from biological system, result in the inability to engineer viruses as the useful tools and there is no universal strategy to solve these serious problems.A new strategy for virus modification is in keen pursuit for offering new alternatives in both biological and material fields. Biomineralization is now an effective physicochemical tool to engineer living organisms by using non-living materials. Herein, we propose a shellization strategy to fabricate virus core-shell structures using self-assembly and biomineralization technologies, and characterized their physical, chemical and biological properties in combined with practical applications, providing feasible reference for virus applications as delivery vectors, gene therapy and vaccine development for the future.The main contents and academic contributions of this thesis are summarized as follows:1 Using yellow fever vaccine YF17D as template, we develop a facile strategy to fabricate encapsulated virus-polyelectrolyte hybrids using Layer-by-Layer (LbL) method with high efficiency and security. The polyelectrolytes. poly(allylamine) hydrochloride (PAH) and poly(sodium styrene sulfonate (PSS). can adsorb on virus surface altemately through electrostatic interaction to form core-shell structure. The modified viruses have regained different physical and biological properties such as concentration by the normal speed centrifugations and infection recovery, which can be understood by the surface repulsive force variation. They can be observed by transmission electron microscopy (TEM) direactly owing to the increasing of surface electron density by the polyelectrolytes. They can also be examined by scaning electron microscope (SEM) and atomic force microscope (AFM) readily without any biological fixation because of the mechenical strength reinforcement by the chemical compounds. The virus-polyelectrolyte core-shell nanoparticle with good biocompatibility can be rapidly internalized in different kinds of cell lines and have low cytotoxicity. Meanwhile, during the delivery, polyelectrolyte shells inhibit the release of enclosed viruses, which leads to the suppression of infectivity. This polyelectrolyte-based modification provides a new strategy to control the biological security of viruses, which encourages the multiplex applications of viral building blocks.2 Biomineralization treatments are used to confer single virus a mineral envelop. By shielding completely the viral surface protein, the living viruse can be masqueraded as inanimate calcium phosphate (CaPi) nanoparticles and they possess different physical and chemical properties from the native ones, resulting in the undetectable of virus components by using conventional methods. Under intracellular conditions, biocompatibilities of CaPi envelope exploit the similar cellular internalization as the conventional CaPi nanoparticles via a receptor independent endocytosis pathway, and virus release/recovery from mineral phase is induced spontaneously by the demineralization of CaPi inorganic phase under a low-pH condition that exists in endolysosomes after internalization. After intravenous administration, mineralized virus can deliver in circulatory system, transfect encoding genes with enhanced efficiency, expand tropisms of native virus and circumvent the neutralizing antibodies in the pre-immunized system. We suggest that single virus biomineralization is an effective and economic method to provide a "Trojan" strategy for virus to circumvent the limitations of receptors and natural traps, which will change our conventional understandings of viral infection and its multiple applications.3 SiO2 nanoparticle can also be assembled onto the adenovirus surface by non-covalent interactions to form the virus-core/SiO2-shell structures. After such a modification, the virus fails to interact with cellular receptor due to the surface is completely blocked by nano-SiO2, leading to the incapability of cellular internalization. The orderly assembly of nano-SiO2 on virus surface provides the basis for virus surface modification with different materials exploring important roles the inorganic phase playing.4 We confirm that biomineralization treatment is uniform and repeatable. and can be employed for both non-envelope and envelope viruses. Enveloped YF17D is modified by biomineralization technique to facilitate the efficient concentration by regular centrifugation too. During intracellular delivery, mineral phase of mineralized virus is degraded to release infectious virus particle. Mineralized shell can prevent neutralizing of monoclonal antibody to keep virus alive during the delivery. Besides, intraperitoneal injection of the mineralized virus can produce higher titers of antibodies in mice than that of normal YF17D, indicating the immunogenic enhancement of mineral phase in vivo. This study provides a new strategy for developing vaccine delivery system.