Differential N- and O-glycosylation signatures of HIV-1 Gag virus-like particles and coproduced extracellular vesicles

Size-based separation of extracellular vesicles investigating the relationship between Tetraspanins and RNA

BACKGROUND

Extracellular vesicles (EVs), nano-sized particles released by cells, exhibit inherent heterogeneity, posing challenges for precise classification. This study introduces a method utilizing the coffee ring effect for size-based separation analysis, driven by the outward flow during droplet evaporation with Marangoni flow resulting from a surface tension gradient.

RESULTS

The controlled separation of nanoparticles based on size was applied to characterize EV and virus-like particle (VLP) samples. Tetraspanin markers exhibited distinct distribution patterns in dried droplets, with CD63-single-positive particles being smaller than those positive for CD9, CD81, or gag. Additionally, using previously developed fluorescence nanoparticle tracking analysis and transmission electron microscopy, single vesicle analysis validated the size disparities in CD-positive particles. RNA analysis through the coffee ring effect and fluorescent NTA revealed differential patterns in EVs and VLPs, providing different insights into RNA packaging.

SIGNIFICANCE

This multifaceted approach enhances understanding EV heterogeneity, emphasizing the potential influence of cellular origin and biogenesis pathways on particle characteristics.

Surface functionalization of virus-like particles via bioorthogonal click reactions for enhanced cell-specific targeting

Surface functionalization of nano drug carriers allows for precise delivery of therapeutic molecules to the target site. This technique involves attaching targeting molecules to the nanoparticle surface, facilitating selective interaction. In this study, we engineered virus-like particles (VLPs) to enhance their targeting capabilities. Azide groups incorporated on the lipid membranes of VLPs enabled bioorthogonal click reactions for conjugation with cycloalkyne-bearing molecules, providing efficient conjugation with high specificity. HIV-1 Gag VLPs were chosen due to their envelope, which allows host membrane component incorporation, and the Gag protein, which serves as a recognition motif for human T cells. This combination, along with antibody-mediated targeting, addresses the limitations of intracellular delivery to T cells, which typically exhibit low uptake of exogenous materials. The selective uptake of azide VLPs by CD3-positive T cells was evaluated in a co-culture system. Even without antibody conjugation, VLP uptake was enhanced in T cells, indicating their intrinsic targeting potential. Antibody conjugation further amplified this effect, demonstrating the synergistic benefits of the combined targeting approach. Our study shows that recombinant production of azide functionalized VLPs results in engineered nanoparticles that can be easily modified using bioorthogonal click reactions, providing high specificity and versatility for conjugation with various molecules, making it applicable to a wide range of biological products.

O-glycosylation in viruses: A sweet tango

O-glycosylation is an ancient yet underappreciated protein posttranslational modification, on which many bacteria and viruses heavily rely to perform critical biological functions involved in numerous infectious diseases or even cancer. But due to the innate complexity of O-glycosylation, research techniques have been limited to study its exact role in viral attachment and entry, assembly and exit, spreading in the host cells, and the innate and adaptive immunity of the host. Recently, the advent of many newly developed methodologies (e.g., mass spectrometry, chemical biology tools, and molecular dynamics simulations) has renewed and rekindled the interest in viral-related O-glycosylation in both viral proteins and host cells, which is further fueled by the COVID-19 pandemic. In this review, we summarize recent advances in viral-related O-glycosylation, with a particular emphasis on the mucin-type O-linked α-N-acetylgalactosamine (O-GalNAc) on viral proteins and the intracellular O-linked β-N-acetylglucosamine (O-GlcNAc) modifications on host proteins. We hope to provide valuable insights into the development of antiviral reagents or vaccines for better prevention or treatment of infectious diseases.

Construction of a novel kinetic model for the production process of a CVA6 VLP vaccine in CHO cells

Bioprocess development benefits from kinetic models in many aspects, including scale-up, optimization, and process understanding. However, current models are unable to simulate the production process of a coxsackievirus A6 (CVA6) virus-like particle (VLP) vaccine using Chinese hamster ovary cell culture. In this study, a novel kinetic model was constructed, correlating (1) cell growth, death, and lysis kinetics, (2) metabolism of major metabolites, and (3) CVA6 VLP production. To construct the model, two batches of a laboratory-scale 2 L bioreactor cell culture were prepared and various pH shift strategies were applied to examine the effect of pH shift. The proposed model described the experimental data under various conditions with high accuracy and quantified the effect of pH shift. Next, cell culture performance with various pH shift timings was predicted by the calibrated model. A trade-off relationship was found between product yield and quality. Consequently, multiple objective optimization was performed by integrating desirability methodology with model simulation. Finally, the optimal operating conditions that balanced product yield and quality were predicted. In general, the proposed model improved the process understanding and enabled in silico process development of a CVA6 VLP vaccine.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10616-023-00598-8.

How promising are HIV-1-based virus-like particles for medical applications

New approaches aimed at identifying patient-specific drug targets and addressing unmet clinical needs in the framework of precision medicine are a strong motivation for researchers worldwide. As scientists learn more about proteins that drive known diseases, they are better able to design promising therapeutic approaches to target those proteins. The field of nanotechnology has been extensively explored in the past years, and nanoparticles (NPs) have emerged as promising systems for target-specific delivery of drugs. Virus-like particles (VLPs) arise as auspicious NPs due to their intrinsic properties. The lack of viral genetic material and the inability to replicate, together with tropism conservation and antigenicity characteristic of the native virus prompted extensive interest in their use as vaccines or as delivery systems for therapeutic and/or imaging agents. Owing to its simplicity and non-complex structure, one of the viruses currently under study for the construction of VLPs is the human immunodeficiency virus type 1 (HIV-1). Typically, HIV-1-based VLPs are used for antibody discovery, vaccines, diagnostic reagent development and protein-based assays. This review will be centered on the use of HIV-1-based VLPs and their potential biomedical applications.