Multi-epitope insert modulates solubility-based and chromatographic purification of human papilloma virus 16 L1-based vaccine without inhibiting virus-like particle assembly

Challenges and Opportunities in the Process Development of Chimeric Vaccines

Vaccines are integral to human life to protect them from life-threatening diseases. However, conventional vaccines often suffer limitations like inefficiency, safety concerns, unavailability for non-culturable microbes, and genetic variability among pathogens. Chimeric vaccines combine multiple antigen-encoding genes of similar or different microbial strains to protect against hyper-evolving drug-resistant pathogens. The outbreaks of dreadful diseases have led researchers to develop economical chimeric vaccines that can cater to a large population in a shorter time. The process development begins with computationally aided omics-based approaches to design chimeric vaccines. Furthermore, developing these vaccines requires optimizing upstream and downstream processes for mass production at an industrial scale. Owing to the complex structures and complicated bioprocessing of evolving pathogens, various high-throughput process technologies have come up with added advantages. Recent advancements in high-throughput tools, process analytical technology (PAT), quality-by-design (QbD), design of experiments (DoE), modeling and simulations, single-use technology, and integrated continuous bioprocessing have made scalable production more convenient and economical. The paradigm shift to innovative strategies requires significant attention to deal with major health threats at the global scale. This review outlines the challenges and emerging avenues in the bioprocess development of chimeric vaccines.

Computational mining of MHC class II epitopes for the development of universal immunogenic proteins

The human leukocyte antigen (HLA) gene complex, one of the most diverse gene complexes found in the human genome, largely dictates how our immune systems recognize pathogens. Specifically, HLA genetic variability has been linked to vaccine effectiveness in humans and it has likely played some role in the shortcomings of the numerous human vaccines that have failed clinical trials. This variability is largely impossible to evaluate in animal models, however, as their immune systems generally 1) lack the diversity of the HLA complex and/or 2) express major histocompatibility complex (MHC) receptors that differ in specificity when compared to human MHC. In order to effectively engage the majority of human MHC receptors during vaccine design, here, we describe the use of HLA population frequency data from the USA and MHC epitope prediction software to facilitate the in silico mining of universal helper T cell epitopes and the subsequent design of a universal human immunogen using these predictions. This research highlights a novel approach to using in silico prediction software and data processing to direct vaccine development efforts.

Biological nanoparticles: Relevance as novel target drug delivery systems and leading chromatographic isolation approaches

Nanotechnology is one of the most promising technologies of the 21st century, and it is now presenting an enormous impact on target drug delivery. In this context, the recent use of natural vesicle-like nanoparticles such as extracellular vesicles (i.e., exosomes, microvesicles, and apoptotic bodies) and virus-like particles is rendering encouraging results mostly because these delivery systems present cargo versatility, favorable body circulating advantages, biocompatibility, immunogenicity, and the capacity to be modified superficially to increase their affinity to a certain target or to control their entrance to the cell. However, some of the biggest challenges toward their clinical implementation are poorly standardized processing operations due to their inherent heterogeneity and expensive, long-lasting, and difficult to scale isolation procedures that can also affect the stability of the particles. Under these circumstances, chromatographic procedures represent an attractive and favorable alternative to overcome their downstream processing. Moreover, even when standardized chromatographic purification protocols are still in development, great achievements have been made using size exclusion, ionic exchange, hydrophobic interaction, and affinity protocols, mostly because of the correct harnessing of the nanovesicle membrane properties. In this sense, this review focuses on presenting the current understanding on the most promising therapeutic biological nanoparticles and the chromatographic isolation approaches employed in their recovery, providing at the same time recent findings and a general overview of the aspects that might impact the outcome of chromatographic techniques for this application.