On the Reproducibility of Early-Stage Thermally Induced and Contact-Stir-Induced Protein Aggregation

DNA Released by Adeno-Associated Virus Strongly Alters Capsid Aggregation Kinetics in a Physiological Solution

While adeno-associated virus is a leading vector for gene therapy, significant gaps remain in understanding AAV degradation and stability. In this work, we study the degradation of an engineered AAV serotype at physiological pH and ionic strength. Viral particles of varying fractions of encapsulated DNA were incubated between 30 and 60 °C, with changes in molecular weight measured by changes in total light scattering intensity at 90° over time. Mostly full vectors demonstrated a rapid decrease in molecular weight corresponding to the release of capsid DNA, followed by slow aggregation. In contrast, empty vectors demonstrated immediate, rapid colloid-type aggregation. Mixtures of full and empty capsids showed a pronounced decrease in initial aggregation that cannot be explained by a linear superposition of empty and full degradation scattering signatures, indicating interactions between capsids and ejected DNA that influenced aggregation mechanisms. This demonstrates key interactions between AAV capsids and their cargo that influence capsid degradation, aggregation, and DNA release mechanisms in a physiological solution.

Route and antigen shape immunity to dmLT-adjuvanted vaccines to a greater extent than biochemical stress or formulation excipients

A key aspect to vaccine efficacy is formulation stability. Biochemical evaluations provide information on optimal compositions or thermal stability but are routinely validated by ex vivo analysis and not efficacy in animal models. Here we assessed formulations identified to improve or reduce stability of the mucosal adjuvant dmLT being investigated in polio and enterotoxigenic E. coli (ETEC) clinical vaccines. We observed biochemical changes to dmLT protein with formulation or thermal stress, including aggregation or subunit dissociation or alternatively resistance against these changes with specific buffer compositions. However, upon injection or mucosal vaccination with ETEC fimbriae adhesin proteins or inactivated polio virus, experimental findings indicated immunization route and co-administered antigen impacted vaccine immunogenicity more so than dmLT formulation stability (or instability). These results indicate the importance of both biochemical and vaccine-derived immunity assessment in formulation optimization. In addition, these studies have implications for use of dmLT in clinical settings and for delivery in resource poor settings.

Effects of stirring speed ladder on the acid-promoted refolding of rice glutelin

The effects of stirring speed (0, 250, 500, 750, 1000, 1250, and 1500 rpm) on the rice glutelin hydrocolloids (1 %, w/v) during the acidified process were investigated. As the stirring speed was increased to 750 rpm, the hydration diameter of the rice glutelin was significantly decreased, but higher stirring speeds had no significant effect on size. The highest and lowest solubility were recorded for the samples treated at 750 and 0 rpm stirring speeds, respectively. The surface hydrophobicity and molecular weight increased first and then decreased, both the minimum value was recorded at 750 rpm sample. The principal component analysis (PCA) was employed to detect patterns between changes in various properties (solubility, particle size, β-sheet content, surface hydrophobicity, and ζ-potential) and stirring treatment. To conclude, the various properties of rice glutelin refold during acidification are drastically affected by employing different stirring speeds. Choosing a suitable stirring speed is important for quality control in protein hydrocolloid production.

Science and art of protein formulation development

Protein pharmaceuticals have become a significant class of marketed drug products and are expected to grow steadily over the next decade. Development of a commercial protein product is, however, a rather complex process. A critical step in this process is formulation development, enabling the final product configuration. A number of challenges still exist in the formulation development process. This review is intended to discuss these challenges, to illustrate the basic formulation development processes, and to compare the options and strategies in practical formulation development.