Science and Risked-Based Stability Testing Strategies-a Test Case on the Global Implementation and Regulatory Reception

Evaluating the Stability of Lytic and Lysogenic Bacteriophages in Various Protectants

Phage therapy has regained value as a potential alternative and a complementary anti-infective approach to antibiotics in the fight against bacterial pathogens. Due to their host specificity, non-pathogenic nature for humans, and low production cost, phages offer an effective opportunity for utilization in healthcare, agriculture, and food preservation. Well-defined storage conditions are essential for commercialization and dissemination of phage usage. For this purpose, in our study, after the isolation and characterization of two different phages, one lytic and the other lysogenic; storage and shelf-life studies of phages were evaluated in a presence of various protectants (glycerol, sodium azide, DMSO with chloroform) and without any protectant during 8-month period at four different temperatures. The short-time stability of the lytic P. syringae phage and lysogenic MRSA phage, which were determined by STEM analysis to belong to the Straboviridae and Siphoviridae families, respectively were also examined for the different temperatures and the pH levels ranging from 1.0 to 14.0. This study revealed the storage-model of phages that exhibit distinct lifecycles, for the first time and provided a theoretical basis for development and application of phages, has yielded valuable findings contributing to understanding of phage biology.

Shelf-life prediction and storage stability of Aeromonas bacteriophage vB_AsM_ZHF

Phage therapy is a potential alternative to antibiotics for the treatment of bacterial infections. Due to the good antibacterial and therapeutic effects of phages, phage therapy has received attention and the demand for clinical applications has gradually increased. Phage storage stability and shelf life are key aspects of biopharmaceutical development and registration. In this study, Aeromonas salmonicida phage was stored at different temperatures for 12 months. We found that 4 °C was the optimal storage temperature. In the case of cryopreservation, 10% dimethyl sulfoxide (DMSO) was more effective at protecting the phage at -20 °C and -80 °C than 30% glycerin. Indeed, the phage titer decreased by only one order of magnitude within one year when DMSO was added. Hydroxyapatite (HAP) reduced the inactivation of phages by six orders of magnitude during storage at 28ºC for 1 year, significantly lower than that of in SM buffer. In addition, for excipients in lyophilization, tryptic soy broth (TSB) and tryptone or skim milk powder (SMP) in combination with trehalose alleviated phage inactivation during lyophilization and subsequent storage at 28 °C. Furthermore, a model for predicting the phage shelf-life was established with the Accelerated Stability Assessment Program (ASAP) based on the Arrhenius equation. The error of the model was less than 15% by comparing the predicted value with the actual value at 28 °C, indicating high accuracy. The study demonstrated the storage stability and shelf-life model of phage for the first time, which provided a theoretical basis for the development and application of phage products.