A comprehensive study on viral nanoparticles: Synthesis, solution state structural properties using dynamic light scattering and its interaction with host bacterium

Abstract Bacterium-virus interactions are very popular in infectious diseases and the viral particles (also called bacteriophages or phages) have a wide range of applications in therapeutics, food industry and agriculture. In-spite of their huge popularity both in fundamental and industrial sectors, there are still challenges with respect to purification, and scaling up processes due to their aggregating nature in solutions. Viral aggregates not only increase their survival efficiency against disinfectants, but also strongly affects their interactions with host bacterium. As the dimension of virus particle falls in the nanometer range, and they undergo Brownian motion in solution, non-invasive popular method like dynamic light scattering can be implemented to evaluate the structural properties of viral particles in the solution state at each step of purification process. In this context, we have carried out systematic studies on a popular model virus particles, P22. These include synthesis of phages and their biological characterizations such as spot test, growth kinetics, specificity test. The solution state structures are characterized before and after purification using extensive using extensive dynamic light scattering. Our studies result in a higher yield of virus particles and above a threshold concentration ratio of virus-to-bacteria, bacterial lysis occurs. Purified viral solution reveals coexistence of two translation diffusion coefficients with hydrodynamics radius of 40 nm and 300 nm respectively. These sizes correspond to single viral particles (20%) coexisting with 80% of higher order structural (multiple viral particles). The affinity study demonstrates a 60 to 70% efficiency of virus binding with their host bacterium. In-silico molecular docking explain the role of different types of molecular interactions between the tail spike protein (TSP) of virus and the o-antigen of the host bacterium. The Van der Waal-hydrophobic-desolvation (Vhd) interaction is the dominant one due to which phage strongly binds to host bacteria. Our methodology can be helpful formulation of different types of viral systems.