MS2 bacteriophage is often used as a model for evaluating pathogenic viruses' behavior in aqueous solution. However, the questions of the virus surface's hydrophilic/hydrophobic balance, the charge distribution, and the binding mechanism are open. Using the dynamic light scattering method and laser Doppler electrophoresis, the hydrodynamic diameter and the ζ-potential of the virus particles were measured at their concentration of 5 × 10 11 particles per mL and ionic strength 0.03 M. The values were found to be 30 nm and -29 or -34 mV (by Smoluchowski or Ohshima approximations), respectively. The MS2 bacteriophage surface was also investigated using a series of acid-base indicator dyes of various charge type, size, and structure. Their spectral and acid-base properties (p K a ) are very sensitive to the microenvironment in aqueous solution, including containing nanoparticles. The electrostatic potential of the surface Ψ was estimated using the common formula: Ψ = 59 × (p K a i - p K a ) in mV at 25 °C. The Ψ values were -50 and +10 mV, respectively, which indicate the "mosaic" way of the charge distribution on the surface. These data are in good agreement with the obtained ζ-potential values and provide even more information about the virus surface. It was found that the surface of the MS2 virus is hydrophilic in solution in contrast to the commonly accepted hypothesis of the hydrophobicity of virus particles. No hydrophobic interactions between various molecular probes and the capsid were observed.
Bibliographical noteThis document is the Accepted Manuscript version of a Published Work that appeared in final form in the Journal of Physical Chemistry B, copyright © American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see https://doi.org/10.1021/acs.jpcb.2c04491
N.M.-P. thanks the Ministry of Education and Science of Ukraine for financial support in the frame of Project #0122U001485. A.L. and V.F. thank the Ministry of Education and Science of Ukraine for financial support in the frame of Project #0120U101064. V.F. and D.N. acknowledge the use of the HPC Midlands supercomputer funded by EPSRC, Grant Number EP/P020232/1; the access to HPC Call Spring 2021, EPSRC Tier-2 Cirrus Service; and the access to Sulis Tier 2 HPC platform hosted by the Scientific Computing Research Technology Platform at the University of Warwick. Sulis is funded by EPSRC Grant EP/T022108/1 and the HPC Midlands+ consortium. The authors thank G. P. Gorbenko and her research group (V. N. Karazin Kharkiv National University) for the estimation of the MS2 amount (the total protein concentration) using the Lowry method.