The presence of RNA cargo is suspected to modify the surface hydrophobicity of the MS2 phage.

The surface hydrophobicity of native or engineered non-enveloped viruses and virus-like particles (VLPs) is a key parameter regulating their fate in living and artificial aqueous systems. Its modulation is mainly depending on the structure and environment of particles. Nevertheless, unexplained variations have been reported between structurally similar viruses and with pH. This indicates that some modulating factors of their hydrophobicity remain to be identified. Herein we investigate the potential involvement of RNA cargo in the MS2 phage used as non-enveloped RNA virus model, by examining the SDS-induced electrophoretic mobility shift (SEMS) determined for native MS2 virions and corresponding RNA-free VLPs at various pH. Interestingly, the SEMS of VLPs was larger and more variable from pH 5 to 9 compared to native virions. These observations are discussed in term of RNA-dependent changes in surface hydrophobicity, suggesting that RNA cargo may be a major modulator/regulator of this viral parameter.