Isoelectric point is an inadequate descriptor of MS2, Phi X 174 and PRD1 phages adhesion on abiotic surfaces

MS2, Phi X 174 and PRD1 bacteriophages are commonly used as surrogates to evaluate pathogenic virus behavior in natural aquatic media. The interfacial properties of these model soft bioparticles are herein discussed in connection with their propensities to adhere onto abiotic surfaces that differ in terms of surface charges and hydrophobicities. The phages considered in this work exhibit distinct multilayered surface structures and their electrostatic charges are evaluated from the dependence of their electrophoretic mobilities on electrolyte concentration at neutral pH on the basis of electrokinetic theory for soft (bio)particles. The charges of the viruses probed by electrokinetics vary according to the sequence Phi X 174 <= PRD1 < MS2, where '<' stands for 'less charged than'. The hydrophobic/hydrophilic balances of the phages are further derived from their adhesions onto model hydrophobic and hydrophilic self-assembled mono-layers. The corresponding results lead to the following hydrophobicity sequence Phi X 174 <= MS2 < PRD1 where '<' means 'less hydrophobic than'. The respective electrostatic and hydrophobic/hydrophilic features of the phages are further shown to be consistent with their measured adhesions onto polyethersulfone-based membranes with distinct hydrophobicities and charge levels. The methodology clearly demonstrates that the traditionally adopted phage isoelectric point as a relevant physicochemical descriptor for phage adhesion is not adequate for MS2, Phi X 174 and PRD1 bacteriophages. (C) 2014 Elsevier Inc. All rights reserved.