Filamentous bacteriophage stability in non-aqueous media

Background: Filamentous bacteriophage are used as general cloning vectors as well as phage display vectors in order to study ligand–receptor interactions. Exposure to biphasic chloroform–water interface leads to specific contraction of phage, to non-infective I- or S-forms. Results: Upon exposure, phage were inactivated (non-infective) at methanol, ethanol and 1-propanol concentrations inversely dependent upon alcohol hydrophobicity. Infectivity loss of phage at certain concentrations of 1-propanol or ethanol coincided with changes in the spectral properties of the f1 virion in ultraviolet fluorescence and circular dichroism studies. Conclusions: The alcohols inactivate filamentous phage by a general mechanism – solvation of coat protein – thereby disrupting the capsid in a manner quite different from the previously reported I- and S-forms. The infectivity retention of phagemid pG8H6 in 99% acetonitrile and the relatively high general solvent resistance of the phage strains studied here open up the possibility of employing phage display in non-aqueous media.