Chimaeric phages

A method of producing a chimaeric filamentous phage particle, the method comprising the steps of:

• a) providing a host cell with a first nucleic acid encoding a fusion protein, wherein the fusion protein comprises a proteinaceous molecule fused to a g3 phage coat protein capable of mediating infection of a host by the chimaeric filamentous phage particle;
• b) providing the host cell with a second nucleic acid encoding a mutant form of the g3 phage coat protein, wherein the mutant form comprises deletion of the D1 region, D2 region or both regions of the g3 phage coat protein, said host cell further comprising a nucleic acid encoding all other proteins that are essential for the assembly of a filamentous phage particle in the host cell;
• and
• c) culturing the host cell to allow assembly of the chimaeric filamentous phage particle, the chimaeric filamentous phase particle displaying a mixture of proteins on its surface, the mixture comprising the mutant form of the g3 phase coat protein and the fusion protein, wherein the fusion protein is attached to the chimaeric filamentous phage particle via the g3 phage coat protein capable of mediating infection of a host by the chimaeric filamentous phage particle.