Methods using a modified bacteriophage for the detection of target molecules

1. A method for detecting a target molecule, comprising:

a) contacting an immobilized target molecule with a modified bacteriophage comprising SEQ ID NO: 1, SEQ ID NO:2, SEQ ID NO:3, or SEQ ID NO:4, wherein the bacteriophage specifically binds the target molecule, under conditions that promote binding of the bacteriophage to the target molecule, to produce a target molecule-bacteriophage complex;

b) contacting the target molecule-bacteriophage complex with a bacterial strain susceptible to infection by the bacteriophage;

c) incubating the target molecule-bacteriophage complex with the bacterial strain under conditions that promote the propagation of the bacteriophage in the bacteria and expression of the luciferase, to produce a bacteriophage-infected culture;

d) adding to the bacteriophage-infected culture a substrate for the luciferase; and

e) measuring the presence and/or magnitude of fluorescence produced from the action of the luciferase on its substrate.

2. The method of claim 1 , wherein the target molecule comprises a first affinity tag and the bacteriophage comprises a second affinity tag, wherein the first and second affinity tags specifically bind to each other.

3. The method of claim 2 , wherein the first and second affinity tags are enzymatically or chemically coupled to the target molecule and the bacteriophage, respectively.

4. The method of claim 2 , wherein the first affinity tag is streptavidin and the second affinity tag is biotin.

5. The method of claim 1 , wherein the bacteriophage is engineered to bind directly to the target molecule using phage display.

6. A method for detecting a target molecule, comprising:

a) contacting an immobilized target molecule with a first affinity ligand that specifically binds the target molecule, under conditions that promote target molecule-affinity ligand binding, to form a target molecule-first affinity ligand complex, and optionally contacting the target molecule-first affinity ligand complex with one or more additional affinity ligands under conditions that promote affinity ligand-affinity ligand binding, to produce a target molecule-first affinity ligand-additional affinity ligand complex, wherein the one or more affinity ligands are added sequentially, and wherein each successive affinity ligand specifically binds to the affinity ligand added immediately previous;

b) contacting the target molecule-first affinity ligand complex or the target molecule-first affinity ligand-additional affinity ligand complex with a modified bacteriophage comprising SEQ ID NO: 1, SEQ ID NO:2, SEQ ID NO:3, or SEQ ID NO:4, wherein the bacteriophage binds to the first affinity ligand, or if one or more additional affinity ligands are used, binds to the ultimate affinity ligand, to form a target molecule-affinity ligand-bacteriophage complex;

c) contacting the target molecule-affinity ligand-bacteriophage complex with a bacterial strain susceptible to infection by the bacteriophage;

d) incubating the target molecule-affinity ligand-bacteriophage complex with the bacterial strain under conditions that promote the propagation of the bacteriophage in the bacteria and expression of the luciferase, to produce a bacteriophage-infected culture;

e) adding to the bacteriophage-infected culture a substrate for the luciferase; and

f) measuring the presence and/or magnitude of fluorescence produced from the action of the luciferase on its substrate.

7. The method of claim 6 , wherein the first affinity ligand, or if one or more additional affinity ligands are used, the ultimate affinity ligand, comprises a first affinity tag, and the bacteriophage comprises a second affinity tag, wherein the first and second affinity tags specifically bind to each other.

8. The method of claim 6 , wherein the first and second affinity tags are enzymatically or chemically coupled to the affinity ligand and the bacteriophage, respectively.

9. The method of claim 6 , wherein the first affinity tag is streptavidin and the second affinity tag is biotin.

10. The method of claim 6 , wherein the bacteriophage is engineered to bind directly to the affinity ligand using phage display.