Colony detection
The present invention provides in one aspect a method for determining a production level of a polypeptide of interest by a cell or cell colony, comprising obtaining an image of one or more cells or cell colonies; and analyzing the image to detect a signal associated with the polypeptide of interest; wherein a signal level is determined for each cell or cell colony based on signal values from a predefined area surrounding the cell or cell colony, the signal level being indicative of the production level of the polypeptide of interest by the cell or cell colony.
1. A method for determining a production level of a polypeptide of interest by a cell or cell colony, comprising:
(a) obtaining, with an image-acquisition device, an image of one or more cells or cell colonies; and
(b) analyzing the image with a data processor programmed to detect a signal associated with the polypeptide of interest;
wherein a signal level is determined by the data processor for each cell or cell colony based on signal values from a predefined area surrounding and excluding the cell or cell colony in the image, the signal level being indicative of the production level of the polypeptide of interest by the cell or cell colony.
2. A method according to claim 1 , wherein the predefined area comprises a circle centered on the cell or cell colony.
3. A method according to claim 2 , wherein the circle has a diameter of 2-5 times a mean diameter of the cells or cell colonies.
4. A method according to claim 1 , wherein the signal level comprises a mean of signal values in the predefined area.
5. A method according to claim 4 , wherein the mean is an arithmetic mean or a geometric mean.
6. A method according to claim 1 , wherein the signal level comprises a median of signal values in the predefined area.
7. A method according to claim 1 , wherein the signal level comprises a sum of signal values in the predefined area.
8. A method according to claim 1 , wherein the predefined area excludes one or more adjacent cells or cell colonies.
9. A method according to claim 1 , wherein the signal level comprises a total exterior intensity value, the total exterior intensity value being calculated as a product of (i) a mean of signal values exterior to the cell or cell colony within the predefined area, excluding any signal values from pixels within adjacent cells or cell colonies; and (ii) a total number of pixels within the predefined area, including any pixels from within adjacent cells or cell colonies.
10. A method according to claim 1 , wherein the polypeptide of interest is secreted by the cell or cell colony.
11. A method for selecting a cell or cell colony which produces a polypeptide of interest, comprising:
(a) determining a production level of the polypeptide of interest by a plurality of cells or cell colonies by a method as defined in claim 1 ; and
(b) selecting one or more cells or cell colonies which produce the polypeptide of interest at an elevated level.
12. A method according to claim 11 , wherein cells or cell colonies having a signal level above a predetermined threshold value are selected.
13. A method according to claim 11 , wherein cells or colonies having a size within a predetermined size range are selected.
14. A method according to claim 11 , wherein the cells or cell colonies are selected based on a ratio of signal levels, each signal level being based on signal values at a particular wavelength.
15. A method according to claim 14 , wherein cells or cell colonies having a signal ratio above a predetermined threshold value are selected.
16. A method according to claim 11 , further comprising picking the selected cells or cell colonies.
17. A method according to claim 16 , wherein the cell or cell colony is picked by an automated cell picking device.
18. A method according to claim 1 , wherein the signal is a fluorescent signal.
19. A method according to claim 1 , further comprising a step of contacting the cells or cell colonies with a marker compound before the step of obtaining an image of the cells or cell colonies.
20. A method according to claim 19 , wherein the marker compound binds to the polypeptide of interest and provides the signal.
21. A method according to claim 19 , wherein the marker compound comprises a fluorescent label.
22. A method according to claim 21 , wherein the fluorescent label comprises fluorescein, rhodamine or phycoerythrin.
23. A method according to claim 1 , further comprising detecting boundaries of the cells or cell colonies by imaging using visible light.
24. A method according to claim 1 , wherein the polypeptide of interest comprises a biotherapeutic molecule.
25. A method according to claim 1 , wherein the polypeptide of interest comprises an immunoglobulin or fragment thereof
26. A method according to claim 1 , wherein the polypeptide of interest comprises a receptor.
27. A method according to claim 1 wherein the polypeptide of interest comprises a recombinant polypeptide expressed by a transfected cell.
28. A method according to claim 1 , wherein the polypeptide of interest is a natural product of the cell.
29. A method according to claim 1 , wherein the cells or cell colonies are cultured cells or cell colonies.
30. A method according to claim 1 , wherein the image is obtained and analysed by an automated imaging system.
31. A method according to claim 1 , wherein the cells or cell colonies are disposed on or in solid or semi-solid media.
32. A method according to claim 1 , where each signal value corresponds to an intensity value from a single pixel in the image.
33. The method of claim 1 , wherein the image is of a plurality of cells or cell colonies, and wherein the predefined area at least generally has the same basic dimensions for each cell or cell colony.
34. The method of claim 1 , wherein the predefined area is substantially annular in shape.
35. A computer program, residing on a non-transitory computer-readable medium, for controlling automated image acquisition and analysis, the computer program comprising instructions for causing an apparatus to:
(a) obtain an image of one or more cells or cell colonies; and
(b) analyze the image to detect a signal associated with a polypeptide of interest, by determining a signal level for each cell or cell colony based on signal values from a predefined area surrounding and excluding the cell or cell colony in the image, the signal level being indicative of the production level of the polypeptide of interest by the cell or cell colony.
36. A computer program according to claim 35 , further comprising instructions for causing the apparatus to pick one or more cells or cell colonies based on the indicated production level.
37. The method of claim 35 , wherein the image is of a plurality of cells or cell colonies, and wherein the predefined area at least generally has the same basic dimensions for each cell or cell colony.