Diagnostic method for identifying carriers of the Marburg I variant of factor VII-activating protease (FSAP) on the basis of differential modulation of FSAP activity

1. A method for identifying whether an individual shows heterozygous or homozygous expression of the Marburg I (MR I) variant of factor MI-activating protease (FSAP), comprising determining FSAP activity in a sample from the individual in the absence and in the presence of aprotinin, wherein aprotinin

reduces FSAP activity, and

reduces FSAP activity in samples from individuals with heterozygous or homozygous expression of the MR I variant of FSAP to a lesser extent than reduces FSAP activity in samples from individuals who do not express said MR I variant of FSAP.

2. The method of claim 1 , wherein the extent of the change in FSAP activity is determined by:

(a) determining FSAP activity in a first portion of the sample in the presence of the aprotinin;

(b) determining FSAP activity in a second portion of the sample in the absence of the aprotinin; and

(c) comparing the activity determined in part (a) to the activity determined in part (b).

3. The method of claim 2 , wherein the activity determined in part (a) is compared to the activity determined in part (b) by calculating a quotient of the activity of part (a) and the activity of part (b).

4. The method of claim 1 , wherein the extent of the change in FSAP activity is determined by:

(a) determining FSAP activity in the sample in the absence of the aprotinin;

(b) adding the aprotinin to the sample and re-determining the FSAP activity in the sample; and

(c) comparing the activity determined in part (a) to the activity determined in part (b).

5. The method of claim 4 , wherein the activity determined in part (a) is compared to the activity determined in part (b) by calculating a quotient of the activity of part (a) and the activity of part (b).

6. A method for identifying whether an individual shows heterozygous or homozygous expression of the Marburg I (MR I) variant of factor VII-activating protease (FSAP), comprising determining FSAP activity in a sample from the individual in the absence and in the presence of a polyclonal or monoclonal anti-FSAP antibody, wherein the antibody

reduces FSAP activity, and

reduces FSAP activity in samples from individuals with heterozygous or homozygous expression of the MR I variant of FSAP to a lesser extent than the antibody reduces FSAP activity in samples from individuals who do not express said MR I variant of FSAP.

7. The method of claim 6 , wherein the anti-FSAP antibody is a monoclonal antibody produced by hybridoma cell line DSM ACC2726.

8. The method of claim 6 , wherein the anti-FSAP antibody binds to an epitope of FSAP to which the monoclonal antibody produced by hybridoma cell line DSM ACC2726 also binds.

9. A method for identifying whether an individual shows heterozygous or homozygous expression of the Marburg I (MR I) variant of factor VII-activating protease (FSAP), comprising determining FSAP activity in a sample from the individual in the absence and in the presence of a monoclonal or polyclonal anti-FSAP antibody, wherein the antibody

increases FSAP activity, and

increases FSAP activity in samples from individuals with heterozygous or homozygous expression of the MR I variant of FSAP to a lesser extent than the antibody increases FSAP activity in samples from individuals who do not express said MR I variant of FSAP.

10. The method of claim 9 , wherein the anti-FSAP antibody is a monoclonal antibody produced by hybridoma cell line DSM ACC2454 or DSM ACC2674.

11. The method of claim 9 , wherein the anti-FSAP antibody binds to an epitope of FSAP to which one or both of the monoclonal antibodies produced by hybridoma cell lines DSM ACC2454 and DSM ACC2674 also binds.

12. The method of claim 6 or 9 , wherein the extent of the change in FSAP activity is determined by:

(a) determining FSAP activity in a first portion of the sample in the presence of the antibody;

(b) determining FSAP activity in a second portion of the sample in the absence of the antibody; and

(c) comparing the activity determined in part (a) to the activity determined in part (b).

13. The method of claim 12 , wherein the activity determined in part (a) is compared to the activity determined in part (b) by calculating a quotient of the activity of part (a) and the activity of part (b).

14. The method of claim 6 or 9 , wherein the extent of the change in FSAP activity is determined by:

(a) determining FSAP activity in the sample in the absence of the antibody;

(b) adding the antibody to the sample and re-determining the FSAP activity in the sample; and

(c) comparing the activity determined in part (a) to the activity determined in part (b).

15. The method of claim 14 , wherein the activity determined in part (a) is compared to the activity determined in part (b) by calculating a quotient of the activity of part (a) and the activity of part (b).

16. The method of claim 1 , 6 , or 9 , wherein FSAP activity is determined by measuring the plasminogen activator activating activity of FSAP.

17. The method of claim 1 , 6 , or 9 , wherein FSAP activity is determined by measuring the prourokinase activating activity of FSAP.

18. The method of claim 1 , 6 , or 9 , wherein FSAP activity is determined by measuring the amidolytic activity of FSAP.

19. The method of claim 1 , 6 , or 9 , wherein the activity of FSAP is determined by measuring reaction rate (V max ) of a substrate conversion.