Chimeric immunogenic polypeptides

1. An isolated polypeptide, wherein the isolated polypeptide comprises:

(i) immunogenic sequences TRP120 (SEQ ID NO:22) and TRP75 (SEQ ID NO:19), or sequences at least 90% identical; and

(ii) wherein at least one of the immunogenic sequences is contiguously repeated in the polypeptide.

2. The isolated polypeptide of claim 1 , wherein each of the TRP120 (SEQ ID NO: 22) and TRP75 (SEQ ID NO: 19), or a sequence at least 90% identical are contiguously repeated 1, 2, 3, 4, 5, 6, or 7 times in the polypeptide.

3. The isolated polypeptide of claim 1 , wherein the isolated polypeptide comprises one or more of (SEQ ID NOs:11-16 or 36-42), wherein the one or more of (SEQ ID NOs:11-16 or 36-42) are contiguously repeated 0, 1, 2, or 3 times.

4. The isolated polypeptide of claim 1 , wherein each of the immunogenic sequences are contiguously repeated from 1 to 3 times in the polypeptide.

5. The isolated polypeptide of claim 4 , wherein each of the immunogenic sequences are contiguously repeated from 1 to 2 times in the polypeptide.

6. The isolated peptide of claim 1 , wherein the isolated polypeptide comprises TRP140 (SEQ ID NO:23), A34N1 (SEQ ID NO:7), TRP63 (SEQ ID NO:18), TRP47 (SEQ ID NO:17), TRP28 (SEQ ID NO:2), TRP36R1 (SEQ ID NO:8), TRP36R2 (SEQ ID NO:9), TRP36R3 (SEQ ID NO:10), TRP36CO (SEQ ID NO:36), TRP19 (SEQ ID NO:1), HSP (SEQ ID NO:24), or a sequence at least 90% identical; wherein each of the immunogenic sequences are contiguously repeated from 1 to 7 times in the polypeptide.

7. The polypeptide of claim 1 , wherein the isolated polypeptide comprises TRP36, TRP140, TRP28, or HSP.

8. The polypeptide of claim 7 , wherein the TRP36R1 if present is repeated 2-6 times, and wherein the other immunogenic sequences are repeated 1-3 times.

9. The polypeptide of claim 8 , wherein the polypeptide comprises all of TRP32, TRP120, TRP36, TRP140, TRP28, and HSP.

10. The polypeptide of claim 9 , wherein the polypeptide comprises SEQ ID NO:28.

11. The polypeptide of claim 1 , wherein the isolated polypeptide comprises at least three, at least four, at least five or all of TRP32R1, TRP32R2, TRP32R3, TRP32R4, TRP120, and A34N1.

12. The polypeptide of claim 11 , wherein TRP120 and A34N1 are each contiguously repeated 1-3 times.

13. The polypeptide of claim 12 , wherein TRP120 and A34N1 are each contiguously repeated 2 times.

14. The polypeptide of claim 1 , wherein the polypeptide comprises A34N1, TRP47, and/or TRP63.

15. The polypeptide of claim 14 , wherein the polypeptide comprises A34N1.

16. The polypeptide of claim 1 , wherein the polypeptide comprises TRP36R1, TRP140, TRP95R, and/or TRP95C.

17. The polypeptide of claim 1 , wherein the polypeptide comprises a polypeptide of SEQ ID NOs: 25-35.

18. The polypeptide of claim 1 , wherein the isolated polypeptide comprises A34N1, TRP63, TRP47, TRP75, TRP28, TRP36, TRP19, TRP140, and/or HSP.

19. The polypeptide of claim 1 , wherein the polypeptide further comprises at least two of TRP36R1, TRP36R2, TRP36R3, and/or TRP36CO.

20. The polypeptide of claim 1 , wherein the different immunogenic sequences are not separated by a linker or a spacer.

21. The polypeptide of claim 1 , wherein the different immunogenic sequences are separated by a linker or a spacer.

22. The polypeptide of claim 21 , wherein the linker is a glycine linker.

23. The polypeptide of claim 22 , wherein the glycine linker has the amino acid sequence -(G) X -, wherein X=3-5.

24. The polypeptide of claim 1 , wherein the polypeptide is comprised in a pharmaceutical preparation.

25. The pharmaceutical preparation of claim 24 , wherein the pharmaceutical preparation is formulated for parenteral, intravenous, subcutaneous, intranasal, sublingual, or intradermal administration.

26. The polypeptide of claim 1 , wherein the polypeptide is attached to a solid support or comprised in a diagnostic kit.

27. The polypeptide of claim 26 , wherein the solid support is glass or plastic.

28. The polypeptide of claim 26 , wherein the solid support is comprised in a lateral flow assay, or microfluidic device.

29. An isolated polypeptide of Formula I (A s -B t —C u -D v -E w -F x -G y -H z ) n ,

wherein A, B, C, D, E, F, G, and H is a peptide selected from SEQ ID NOs:1-24 and 36-42, or a sequence at least 90% identical to any one of (SEQ ID NOs:1-24 or 36-42),

wherein s, t, u, v, x, y, and z is an integer 0-8, wherein at least two of s-z are ≥1 and at least one of s-z is ≥2, and

wherein n is an integer 1-5;

wherein the polypeptide comprises TRP120 (SEQ ID NO:22) and TRP75 (SEQ ID NO:19).

30. A pharmaceutical preparation comprising the polypeptide of claim 1 and a pharmaceutically acceptable excipient.

31. A method of detecting antibodies that specifically bind an Ehrlichia organism in a test sample, comprising: (a) contacting an isolated polypeptide of claim 1 ; (b) detecting the peptide-antibody complexes; wherein the detection of the peptide-antibody complexes is an indication that antibodies specific for an Ehrlichia organism are present in the test sample, and wherein the absence of the peptide-antibody complexes is an indication that antibodies specific an Ehrlichia organism are not present in the test sample.

32. A method of identifying an Ehrlichia infection in a mammalian subject comprising: (a) contacting a biological sample from the subject with an isolated polypeptide of claim 1 under conditions that allow peptide-antibody complexes to form; and (b) detecting the peptide-antibody complexes; wherein the detection of the peptide-antibody complexes is an indication that the subject has an Ehrlichia infection.

33. A method of inducing an immune response in a mammalian subject comprising administering to the subject an effective amount of a pharmaceutical preparation comprising a polypeptide of a pharmaceutical composition of claim 30 .

34. A method of treating an Ehrlichia chaffeensis or Ehrlichia canis infection in a subject comprising:

(a) contacting a biological sample from the subject with an isolated polypeptide of claim 1 under conditions that allow peptide-antibody complexes to form;

(b) detecting the peptide-antibody complexes; wherein the detection of the peptide-antibody complexes is an indication that the subject has an Ehrlichia chaffeensis or Ehrlichia canis infection; and

(c) administering a therapeutic compound to treat Ehrlichia infection in the subject.

35. The polypeptide of claim 1 , wherein the polypeptide comprises A34N1, TRP63, and TRP75.

36. The polypeptide of claim 35 , wherein the polypeptide comprises SEQ ID NO:34.