Patent

1. A method for detecting antibodies specific for both E. ewingii (EE) and/or E. chaffeensis , comprising: (a) contacting a test sample with one or more isolated EE polypeptides under conditions that allow polypeptide/antibody complexes to form; and (b) assaying for the formation of a complex between antibodies in the test sample and the one or more EE polypeptides; wherein the formation of said complex is an indication that antibodies specific for E. ewingii and/or E. chaffeensis are present in the test sample; wherein at least one of the one or more isolated EE polypeptides comprises an amino acid sequence that comprises 6 or more consecutive amino acids of a mature OMP-1-15 protein encoded by nucleotide 15689-16450 of SEQ ID NO: 1, and wherein an anti- E. ewingii and/or E. chaffeensis antibody has a specific binding affinity for the at least one of the one or more isolated EE polypeptides.

2. The method of claim 1 , wherein the one or more amino acid sequences of variable region loops 1-4 comprises an amino acid sequence that is set forth in as SEQ ID NO:151, SEQ ID NO:170, SEQ ID NO:188, SEQ ID NO:205, and/or SEQ ID NO: 223.

3. The method of claim 1 , wherein the one or more isolated EE polypeptides comprises 6 or more consecutive amino acids of the amino acid sequence that is set forth as SEQ ID NO:39.

4. The method of claim 1 , wherein the one or more isolated EE polypeptides comprises an amino acid sequence of a mature OMP-1-15 protein that comprises amino acids 26 to 278 of SEQ ID NO: 18.

5. The method of claim 1 , wherein the one or more isolated EE polypeptides comprises an amino acid sequence of a mature OMP-1-15 protein that consists of amino acids 26 to 278 of SEQ ID NO: 18.

6. The method of claim 1 , wherein the one or more isolated EE polypeptides is operatively linked to an N-terminal or C-terminal peptide or tag.

7. The method of claim 1 , wherein the one or more isolated EE polypeptides is a recombinant form of the EE polypeptide(s).

8. The method of claim 1 , wherein the one or more isolated EE polypeptides is attached to a substrate.

9. The method of claim 8 , wherein the substrate is a column, plastic dish, matrix, or membrane.

10. The method of claim 9 , wherein the membrane comprises nitrocellulose.

11. The method of claim 1 , wherein the test sample is untreated, or subjected to precipitation, fractionation, separation, or purification before combining with the EE polypeptide(s).

12. The method of claim 1 , wherein the formation of a complex between antibodies in the test sample and the one or more EE polypeptides is detected by radiometric, calorimetric, or fluorometric means, or by size-separation or precipitation.

13. The method of claim 1 , which is used in an assay format selected from the group consisting of a microtiter plate assay, a reversible flow chromatographic binding assay, an enzyme linked immunosorbent assay, a radioimmunoassay, a hemagglutination assay, a western blot assay, a fluorescence polarization immunoassay, an indirect immunofluorescence assay, a diffusion based Ouchterlony, and a rocket immunofluorescent assay.

14. The method of claim 1 , wherein the formation of a complex between antibodies in the test sample and the one or more EE polypeptides is detected by addition of a secondary antibody that is coupled to a detectable tag.

15. The method of claim 14 , wherein the detectable tag is an enzyme, a fluorophore, or a chromophore.

16. The method of claim 1 , which is used to determine whether a subject is infected with E. ewingii and/or E. chaffeensis.

17. The method of claim 16 , wherein the subject is a human.

18. The method of claim 16 , wherein the subject is an animal.

19. The method of claim 18 , wherein the animal is a horse, a deer, a cattle, a pig, a sheep, a dog, a cat or a chicken.