Patent ID: 7842474

Claim:
A method of distinguishing between animals that (1) have been infected with Ehrlichia canis and animals that (2) have not been infected with E. canis regardless of whether the animal has been vaccinated with an inactivated whole cell E. canis vaccine, the method comprising: (a) contacting a biological sample from an animal with one or more purified E. canis polypeptides that do not specifically bind to antibodies that are a component of the animal's immune response to an E. canis vaccine; wherein the one or more purified E. canis polypeptides consist of the amino acid sequence set forth in SEQ ID NO:18, SEQ ID NO:19, SEQ ID NO:20, SEQ ID NO:22, or combinations thereof and wherein, optionally, the one or more purified E. canis polypeptides are linked to a heterologous protein, an indicator reagent, an amino acid spacer, a signal sequence, a stop transfer sequence, a transmembrane domain, a protein purification ligand, or a combination thereof; (b) detecting whether antibodies in the sample specifically bind to the one or more purified E. canis polypeptides; and (c) wherein if antibodies in the sample specifically bind to the one or more purified E. canis polypeptides, then the animal has been infected with E. canis.