Methods and compositions for diagnosing and vaccinating against Ehrlichia canis and Ehrlichia chaffeensis are provided.

Compositions and methods for inducing a protective immune response against Coxiella burnetii, to reduce a subject's risk of developing Q fever.

Targeted disruption of a specific gene and its subsequent restoration in obligate intracellular bacteria remains extremely challenging due to their absolute requirement for residence inside a host cell to replicate. Here, targeted allelic exchange mutations were created to inactivate two genes and then to restore one of the two genes of a rickettsial pathogen, Ehrlichia chaffeensis. These methods were then also successfully utilized in Ehrlichia canis and Anaplasma phagocyophilum. The resultant mutated pathogens are useful in immunogenic compositions for reducing the incidence of or severity of infection with ricksettsial pathogens.

Provided herein are immunogenic compositions that may be used, in some aspects, to induce an immune response against an Ehrlichia such as Ehrlichia cams. In some embodiments, the immunogenic composition comprises an E. canis bacterin and/or adjuvant, such as for example an emulsion or liposomal adjuvant. Related methods such as for diagnosis of or vaccination against ehrlichiosis are also provided.

The present invention encompasses a vaccine composition and method of use for treating heartworm infestation in mammals. The vaccine composition includes chimeric antigens engineered and manufactured using the genetic code (i.e., the amino acid or protein sequence) of the target sequence. After introduction of the vaccine composition containing the target antigen into the host (e.g., a canine), the host will generate antibodies as part of its robust immune response to the antigen. As the antibodies circulate through the host's plasma, heartworm larvae will consume the antibodies as they feed on the plasma. The antibodies will then act on internal targets of the worm recognized as antigens.

Neorickettsia helminthoeca is an obligate intra-cytoplasmic bacterium that causes salmon poisoning disease (SPD), an acute, febrile, fatal disease of dogs. Disclosed are compositions and methods for the immunodetection of N. helminthoeca in a canine subject. Also disclosed are immunogenic N. helminthoeca peptides that can be used in a vaccine for N. helminthoeca.

Anaplasma Marginale surface protein OmpA and homologous genes from Anaplasmatacaea family members are used in compositions suitable for vaccines to treat or prevent infections caused by tick-born bacteria of the Anaplasmatacaea family. OmpA proteins or peptide fragments may be used in combination with other Anaplasmatacaea surface proteins to elicit an immune response. Furthermore, antibodies to OmpA proteins can be used in diagnostic methods to determine whether an individual has contracted an Anaplasmatacaea infection.

The present invention discloses novel isolates of Neorickettsia risticii, compositions comprising such isolates, vaccines and methods for using such vaccines against Potomac Horse Fever.

Provided herein are chimeric recombinant polypeptides (chimeritopes) for use in vaccines against Anaplasmosis, in assays for diagnosing Anaplasmosis and in assays for measuring antibody titers induced by vaccination. The chimeritopes comprise, for example, antigenic segments of three Anaplasma proteins (OmpA, AipA and Asp14) and a non-antigenic segment of a Borrelia Osp protein (e.g. OspC) that is 10 amino acids in length, proline rich and random coil in conformation. Compositions comprising the chimeritopes, optionally in combination with additional Anaplasma proteins of interest, are also provided, as are methods of using the compositions as vaccines and diagnostic tools.

Provided herein are chimeric polypeptides that may be used, e.g., for the diagnosis of or vaccination against Ehrlichia chaffeensis and/or Ehrlichia canis.