Long-Term Protective Immunity against Infection Induced by a Genetically Modified Live Vaccine.

Human monocytic ehrlichiosis, an emerging tick-borne disease, is caused by . Infections with the pathogen are also common in the canine host. Our previous studies demonstrated that functional disruption within the phage head-to-tail connector protein gene results in bacterial attenuation, creating a modified live attenuated vaccine (MLAV).

Targeted mutagenesis in Anaplasma marginale to define virulence and vaccine development against bovine anaplasmosis.

Tick-borne Anaplasma species are obligate, intracellular, bacterial pathogens that cause important diseases globally in people, agricultural animals, and dogs. Targeted mutagenesis methods are yet to be developed to define genes essential for these pathogens. In addition, vaccines conferring protection against diseases caused by Anaplasma species are not available.

Experimental Infection of North American Sheep with .

, a tick-borne rickettsial, causes heartwater in ruminants resulting from vascular damage. Severity of heartwater varies greatly in ruminant species and breeds, age of animals and for diverse geographic . strains.

Molecular detection and characterization of Anaplasma platys and Ehrlichia canis in dogs from the Caribbean.

Anaplasma platys is a tick-transmitted rickettsial pathogen, which is known to be the etiologic agent for cyclic thrombocytopenia in its primary canine host. Infections with this pathogen are also reported in cats, cattle and people. Similarly, Ehrlichia canis is another tick-borne rickettsial pathogen responsible for canine monocytic ehrlichiosis and is also reported to cause infections in people.

Multiple Ehrlichia chaffeensis Genes Critical for Its Persistent Infection in a Vertebrate Host Are Identified by Random Mutagenesis Coupled with Infection Assessment.

, a tick-transmitted obligate intracellular rickettsial agent, causes human monocytic ehrlichiosis. In recent reports, we described substantial advances in developing random and targeted gene disruption methods to investigate the functions of genes. We reported earlier that the Himar1 transposon-based random mutagenesis is a valuable tool in defining genes critical for its persistent growth in reservoir and incidental hosts.

Anaplasma marginale outer membrane protein vaccine candidates are conserved in North American and South African strains.

Bovine anaplasmosis is a globally economically important tick-borne disease caused by the obligate intraerythrocytic rickettsia, Anaplasma marginale. A live Anaplasma centrale blood-based vaccine is available, but it does not protect against all A. marginale field strains and may also transmit other blood-borne pathogens.

Detection and Characterisation of Anaplasma marginale and A. centrale in South Africa.

Bovine anaplasmosis is endemic in South Africa and it has a negative economic impact on cattle farming. An improved understanding of and variety transmission, together with improved tools for pathogen detection and characterisation, are required to inform best management practices. Direct detection methods currently in use for and in South Africa are light microscopic examination of tissue and organ smears, conventional, nested, and quantitative real-time polymerase chain reaction (qPCR) assays, and a reverse line blot hybridisation assay.

Co-infections with multiple genotypes of Anaplasma marginale in cattle indicate pathogen diversity.

Background: Only a few studies have examined the presence of Anaplasma marginale and Anaplasma centrale in South Africa, and no studies have comprehensively examined these species across the whole country. To undertake this country-wide study we adapted a duplex quantitative real-time PCR (qPCR) assay for use in South Africa but found that one of the genes on which the assay was based was variable. Therefore, we sequenced a variety of field samples and tested the assay on the variants detected.

Comparison of three nucleic acid-based tests for detecting and in cattle.

Several nucleic acid-based assays have been developed for detecting Anaplasma marginale and Anaplasma centrale in vectors and hosts, making the choice of method to use in endemic areas difficult. We evaluated the ability of the reverse line blot (RLB) hybridisation assay, two nested polymerase chain reaction (nPCR) assays and a duplex real-time quantitative polymerase chain reaction (qPCR) assay to detect A. marginale and A.

Characterization of Anaplasma marginale subsp. centrale Strains by Use of msp1aS Genotyping Reveals a Wildlife Reservoir.

Bovine anaplasmosis caused by the intraerythrocytic rickettsial pathogen Anaplasma marginale is endemic in South Africa. Anaplasma marginale subspecies centrale also infects cattle; however, it causes a milder form of anaplasmosis and is used as a live vaccine against A. marginale There has been less interest in the epidemiology of A.