Anaplasma marginale str. Florida

Anaplasma marginale is the most prevalent tick-borne pathogen of cattle. It is transmitted by ixodid ticks. Symptoms of acute disease are anemia, weight loss, and often death. A.marginale establishes life-long persistent infection in animals that survive disease. These animals are clinically healthy but serve as reservoirs for transmission of the pathogen. Sequencing has revealed a small genome size due to reductive evolution, and it is related to several other intracellular pathogens, including those in the genera Ehrlichia, and Rickettsia. The Florida strain was originally isolated from a pool of blood samples collected from cattle in 1955. It is not able to be transmitted by the tick Dermacentor andersoni. It has been passed continuously since isolation. Comparisons between 2 fully sequenced genomes (strains St. Maries and Florida) and 3 unfinished genomes (two tick transmissible strains; Virginia and Puerto Rico, and one D.andersoni non-transmissible strain, Mississippi) showed that A. marginale has a closed-core genome with few highly plastic regions, which include the msp2 and msp3 genes, as well as the aaap locus. This means that few to no new genes are expected to be found when new genomes are sequenced. It has however a medium level of single-nucleotide polymorphisms (SNPs), having at least 20,028 variable sites found among these five genomes which is approximately 1.67% of the estimated size of the pan-genome. (HAMAP: ANAMF)