%0 Journal Article
%T Genetic variants of Anaplasma phagocytophilum from 14 equine granulocytic anaplasmosis cases
%A Cornelia Silaghi
%A Gabriele Liebisch
%A Kurt Pfister
%J Parasites & Vectors
%D 2011
%I BioMed Central
%R 10.1186/1756-3305-4-161
%X All DNA extracts of EDTA-blood samples of the horses gave bands of the correct nucleotide size in all four genotyping PCRs. Sequence analysis revealed 4 different variants in the partial 16S rRNA, groEL gene and msp2 genes, and 3 in the msp4 gene. One 16S rRNA gene variant involved in 11 of the 14 cases was identical to the "prototype" variant causing disease in humans in the amplified part [GenBank: U02521]. Phylogenetic analysis revealed as expected for the groEL gene that sequences from horses clustered separately from roe deer. Sequences of the partial msp2 gene from this study formed a separate cluster from ruminant variants in Europe and from all US variants.The results show that more than one variant of A. phagocytophilum seems to be involved in EGA in Germany. The comparative genetic analysis of the variants involved points towards different natural cycles in the epidemiology of A. phagocytophilum, possibly involving different reservoir hosts or host adaptation, rather than a strict species separation.Equine Granulocytic Anaplasmosis (EGA) is caused by Anaplasma phagocytophilum, a tick-transmitted, obligate intracellular bacterium. The vectors are ticks of the genus Ixodes; the main vector in Europe is I. ricinus, in North America I. pacificus and I. scapularis. As no transovarial transmission has been shown, a reservoir animal is necessary for the maintenance in nature [1]. Before 2001, when a reclassification based on 16S rRNA gene similarities was proposed, the causing agent of EGA was known as Ehrlichia equi, which was part of the E. phagocytophila group (including also E. phagocytophila, the causing agent of tick-borne fever of ruminants, and the Human Granulocytic Anaplasmosis (HGA) - agent [2]). Different partial 16S rRNA gene variants of A. phagocytophilum have been detected in previous studies from various host animals and ticks [3-7].The first case of EGA was reported from northern California in 1969 [8]. Since then reports came from North America
%U http://www.parasitesandvectors.com/content/4/1/161