Distant genetic variants of Anaplasma phagocytophilum from Ixodes ricinus attached to people

Abstract

Abstract Background Tick-borne pathogen, Anaplasma phagocytophilum is currently described as a single species; however, studies using genetic markers can distinguish groups of variants associated with different hosts, pathogenicity, zoonotic potential, and biotic and geographic niches. The objective of our study was to investigate the genetic diversity of A. phagocytophilum from Ixodes ricinus ticks attached to people. Methods In collaboration with a commercial diagnostic company, a total of 52 DNA samples were obtained from ticks that tested positive for A. phagocytophilum by qPCR. The genetic profile of each sample was described using the groEL and ankA gene. Identification of the tick species was confirmed by partial sequencing of the COI subunit and the portion of the TrospA gene. Results All 52 ticks were identified as I. ricinus. Two protocols of nested PCR amplifying 1293 bp and 407 bp fragments of the groEL gene of A. phagocytophilum yielded the amplicons of the expected size for all 52 samples. Among all sequences, we identified 10 unique genetic variants of the groEL gene belonging to ecotype I and ecotype II. The analysis targeting the ankA gene was successful in 46 of 52 ticks. Among all sequences, we identified 21 unique genetic variants phylogenetically belonging to three clusters. Conclusions Our results indicate that ticks attached to people harbor distant genetic variants of A. phagocytophilum, some of which are not recognized as zoonotic. Further studies are needed to determine the risk of human infection by genetic variants other than those designated as zoonotic.