Molecular detection, genotyping and phylogeny of Anaplasma spp. in Rhipicephalus ticks from Tunisia

In Tunisia, most of Anaplasma species and unclassified strains have been detected in several animals, but data on the occurrence of Anaplasma spp. in ticks are still lacking. In this study, we report the molecular evidence, genetic characterization and phylogeny of Anaplasma spp. in ticks collected from small ruminants. A total of 395 ticks (178 males and 179 females) were collected from sheep (n = 215) and goats (n = 180). Tick species were identified as 232 Rhipicephalus turanicus, 99 Rhipicephalus sanguineus sensu lato, 34 Rhipicephalus bursa and 30 Rhipicephalus annulatus. Overall infection rate of Anaplasma spp. was 5.6% (20/357 analyzed ticks). All positive ticks were collected from goats and found to be infected by A. ovis. R. turanicus is the most infected tick species by A. ovis (7.9%) followed by R. sanguineus s.l. (2.5%) with an absence of infection in R. bursa and R. annulatus. A. ovis prevalence rate varied significantly according to bioclimatic areas and geographic regions. GroEL typing and phylogenetic analysis revealed that these analyzed ticks are infected with various and novel strains of A. ovis. The use of PCR-RFLP method complemented with sequencing and phylogenetic analysis based on 16S rRNA gene confirm that one R. turanicus tick, positive to A. ovis, is co-infected with A. phagocytophilum-like 2 (0.3%). Specific A. phagocytophilum, A. phagocytophilum-like 1, A. marginale, A. centrale, A. bovis, and A. platys and related strains were not detected in any of the tested ticks. Present data expand knowledge about tick-borne bacteria present in ticks and further clarify the transmission cycles of these bacteria and their different elements in Tunisia.