Molecular detection and characterization of Anaplasma phagocytophilum, the causative agent of human granulocytic anaplasmosis, in some animals suspected to be competent reservoirs in Taif district, Kingdom of Saudi Arabia

Anaplasma phagocytophilum is the causative agent of human granulocytic anaplasmosis (HGA), an emerging tick-borne zoonosis. The pathogen utilizes cattle, sheep, goats, and wide variety of animal species as reservoirs and members of genus Ixodes tick as vectors. Although conditions for transmission of the agent in Kingdom of Saudi Arabia do exist, there is no work of any kind was done to address the existence and epidemiology of the disease in the country. The objectives of this study are to molecularly detect and characterize A. phagocytophilum in some animals suspected to be competent reservoirs in Taif district, KSA. DNA was extracted from EDTA whole-blood samples from 44 dromedary camels, 20 cattle, 50 sheep, 5 desert foxes (Vulpes rueppellii), and 10 Dabb lizards (Uromastyx ornata). For screening purposes, PCR targeting 16S rRNA gene using the common primer pair ECC and ECB was conducted to all samples. All purified DNA preparations were also tested using heminested (targeting 16S rRNA gene) and standard (targeting msp4 gene) species-specific PCR. All animals were negative to A. phagocytophilum while the prevalence of unidentified species belonging to family Anaplasmataceae, when common primers were used, was 95.5%, 95%, 100%, 80%, and 100% for camels, cattle, sheep, foxes, and Dabb lizards respectively. To confirm our results that tested animals do not harbor A. phagocytophilum while other related organisms do exist, we had selected some cattle samples that yielded positive in screening PCR for downstream sequencing experiment. Purified double stranded DNA from the agarose gel of selected samples was subjected to bidirectional sequencing. Partial 16S rRNA sequence and phylogenetic analysis revealed that cattle residing Taif district are infected with 2 strains of Anaplasma spp. closely related to A. marginale (99% identity). In conclusion, this study is considered not only the first molecular survey of A. phagocytophilum in the kingdom, but also the first report that molecularly addressed existence of A. marginale in cattle from KSA. Extensive molecular surveys are needed to address the prevalence and geographical distribution of A. marginale in cattle from all-over the country. Moreover, additional sequencing and species-specific PCR experiments are needed to elucidate the molecular identity of the organisms detected when common primers were used. [Mohamed W. Ghafar and Mohammed Y. Shobrak. Molecular detection and characterization of Anaplasma phagocytophilum, the causative agent of human granulocytic anaplasmosis, in some animals suspected to be competent reservoirs in Taif district, Kingdom of Saudi Arabia. Life Sci J 2014;11(6):63-69]. (ISSN:10978135). http://www.lifesciencesite.com. 9