Molecular characterization reveals distinct genospecies of Anaplasma phagocytophilum from diverse North American hosts

Abstract

Anaplasma phagocytophilum is an emerging tick-borne pathogen that infects humans, domestic animals and wildlife throughout the Holarctic. In the far-western United States, multiple rodent species have been implicated as natural reservoirs for A. phagocytophilum. However, the presence of multiple A. phagocytophilum strains has made it difficult to determine which reservoir hosts pose the greatest risk to humans and domestic animals. Here we characterized three genetic markers (23S-5S rRNA intergenic spacer, ank and groESL) from 73 real-time TaqMan PCR-positive A. phagocytophilum strains infecting multiple rodent and reptile species, as well as a dog and a horse, from California. Bayesian and maximum-likelihood phylogenetic analyses of all three genetic markers consistently identified two major clades, one of which consisted of A. phagocytophilum strains infecting woodrats and the other consisting of strains infecting sciurids (chipmunks and squirrels) as well as the dog and horse strains. In addition, analysis of the 23S-5S rRNA spacer region identified two unique and highly dissimilar clades of A. phagocytophilum strains infecting several lizard species. Our findings indicate that multiple unique strains of A. phagocytophilum with distinct host tropisms exist in California. Future epidemiological studies evaluating human and domestic animal risk should incorporate these distinctions.

Antigen variability in Anaplasma phagocytophilum during chronic infection of a reservoir host

“…Similar betweenstrain variation across the msp2(p44) hypervariable region has been reported among other A. phagocytophilum strains (Barbet et al, 2006). Interestingly, three of the DU-1 strain pseudogenes were identical or nearly identical (1 nt difference) to those in the HZ strain even though these two strains have been shown to be dissimilar across multiple genes, consistently falling into separate phylogenetic clades (Rejmanek et al, 2012a). It may be that these particular pseudogenes play an especially important role in cellular adhesion or host immune evasion and are thus less likely to acquire mutations.…”

Intraerythrocytic iridovirus in central bearded dragons (Pogona vitticeps)

“…6,11,44 In addition, PCR was performed with consensus primers for the genus Ranavirus 25 and consensus primers for Rickettsiales groESL. 29 An additional PCR was performed with remaining heparinized blood from lizard no. 12.…”

Epidemiology and Genetic Diversity of Anaplasma phagocytophilum in the San Francisco Bay Area, California

“…sequences are as follows: Lizard 1 (JF487930), Lizard 2 (JF487929), gray squirrel (JF451142), and dusky-footed woodrat (JF451141) were described previously from northern California. 21 MRK, horse origin (JF451139); HZ, human isolate (JF451140); Anaplasma marginale (AY048815); Anaplasma central (NR_076686); and Ehrlichia chaffeensis (NR_076400) are all clinical isolates from North America.…”

“…To specifically identify A. phagocytophilum genotype, we sequenced the 23S-5S rRNA intergenic spacer (rrl-rrs) of each qPCR-positive animal sample using a nested protocol and high-fidelity Phusion taq polymerase (Thermo Fisher Scientific, Waltham, MA). 21 PCR product was further purified using the QIAquick kit (Qiagen) and then sequenced using capillary Sanger sequencing on an ABI 3730 sequencer (EnGGen; Northern Arizona University, Flagstaff, AZ). To initially identify pathogen homology, each sequence was compared with other pathogen sequences available from GenBank using basic local alignment tool (BLAST) (National Center for Biotechnology Information, National Library of Medicine, Bethesda, MD).…”