Abstract
BackgroundHepatozoon canis is a protozoan transmitted to dogs and other wild carnivores by the ingestion of ticks containing mature oocysts and is considered the principal cause of canine hepatozoonosis in the world. Here, we examined ribosomal RNA 18S gene sequence variation to determine the genetic differences and phylogeographic diversity of H. canis from various geographical areas around the world.MethodsWe used 550 publicly available sequences of H. canis from 46 countries to assess haplotype relationships, geographical structure, genetic diversity indices, and relationships among populations. We performed neutrality tests and pairwise comparisons of fixation index (FST) values between groups and pairwise comparisons of FST values between populations. To determine whether populations are structured, analyses of molecular variance (AMOVAs) and spatial analysis of molecular variance (SAMOVA) were performed.ResultsThe dataset of H. canis yielded 76 haplotypes. Differentiation among populations indicated that there is no phylogeographical structure (GST = 0.302 ± 0.0475). Moreover, when samples were grouped by continents a significant FST was obtained, meaning that populations were genetically differentiated. The AMOVA showed that 57.4% of the genetic variation was explained by differences within populations when all locations were treated as a single group and revealed that there is no population structure when populations are grouped into two, three, and four groups (FCT, p > 0.05), suggesting that dispersal between populations is high. SAMOVA revealed significant FCT values for groups K = 5. The Tajima’s D and Fu’s Fs show that populations have undergone recent expansion, and the mismatch distribution analysis showed population expansion (multimodal distribution).ConclusionsThe current molecular data confirmed that H. canis does not show phylogeographic or population structure. The haplotypes exhibit low genetic differentiation, suggesting a recent expansion due to gene flow among populations. These results provide pivotal information required for future detailed population genetic analysis or to establish control strategies of this parasite.Graphical abstract
Highlights
Hepatozoon canis is a protozoan transmitted to dogs and other wild carnivores by the ingestion of ticks containing mature oocysts and is considered the principal cause of canine hepatozoonosis in the world
Sequence selection To define the final dataset of sequences included in this study, several filtering steps were applied as follows: (1) a total of 1170 sequences were downloaded from the ENA/ GenBank database using as searching criteria “Hepatozoon canis” to discard any sequences not identified to species level (Hepatozoon sp.); (2) 55 sequences without complete metadata lacking host and country of origin were discarded; (3) sequences with duplicated accession number or missed annotations from parasites different from H. canis were not selected; (4) considering an observed wide range in sequence length between 140 bp and 3.1 kbp, sequences < 500 bp were omitted from further analysis
It was followed by haplotypes H7 (18%, 99/550 sequences) in populations located in the Old World and H9 (13.3%, 73/550 sequences) retrieved in populations located in the four continents
Summary
Hepatozoon canis is a protozoan transmitted to dogs and other wild carnivores by the ingestion of ticks containing mature oocysts and is considered the principal cause of canine hepatozoonosis in the world. The vector-borne pathogens of the genus Hepatozoon infect a wide range of species of mammals, reptiles, amphibians, and birds [1,2,3,4,5] These parasites are Vásquez‐Aguilar et al Parasites Vectors (2021) 14:467 transmitted by different groups of arthropods including ticks, lice, mosquitoes, mites, sand flies, tsetse flies, kissing bugs, and leeches [6,7,8]. Hepatozoon americanum and H. canis are protozoa transmitted to dogs and other wild carnivores by ingestion of ticks containing mature oocysts [9, 10] Both H. americanum and H. canis are reported in canids, the latter is widely spread and is considered the principal cause of canine hepatozoonosis in the world [11]. Following ingestion of infected ticks, H. canis sporozoites spread via the bloodstream and lymph to several organs including the spleen, bone marrow, lung, liver, and kidney, infecting leukocytes and parenchymal tissue cells
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