Phylogenetic Inferences Based on Distinct Molecular Markers Confirm a Novel Babesia Species (Babesia goianiaensis nov. sp.) in Capybaras (Hydrochoerus hydrochaeris) and Associated Ticks

Abstract

Piroplasmids (order Piroplasmida) are a diverse group of tick-borne protozoa that may cause disease in animals and occasionally in humans. Novel Piroplasmida clades and species have been found in wild animals from Brazil based on the phylogenetic assessment of near-complete 18S rRNA, mitochondrial and heat-shock protein genes. For instance, a putative novel Babesia species has been detected in capybaras and Amblyomma ticks in three Brazilian states. The present work aimed to describe, using phylogenetic assessments based on distinct molecular markers, this novel Babesia species in capybaras and associated ticks (Amblyomma sculptum and Amblyomma dubitatum) sampled in Goiânia city, Goiás state, midwestern Brazil. While the phylogenetic analysis based on both near-complete 18S rRNA and hsp-70 genes positioned the sequences obtained from capybara blood samples into a new clade sister to the Babesia sensu stricto clade, the phylogenetic inference based on the COX-3 amino acid positioned the obtained sequences from capybara blood samples and A. sculptum ticks also into a clade sister to the Theileria sensu stricto clade, highlighting the inappropriateness of this marker inferring evolutionary relationships among piroplasmids. Pairwise distance analysis demonstrated that the divergence rates between the 18S rRNA sequences detected in capybaras and other Piroplasmida already described were very high and ranged from 9.4 to 12.9%. Genotype analysis based on the near-full 18S rRNA sequences of the Piroplasmida detected in capybaras and associated ticks demonstrated the occurrence of high genotype diversity at an intra-species level. In conclusion, phylogenetic analyses based on distinct molecular markers supported the description of Babesia goianiaensis nov. sp. in capybaras and associated Amblyomma ticks. Additionally, a novel phylogenetic clade, apart from the previously described ones, was described in the present study and contributed to untangling the complex evolutionary history of the Piroplasmida.

Susceptibility of Amblyomma sculptum, Vector of Rickettsia rickettsii, Ticks from a National Park and an Experimental Farm to Different Synthetic Acaricides

“…Our results did not confirm deltamethrin resistance in the studied A. sculptum populations, but indicate a tolerance to cypermethrin in the GYN strain. The finding of deltamethrin resistance by Freitas et al [16] may be attributed to the fact that ticks used were collected from horses and had a greater exposure to this synthetic pyrethroid, which is the most common acaricide used on horses [9]. On the contrary, our ticks were collected from the environment in an experimental farm where ticks are less exposed to deltamethrin or other synthetic pyrethroids.…”

“…These ticks are commonly found in tropical and subtropical moist broadleaf forests and grasslands savannas [6]. Amblyomma sculptum, which is a member of the Amblyomma cajennense complex, is the principal vector of Rickettsia rickettsii, the main agent of spotted fever rickettsiosis in Brazil [7,8], and can possibly transmit other pathogens to horses and other animals [9]. Therefore, its control is extremely important from a One Health perspective.…”