Molecular detection and characterization of filarioid nematodes in wild armadillos and anteaters from Central-Western Brazil.

Armadillos and anteaters usually interact with a wide range of ectoparasites and associated pathogens. Combined with their unique physiological and ecological characteristics, these interactions make them potential hosts for a diverse range of vector-borne agents (VBA). Despite this, relatively few studies have investigated the occurrence of VBA in mammals of the superorder Xenarthra in Brazil. The present study aimed to investigate the occurrence and phylogenetic assessment of filarioid nematodes in wild armadillos and anteaters sampled in the state of Mato Grosso do Sul, Central-Western Brazil. A total of 123 biological samples, comprising 105 blood and 18 spleen samples, were analyzed. The spleen samples were collected from five southern tamanduas (Tamandua tetradactyla) and 13 giant anteaters (Myrmecophaga tridactyla), whereas the blood samples were obtained from 42 six-banded armadillos (Euphractus sexcinctus), 15 giant armadillos (Priodontes maximus), and 44 giant anteaters (M. tridactyla). Following DNA extraction and confirmation of DNA quality by PCR amplification of the mammalian gapdh gene, all samples were screened for filarioid DNA using a PCR assay targeting the mitochondrial cox1 (cytochrome c oxidase subunit I) gene. Samples testing positive in the screening assay were subsequently subjected to PCR amplification of the mitochondrial 12 S rRNA gene for further molecular characterization. Overall, 53/123 (43.08%) samples were positive in the cox1-based screening PCR, including 24/42 E. sexcinctus, 4/19 P. maximus, 23/57 M. tridactyla, and 2/5 T. tetradactyla samples. Of these, 14/53 (26.41%) were also positive in the PCR targeting the filiarioid 12 S rRNA gene, including 11 E. sexcinctus, one P. maximus, one M. tridactyla, and one T. tetradactyla sample. Phylogenetic analysis based on the cox1 gene showed that the five sequences obtained from E. sexcinctus and the single sequence from P. maximus clustered together in a distinct clade closely related to Onchocerca spp., whereas the sequence obtained from T. tetradactyla formed a separate, isolated lineage. In contrast, phylogenetic analysis based on the 12 S rRNA gene positioned the sequences detected in E. sexcinctus and P. maximus within the same clade as a unclassified Filariidae previously detected in M. tridactyla from Mato Grosso do Sul. To the best of authors' knowledge, this is the first molecular detection of filarioid nematodes in armadillos. Furthermore, phylogenetic analyses based on two independent molecular markers (cox1 and 12 S rRNA) revealed the occurrence of distinct filarioid lineages associated with mammals of the superorder Xenarthra in Brazil, expanding current knowledge on the diversity and host associations of these parasites in neotropical wildlife.