Phylogenetic insights on Leishmania detected in cats as revealed by nucleotide sequence analysis of multiple genetic markers

摘要

Cats have been found infected by the same Leishmania species that also infect dogs and humans in both the New and Old Worlds, and their role as additional reservoir hosts of L. infantum has been previously suggested. Currently, the genetic diversity of Leishmania spp. detected in cats is poorly understood. In this cross-sectional study, the partial nucleotide sequences of four gene markers (cytB, g6pdh, hsp70 and ITS-rDNA) were explored to investigate the genetic diversity and the phylogenetic relationships of Leishmania parasites detected in cats. A total of 25 cat buffy coat samples where the presence of Leishmania SSU-rDNA was revealed by PCR (from a convenience sample of 465 cats screened), as well as six Leishmania strains previously isolated from cats, were included in this study. Phylogenetic analyses showed that the majority of Leishmania parasites detected in cats did not display distinctive genetic features, sharing the same genetic types with L. infantum strains isolated from humans, dogs and phlebotomine sand flies. Unexpectedly, DNA of L. major and/or of a L. major/L. donovani sensu lato hybrid was detected in buffy coat samples of two cats from different regions of Portugal. However, a mix infection hypothesis cannot be formally excluded. To our knowledge, this study represents the first evidence for the presence of DNA of Leishmania hybrid parasites in cats. The results reported here not only reinforce the idea that cats play a role in the epidemiology of zoonotic leishmaniosis but also indicate the circulation of L. major and/or L. major/L. donovani s.l. hybrid parasites in Portugal. Also, whenever sequencing of whole Leishmania genomes regularly cannot be accomplished, and while their complete genomes remain under-represented in the nucleotide sequence databases, the combined use of multiple genetic markers, including kinetoplast maxicircle DNA, seems to be essential for typing of Leishmania parasites.