Identification of a putatively novel trichomonad species in the intestine of a common quail (Coturnix coturnix)

Abstract

A common quail (Coturnix coturnix) from a private keeping died unexpectedly and showed a moderate lymphocytic infiltration of the colonic mucosa associated with numerous protozoa-like objects at the pathological examination. These organisms were further identified using chromogenic in situ hybridization (ISH) and gene sequencing. ISH was performed on paraffin embedded tissue sections and produced a positive signal using a probe specific for the 18S ribosomal RNA (rRNA) gene of the order Trichomonadida, but remained negative with probes specific for the 18S rRNA gene of the common bird parasites Histomonas meleagridis, Tetratrichomonas gallinarum or Trichomonas gallinae. The trichomonads were found on the mucosal surface, inside the crypts and also immigrating into the lamina propria mucosae. DNA was extracted from the paraffin embedded tissue and the entire 18S rRNA gene, ITS-1 region, 5.8S rRNA gene, ITS-2 region and a part of the 28S rRNA gene were sequenced using primer walking. The acquired sequence showed 95% homology with Tritrichomonas foetus, a trichomonad never described in birds. A phylogenetic analysis of a part of the 18S rRNA gene or of the ITS-1, 5.8S and ITS-2 region clearly placed this nucleotide sequence within the family of Tritrichomonadidae. Therefore, the authors propose the detection of a putative new Tritrichomonas sp. in the intestine of a common quail.