Comparison of the 5.8S rRNA gene and internal transcribed spacer regions of trichomonadid protozoa recovered from the bovine preputial cavity

California Animal Health and Food Safety Laboratory, School of Veterinary Medicine, University of California, Davis, CA 95616, USA.

Sequence analysis of the 5.8S rRNA gene and the internal transcribed spacer regions (ITSRs) was used to compare trichomonadid protozoa (n = 39) of varying morphologies isolated from the bovine preputial cavity. A multiple sequence alignment was performed with bovine isolate sequences and other trichomonadid protozoa sequences available in GenBank. As a group, Tritrichomonasfoetus isolates (n = 7) had nearly complete homology. A similarity matrix showed low homology between the T. foetus isolates and other trichomonads recovered from cattle (<70%). Two clusters of trichomonads other than T. foetus were identified. Eighteen isolates comprised 1 group. These isolates shared >99% homology among themselves and with Pentatrichomonas hominis. The other non-T. foetus cluster (n = 14) did not exhibit a high degree of homology (<87%) with other bovine isolates or any of the trichomonad sequences available in GenBank. The sequence homology among isolates in that cluster was >99%, except for 1 isolate that varied from the others in both ITSRs (approximately 2% dissimilarity). Sequence analysis of the 5.8S rRNA gene and ITSRs was useful for comparing trichomonadid protozoa isolated from the bovine preputial cavity and demonstrated that 2 distinct types of trichomonads constituted the non-T. foetus isolates recovered from the bovine preputial cavity.