Rhomboid protease gene expression in the protozoan parasite Tritrichomonas foetus

Bovine trichomoniasis is a sexually transmitted parasitic disease caused by the protozoan Tritrichomonas foetus, infecting both sexes and costing the US beef industry hundreds of millions of dollars annually. Bovine trichomoniasis causes early and occasionally late abortion, extending the breeding and calving seasons, and causes numerous reproductive diseases in females. Males are often asymptomatic. The mechanism of host-cell invasion by T. foetus is still unknown. Rhomboids are trans-membrane proteins that have been shown to play a role in the infection process of protozoan parasites such as those that cause toxoplasmosis and malaria, and are currently under intense study. The recently annotated genome of a related trichomonad, Trichomonas vaginalis, has eight putative rhomboid-like genes. Using the sequences from the T. vaginalis genome, we have characterized rhomboid-like genes from three isolates of T. foetus, Tf-K & Tf-31. Sequencing analysis of the PCR products corresponding to three of the eight gene products revealed approximately 90% homology to the T. vaginalis rhomboid-like genes. RT-PCR based gene expression studies showed differential expression of rhomboid-like genes between the two isolates tested under different physiological conditions. Functional insight of these rhomboids will help us better understand the host-parasite interactions of this important veterinary pathogen.