Real-time polymerase chain reaction was used to characterize the temporal distribution of transcripts of two cathepsins in different developmental stages of Trichobilharzia regenti: cathepsin B1 originally described from the gut lumen of schistosomula with presumptive role in nutrient digestion and cathepsin B2 originally found in penetration glands of cercariae with probable involvement in invasion of the final host. The mRNA expression profiles clearly show distinct expression of cathepsins B1 and B2 during the development from eggs to cercariae.
In the case of both cathepsins, the highest level of transcription was detected in intravertebrate stages.