Therapeutic Effects of Psoralea corylifolia and Morus alba Aqueous Extracts on Tetrahymena pyriformis-Infected Guppies (Poecilia reticulata) and Underlying Transcriptomic Mechanisms: Implications for Ciliate Parasite Control.

Tetrahymena pyriformis is biologically similar to Ichthyophthirius multifiliis, the parasite that causes "white spot disease" in fish. Because it has immune evasion genes and grows quickly, T. pyriformis serves as an ideal model for developing treatments against I. multifiliis and related parasites. This study tested water extracts from 10 traditional Chinese herbs against T. pyriformis and identified 5 with strong antiparasitic effects: Morus alba, Psoralea corylifolia, Sophora flavescens, Polygonum cuspidatum, and Pomegranate Peel. Combination tests showed that certain pairs, especially P. corylifolia with M. alba, worked together synergistically. When infected guppies were treated with this herbal combination at a concentration of 1.39 g/L (1:144 dilution), their 10-day survival rate reached 66.7%. Gill tissue analysis identified 577 genes with changed activity after treatment-228 increased and 349 decreased. These genes were linked to immune responses, metabolism, and cell processes. The key differentially expressed genes include those involved in the IL-17 signaling pathway, amino sugar metabolism, and the cytosolic DNA-sensing pathway. These results show that the herbal combination works by both directly killing parasites and boosting the fish's immune system. This study provides a scientific basis for using natural herbal treatments as an eco-friendly way to control parasitic diseases in aquaculture.