In order to understand T. ovatus response to C. irritans and S. iniae co-infection at the transcriptomic level, we examined the gene expression pattern in spleen of single and co-infection at 2 days post infection. By comparing the gene expression pattern of single and co-infection groups, we discovered that expression of many important immune-related genes suppressed differentially after the challenge. This result provides important recourses to understanding the molecular mechanism of C. irritans and S. iniae co-infection in T. ovatus. Twelve samples were used in this program and divided into four groups for C.irritans single infection group, S .iniae single infection group, co-infection group and PBS injection group as the control. Three replicates in each group.