Transcriptome Changes Associated with Protective Immunity in T and B Cell-Deficient Rag1-/- Mutant Zebrafish

To elucidate the basis of protective immunity in T and B cell deficient rag1-/- mutant zebrafish, we conducted microarray analysis of 15,617 genes from rag1-/- mutant zebrafish 48 hours after a primary response and 48 hours after a secondary response. Following primary exposure, the highest fold expression differences (3.8 to 4.95) were genes for serum amyloid A, chemokine CCL-C5a (CCL-19a), signal transducer and activator of transcription (STAT) 1b, interferon regulatory factor 11, and myxovirus resistance A. Strong induction of these genes demonstrated that primary immune responses and innate immune cells were not impaired in T and B cell deficient mutant zebrafish. Following bacterial re-exposure, the highest fold expression differences (2 to 3 fold) were in chemokine CCL-C5a (CCL-19a), myomegalin, bone morphogenetic protein 4, and relaxin 3a. These genes are involved in the immune response and cell proliferation. Genes for cell receptor activation and signal transduction, cell proliferation and cytotoxic functions were also up-regulated. These findings suggest receptor activation and expansion of a cell population. Increased ifnγ expression at 48 hpi was associated with both primary and secondary immune responses.