Differential Gene Expression Profiling during Avian Immune Organ Development: Insights from Thymus and Bursa of Fabricius Transcriptome Analysis

Pluripotent hematopoietic stem cells undergo maturation to regenerate blood cells. T-cell and B-cell maturation from common lymphoid progenitors (CLPs) is regulated by distinct transcription factors and signaling pathways. Notch signaling, GATA3, and TCF1 drive T-cell fate, while EBF1, PU.1, E2A, Pax5, TCF1, and Foxo1 regulate B-cell differentiation. Alterations in these factors can cause lineage deviations. Gene expression profiling of the chick thymus and bursa reveals dynamic expression patterns of transcription factors, cytokines, and signal molecules. Notch1 and Dll1 expression that increase during later stages indicate the ongoing role of Notch signaling in T-cell lineage maintenance. The current study aimed to identify differentially expressed genes during the development of the avian immune organs, focusing on the thymus and bursa using 24 Ross 308 avian breed. The mRNA libraries from these organs were analyzed using quantitative Real-time PCR analysis at six time points spanning the embryonic ages (days 15 and 18) and post-hatch age (days 3, 7, 14, and 28). The data for the gene expression indicated significant variations across different stages of immune organ development. Differential gene expression was observed between sorted T and B-cells, with GATA3, CD3e, CD4, and Ptprc showing higher expression in the T-cell population, and Pax5 and CD81 exhibiting higher expression in the B-cell population. Notably, ENO1 and IRF4 showed higher expression in T-cells at E15 and B-cells at E18. The study highlights the importance of regulatory factors and genes in maintaining cellular identity, furthers the understanding of avian immunology, and has the potential for improving poultry health and studying immune-related diseases in humans. These findings pave the way for further research on the role of biochemical components under important disease conditions in avian immunology and their potential applications for poultry health.