Unveiling the functional landscape of A-to-I RNA editing associated with Marek’s disease in chickens

Genetic improvement of disease resistance against viral infections represents a longstanding and formidable challenge in animal breeding. The antiviral innate immune response is highly regulated at the RNA level, especially through RNA modifications. Adenosine-to-Inosine (A-to-I) RNA editing modifies the mRNA sequence. Growing evidence shows that this type of RNA editing plays a key role in mediating cellular responses to viral infections and disease resistance. However, the role of RNA editing in cellular response to MD remains unclear. In this study, we examined A-to-I editing in CD4 + T cells during Marek’s disease virus (MDV) infection. By comparing MD-resistant and susceptible chicken lines, we identified 642 A-to-I RNA editing events in CD4 + T cells, most of which were located within repeat elements, particularly in the CR1 family. We observed differences in RNA editing levels and counts between the two chicken lines with different infection statuses, indicating distinct editing patterns across genetic backgrounds and infection states. Additionally, ADAR (adenosine deaminases acting on RNA) expression was correlated with RNA editing frequency. We identified 21 RNA editing sites (RESs) associated with gene expression and 42, 14, and 38 RESs with predicted effects on amino acid sequences, alternative splicing, and miRNA-target binding, respectively. A comparative analysis revealed 131 group-specific RESs and 21 RESs shared across groups. Functional enrichment analysis of genes associated with group-specific RESs highlighted several terms related to MD resistance, including the MHC class I protein complex in non-infected MD-resistant birds. Significantly, we identified two L63-specific candidate RNA editing sites, chr6:26,600,122 in MXI1 and chr16:1,716,632 in MHCY57 , which were predicted to affect gga-miR-1759-3p binding and amino acid sequence, respectively. Our findings reveal the landscape of A-to-I RNA editing in CD4 ⁺ T cells during MDV infection and provide new insights into its potential association with immune regulation and MD resistance.