To compare the functional characteristics of CD8αα+hiCD4-TCR1- cells from TCR Cγ−/− birds with their counterparts — CD8αα+hiCD4-TCR1- and CD8αα+hi γδ T cells (TCR1+, CD4-) — from wild-type chickens after infection, we analyzed the transcription levels of immune-related genes in sorted cells using quantitative real-time RT-PCR. This evidence concerns the gene CD4 and infection.