CDR3 analysis of TCR Vβ repertoire of CD8+ T cells from chickens infected with Eimeria maxima

• Frequent CDR3 motifs of CD8+ T cells were observed in chickens.
• Chickens were immunized and challenged with Eimeria maxima.
• One common CDR3 motif was found in E. maxima infected or uninfected birds.

CD8+ T cells play a major role in the immune protection of host against the reinfection of Eimeria maxima, the most immunogenic species of eimerian parasites in chickens. To explore the dominant complementarity-determining regions 3 (CDR3) of CD8+ T cell populations induced by the infection of this parasite, sequence analysis was performed in this study for CDR3 of CD8+ T cells from E. maxima infected chickens. After 5 days post the third or forth infection, intraepithelial lymphocytes were isolated from the jejunum of bird. CD3+CD8+ T cells were sorted and subjected to total RNA isolation and cDNA preparation. PCR amplification and cloning of the loci between Vβ1 and Cβ was conducted for the subsequent sequencing of CDR3 of T cell receptor (TCR). After the forth infection, 2 birds exhibited two same frequent TCR CDR3 sequences, i.e., AKQDWGTGGYSNMI and AGRVLNIQY; while the third bird showed two different frequent TCR CDR3 sequences, AKQGARGHTPLN and AKQDIEVRGPNTPLN. No frequent CDR3 sequence was detected from uninfected birds, though AGRVLNIQY was also found in two uninfected birds. Our result preliminarily demonstrates that frequent CDR3 sequences may exist in E. maxima immunized chickens, encouraging the mining of the immunodominant CD8+ T cells against E. maxima infection.

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