Characterization of two thymosins as immune-related genes in common carp (Cyprinus carpio L.)

• Full cDNA sequences of two common carp thymosins have been identified.
• The expression patterns of common carp thymosin genes in different tissues and during embryogenesis have been determined.
• The transcriptional changes of carp thymosin genes after spring viraemia of carp virus (SVCV) infection have been detected.
• The expressions of T lymphocyte-related genes increased after transient over-expression of carp thymosins in zebrafish.

Prothymosin alpha (ProTα) and thymosin beta (Tβ) belong to thymosin family, which consists of a series of highly conserved peptides involved in stimulating immune responses. ProTα b and Tβ are still poorly studied in teleost. Here, the full-length cDNAs of ProTα b and Tβ-like (Tβ-l) were cloned and identified in common carp (Cyprinus carpio L.). The expressions of carp ProTα b and Tβ-l exhibited rise-fall pattern and then trended to be stable during early development. After spring viraemia of carp virus (SVCV) infection, the carp ProTα b and Tβ-l transcripts were significantly up-regulated in some immune-related organs. When transiently over-expressed carp ProTα b and Tβ-l in zebrafish, these two proteins up-regulated the expressions of T lymphocytes-related genes (Rag 1, TCR-γ, CD4 and CD8α). These results suggest that carp ProTα b and Tβ may ultimately enhance the immune response during viral infection and modulate the development of T lymphocytes in teleost.