Tissue expression distribution characterization of the host defense peptide dCATH in Anas platyrhynchos

Cathelicidin host defense peptides (cHDPs) widely exist in animals with the functions of innate immunity and acquired immunity. To investigate the tissue and sequential expression patterns of the dCATH gene, which encodes the only cHDPs found in waterfowls, we analyzed the internal organs of healthy ducks (Shaxoxing Sheldrake) from 1-day-old to 28-day-old raised in the natural environment. The dCATH mRNA expression level across tissues was determined via quantitative real-time polymerase chain reaction (qRT-PCR). Monoclonal antibody against the mature dCATH peptide used in enzyme-linked immunosorbent assay (ELISA) was prepared by the lymphocyte hybridoma technique for the first time. The concentration of the dCATH peptide in tissues was determined by ELISA. It showed that the dCATH mRNA had a clear tissue-specificity and age-dependent expression pattern, and it was highly expressed in the bone marrow and moderately expressed in the liver, kidney, spleen, pancreas and bursa of healthy duck. The peptide levels of dCATH in liver, kidney, spleen, pancreas and bursa changed with the age of duck, and the peptide concentration in these organs was between 88 and 128 ng/g tissue. For the first time, we characterized the concentration of the cHDP dCATH in vivo. Our study may represent new insights into the crosstalk of innate immunity, tissue development and age.