Effects of the “all-fish” growth hormone transgene expression on non-specific immune functions of common carp, Cyprinus carpio L.

This study investigated non-specific immune functions of the F2 generation of “all-fish” growth hormone transgenic carp, Cyprinus carpio L. Lysozyme activity was 145.0 (± 30.7) U ml− 1 in the transgenic fish serum and 105.0 (± 38.7) U ml− 1 in age-matched non-transgenic control fish serum, a significant difference (P < 0.01). The serum bactericidal activity in the transgenics was significantly higher than that in the controls (P < 0.05), with the percentage serum killing of 59.5% (± 6.83%) and 50.8% (± 8.67%), respectively. Values for leukocrit and phagocytic percent of macrophages in head kidney were higher in transgenics than controls (P < 0.05). However, the phagocytic indices in the transgenics and the controls were not different. In addition, the mean body weight of the transgenics was 63.4 (± 6.65) g, much higher than that of the controls [39.2 (± 3.30) g, P < 0.01]. The absolute weight of spleen of the transgenics [0.13 (± 0.03) g] was higher than that of the controls [0.08 (± 0.02) g, P < 0.01]. However, there was no difference in the relative weight of spleen between the transgenics and the controls, with the spleen mass index being 0.21% (± 0.02%) and 0.20% (± 0.03%), respectively. This study suggests that the “all-fish” growth hormone transgene expression could stimulate not only the growth but also the non-specific immune functions of carp.