Effects of Prunella vulgaris labiatae extract on specific and non-specific immune responses in tilapia (Oreochromis niloticus)

We examined the effects of Prunella vulgaris Labiatae (P. vulgaris L.) on specific and non-specific immune responses of Nile tilapia, Oreochromis niloticus. The optimal concentration without toxicity of P. vulgaris was determined to 30-40 μg/ml in vitro and 120 μg/100 g of fish in vivo. P. vulgaris significantly elicited an antibody titer compared to FCA or β-glucan. β-glucan plus P. vulgaris group synergistically enhanced antibody production. No significant difference in antibody production was observed between P. vulgaris and P. vulgaris plus β-glucan group. A respiratory burst activity of head kidney (HK) leucocytes of tilapia administered with 300 or 500 μg P. vulgaris was significantly (p < 0.05) enhanced compared with the PBS-injected control group and FCA-treated group. Maximum increase in the NBT reduction value was observed in 500 μg P. vulgaris group but no significant difference was found between 300 and 500 μg P. vulgaris group. The level of serum lysozyme activity was significantly (p < 0.05) higher in the 300 and 500 μg P. vulgaris than 100 μg P. vulgaris and FCA group. The phagocytic activities of HK leucocytes from tilapia administered with 300 and 500 μg P. vulgaris were significantly (p < 0.05) higher than 100 μg P. vulgaris and the control group. P. vulgaris was revealed with a good immunoadjuvant evoking the specific and non-specific immune responses of tilapia.