Shrimp that have received carrageenan via immersion and diet exhibit immunocompetence in phagocytosis despite a post-plateau in immune parameters.

The effect of carrageenan on the immune response of white shrimp Litopenaeus vannamei, was studied in vitro and in vivo. Shrimp haemocytes receiving carrageenan at 1 mg ml⁻¹ experienced change in cell size, reduction in cell viability, increase in PO activity, serine proteinase activity, and RB in vitro. Shrimp received carrageenan via immersion at 200, 400 and 600 mg L⁻¹ after 3 h and orally at 0.5, 1.0 and 2.0 g kg⁻¹ after 3 weeks showed higher proliferation of haematopoietic tissues (HPTs) together with increases in haemocyte count and other immune parameters. Shrimp that fed a diet containing carrageenan at 0.5 g kg⁻¹ after 3 weeks significantly up-regulated gene expressions of several immune-related proteins. The immune parameters of shrimp that received carrageenan via immersion and orally increased to a plateau after 3 h and after 3 weeks, but decreased after 5 h and 6 weeks, respectively. Phagocytosis and clearance of Vibrio alginolyticus remained high in shrimp that had received carrageenan via immersion after 5 h and orally after 6 weeks, respectively. Resistances of shrimp against V. alginolyticus and white spot syndrome virus were higher over 24-144 h and 72-144 h, respectively in shrimp that received carrageenan at 600 mg L⁻¹ via immersion after 3 and 5 h. It was concluded that carrageenan effectively triggers an innate immunity in vitro, and increases mitotic index of HPT, immune parameters, gene expressions and resistance against pathogens in vivo. Shrimp received carrageenan via immersion and orally exhibited immunocompetence in phagocytosis and clearance of V. alginolyticus, and resistance to pathogen despite the trend in immune parameters to recover to background values.

Fucoidan effectively provokes the innate immunity of white shrimp Litopenaeus vannamei and its resistance against experimental Vibrio alginolyticus infection.

In this study, we examined the effect of fucoidan on the immune response of white shrimp Litopenaeus vannamei and its resistance against Vibrio alginolyticus infection. Fucoidan induced degranulation, caused changes in the cell morphology, and increased activation of prophenoloxidase (proPO) and the production of superoxide anions in vitro. Shrimp that received fucoidan via immersion at 100, 200, and 400 mg l(-1) after 3 h showed haemocyte proliferation and a higher mitotic index of haematopoietic tissue. In another experiment, the haemocyte count, phenoloxidase (PO) activity, and respiratory bursts (RBs) were examined after the shrimp had been fed diets containing fucoidan at 0 (control), 0.5, 1.0, and 2.0 g kg(-1) for 7-21 days. Results indicated that these parameters directly increased with time. The immune parameters of shrimp fed the 1.0 g kg(-1) diet were significantly higher than those of shrimp fed the 2.0 g kg(-1) diet after 14 and 21 days. Phagocytic activity and the clearance efficiency against V. alginolyticus were significantly higher in shrimp fed the 1.0 g kg(-1) diet compared to those of shrimp fed the 0, 0.5 and 2.0 g kg(-1) diets. In a separate experiment, shrimp that had been fed diets containing fucoidan for 21 days were challenged with V. alginolyticus at 10(6) colony-forming units shrimp(-1). Survival rates of shrimp fed the 1.0 and 2.0 g kg(-1) diets were significantly higher than those of shrimp fed the 0 and 0.5 g kg(-1) diets for 96-120 h. We concluded that fucoidan provokes innate immunity of shrimp as evidenced by haemocyte degranulation, proPO activation, and the mitotic index of haematopoietic tissue, and that dietary administration of fucoidan at 1.0 g kg(-1) enhanced the immune response of shrimp and their resistance against V. alginolyticus infection.

Dietary administration of a Gracilaria tenuistipitata extract enhances the immune response and resistance against Vibrio alginolyticus and white spot syndrome virus in the white shrimp Litopenaeus vannamei.

The haemogram, phenoloxidase (PO) activity, respiratory bursts (RBs), superoxide dismutase (SOD) activity, glutathione peroxidase (GPx) activity, lysozyme activity, and the mitotic index of haematopoietic tissue (HPT) were examined after the white shrimp Litopenaeus vannamei had been fed diets containing the hot-water extract of Gracilaria tenuistipitata at 0 (control), 0.5, 1.0, and 2.0 g kg(-1) for 7-35 days. Results indicated that these parameters directly increased with the amount of extract and time, but slightly decreased after 35 days. RBs, SOD activity, and GPx activity reached the highest levels after 14 days, whereas PO and lysozyme activities reached the highest levels after 28 days. In a separate experiment, white shrimp L. vannamei, which had been fed diets containing the extract for 14 days, were challenged with Vibrio alginolyticus at 2 × 10(6) cfu shrimp(-1) and white spot syndrome virus (WSSV) at 1 × 10(3) copies shrimp(-1), and then placed in seawater. The survival rate of shrimp fed the extract-containing diets was significantly higher than that of shrimp fed the control diet at 72-144 h post-challenge. We concluded that dietary administration of the G. tenuistipitata extract at ≤1.0 g kg(-1) could enhance the innate immunity within 14 days as evidenced by the increases in immune parameters and mitotic index of HPT in shrimp and their enhanced resistance against V. alginolyticus and WSSV infections. Shrimp fed the extract-containing diets showed a higher and continuous increase in the humoral response indicating its persistent role in innate immunity.

Administration of the hot-water extract of Spirulina platensis enhanced the immune response of white shrimp Litopenaeus vannamei and its resistance against Vibrio alginolyticus.

White shrimp Litopenaeus vannamei which had been injected with the hot-water extract of Spirulina platensis at 6, 10, and 20 microg g(-1), or immersed in aerated seawater containing extract at 200, 400, and 600 mg L(-1) were challenged with Vibrio alginolyticus at 1.5 x 10(6) or 1.4 x 10(6) colony-forming units (cfu) shrimp(-1), and then placed in seawater. Survival rates of shrimp that received the extract of S. platensis at 6-20 microg g(-1), and those of shrimp immersed in seawater containing the extract at 400 and 600 mg L(-1) were significantly higher than those of control shrimp after 24-96 and 48-96 h, respectively. In a separate experiment, the hyaline cell (HC) count, granular cell (GC, including semi-granular cell) count, total haemocyte count (THC), phenoloxidase (PO) activity, respiratory burst (RB), superoxide dismutase (SOD) activity, glutathione peroxidase (GPx) activity, and lysozyme activity were measured when shrimp were injected with the extract at 6, 10, and 20 microg g(-1), and immersed in seawater containing the extract at 200, 400, and 600 mg L(-1). These parameters directly increased with the concentration, and significantly increased when shrimp were immersed in the seawater containing the extract at 0.5-4 h. L. vannamei that received all doses of the extract via injection or via immersion all had increased phagocytic activity and clearance efficiency to V. alginolyticus at 12-72 h and 3-4 h, respectively. It was concluded that L. vannamei that received the hot-water extract of S. platensis had enhanced innate immunity and increased resistance against V. alginolyticus infection.