Possible effect of hala extract (Pandanus tectorius) on immune status, anti-tumour and resistance to Yersinia ruckeri infection in rainbow trout (Oncorhynchus mykiss).

The possible effect of dietary administration of hala extract (Pandanus tectorius) on rainbow trout (Oncorhynchus mykiss) immune status as well as its effect as an anti-tumour agent was studied. Fish were divided into 4 groups before feeding with commercial diet (0%, control; 0.5%, 1% and 2% of hala extract) for 2 weeks. The effect of diet on the humoral immune parameters, ie total protein, myeloperoxidase content, antiproteases, lysozyme and bactericidal activities were studied. Also, the effect of the diets on the expression of some immune-related genes in rainbow trout head-kidney (TNF, LYZ2, IL-8 and CD-4) as well as tumour suppressor gene (WT-1a) was investigated. At the end of the feeding trial fish groups were challenged with Yersinia ruckeri. The results demonstrated enhancement in all the immune parameters in fish fed hala extract diets compared to control fish especially with the highest dose (2%) which recorded the highest significant increase (p < 0.05) in some parameters (total protein, myeloperoxidase content, antiproteases, and bactericidal activities) compared to the control. The results obtained from challenge with Y. ruckeri revealed reduction in the mortalities in fish groups fed with 1% and 2% doses of hala extract. Feeding with hala extract provoked upregulation in all immune- related genes. Again, the highest dose of hala extract showed a significant upregulation in WT1a expression (p < 0.05). The current study suggest that the hala extract, especially the highest dose, could be considered a good food additive to improve the immune status, resist tumour formation and to resist or control infectious diseases of rainbow trout.

Role of medicinal plants on growth performance and immune status in fish.

Disease outbreaks increase proportionally with increases in intensive aquaculture. Natural products including medicinal plants have been known from thousands of years for treating some human diseases. It is well known that many active compounds are responsible for potential bio-activities. For that reason, there has been considerable interest in the use of medicinal plants in aquaculture with a view to providing safe and eco-friendly compounds for replacing antibiotics and chemical compounds as well as to enhance immune status and control fish diseases. This article describes a wide range of medicinal plants such as herbs, seeds, and spices with different forms such as crude, extracts, mixed and active compounds, used as immunostimulants and resulting in a marked enhancement in the immune system of fish to prevent and control microbial diseases. Moreover, different activity was recorded from plant parts like seeds, roots, flowers and leaves. The mode of action of medicinal plants was stimulation of the cellular and humoral immune response which was monitored through elevation in immune parameters. Various levels of immune stimulation have been shown by medicinal plants at different concentrations through injection or immersion or oral administration. However, it is critically important to determine the optimal dose to enhance the immune system of fish and avoid the risk of immunosuppression. Some medicinal plants have been used to replace the protein in fishmeal as a cheap source of protein and proved to be efficient in this respect. Medicinal plants can act as a growth promoter and immunomodulator at the same time. Further investigations should be carried out to examine the influence of those plants on fish health (including physiological and histological parameters) as a preliminary step for use in large scale in aquaculture. The current review describes the role of medicinal plants and their derivatives on innate and adaptive immune status as well as growth performance in fish.

An oral chitosan DNA vaccine against nodavirus improves transcription of cell-mediated cytotoxicity and interferon genes in the European sea bass juveniles gut and survival upon infection.

Vaccines for fish need to be improved for the aquaculture sector, with DNA vaccines and the oral administration route providing the most promising improvements. In this study, we have created an oral chitosan-encapsulated DNA vaccine (CP-pNNV) for the nodavirus (NNV) in order to protect the very susceptible European sea bass (Dicentrarchus labrax). Our data show that the oral CP-pNNV vaccine failed to induce serum circulating or neutralizing specific antibodies (immunoglobulin M) or to up-regulate their gene expression in the posterior gut. However, the vaccine up-regulated the expression of genes related to the cell-mediated cytotoxicity (CMC; tcrb and cd8a) and the interferon pathway (IFN; ifn, mx and ifng). In addition, 3 months after vaccination, challenged fish showed a retarded onset of fish death and lower cumulative mortality with a relative survival of 45%. Thus, we created a chitosan-encapsulated DNA vaccine against NNV that is partly protective to European sea bass juveniles and up-regulates the transcription of genes related to CMC and IFN. However, further studies are needed to improve the anti-NNV vaccine and to understand its mechanisms.

Effects of fenugreek (Trigonella foenum graecum) on gilthead seabream (Sparus aurata L.) immune status and growth performance.

The possible effect of dietary administration of fenugreek (Trigonella foenum graecum) on gilthead seabream (Sparus aurata L.) immune status and growth performance was studied. Fish were divided into 4 groups before being fed with commercial diet supplemented with 0% (control), 1%, 5% and 10% of fenugreek seeds for 4 weeks. The effects of the diets were analysed on the cellular (respiratory burst activity and leucocyte peroxidase content) and humoral (complement activity, antiprotease, total protein, peroxidase, and IgM level) immune parameters, as well as growth and haematological parameters (WBC and RBC counts). The results recorded enhancement in all the assayed parameters in fish fed fenugreek diets comparing to control fish. The expression of several immune-related genes in head-kidney (MHC1, CSF-1R, IL-8, and IgM) and different antioxidant enzyme genes in liver (GR, CAT and SOD) of seabream specimens were also investigated. Again, the highest fenugreek doses tested provoked significant up-regulation in most of immune-related genes and antioxidant enzyme genes (p < 0.05). No adverse effects were observed on intestine and liver morphology on fish fed fenugreek diets. The present results suggest that the fenugreek seed, specially the highest dosage used in the present work could be considered a good food supplement to improve the immune status and increase the production of gilthead seabream.

Effects of dihydroquercetin obtained from deodar (Cedrus deodara) on immune status of gilthead seabream (Sparus aurata L.).

The use of medicinal plants as prophylactic method in fish is considered safe and a very promising alternative to the use of chemicals in aquaculture practices. The prospective mode of action of dihydroquercetin, fraction of the medical plant deodar (Cedrus deodara), was evaluated on immune status of gilthead seabream (Sparus aurata L.). Fish were divided into 4 groups before being fed for 14 days with commercial diets supplemented with 0% (control), 0.1%, 0.5% and 1% of dihydroquercetin. Cellular (phagocytosis and respiratory burst activities) and humoral (seric complement activity, antiprotease, total protein, peroxidase, bactericidal activity and IgM level) immune parameters were investigated. The results recorded enhancement in all the tested parameters and in all the dihydroquercetin supplemented groups compared to the control. Interestingly, the fish received the lowest dose of dihydroquercetin (0.1%) showed a highly significant difference (p < 0.05) in phagocytosis, respiratory burst, IgM level, total protein, complement, antiprotease and bactericidal activities compared to the control. Direct effect of different doses of dihydroquercetin on head-kidney leucocytes was also studied in a previous in vitro assay. Again, the lowest doses tested provoked the highest immune cellular activities, where, the highest phagocytic and respiratory bust activities were recorded in leucocytes incubated with 0.025% and 0.0125% doses, respectively. Therefore, the results suggest that low concentrations of dihydroquercetin as food supplements are able to increase the immune status of gilthead seabream.

Anti-leishmanial activities of extracts and isolated compounds from Drechslera rostrata and Eurotium tonpholium.

The fungal extract of Drechslera rostrata and Eurotium tonpholium showed a significant anti-leishmanial activity against Leishmania major; IC50 was 28.8 and 28.2 µg/mL, respectively. Seven compounds, five from D. rostrata (H1-H5) and two from E. tonpholium (H6 and H7), were isolated and identified using different spectroscopic analysis including (1) HNMR, (13) CNMR, Hetero-nuclear multiple bond connectivity (HMBC), Hetero-nuclear Multiple Quantum Correlation (HMQC), and EI-MS. The isolated compounds are: di-2-ethylhexyl phthalate (1), (22E)-5α,8α-epidioxyergosta-6,22-diene-3ß-ol (2),1,3,8-trihydroxy-6-methyl-nthraquinone (3), aloe-emodine 8-O-glucopyranoside(4), 2R, 3R,4R,5R hexane 1, 2, 3, 4, 5, 6 hexole (Mannitol) (5), 1,8-dihydroxy-3-methoxy-6-methyl-anthraquinone (6) and 1, 4, 5-trihydroxy-7-methoxy-2-methyl-anthraquinone (7). However, compounds (1) and (6) showed activity against L. major with IC50 of 3.2 and 10.38 µg/mL, respectively. On the other hand, oral administration of the two extracts (100 mg/kg) and compounds 1 and 6 (50 mg/kg) showed very good activity when compared with the anti-leishmanial drug Pentostam (125 mg/kg). Interestingly, the complete heeling activity of the extracts and compounds (1) and (6) was obtained after 13-17 days of treatment, while complete healing activity of Pentostam was obtained after 28 days. No alteration on liver and kidney functions was recorded on animals treated with the two extracts for 15 consecutive days.