Effect of Homeopathic Medicines on Intestinal Coccidia and Immune Response Cells in Spotted Rose Snapper (Lutjanus guttatus).

BACKGROUND: Homeopathy has been widely applied in freshwater species but rarely in marine fish. Farm stress destabilises host-pathogen equilibrium, favouring parasites and disease. Coccidian endoparasites cause intestinal infections and cell degeneration. MATERIALS AND METHODS: Naturally parasite-infested juvenile snapper Lutjanus guttatus (n = 430; weight 1.9 ± 0.01 g; length 4.9 ± 0.03 cm) specimens were distributed in group sizes of 43, in 10 fiberglass tanks (100 L) with aeration and continuous water change. Five groups in duplicate were assessed: Passival (PaV); Passival and Phosphoricum acid Similia (PaV-PhA); Passival and Silicea terra Similia (PaV-SiT); Endecto and Infecçoes (End-Inf) and a control (Ethanol) for 45 days. Feed was sprinkled with treatment (5% v/w) and dried to avoid ethanol side-effects. Statistical results were expressed as mean ± standard error of the mean. RESULTS: Intestinal coccidia were recorded histopathologically, with the least incidence attained at T45 with End-Inf treatment (p < 0.001), coinciding with the highest lymphocyte (p = 0.015) count. Fish treated with PaV-PhA recorded a higher percentage of neutrophils (p = 0.015), and those treated with PaV-PhA, PaV-SiT and End-Inf revealed a decrease in lesions, degree of alteration and change in intestine and stomach tissues (p < 0.05). The number of mucous cells in gills was greater (p < 0.001) for End-Inf (43 ± 0.58), PaV-SiT (40 ± 2.89) and PaV-PhA (39 ± 3.46) as compared respectively with T0 and control (19 ± 0.58 and 28 ± 2.31). PaV and PaV-SiT increased carbohydrate reserves in liver (28.4 ± 1.39% and 22.4 ± 0.12%, respectively) compared with T0 and control (3.4 ± 0.32 and 5.6 ± 0.66%). The highest survival rate was 97.7 ± 0.16% in fish treated with PaV and End-Inf. CONCLUSION: Homeopathic treatments had a positive effect on fish health. Besides the accumulation of metabolic reserves in the liver, homeopathic treatment was associated with mucin increase in gills as well as raised production of lymphocytes and neutrophils in blood, which could act as macrophages against intestinal coccidia.

Evaluation of DNA vaccination of spotted sand bass (Paralabrax maculatofasciatus) with two major outer-membrane protein-encoding genes from Aeromonas veronii.

Genes encoding two major outer membrane proteins (OMPs) of the bacterial pathogen Aeromonas veronii, Omp38 and Omp48, were used to construct DNA vaccines. The protective effect of such vaccines against motile aeromonad septicaemia was evaluated in spotted sand bass (Paralabrax maculatofasciatus), an endemic species of the Mexican Northwest Pacific coast and a potential resource for the aquaculture industry. Weak protein expression, as determined by immunoblotting, was observed after transfection of eukaryotic cells with the DNA vaccines. Fish immunized with a single intramuscular injection of 20 microg of the omp38 and omp48 DNA vaccines showed slightly, but significantly elevated serum antibody levels 4 and 6 weeks after vaccination, compared to fish vaccinated with the control plasmid pcDNA3.1. Spotted sand bass vaccinated with the omp38 and omp48 DNA vaccines and challenged with A. veronii by intraperitoneal route recorded a relative percent survival (RPS) between 50 and 60%. Histopathological signs of motile aeromonad septicaemia were observed in around 40% of omp38 and omp48-vaccinated fish and 80% of pcDNA3.1-vaccinated control fish. The results indicate that P. maculatofasciatus vaccinated with a single dose of DNA plasmids encoding the major OMPs from A. veronii shows partial protection against infection and mortality by A. veronii experimental infection.