Inhibition of luminous Vibrio harveyi by "green water" obtained from tank culture of tilapia, Oreochromis mossambicus

Background. Luminous vibriosis caused by Vibrio harveyi, is a serious disease problem in shrimp aquaculture. The use of "green water", a technique that involves the stocking of tilapia, Oreochromis in the reservoir for the production of green microalgae, Chlorella is believed to help in the reduction of the incidence of luminous vibriosis. Though most shrimp farmers have been using Mozambique tilapia, Oreochromis mossambicus for the production of "green water", the mechanism involved in the efficiency of using this fish species in reducing luminous vibriosis remains unknown and is largely based on speculations. It was for this reason that the present experiment was conducted. The aim of the study was to determine the antibacterial activity of "green water" obtained from tank culture of Oreochromis mossambicus against Vibrio harveyi under laboratory conditions. Materials and methods. "Green water" collected from broodstock and juvenile tanks of Oreochromis mossambicus as well as water from a commercial shrimp pond, and filtered boiled seawater were inoculated with Vibrio harveyi. Luminous bacteria were counted in nutrient agar, while presumptive and green colony-forming vibrios were determined on thiosulfate-citrate bile salt (TCBS). The experiment was carried out for one week. Results. Luminous bacteria were not detected, and the presumptive and the green colony-forming vibrios were generally lowest in "green water" obtained from the broodstock tank. Luminous bacteria in "green water" obtained from juvenile tank were not detected starting day 5, indicating delayed inhibition. Conclusion. The present findings show that "green water" from broodstock tank of O. mossambicus has the ability to inhibit luminous vibriosis over a one-week period, and that broodstock are a better source of "green water" than juveniles in controlling luminous vibriosis

Differential expression of immune and stress genes in the skin of Atlantic cod (Gadus morhua)

The present study describes the transcriptional profiles of selected immune and stress genes with putative important roles in the cutaneous immune defense of Atlantic cod (Gadus morhua). In addition it shows differential expression of many genes at the dorsal and ventral sides of fish, in general having the highest expression at the latter side. Genes related to antibacterial activity, antiviral response, cytokine production, glucose transport, stress response and anti-apoptotic activity were monitored and bactericidal/permeability-increasing protein/lipopolysaccharide-binding protein (BPI-LBP), g-type lysozyme, transferrin, metallothionein, fortilin, interferon regulatory factor-1 (IRF-1), a CC chemokine isoform, interleukin-8 (IL-8), glucose transport (GLUT)-1, -3 and -4, Cu,Zn-superoxide dismutase (Cu,Zn-SOD), catalase and hsp 70 showed significantly higher expression at the ventral side. Further g-type lysozyme, metallothionein, fortilin, IRF-1, interferon ¿, interleukin-1ß (IL-1ß), GLUT-3 and -4, catalase and anti apoptotic gene Bcl-X1 were highly expressed in adult cod skin. Therefore fish skin can be considered an immunological active site, especially at the ventral side of Atlantic co

Proteome reference map of the skin mucus of Atlantic cod (Gadus morhua) revealing immune competent molecules

The skin mucosal proteome of Atlantic cod (Gadus morhua) was mapped using a 2D PAGE, LC–MS/MS coupled approach. Mucosal proteins from naive fish were identified primarily by similarity searches across various cod EST databases. The identified proteins were clustered into 8 groups based on gene ontology classification for biological process. Most of the proteins identified from the gel are hitherto unreported for cod. Galectin-1, mannan binding lectin (MBL), serpins, cystatin B, cyclophilin A, FK-506 binding protein, proteasome subunits (alpha-3 and -7), ubiquitin, and g-type lysozyme are considered immune competent molecules. Five of the aforementioned proteins were cloned and their tissue distribution was analysed by RT-PC

Evaluation of immune and apoptosis related gene responses using an RNAi approach in vaccinated Penaeus monodon during oral WSSV infection

In the present study RNA interference was used to elucidate the connection between two endogenous genes [Penaeus monodon Rab7 (PmRab7) or P. monodon inhibitor of apoptosis (PmIAP)], and selected immune/apoptosis-related genes in orally ‘vaccinated’ shrimp after white spot syndrome virus (WSSV) infection. P. monodon were vaccinated by feeding them with formalin inactivated WSSV-coated feed. Thereafter, PmRab7 or PmIAP genes were silenced by injecting the shrimps with their respective dsRNA. The resulting groups of shrimps, Rab7 and IAP, were orally infected with WSSV and the expression of three immune-relevant genes in Rab7 group and five apoptosis-related genes in IAP group was evaluated. In the Rab7 group, PmToll, PmPPAE 2 and Pm penaeidin genes were down-regulated. The IAP-silenced shrimps were characterized by down-regulation of Pm caspase, PmERp57, Pm14-3-3 e, Pm ald, and up-regulation of PmSTAT. Thus, silencing of PmRab7/PmIAP has provided important clues on their relationship with selected immune/apoptosis genes in orally vaccinated P. monodon during WSSV infection

Truncated VP28 as oral vaccine candidate against WSSV infection in shrimp: an uptake and processing study in the midgut of Penaeus monodon

Several oral vaccination studies have been undertaken to evoke a better protection against white spot syndrome virus (WSSV), a major shrimp pathogen. Formalin-inactivated virus and WSSV envelope protein VP28 were suggested as candidate vaccine components, but their uptake mechanism upon oral delivery was not elucidated. In this study the fate of these components and of live WSSV, orally intubated to black tiger shrimp (Penaeus monodon) was investigated by immunohistochemistry, employing antibodies specific for VP28 and haemocytes. The midgut has been identified as the most prominent site of WSSV uptake and processing. The truncated recombinant VP28 (rec-VP28), formalin-inactivated virus (IVP) and live WSSV follow an identical uptake route suggested as receptor-mediated endocytosis that starts with adherence of luminal antigens at the apical layers of gut epithelium. Processing of internalized antigens is performed in endo-lysosomal compartments leading to formation of supra-nuclear vacuoles. However, the majority of WSSV-antigens escape these compartments and are transported to the inter-cellular space via transcytosis. Accumulation of the transcytosed antigens in the connective tissue initiates aggregation and degranulation of haemocytes. Finally the antigens exiting the midgut seem to reach the haemolymph. The nearly identical uptake pattern of the different WSSV-antigens suggests that receptors on the apical membrane of shrimp enterocytes recognize rec-VP28 efficiently. Hence the truncated VP28 can be considered suitable for oral vaccination, when the digestion in the foregut can be bypassed