Activation of an immune response in Litopenaeus vannamei by oral immunization with phagocytosis activating protein (PAP) DNA

A Bioactive Extract Rich in Triterpenic Acid and Polyphenols from Olea europaea Promotes Systemic Immunity and Protects Atlantic Salmon Smolts Against Furunculosis

In the present study, the modulation of the transcriptional immune response (microarray analysis) in the head kidney (HK) of the anadromous fish Atlantic salmon (Salmo salar) fed a diet supplemented with an olive fruit extract (AQUOLIVE^®) was evaluated. At the end of the trial (133 days), in order to investigate the immunomodulatory properties of the phytogenic tested against a bacterial infection, an in vivo challenge with Aeromonas salmonicida was performed. A total number of 1,027 differentially expressed genes (DEGs) (805 up- and 222 downregulated) were found when comparing the transcriptomic profiling of the HK from fish fed the control and AQUOLIVE^® diets. The HK transcripteractome revealed an expression profile that mainly favored biological processes related to immunity. Particularly, the signaling of i-kappa B kinase/NF-kappa and the activation of leukocytes, such as granulocytes and neutrophils degranulation, were suggested to be the primary actors of the innate immune response promoted by the tested functional feed additive in the HK. Moreover, the bacterial challenge with A. salmonicida that lasted 12 days showed that the cumulative survival was higher in fish fed the AQUOLIVE^® diet (96.9 ± 6.4%) than the control group (60.7 ± 13.5%). These results indicate that the dietary supplementation of AQUOLIVE^® at the level of 0.15% enhanced the systemic immune response and reduced the A. salmonicida cumulative mortality in Atlantic salmon smolts.

Chitosan-Based Nanoparticles Against Viral Infections

Viral infections, in addition to damaging host cells, can compromise the host immune system, leading to frequent relapse or long-term persistence. Viruses have the capacity to destroy the host cell while liberating their own RNA or DNA in order to replicate within additional host cells. The viral life cycle makes it challenging to develop anti-viral drugs. Nanotechnology-based approaches have been suggested to deal effectively with viral diseases, and overcome some limitations of anti-viral drugs. Nanotechnology has enabled scientists to overcome the challenges of solubility and toxicity of anti-viral drugs, and can enhance their selectivity towards viruses and virally infected cells, while preserving healthy host cells. Chitosan is a naturally occurring polymer that has been used to construct nanoparticles (NPs), which are biocompatible, biodegradable, less toxic, easy to prepare, and can function as effective drug delivery systems (DDSs). Furthermore, chitosan is Generally Recognized as Safe (GRAS) by the US Food and Drug Administration (U.S. FDA). Chitosan NPs have been used in drug delivery by the oral, ocular, pulmonary, nasal, mucosal, buccal, or vaginal routes. They have also been studied for gene delivery, vaccine delivery, and advanced cancer therapy. Multiple lines of evidence suggest that chitosan NPs could be used as new therapeutic tools against viral infections. In this review we summarize reports concerning the therapeutic potential of chitosan NPs against various viral infections.

Evaluation of a new Argovit as an antiviral agent included in feed to protect the shrimp Litopenaeus vannamei against White Spot Syndrome Virus infection

In this study, four experimental assays were conducted to evaluate the use of a new silver nanoparticle formulation named Argovit-4, which was prepared with slight modifications to enhance its biological activity against white spot syndrome virus (WSSV) in shrimp culture. The goals of these assays were to (1) determine the protective effect of Argovit-4 against WSSV, (2) determine whether Argovit-4 supplemented in feed exhibits toxicity towards shrimp, (3) determine whether Argovit-4 as antiviral additive in feed can prevent or delay/reduce WSSV-induced shrimp mortality, and (4) determine whether Argovit-4 supplemented in feed alters the early stages of the shrimp immune response. In bioassay 1, several viral inocula calibrated at 7 SID₅₀(shrimp infectious doses 50% endpoint) were exposed to 40, 100, 200 and 1,000 ng/SID₅₀ of Ag⁺ and then intramuscularly injected into shrimp for 96 h. In bioassay 2, shrimp were fed Argovit-4 supplemented in feed at different concentrations (10, 100 and 1,000 µg per gram of feed) for 192 h. In bioassay 3, shrimp were treated with Argovit-4 supplemented in feed at different concentrations and then challenged against WSSV for 192 h. In bioassay 4, quantitative real-time RT-qPCR was performed to measure the transcriptional responses of five immune-relevant genes in haemocytes of experimental shrimp treated with Argovit-4 supplemented in feed at 0, 6, 12, 24 and 48 h. The intramuscularly injected Argovit-4 showed a dose-dependent effect (p < 0.05) on the cumulative shrimp mortality from 0–96 h post-infection. In the second bioassay, shrimp fed Argovit-4 supplemented in feed did not show signs of toxicity for the assayed doses over the 192-h experiment. The third and fourth bioassays showed that shrimp challenged with WSSV at 1,000 µg/g feed exhibited reduced mortality without altering the expression of some immune system-related genes according to the observed level of transcriptional. This study is the first show that the new Argovit-4 formulation has potential as an antiviral additive in feed against WSSV and demonstrates a practical therapeutic strategy to control WSSV and possibly other invertebrate pathogens in shrimp aquaculture.

Recombinant Epinephelus lanceolatus serum amyloid A as a feed additive: Effects on immune gene expression and resistance to Vibrio alginolyticus infection in Epinephelus lanceolatus

Recombinant Epinephelus lanceolatus serum amyloid A (rElSAA) exhibits strong immunostimulant activity and enhances phagocytic clearance of bacteria by macrophages. However, the effects of dietary rElSAA supplementation on growth performance, immunomodulation and disease resistance in giant grouper have not been previously evaluated. To test whether oral administration of rElSAA affects growth, fish were fed with 0, 0.88, 4.4 or 22 mg/kg rElSAA-containing diet for 28 days. No statistically significant differences in body weight were observed between groups. Next, we tested whether oral administration of rElSAA may enhance disease resistance. Fish were fed with 0, 0.88, 4.4 or 22 mg/kg rElSAA-containing diet for 3, 7, 14, 21 or 28 days, followed by challenge with Vibrio alginolyticus. Survival was then monitored for 4 days. Fish that were fed with rElSAA-containing diet for 28 days showed significantly improved survival after infection. In addition, the expression levels of immune defense-associated genes in hepatic tissue were assessed by quantitative real-time polymerase chain reaction before and after V. alginolyticus infection. Oral administration of rElSAA increased the expression level of toll-like receptor 5, whereas the expression levels of CC chemokine 1, SAA and C reactive protein were decreased. Thus, the data suggest that rElSAA may enhance host immunity by attenuating regulatory T cell-mediated suppression of inflammation. Together, our results demonstrate that rElSAA is a promising candidate as a feed additive for giant grouper, which may effectively enhance disease resistance after being administered for several weeks.

Immune response of anti-lectin Pjlec antibody in freshwater crab Paratelphusa jacquemontii

Sialic acid specific lectin Pjlec isolated from serum of the freshwater crab Paratelphusa jacquemontii served as an antigen for the production of immunoglobulin (Ig) in Balb/c mice sera. Enzyme-linked immunosorbent assay (ELISA) of mice anti-sera with Pjlec lectin affirmed the induction and production of antibody. Anti-Pjlec antibody was isolated from the antisera of mice by Protein A Sepharose affinity chromatography and checked for purity by immunoblot with lectin. Mass spectrometry (MS/MS) of papain digethe peptide sequence of antigen binding fragment (Fab) and fragment crystallizable (Fc). Coatingsted anti-Pjlec revealed of anti-Pjlec to the target cell, rabbit erythrocyte failed to enhance in vitro phagocytosis in the crab. However, inoculation of anti-Pjlec in the hemolymph of the crab elicited in vitro phagocytosis. Proteins in hemocyte lysate supernatant (HLS) were separated by electrophoresis failed to immunoblot with Pjlec or anti-Pjlec. Peptide sequences of trypsin digested lectin protein appeared homologous to deuterostome chordate. The protostome crab that lack the ability to synthesize sialic acid however bind to sialic acid a deuterostome sugar to suggest the complexity in innate immune system of invertebrates. The application of lectin and its antibody require further study on application of pathological conditions associated with alterations in sialylated cell surface.

Roles of phagocytosis activating protein (PAP) in Aeromonas hydrophila infected Cyprinus carpio

Cyprinus carpio (koi) is one of the most popular ornamental fish. A major problem for C. carpio farming is bacterial infections especially by Aeromonas hydrophila. Previously studies had shown that the Phagocytosis Activating Protein (PAP) gene was involved in the innate immune response of animals. Therefore, we attempted to identify a role for the PAP gene in the immunology of C. carpio. The expression of the PAP was found in C. carpio whole blood and increased when the fish were stimulated by inactivated A. hydrophila. In addition, PAP-phMGFP DNA was injected as an immunostimulant. The survival rate and the phagocytic index were significantly increased in the A. hydrophila infected fish that received the PAP-phMGFP DNA immunostimulant. A chitosan-PAP-phMGFP nanoparticle was then developed and feeded into fish which infected with A. hydrophila. These fish had a significantly lower mortality rate than the control. Therefore, this research confirmed a key role for PAP in protection fish from bacterial infection and the chitosan-PAP-phMGFP nanoparticle could be a good prototype for fish immunostimulant in the future.