epiglucan and Enterobacteriaceae-Infections

Trained immunity is a long-term memory of innate immune cells, generating an improved response upon reinfection.

Topics: Animals; beta-Glucans; Enterobacteriaceae Infections; Epigenesis, Genetic; Larva; Mitochondria; Mycobacterium bovis; Neutrophils; Reactive Oxygen Species; Shigella flexneri; Trained Immunity; Zebrafish

In this study, we prepared and characterized the oats origin of nano scale β-glucan (NBG) and investigated the immunomodulatory properties in zebrafish larvae. Newly prepared NBG (average particle size of 465 nm) was fully soluble in water. Zebrafish larvae survival rate was increased against pathogenic bacteria Edwardsiella tarda, when NBG was added to the water (500 μg/mL) compared to NBG non-exposed controls. Moreover, quantitative real time PCR (qRT-PCR) results showed up-regulation of immune functional genes including TNF-α, IL-1β, β-defensin, lysozyme, IL 10, IL 12 and C-Rel indicating higher survival rate could be due to stronger immunomodulatory function of NBG (500 μg/mL). Thus, non-toxic, water soluble and biodegradable NBG from oats could be considered as the potential immunostimulant for larval aquaculture.

Topics: Adjuvants, Immunologic; Animals; Avena; beta-Glucans; Dietary Supplements; Edwardsiella tarda; Enterobacteriaceae Infections; Fish Diseases; Nanoparticles; Real-Time Polymerase Chain Reaction; Up-Regulation; Zebrafish

Carbapenem-resistant Enterobacteriaceae (CRE) are responsible for worldwide outbreaks and antibiotic treatments are problematic. The polysaccharide poly-(β-1,6)-N-acetyl glucosamine (PNAG) is a vaccine target detected on the surface of numerous pathogenic bacteria, including Escherichia coli. Genes encoding PNAG biosynthetic proteins have been identified in two other main pathogenic Enterobacteriaceae, Enterobacter cloacae and Klebsiella pneumoniae. We hypothesized that antibodies to PNAG might be a new therapeutic option for the different pan-resistant pathogenic species of CRE.. PNAG production was detected by confocal microscopy and its role in the formation of the biofilm (for E. cloacae) and as a virulence factor (for K. pneumoniae) was analysed. The in vitro (opsonophagocytosis killing assay) and in vivo (mouse models of peritonitis) activity of antibodies to PNAG were studied using antibiotic-susceptible and -resistant E. coli, E. cloacae and K. pneumoniae. A PNAG-producing strain of Pseudomonas aeruginosa, an organism that does not naturally produce this antigen, was constructed by adding the pga locus to a strain with inactive alg genes responsible for the production of P. aeruginosa alginate. Antibodies to PNAG were tested in vitro and in vivo as above.. PNAG is a major component of the E. cloacae biofilm and a virulence factor for K. pneumoniae. Antibodies to PNAG mediated in vitro killing (>50%) and significantly protected mice against the New Delhi metallo-β-lactamase-producing E. coli (P = 0.02), E. cloacae (P = 0.0196) and K. pneumoniae (P = 0.006), against K. pneumoniae carbapenemase (KPC)-producing K. pneumoniae (P = 0.02) and against PNAG-producing P. aeruginosa (P = 0.0013). Thus, regardless of the Gram-negative bacterial species, PNAG expression is the sole determinant of the protective efficacy of antibodies to this antigen.. Our findings suggest antibodies to PNAG may provide extended-spectrum antibacterial protective activity.

Topics: Animals; Antibodies, Bacterial; Bacterial Proteins; Bacterial Vaccines; beta-Glucans; beta-Lactamases; Biofilms; Drug Resistance, Bacterial; Enterobacteriaceae; Enterobacteriaceae Infections; Mice; Virulence Factors

Immunostimulants are food additives used by the aquaculture industry to enhance the immune response of fish, and although β-glucans are now commonly used for this purpose in aquaculture, little is known about their effects on the immune response of Pangasianodon hypophthalmus. Thus, a variety of immune parameters (e.g. phagocytosis, respiratory burst, lysozyme, complement, peroxidase, total protein, total anti-protease, total IgM, natural antibody titres, and specific IgM titres) was examined in this species after feeding fish with a basal control diet or diets supplemented with 0.05, 0.1, or 0.2 g/kg fungal-derived β-glucan or 0.1% commercial yeast-derived β-glucan, as a positive control diet, for a period of four weeks. The effect of the glucans on disease resistance was then evaluated by experimentally infecting the fish with Edwardsiella ictaluri by immersion and mortalities monitored for 14 days. Samples were collected from fish for analysis at 0, 1, 3, 7, 14, 21 and 28 days post-feeding (dpf), and also at 14 days post infection (dpi). The lowest dose of fungal-derived β-glucan (0.05%) appeared insufficient to effectively stimulate the immune response of the fish, while those fed with the two highest levels of fungal-derived β-glucan had enhanced immune responses compared to the control group. Significantly elevated levels of respiratory burst activity on all days examined (P < 0.05) and lysozyme activity on 7 dpf were found in the group fed 0.2% fungal-derived β-glucan, while plasma anti-protease activity was significantly enhanced (P < 0.05) by 21 dpf, natural antibody titres by 3 dpf and complement activity by 7 dpf and also at 14 dpi in the group fed 0.1% fungal-derived β-glucan. No statistical differences was seen in the level of mortalities between the dietary groups, although the group fed with the control diet had the highest level of mortalities and the groups fed with commercial yeast-derived β-glucan and 0.2% fungal-derived β-glucan the lowest.

Topics: Adjuvants, Immunologic; Animal Feed; Animals; beta-Glucans; Catfishes; Diet; Dietary Supplements; Edwardsiella ictaluri; Enterobacteriaceae Infections; Fish Diseases; Immunity, Innate

Pangasianodon hypophthalmus (striped catfish) is an important aquaculture species and intensification of farming has increased disease problems, particularly Edwardsiella ictaluri. The effects of feeding β-glucans on immune gene expression and resistance to E. ictaluri in P. hypophthalmus were explored. Fish were fed 0.1% fungal-derived β-glucan or 0.1% commercial yeast-derived β-glucan or a basal control diet without glucan. After 14 days of feeding, the mRNA expression of immune genes (transferrin, C-reactive protein, precerebellin-like protein, Complement C3 and factor B, 2a MHC class II and interleukin-1 beta) in liver, kidney and spleen were determined. Following this fish from each of the three diet treatment groups were infected with E. ictaluri and further gene expression measured 24 h post-infection (h.p.i.), while the remaining fish were monitored over 2 weeks for mortalities. Cumulative percentage mortality at 14 days post-infection (d.p.i.) was less in β-glucan fed fish compared to controls. There was no difference in gene expression between dietary groups after feeding for 14 days, but there was a clear difference between infected and uninfected fish at 24 h.p.i., and based on principal component analysis β-glucans stimulated the overall expression of immune genes in the liver, kidney and spleen at 24 h.p.i.

Topics: Animal Feed; Animals; beta-Glucans; Catfishes; Diet; Dietary Supplements; Edwardsiella ictaluri; Enterobacteriaceae Infections; Fish Diseases; Fish Proteins; Gene Expression Regulation; Longevity

The purpose of this study was to determine if multiple injections of different dosages of beta-glucan derived from barley would enhance the immune response and disease resistance against infections due to opportunistic pathogens Aeromonas hydrophila and Edwardsiella tarda in Labeo rohita fingerlings. Hence, four different dosages of beta-glucan suspension in phosphate-buffered saline at the rate of 0, 5, 10, 15 mg kg(-1) body weight of fish were injected intraperitoneally to the fingerlings of Labeo rohita at two-week intervals for four times. After every two-week interval different serum biochemical, haematological and immunological parameters of fish were evaluated. At the end of immunostimulation trial of 56 days, fish were divided into four subgroups under each major treatment group for challenge through i.p injection and bath immersion with two pathogens, A. hydrophila and E. tarda. The mortality (%) and agglutinating antibody titre was recoded on 28th day post challenge. Most of the immune parameters such as leucocyte count, phagocytic ratio, phagocytic index, lysozyme activity, complement activity, serum bactericidal activity were significantly (P < 0.05) enhanced on 42 days after three i.p injections of 10 mg of beta-glucan kg(-1) body wt. Challenge study indicated least mortality in the group of fishes injected with medium dose of 10 mg of beta-glucan kg(-1) body wt. four times. Multiple injections of beta-glucan might have maintained the activation of phagocytic cells for a long period which in turn would lead to long-term protection in fishes. Thus, injections of 10 mg of beta-glucan kg(-1) body wt. for three times can be advocated to enhance the immune response of fish species under aquaculture.

Topics: Aeromonas hydrophila; Animals; beta-Glucans; Blood Chemical Analysis; Cyprinidae; Dose-Response Relationship, Drug; Edwardsiella tarda; Enterobacteriaceae Infections; Fish Diseases; Gram-Negative Bacterial Infections; Immunity, Innate; Injections, Intraperitoneal; Leukocytes; Linear Models; Muramidase; Phagocytosis; Superoxides

In order to determine the impact on disease resistance of four dietary immunomodulators viz., beta-1,3 glucan, levamisole, vitamins C and E, in an important farmed Indian major carp species, rohu (Labeo rohita Ham.), fish were fed diets containing various levels of these substances during a 60 day trial. Aflatoxin B1 (AFB,) at 125 mg kg(-1) body weight was injected intraperitoneally (i.p.) into fish to induce an immunosuppressive state on the first day of the experiment in some individuals. The fish were vaccinated against formalin-killed Edwardsiella tarda vaccine on day 30 of the experiment. Specific immunity, as measured by bacterial agglutination titre and disease resistance against E. tarda, was determined at the end of the trial. The results demonstrate that all the four immunomodulators were capable of significantly (P<0.05) increasing specific immunity and reducing mortality in immunocompromised fish but failed to enhance specific immunity and protection in healthy fish. The increased bacterial agglutination titre by beta-1,3 glucan, and reduced mortality losses by both beta-1,3 glucan and levamisole were marked in healthy vaccinated fish compared with their controls. Similarly, all four substances significantly reduced the mortality rates in immunocompromised and healthy unvaccinated fish. Out of these four substances, glucan was recorded to be the most effective immunomodulator in rohu. The present results suggest that the introduction of these substances into the diet of fish grown in farms under immunosuppressive/stressful conditions could increase their resistance to infection by reducing mortality rates and offer economic benefits.

Topics: Adjuvants, Immunologic; Aflatoxin B1; Agglutination Tests; Animal Feed; Animals; Antibodies, Bacterial; Antioxidants; Ascorbic Acid; Bacterial Vaccines; beta-Glucans; Cyprinidae; Edwardsiella tarda; Enterobacteriaceae Infections; Fish Diseases; Glucans; Immunization; Immunocompromised Host; Injections, Intraperitoneal; Levamisole; Vitamin E