acid-phosphatase and Gram-Negative-Bacterial-Infections

The biochemical mechanisms involved in phagocytosis and the intracellular survival of Aeromonas hydrophila (Ah) in host macrophages (MΦs) are complex processes that affect infection success or failure. Thus, in the present study, we described the in vitro infection of Nile tilapia MΦs by a homologous bacterium and tested the effects of anti-A. hydrophila immunoglobulin Y (IgY) on the phagolysosomal activity and intracellular survival of the pathogen. The anti-Ah IgY modulated lysosomal acid phosphatase (LAP) activity as well as the production of reactive oxygen intermediates (ROIs) and nitric oxide (NO), thereby potentiating phagocytosis and the elimination of Ah. Thus, we assume that the specific IgY had a beneficial effect on infection control and postulated the use of the Nile tilapia MΦs as an important in vitro experimental model for the functional and therapeutic study of Ah infection.

Topics: Acid Phosphatase; Aeromonas hydrophila; Animals; Cichlids; Fish Diseases; Gram-Negative Bacterial Infections; Immunoglobulins; In Vitro Techniques; Macrophages; Nitric Oxide; Phagocytosis; Reactive Oxygen Species

The present experiment was carried out to study the effect of different dosages of beta-glucan suspension derived from barley on the innate immune response and disease resistance of Anabas testudineus spawns against infection caused by Aeromonas hydrophila. Four different dosages of beta-glucan suspension in phosphate buffered saline at the rate of 0, 5, 10, 15 mg l(-1) were taken and 8 days old spawn were exposed for 2 h and 3 h. The cell suspension of spawn was assayed for total protein, acid phosphatase activity, lysozyme activity, bactericidal and NBT. Further, the spawns were challenged with 3 x 10(5) cells ml(-1) of A. hydrophila and survivability percentage and immunological parameters were assayed upto day 7. On day 7, most of the immunological parameters such as lysozyme activity, bactericidal activity and NBT activity were significantly enhanced after exposing the fish to all the concentrations of beta-glucan. Challenge study indicated least mortality in the group of spawns immersed in 15 mg l(-1) beta-glucan suspension for 3 h. Thus, 3 h exposure to beta-glucan suspension could reduce the mortality and increase the immunity of A. testudineus spawns.

Topics: Acid Phosphatase; Aeromonas hydrophila; Animals; beta-Glucans; Fish Diseases; Gram-Negative Bacterial Infections; Immunity, Innate; Muramidase; Perches; Superoxides; Survival Analysis

The extracellular products (ECP) secreted by two strains of gram-negative bacteria isolated from Nephrops norvegicus exhibiting signs of an opportunistic bacterial infection were investigated with the objective of understanding their role in the spoilage of host muscle tissue and identifying disease related virulence mechanisms. ECP from Vibrio sp. demonstrated no proteolytic activity. ECP from Pseudoalteromonas sp. (isolate N10) degraded several substrates, including azocasein and host muscle tissue. Proteolytic activity increased with temperature. Substrate-impregnated sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) analysis of the effect of the isolates' ECP on the molecular weight of proteins derived from abdominal muscle tissue revealed that the ECP of Pseudoalteromonas sp. selectively degraded the myosin heavy chain, troponin-T, troponin-I, paramyosin and several unidentified muscle proteins approximately 110 kDa in size. Topomyosin was also reduced in quantity. Degradation of SDS-PAGE gels impregnated with host muscle proteins, by the ECP of Pseudoalteromonas sp. revealed 3 zones of proteolysis, with estimated molecular weights between 100 and 30 kDa, indicating multiple proteases in the ECP. Through the API ZYM system, both isolates demonstrated strong leucine arylamidase activity, with the Vibrio sp. showing strong acid phosphatase activity. These enzymes have been identified as disease related virulence mechanisms in other bacterial pathogens. There is likely a complex pathway to the final condition, involving virulence factors of other species and the stresses involved in capture and transport.

Topics: Acid Phosphatase; Animals; Electrophoresis, Polyacrylamide Gel; Gram-Negative Bacteria; Gram-Negative Bacterial Infections; Leucyl Aminopeptidase; Muscle Proteins; Muscle, Skeletal; Nephropidae; Peptide Hydrolases; Virulence; Virulence Factors