Bacterial virulence factors play a major role in infection, which provides devastating effect on the aquaculture industry. Bacterial toxins are the major virulence factors that influence the roles of host cells and take control of living organisms’ vital processes to facilitate microbial infection. Various other bacterial virulent components such as adhesins, capsular polysaccharides, lipopolysaccharides, bacterial flagellum, pili and microbial siderophore provide a diverse effect in the microbial pathogenesis and express a variety of pathogenic molecules including aebABCEG, HutA, cpsD and pPHDD1. Bacterial protein secretion system secretes enzymes and toxins from bacterial cytoplasm to the host membrane targeting the immune cells and promoting biofilm formation. However, as they enter, the host body expresses various immune molecules that interact to utilize the pathogen recognition receptors. Toxins are powerful molecules formed by a broad range of bacterial pathogens attacking host cells and playing key roles in the dialogue between host and pathogen. They are important virulence factors that are often enough to decide the outcome of the infection. Hence, a detailed view on the virulence molecules majorly exotoxins from various bacterial pathogenic strains that are necessary to understand the pathogenesis. This review focuses on bacterial toxins and various other virulence factors, which influence the pathogenesis in fish.

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An antioxidant molecule namely, adenosyl homocysteinase (AHc) was identified from the earlier constructed transcriptome database of Spirulina, where it was cultured in a sulphur deprived condition. From the AHc protein, a small peptide NL13 was identified using bioinformatics tools and was predicted to have antioxidant property. Further, the peptide was synthesised and its antioxidant mechanism was addressed at molecular level. NL13 was subjected to various antioxidant assays including DPPH assay, HARS assay, SARS Assay, NO assay and ABTS assay, where NL13 exhibited significant (P < 0.05) potential antioxidant activity compared to its antioxidant control, Trolox. Cytotoxicity was performed on Human whole blood and the cell viability was performed on VERO fibroblast cells. In both assays, it was found that NL13 did not exhibit any cytotoxic effect towards the cells. Further, the intracellular ROS was performed on Multimode reader followed by imaging on fluorescence microscope which showed scavenging activity even at lower concentration of NL13 (31.2 µM). An effective wound healing property of NL13 on VERO cells was confirmed by analysing the cell migration rate at two different time intervals (24 and 48 h). Overall, the study shows that NL13 peptide scavenges the intracellular oxidative stress. Keywords Cyanobacteria • Adenosyl homocysteinase • Wound healing • Fibroblast cells • Spirulina Abbreviations AHc Adenosyl homocysteinase ROS Reactive oxygen species Ap Arthrospira platensis TEAE Trolox equivalent antioxidant capacity HRS Hydroxyl radical scavenging VERO Fibroblast cells Electronic supplementary material The online version of this article (

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Oxidative stress plays the central role in the pathogenesis and progression of diabetic complications. The present study aims to investigate the beneficial effect of oral administration of flavone baicalein in streptozotocin-nicotinamide (STZ-NA) induced diabetic rats by measuring oxidative stress markers, antioxidant enzyme activities and expression analysis of antioxidant genes. Experimental diabetes was induced by a single intraperitoneal (i.p.) injection of STZ (55 mg /kg b.wt), 15 min after the i.p. administration of NA. At the end of the experimental period, thiobarbituric acid reactive substances (TBARS), activities of antioxidant enzymes and expression levels of superoxide dismutase (SOD), catalase (CAT), glutathione (GSH) and glutathione peroxidase (GPx) were measured in diabetic rats along with serum biochemical parameters namely total cholesterol (TC), total triglyceride (TG), aspartate transaminase (AST) alanine transaminase (ALT) and glycosylated hemoglobin (HbA1c). Oral administration of baicalein (40 mg/kg b.wt/day) demonstrated a significant ameliorative effect on all studied biochemical and oxidative stress parameters. Biochemical findings were corroborated by qPCR expression analysis which showed significant upregulation of antioxidant genes in diabetic rats. These results suggest that baicalein supplementation may reduce diabetes and its complications by suppressing oxidative stress and enhancing gene expression and antioxidant enzyme activities in diabetic rats.