β-Glucan administration enhances disease resistance and some innate immune responses in zebrafish (Danio rerio)

The present study was conducted to investigate the effect of β-glucan (derived from Saccharomyces cerevisiae) on the immune response and its protection against an infection of the bacterial pathogen Aeromonas hydrophila in zebrafish (Danio rerio). Zebrafish received β-glucan by intraperitoneal injection at three different concentrations (5, 2 and 0.5 mg ml−1) at 6, 4 and 2 days prior the challenge. On challenge day the control and β-glucan pretreated zebrafish were intraperitoneally injected with A. hydrophila and mortality was recorded for 4 days. Intraperitoneal injection of 5 mg ml−1 of β-glucan significantly reduced the mortality. A single injection of 5 mg ml−1 of β-glucan 6 days before challenge also enhanced significantly the survival against the infection. The treatment with β-glucan increased the myelomonocytic cell population in the kidney at 6 h postchallenge with A. hydrophila. Moreover it enhanced the ability of kidney cells to kill A. hydrophila. β-glucan did not affect the expression of TNFα or IL-1β but seemed to modulate IFNγ and chemokine expression in kidney.