The effect of dietary immunostimulants on the susceptibility of common carp (Cyprinus carpio) to the white spot parasite, Ichthyophthirius multifiliis

Abstract

One of the main obstacles in freshwater aquaculture is the parasitic ciliate Ichthyophthirius multifiliis (Ich), the causative agent of white spot disease. The use of immunostimulants as feed additives may be a promising approach to control Ich infection. In the present study, we tested the prophylactic effect of orally administered β-1,3/1,6-glucan and propolis extract E50 against Ich infection in common carp. In total, 122 fish were separated into three experimental groups fed with a control, 3% β-glucan and 1% propolis diet for 40 consecutive days, respectively. On day 40, 16 fish per group were individually exposed to Ich theronts and the number of trophonts was counted 5 days post exposure. Relative gene expression of interleukin 1-β (IL-1-β) in common carp liver was examined by qPCR. Compared to control, the mean infection intensity was lower in the β-glucan-and propolis-fed groups; however, the difference was not statistically significant. The relative expression of IL-1-β significantly decreased in the propolis-fed group at day 10. In the β-glucan-fed group, a significant IL-1-β decrease was detected at day 15 compared to control. Although the Ich infection intensity was slightly decreased in both treated groups, and IL-1-β was moderately down-regulated in the liver of common carp, our results suggest that the applied feeding regime is insufficient to prevent Ich outbreaks in common carp.

β-Glucan and parasites

“…In addition, glucan offered protection against Loma salmonae given either intraperitoneally or orally (Guselle et al, 2010), offering a new window for successful vaccination of commercially farmed fish. Later studies using common carp, however, did not confirm these results (Herczeg et al, 2017). For a summary on glucan-derived stimulation of immune reaction in case of L. salmonae infection, see Rodriguez-Tovar et al (2011).…”

Susceptibility-related differences in the quantity of developmental stages of Myxobolus spp. (Myxozoa) in fish blood

“…The lowest gene copy number was 100 that was reliably detected in every run. Raw Ct data were normalised to the reference gene, and inter-run calibration was performed with the software qBasePlus [ 29 ] to eliminate the effect of amplification efficiency differences among different qPCR runs [ 30 – 31 ]. Calibrated normalised relative quantities (CNRQ values) were calculated, which represented the relative amount of the target gene (i.e.…”

Effects of dietary astaxanthin on growth, blood biochemistry, antioxidant, immune and inflammatory response in lipopolysaccharide‐challengedChanna argus

“…However, the abuse of antibiotics not only affects the safety of fish products but also causes environmental pollution and induces the emergence of drug‐resistant bacteria (Cabello, ), causing problems for future disease treatment. However, immunopotentiators can enhance the disease resistance of fish, promote their innate immune function and enhance their adaptive immunity (Herczeg et al, ). The aforementioned studies suggest that the development of green, economic and effective immunopotentiators plays an important role in the healthy development of aquaculture.…”