藻毒素对虹彩病毒侵染虾类的影响研究

Objective: Exploring the inhibitory role of algal toxins on aquatic viruses. Methods: Two typical toxin-producing algae (Alexandrium sp. and Gambierdisc sp.) were isolated by capillary picking. After detected by HPLC (high performance liquid chromatography) method, we found that the former (Alexandrium sp.) had the ability to produce the water-soluble toxin (paralytic shellfish toxin, PST), and the latter (Gambierdisc sp.) had the ability to produce the fat-soluble toxin (ciguatoxin, CXT). During the animal experiment, the shrimp (Penaeus vannamei) was exposed by two algal toxins at low-dose concentration (nM level). Then, the shrimp were infected by the iridovirus. The infection rate and shrimp related functional genes expression were determined. Meanwhile, the immunostimulatory effects and molecular response mechanisms were also analyzed. Results: Compared with the control group, the infection rate was decreased by 30.83% and 65.84% in PSTs and CXTs experimental groups. The RT-PCR results indicated that algal toxin exposure activated the host immune system, and the expression of genes involved in immunoprevention (Lvβ-catenin family members, Hsp70, lectin, β-GBP-HDL, Dscam), anti-stress response genes (SOD, CAT, ACP, PO, AKP), and apoptosis genes (Bantam) were up-regulated more than 2-fold in enperimental groups. Conclusions: This work confirmed that low doses of algal toxin exposure enhanced the animal's resistance to exogenous viruses. The possible protective mechanism is toxins activate the shrimp's immune function and enhanced their defence ability to viruses. This study improves our understanding of the "fighting poison with poison" effect of algal toxins. The immune-enhancing effect induced by low-dose algal toxins can be used as a potential strategy for aquatic animals' protection.