| A NOVEL HEAT SHOCK PROTEIN INDUCER GENERATES PROTECTIVE IMMUNITY IN ARTEMIA FRANCISCANA NAUPLII AGAINST PATHOGENIC VIBRIO CAMPBELLII |
| BARUAH, K., Laboratory of Aquaculture & Artemia Reference Center, Faculty of Bioscience Engineering, Ghent University, Rozier 44, Gent 9000, Belgium, baruahkartik4@rediffmail.com; Norouzitallab, P., pnorouzitallab@gmail.com; Sorgeloos, P., patrick.sorgeloos@ugent.be; Bossier, P., peter.bossier@ugent.be |
| The Hsp70 class of heat shock proteins (Hsps) has received considerable attention owing to their multi-functional features. They are soluble intracellular chaperones present in all known organisms. Most Hsp70s are constitutively expressed under normal physiological conditions, however, their expression is up-regulated by various physiological stressors, such as high temperature, toxins, osmotic stress, certain chemicals and drugs, hypoxia and microbial infection that could potentially damage the cellular and molecular structures in the cells. Hsp70s perform essential biological functions under both normal and stressful conditions such as assisting in the folding of nascent proteins, translocation of these proteins between cell organelles, assembly and disassembly of multi-subunit complexes, refolding or degradation of denatured proteins due to stresses, dissolution of pathological protein aggregates, and other processes enhancing the survival of normal and diseased cells. In addition, a considerable number of published investigations suggested that Hsp70 can generate strong innate and adaptive immune responses against many diseases. The cytoprotective role of the Hsp70 described in a variety of animal disease models, including vibriosis in aquaculture animals, suggests new protective strategies relying upon the development of non-toxic compounds that selectively turn on heat shock genes. The product Pro-TexŽ, a soluble version of Tex-OEŽ, which is extracted from the skin of the prickly pear fruit, Opuntia ficus indica, was shown to function as trigger for Hsp synthesis in a non-stressful situation in a variety of animal tissues and subsequently protect the animals against various abiotic stressors. In this study, we investigated whether Tex-OEŽ could boost immunoregulatory mechanisms in a gnotobiotically cultured invertebrate model Artemia fransciscana and subsequently induce resistance in Artemia to combat against pathogenic Vibrio campbellii. Results demonstrated that Tex-OEŽ induced Hsp70 in Artemia and that pretreatment of Tex-OEŽ remarkably protects Artemia against V. campbellii challenge. Additionally, Tex-OEŽ pretreatment elicited the prophenolxidase system, at both mRNA and protein activity levels, and also induced the level of nitric oxide. Interestingly, this increase in the immune responses in the Vibrio-challenged Artemia pretreated with Tex-OEŽ was accompanied by a significant decrease of V. campbellii count. These results suggest that Tex-OEŽ is undoubtedly beneficial for the induction of protective immunity in the invertebrate Artemia against vibriosis and thus it can potentially be a useful preventative treatment modality for luminescent vibrios. This is the first in vivo report on the protective activity of an Hsp70-inducing compound Tex-OEŽ in an invertebrate. |
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