A soluble nonglycosylated recombinant infectious hematopoietic necrosis virus (IHNV) G-protein induces IFNs in rainbow trout (Oncorhynchus mykiss).

Viral glycoproteins interact with cell-surface receptors to mediate virus entry and innate immune system activation. We found that a soluble recombinant infectious hematopoietic necrosis virus G-protein (rIHNV-G) stimulated an early innate immune response mediated by proinflammatory cytokines, IFN1 and IFN-gamma in rainbow trout (Oncorhynchus mykiss) fry. Expression of both IFN1 and IFN-gamma mRNA transcripts was an early event and was rIHNV-G dose-dependent. In addition, preliminary evidence revealed that the innate immune response induced by rIHNV-G protein could protect rainbow trout fry from a subsequent IHNV virus challenge. Finally, the binding and distribution of FITC-rIHNV-G protein on rainbow trout spleen and head kidney leukocytes resemble morphological changes which occur on the cell membrane during antigen-receptor interaction including membrane reorganization, patching, polarization and capping. Thus a soluble nonglycosylated rIHNV-G protein could mediate the activation of rainbow trout leukocytes, with concomitant production of proinflammatory cytokines and IFNs.