Abstract
Simple SummaryAn antioxidant protein has been identified in a sample of erythrocytes exposed to a fish virus. We evaluated the role of this protein as an antiviral molecule in fish. Through silencing and overexpression assays we determined the antiviral effect of this protein in the infectivity of the virus. In conclusion, this antioxidant protein may be a potential target for new therapeutic strategies against viral infections.Natural killer enhancing factor (NKEF) belongs to the peroxiredoxin family of proteins, a group of antioxidants that has been extensively studied in mammals. Recently, we identified NKEF in the immunoprecipitated proteome of rainbow trout red blood cells (RBCs) exposed to viral hemorrhagic septicemia virus (VHSV). In the present study, we evaluated the role of NKEF in the antiviral response of rainbow trout against VHSV by examining the expression profile of NKEF in VHSV-exposed RBCs and rainbow trout gonad-2 (RTG-2) cell line. We found an in vitro correlation between decreased VHSV replication and increased NKEF expression after RBCs were exposed to VHSV, however this was not found in RTG-2 cells where the infection highly increased and nkef transcripts remained almost unchanged. In addition, siRNA silencing of the nkef gene in rainbow trout RBCs and RTG-2 cells resulted in increased VHSV replication. We also found a correlation between nkef gene silencing and a decrease in the expression of genes related to type 1 interferon (IFN1) pathway. These findings indicated that NKEF is involved in the antiviral mechanisms of rainbow trout RBCs against VHSV and thus support its antiviral role and implication in the modulation of their immune response. Finally, overexpression of NKEF in an EPC cell line significantly reduced VHSV infectivity and was coupled to an increment in IFN1-related genes. In conclusion, NKEF may be a potential target for new therapeutic strategies against viral infections.
Highlights
The peroxiredoxin (PRDX) family is a highly conserved gene family, containing six members that are expressed in a broad range of organisms, including both prokaryotes and eukaryotes [1]
Nkef transcripts expression increased in the peripheral blood leukocytes, head kidney, and blood of rainbow trout challenged with viral hemorrhagic septicemia virus (VHSV) [14,15] and in the peripheral blood leukocytes of common carp challenged with spring viremia carp virus (SVCV) [16]
We demonstrated the implication of natural killer enhancing factor (NKEF) in the modulation of the IFN1-related cell response. All these results suggested that NKEF may be a potential target for new therapeutic strategies against viral infections
Summary
The peroxiredoxin (PRDX) family is a highly conserved gene family, containing six members that are expressed in a broad range of organisms, including both prokaryotes and eukaryotes [1]. Several studies looked at the role of NKEF in the fish immune response as well as NKEF gene and protein expression levels after bacterial, viral, and parasitic infections [13]. Nkef transcripts expression increased in the peripheral blood leukocytes, head kidney, and blood of rainbow trout challenged with viral hemorrhagic septicemia virus (VHSV) [14,15] and in the peripheral blood leukocytes of common carp challenged with spring viremia carp virus (SVCV) [16]. Nkef transcript levels increased in the rainbow trout monocyte-macrophage cell line RTS11 [17] and in VHSVexposed RBCs [18], as well as in nodavirus-infected seabream and sea bass brain and head kidney [19]. Several mechanisms have been proposed for the antiviral response against VHSV in rainbow trout RBCs [18,20,21,22], but the role of NKEF in this context is not known yet
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