Potential Role of Rainbow Trout Erythrocytes as Mediators in the Immune Response Induced by a DNA Vaccine in Fish

Abstract

In recent years, fish nucleated red blood cells (RBCs) have been implicated in the response against viral infections. We have demonstrated that rainbow trout RBCs can express the antigen encoded by a DNA vaccine against viral hemorrhagic septicemia virus (VHSV) and mount an immune response to the antigen in vitro. In this manuscript, we show, for the first time, the role of RBCs in the immune response triggered by DNA immunization of rainbow trout with glycoprotein G of VHSV (GVHSV). Transcriptomic and proteomic profiles of RBCs revealed genes and proteins involved in antigen processing and presentation of exogenous peptide antigen via MHC class I, the Fc receptor signaling pathway, the autophagy pathway, and the activation of the innate immune response, among others. On the other hand, GVHSV-transfected RBCs induce specific antibodies against VHSV in the serum of rainbow trout which shows that RBCs expressing a DNA vaccine are able to elicit a humoral response. These results open a new direction in the research of vaccination strategies for fish since rainbow trout RBCs actively participate in the innate and adaptive immune response in DNA vaccination. Based on our findings, we suggest the use of RBCs as target cells or carriers for the future design of novel vaccine strategies.

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“…Moreover, RBCs develop specific responses to different pathogen-associated molecular patterns (PAMPS) [35], overexpression of toll-like receptors (TLRs) [36], and are involved in the production of interferon, inflammatory cytokines, and chemokines [27,[30][31][32]37,38]. Within the field of rational design of new prophylactic treatments, nucleated rainbow trout RBCs have been shown to express the antigen encoded by a DNA vaccine and respond to a DNA vaccine immunization inducing exogenous peptide presentation processes [31,39]. In addition, rainbow trout RBCs have been shown to be capable to endocytose bacterial inclusion bodies made of nanostructured recombinant antigenic proteins and modulate the expression of immune system genes [30].…”