Modulation of the Tissue Expression Pattern of Zebrafish CRP-Like Molecules Suggests a Relevant Antiviral Role in Fish Skin.

Recent studies suggest that short pentraxins in fish might serve as biomarkers for not only bacterial infections, as in higher vertebrates including humans, but also for viral ones. These fish orthologs of mammalian short pentraxins are currently attracting interest because of their newly discovered antiviral activity. In the present work, the modulation of the gene expression of all zebrafish short pentraxins (CRP-like proteins, CRP1-7) was extensively analyzed by quantitative polymerase chain reaction. Initially, the tissue distribution of - transcripts and how the transcripts varied in response to a bath infection with the spring viremia of carp virus, were determined. The expression of - was widely distributed and generally increased after infection (mostly at 5 days post infection), except for (downregulated). Interestingly, several transcription levels significantly increased in skin. Further assays in mutant zebrafish of recombinant activation gene 1 () showed that all s (except for , downregulated) were already constitutively highly expressed in skin from knockouts and only increased moderately after viral infection. Similar results were obtained for most isoforms (a reporter gene of the interferon response), suggesting a general overcompensation of the innate immunity in the absence of the adaptive one.