Aims: To determine the immune gene expression response of gilthead
seabream (Sparus aurata) that is experimentally infected with the
lymphocystivirus LCDV-Sa.
Methods and Results: Viral DNA and transcripts were detected by qPCR in all
samples from fish injected with LCDV-Sa, demonstrating that the virus
establish a systemic and asymptomatic infection. The expression of 23
immune-related genes was also analysed by RT-qPCR in the head kidney (HK)
and intestine at several times post-infection (dpi). In HK, the expression of
five type I interferon (IFN)-related genes (ifn, irf3, mx2, mx3 and isg15), il10
and ck10 was upregulated at 1–3 dpi, while genes related to the inflammation
process (tnfa, il1ß, il6, casp1) were not differentially expressed or even
downregulated. The expression profile in the intestine was different regarding
type I INF-related genes. An upregulated c3 and ighm expression was observed
in both HK and intestine at 3–8 dpi. Finally, the transcription of nccrp1 and
mhcIIa was induced in HK, whereas tcrb expression was downregulated in
both organs.
Conclusions: LCDV-Sa seems to trigger an immune response in gilthead
seabream characterized by a partial activation of type I IFN system and a lack
of systemic inflammatory response which may be related to viral persistence.
Significance and Impact of the Study: The immune response observed in
gilthead seabream infected by LCDV-Sa could be implicated in the
establishment of an asymptomatic persistent infection.
