The expression analysis of inflammatory and antimicrobial genes in the goldfish (Carassius auratus L.) infected with Trypanosoma carassii

We report results of a comprehensive analysis of inflammatory gene expression during the course of infection of Trypanosoma carassii in the goldfish. We observed significant increases in mRNA levels of genes encoding pro-inflammatory cytokines IFN-γ, TNFα1 and TNFα2; IL-1β-1 and IL-1β-2; IL-12-p35 and IL-12-p40; CCL1; CXCL8, anti-inflammatory cytokines IL-10 and TGFβ and iNOS A and iNOS B, using quantitative PCR. Expression levels and profiles of these cytokines and iNOS isoforms varied in the different tissues (kidney, spleen, liver) of goldfish during the course of T. carassii infection. The expression of majority of genes that encode pro- and anti-inflammatory cytokines were up-regulated during the acute phase of infection (days 7–21 post-infection). The mRNA levels of these cytokines returned to normal levels or were down-regulated during the elimination phase of infection (days 28–56), with exception of IL-10 in the spleen and liver of infected fish. A parallel up-regulation of IFN-γ and IL-10 mRNA levels were observed in all tissues of infected fish during the acute phase of the infection. The expression of iNOS genes (iNOS A and B) was significantly delayed (day 14 pi) in the kidney, liver and spleen of infected fish. These results provide insights into the interaction between T. carassii and goldfish, and suggest that Th1/Th2-like responses may be important for controlling T. carassii infection in the goldfish.

► Immune genes were up-regulated during acute and down-regulated during elimination phases of infection. ► Both Th1 cytokine (IFN-γ) and Th2 cytokine (IL-10) were up-regulated during the acute phase of the infection. ► A delay (day 14 post-infection) in the expression of iNOS genes was documented.