Figure 10: Modulation of SOCS gene expression in rainbow trout by PKD infection. Rainbow trout (50–100 g) were sampled in the summer of 2001 during a natural outbreak of PKD on a fish farm in Hampshire (UK). The fish exhibited clinical pathology and kidneys graded from 1 to 3 on the swelling grade. Approximately 100 mg of kidney tissue was removed from an area of the posterior kidney immediately below the dorsal fin, an area of the kidney normally associated with the onset of pathology [50] and stored in RNAlater (Ambion) at −80°C. A naïve unexposed control group (grade 0), from the same egg source, was sampled from a farm with no history of PKD infection. Routine checks for other parasite infestations and opportunistic bacterial pathogens presence were negative. Following total RNA extraction, 48 individual cDNAs were generated for real-time RT-PCR analysis of the expression of CISHa (a), SOCS1 (b), SOCS2 (c), SOCS3 (d), SOCS5 (e), and SOCS7 (f), as described in Figure 8. The gene expression was first normalised to that of the housekeeping gene EF-1α and expressed as a fold change relative to the grade 0 fish. The results are presented as mean + SEM ( , grade 0; 6, grade 1; 9, grade 1-2; 10, grade 2; 10, grade 3). The value of an LSD post hoc test after a significant one-way analysis of variance between the PKD exposed groups and grade 0 control fish is shown above the bars as * , ** , and *** . For comparison of the relative expression levels of genes examined, the cp values in the real-time PCR in the kidney of 13 unexposed grade 0 fish are presented as means ± SD (g). Please note that the higher the cp value, the lower the expression level.