Complement-related pathway gene expression in controls and grouper challenged with 1.3 × 106 CFU/ml (20 μl/fish) Vibrio alginolyticus , as determined by qRT-PCR. ( A ) A2M, ( B ) BF, ( C ) CR2, ( D ) C1q, ( E ) C1r, ( F ) C1s, ( G ) C3, ( H ) C4, ( I ) C4BP, ( J ) C5, ( K ) C6, and ( L ) C6-d. Values are presented as the mean ± SEM (n = 5). Values with different letters differ significantly. Significance was set at P < 0.05, as determined by one-way ANOVA followed by Duncan’s test.