OnMBL/CD91a regulates the expression of Rab5A/Rab7. (A–D) Head kidney MФ were stimulated with OnMBL in the presence of S. agalactiae, and mRNA and protein levels of Rab5A and Rab7 were examined by qRT-PCR (n = 4), Western blot, and immunofluorescence. Scale bar, 5 μm. (E) After OnMBL RNAi for 12 h, the relative mRNA levels of Rab5A and Rab7 in the head kidney were analyzed by qRT-PCR at different time points following bacterial infection. (F and G) Tilapia were i.m. injected with dsOnMBL. After 12 h, fish were intraperitoneally infected with S. agalactiae in the absence or presence of OnMBL and Trx. The protein expression levels of Rab5A and Rab7 in the head kidney were analyzed by Western blot. (H and I) Head kidney MФ were stimulated with OnMBL in the presence or absence of AKT-IN-6. The relative mRNA and protein levels of Rab5A and Rab7 were examined by qRT-PCR (n = 4) and Western blot at different time points. (J and K) Tilapia individuals were intraperitoneally injected with AKT-IN-6 in the presence of S. agalactiae for 2 consecutive days. The isolated head kidney MФ from inhibitor-treated or untreated tilapia were stimulated by OnMBL for 6 h, and the relative mRNA and protein levels of Rab5A and Rab7 were detected by qRT-PCR (n = 4) and Western blot. (L) After OnCD91 RNAi for 12 h, the relative mRNA levels of the Rab5A and Rab7 in the head kidney were analyzed by qRT-PCR at 24 h post–bacterial infection (n = 4). (M) Tilapia were i.m. injected with dsOnCD91a. After 12 h, fish were intraperitoneally infected with S. agalactiae in the presence or absence of OnMBL. The protein levels of Rab5A and Rab7 in the head kidney were analyzed by Western blot at 12 h post–bacterial infection. (N) After OnMBL or OnCD91a RNAi for 12 h, the relative mRNA levels of the Rab5A/Rab7 effector molecules in the head kidney were analyzed by qRT-PCR at 12 h post–bacterial infection (n = 4).