Figure 4.

Therapeutic efficacy of CiIFN-υ in grass carp following infection with A. hydrophila

Infective model of grass carp was established to determine the median lethal dose 50 (LD50) and assess the therapeutic effects of CiIFN-υ (5 μg/fish). CiIFN-υ was administered 1 h post-bacterial injection. A: Survival rates were recorded for one week following treatment (n=50 per group). B–G: Samples from various tissues, including head kidney, trunk kidney, hepatopancreas, spleen, hind intestine, and gill, were harvested on D3 post-treatment, and assessed for dry-to-wet weight ratios. H–K: Tissues, including head kidney, spleen, hind intestine, and blood, were sampled on D1 and D3 post-treatment (n=6). Collected samples were homogenized and diluted in sterile PBS and plated on selective medium, with colonies then counted after 12–16 h. L–N: Tissue sections were examined histopathologically, with images (left to right) showing sparse renal interstitial tissue in the head kidney, areas of nuclear consolidation and dissolved peritoneum in the spleen, and edema in the posterior intestinal wall. Control: Supernatants were collected from FHM cells transfected with empty pcDNA4 vector. Each experiment was conducted in triplicate, and results are presented as mean±SD. ns: Not significant; ^*: P<0.05; ^**: P<0.01; ^***: P<0.001.