FIG 2.

Phage retention on mucus allows for the prophylactic use of phages against bacterial infections. Fish were pretreated with FCL-2 alone (1, 3 or 7 days) or with FCL-2 and T4 (1 or 7 days) before infection with Flavobacterium columnare. (A) FCL-2 phage titers in fish mucus and aquarium water (before infection) from FCL-2-only groups. (B) FCL-2 and T4 titers from fish mucus and aquarium water (before infection) in the combined FCL-2 and T4 groups. (C) Fish survival in the FCL-2-only-pretreated groups. (D) Fish survival in the combined FCL-2- and T4-pretreated groups. (E) FCL-2 titers in water after infection in the FCL-2-only groups. (F) FCL-2 and T4 titers in water after infection in the combined FCL-2 and T4 groups. (G) F. columnare quantity (genomic copies) in water after infection in the FCL-2-only-pretreated groups. (H) F. columnare quantity (genomic copies) in water after infection in the combined FCL-2- and T4-pretreated groups. Each data point represents one individual fish or water sample and the standard deviations in panels A and B. In panels C and D, the number of fishes used was 15 per group, except in the negative control (n = 16) and the group exposed to FCL-2 alone for 7 days (n = 12). In panels E, F, G, and H, the data points represent the average of triplicates and their standard deviation. The log-rank (Mantel-Cox) test was used for evaluation of the survival curves in panels C and D. Unpaired t tests were used to compare the controls and tested conditions in panels G and H (*, P < 0.05; **, P < 0.001).