O-Antigen Prevents Phagocytosis by Fish Skin Cells Figure 7. Bioluminescent imaging of V. anguillarum infections in rainbow trout. Rainbow trout (20 g) were infected with V. anguillarum strains carrying pNQFlaC4-lac::lux by bathing in infected seawater. At 24 h and 48 h, fish were sacrificed and images of the fish were obtained as described in Materials and Methods. To image internal organs, one side of the fish was removed after the skin was imaged. To measure photons from the intestines, the contents were pushed out the anus and are indicated by a white arrow. A blue arrow indicates the spleen. Strains are designated by their mutation. Mutation designations followed by a C are complemented. doi:10.1371/journal.pone.0037678.g007 ing bacterial mechanisms required for colonization of fish skin tissues is vital to provide better insight into how bacteria are transmitted from fish to fish or from fish to human within aquaculture or in the wild and to develop improved therapeutics for the prevention of fish and/or human disease. PLoS ONE | www.plosone.org 8 May 2012 | Volume 7 | Issue 5 | e37678