- To study the accumulation and retention of recombinant proteins in Artemia gut for optimizing paratransgenic disease control in shrimp aquaculture.Transgenic Escherichia coli expressing fluorescent marker proteins and the transgenic cyanobacterium Synechococcus bacillarus expressing a functional murine single chain antibody, DB3, were fed to Artemia franciscana. Stable expression and retention of several marker molecules (e.g. GFP, DS Red and DB3) up to 10 h after of feeding with E. coli were evident within the gut of Artemia. Engineered strains of S. bacillarus expressing DB3 accumulated within the gut of Artemia with detectable antibody activity for 8-10 h of feeding via ELISA, coincident with the time period of the highest density of transgenic S. bacillarus in the Artemia gut.Artemia fed transgenic bacteria or algae accumulated recombinant proteins for up to 10 h that retained biological activity. Co-delivery of multiple recombinant proteins simultaneously in the gut of Artemia was also demonstrated.Expression of molecules that target infectious agents of mariculture in shrimp via commonly deployed feed organisms such as Artemia could potentially offer powerful new tools in the ongoing global effort to increase food supply.