Methods and constructs for genetic manipulation of one or more of shrimp, shellfish, mollusks, and fish are disclosed. The nucleic acid construct includes a promoter and an internal ribosome entry site of an insect picomavirus, such as a cricket paralysis-like picomavirus. One or more open reading frames can be operably associated with one or both of the promoter and the internal ribosome entry site, and one or more proteins or protein subunits can be expressed upon introduction of the construct into a host cell, such as into a shrimp. Method for producing immortalized crustacean cell lines using enhancer elements derived from shrimp and/or shrimp viruses are also described.