Testing Vivo-Morpholino Mediated Gene Knockdown of STAT6, Spi1b, and HNF4α in Adult Threespine Stickleback

The fibrotic immune response to the cestode parasite, Schistocephalus solidus, varies among threespine stickleback populations. Fibrosis suppresses parasite growth but has costly effects on the fish. Previous genomic studies in stickleback have suggested potential roles of Spi1b, STAT6, and HNF4α in modulating fibrosis severity, but there is presently no evidence for this in-vivo. We used antisense vivo-morpholino oligonucleotides (MOs) to attempt to knockdown the expression of each gene in the liver, spleen, and intestine of adult stickleback. Vivo-MOs have been proven effective in other species of teleost fish, as well as in mice and humans, but no prior studies have evaluated their use in stickleback. Knockdown was assessed at 24 and 48 hours after intraperitoneal injection of each MO. A significant knockdown of Spi1b was observed in the spleen at 24 hours-post-injection, however, this technique was otherwise unsuccessful. Injection of a fluoresceinated control MO demonstrated successful delivery of a vivo-MO into each organ, validating this approach. These findings suggest a potential use for vivo-MOs in stickleback, and this technique should be modified in future studies to increase knockdown efficiency.