We first established that the larval to adult globin switch reported in other amphibian species also occurred in B. marinus. It is well documented that a tadpole form of globin in anurans is replaced by adult globin during the course of metamorphosis [18, 26, 27] and here we demonstrate the existence of this switch for the first time in a Bufo species. We have previously demonstrated strong upregulation of adult globin genes during cane toad metamorphosis and that this was more pronounced than for any of the other genes induced at metamorphosis [17] . We have also previously shown that the recombinant BIV can be genetically modified to express adult globin in vitro [11] and confirmed here that this virus (rBIV/neo r /Adglob) is capable of infecting cane toad tadpoles. We therefore used rBIV/neo r /Adglob to assess the effect of viral delivery of an adult specific gene or protein to tadpoles on subsequent metamorphosis, and compared this to the effects of immunisation with purified protein and adjuvants.