The present invention provides a mechanism for studies of apoptosis in aquatic organisms by infecting the aquatic organisms with aquabirnavirus, especially infectious pancreatic necrosis virus (IPNV). The infection of IPNV in an aquatic cell such as a Chinook salmon embryo cell (CHSE-214) converts the cell into an apoptotic cell. The present invention also provides a method for monitoring the morphological changes during apoptosis by cloning EGFP (a variant type of GFP) to an aquatic cell and monitoring the fluorescence using microscopic techniques. The intensity of the fluorescence reflects the expression of EGFP in cells. Finally, the present invention provides means for inducing or preventing/rescuing apoptosis in a host, which include aquatic and vertebrate. The apoptosis can be induced by IPNV infection or VP3 transfection that VP3 is a 32 kDa protein derived from IPNV segment A. The apoptosis can be prevented or rescued by an antisense VP3 RNA or a zfMcl-1a protein.