we prepared retrovirus packaging cell lines containing gag-pol genes from spleen necrosis virus ( expressed from a cytomegalovirus promoter and the simian virus 40 ( sv40 ) polyadenylation sequences ) and , on a separate vector , either the env gene from spleen necrosis virus ( expressed from the rous sarcoma virus promoter and the sv40 polyadenylation sequences ) or the env gene from amphotropic murine leukemia virus ( expressed from a cytomegalovirus promoter and the sv40 polyadenylation sequences ) .
C0035366
retrovirus
C0017343
env gene