The invention provides an adenoviral vector comprising (a) at least a portion of an adenoviral genome comprising a major late transcription unit containing a terminal exon, wherein the terminal exon comprises a 5' splice acceptor DNA sequence element and a 3' polyadenylation signal sequence, and (b) a non-native nucleic acid sequence encoding a protein that does not contribute to the adenoviral vector entry into a host cell, wherein the non-native nucleic acid sequence is positioned within the terminal exon, such that the non-native nucleic acid sequence is selectively expressed in cells within which the adenoviral vector can replicate. The invention further provides an adenoviral vector composition and a method for treating or preventing a pathologic state in a mammal, comprising administering to the mammal the adenoviral vector composition of the invention in an amount sufficient to treat or prevent the pathologic state in the mammal.