A method for generating an adenoviral expression library, said library comprising a plurality of recombinant adenoviruses, each recombinant adenovirus comprising an expressible piece of exogenous DNA, said method comprising the steps of:
- providing a first piece of DNA consisting of the adenoviral genome or a substantial part thereof, said first piece of DNA being deleted for an essential gene of a late transcriptional region.
- providing a plurality of second pieces of DNA, each said second piece of DNA comprising a second transcriptional region of adenoviral genome or a part thereof, said second region or a part thereof comprising a first expression cassette for expressing the essential gene, said second piece of DNA further comprising the expressible piece of exogenous DNA, said first and second pieces of DNA comprising a common polynucleotide sequence permitting homologous recombination thereof in vivo,
- transfecting non-complementing cells capable of hosting the recombinant adenovirus with the first piece of DNA and the plurality of second pieces of DNA,
- incubating said cells, and
- harvesting the recombinant adenoviruses.