Ectopic expression of pancreatic transcription factors was mediated by viral infection with non-integrating, recombinant adenoviruses, Ad-CMV-PDX-1, Ad-CMV-NGN3, Ad-CMV-NEUROD1, Ad-CMV-MAFA, or Ad-CMV-NKX6.1 (all at 1000 moi). This evidence concerns the gene NEUROG3 and viral infectious disease.