Recombinant replication-defective human adenoviruses (Ad5-POL and Ad5-LacZ) were constructed and maintained in our laboratory [6] . Ad5-POL expressed siRNA targeting the FMDV 3D sequence corresponding to nucleotides (nt) 1225-1280 of HNK/2002 3D. As a control for nonspecific effects of rAd5, Ad5-LacZ expressed siRNA corresponding to nt 1353 to 1435 of the b-galactosidase gene of Escherichia coli, which has no homology to the HKN/2002 genome as confirmed by sequence analysis. The sequence of Ad5-POL encoding the FMDV 3D-specific siRNA was 5 0 -GAGGCTATCCTCTC CTTTGCACGCCGTGGGACCATACAGGAGAAG TTGATCTCCGT-3 0 (sense), and that of Ad5-LacZ encoding the E. coli b-galactosidase-specific siRNA was 5 0 -GAGTGTGATCATCTGGTCGCTGGGGA ATGAATCAGGCCACGGCGCTAATCACGACGC GCTGTATCGCTGGATCAAATCTGTCG-3 0 (sense).