Differences in the E3 regions of the canine adenovirus type 1 and type 2.

Sequence analysis of a region extending between the pVIII and the fiber gene of Canine adenovirus type 1 (Cav-1, Utrecht) and type 2 (Cav-2, Manhattan) was performed. The results revealed a high level of identity between the two viruses when the pVIII gene and the N-terminal part of the fiber gene were compared. The open reading frames of region E3 in of Cav-1 and Cav-2 encoded a 22 kDa and 40.7 kDa polypeptide, respectively. The Cav-1 and Cav-2 E3 region polypeptides shared conserved amino and carboxyl domains. In Cav-2 an extra sequence of about 500 nucleotides was present, appearing like an in frame insertion of foreign DNA. It can be speculated that this insertion in the E3 region contributes to the observed biological differences between Cav-1 and Cav-2.