The present inventors concerns vectors carrying a truncated chimeric CMV-chicken β-actin (smCBA) promoter in which the hybrid chicken β-actin / rabbit β-globin intron is greatly shortened, and their use to deliver to an operatively linked polynucleotide to host cells in vitro or in vivo, resulting in expression of the polynucleotide in the host cells. In one embodiment, the vector carrying the smCBA promoter is administered to the eye. In another embodiment, the vector carrying the smCBA promoter is a self-complementary adeno-associated virus (AAV). The AAV vector may be of any serotype (e.g., type 1, type 2, type 3, type 4, type 5, type 6, type 7, type 8, type 9, type 10). In another embodiment, a self-complementary vector carrying the smCBA promoter is administered to the eye. Another aspect of the invention concerns host cells carrying a vector of the invention. Another aspect of the invention concerns pharmaceutical composition comprising the vectors or host cells of the invention, and a pharmaceutically acceptable carrier.