Enhanced infectivity of adenovirus type 2 DNA and a DNA-protein complex

Abstract

The infectivity of adenovirus type 2 DNA and a DNA-protein complex was studied in 293 cells, a human embryonic kidney cell line transformed by sheared adenovirus type 5 DNA, and in human [oral carcinoma] KB cells. Adenovirus type 2 DNA was more infectious (up to about 40-fold) in 293 cells than in KB cells, but a DNA-protein complex (prepared by a rapid procedure) had about the same infectivity in both cell lines. These data may mean that a factor present in 293 cells (perhaps a viral-coded protein) enhances the infectivity of free viral DNA. The infectivity of DNA and the DNA-protein complex was increased up to 5-fold by brief treatment of cell monolayers with 25% dimethyl sulfoxide after transfection. Under these conditions, the infectivity of native adenovirus type 2 DNA ranged from 400-1300 PFU[plague forming units]/.mu.g of DNA in 293 cells and from about 9-14 PFUl .mu.g of DNA in KB cells, and the infectivity of the DNA-protein complex was 6 .times. 103 .times. 2 .times. 104 PFU/.mu.g in 293 cells and 1.4 .times. 104-1.6 .times. 104 PFU/.mu.g in KB cells.