Mouse adenovirus: growth of plaque-purified FL virus in cell lines and characterization of viral DNA

The FL strain of mouse adenovirus (AdFL) was plaque-purified and grown in mouse 3T6 cells. Purified virions resemble human adenoviruses by electron microscopy, and viral DNA shares physical properties with human adenovirus DNA. AdFL-DNA is a linear duplex with a molecular weight of 20 × 10⁶, shows evidence of protein covalently linked at each end, and forms single-strand circles after denaturation, indicating inverted repeat sequences at or near the ends of the molecule. However, less than 10% nucleotide sequence homology was found between AdFL-DNA and the DNAs of Ad2, 7, or 12. Also, the C + G content of AdFL-DNA (44%) is lower than that of human adenovirus DNAs. While there was reactivity between extracts of AdFL-infected cells and antiserum against human adenovirus, sera against the T antigens of human adenoviruses of groups A, B, and C did not react with AdFL-infected cell lysates. Six restriction endonucleases were used to cleave AdFL-DNA and to construct cleavage maps of the DNA. These maps differed from those of Ad2 or Ad5.