Electron microscopic comparison of the sequences of single-stranded genomes of mammalian parvoviruses by heteroduplex mapping

The sequence homologies among the linear single-stranded genomes of several mammalian parvoviruses have been studied by electron microscopic analysis of the heteroduplexes produced by reannealing the complementary strands of their DNAs. The genomes of Kilham rat virus, H-1, minute virus of mice and LuIII, which are antigenically distinct non-defective parvoviruses, have considerable homology: about 70% of their sequences are conserved. The homologous regions map at similar locations in the left halves (from the 3′ ends) of the genomes. No sequence homology, however, is observed between the DNAs of these nondefective parvoviruses and that of bovine parvovirus, another non-defective virus, or that of defective adenoassociated virus, nor between the genomes of bovine parvovirus and adenoassociated virus. This suggests that only very short, if any, homologous regions are present. From our results, we predict an evolutionary relationship among Kilham rat virus, H-1, minute virus of mice and LuIII. It is interesting to note that, although LuIII was originally isolated from a human cell line and is specific for human cells in vitro, its genome has sequences in common only with the rodent viruses Kilham rat virus, minute virus of mice and H-1, and not with the other two mammalian parvoviruses tested.