ANALYSIS OF THE STRUCTURE OF THE GENOME OF PSEUDORABIES VIRUS

Examination by electron microscopy of self-annealed single strands of pseudorabies virus DNA revealed the following structure: a sequence, (molecular weight, 9.9 × 106) which is repeated in a complementary, inverted form on the other side of a short unique sequence (molecular weight, 6.0 × 106), is present at one end of the molecule. The extreme end of the inverted repeat, the terminal region, is not repeated internally. A long unique sequence (molecular weight, 65 × 106) comprises the remainder of the molecule. A sequence homologous to the end of the long unique sequence is also found approximately 350 bases from the end. In addition, examination of self-annealed exonuclease-treated DNA revealed the presence of double-stranded lariats, as well as smaller-than-unit-size circles, indicating that other sequences homologous to the end of the molecule are present at various distances from the ends. After exonuclease digestion of the ends and self-annealing, circular unit-size molecules were not observed. The number of nicks and gaps on individual pseudorabies viral DNA molecules varied between 1 and 10 per molecule; on the average, each molecule contained approximately 3.5 nicks or gaps. The nicks or gaps were found to be located at random sites along the molecule. No alkali-sensitive bonds were detected in the DNA. © 1979.