Restriction endonucleases recognizing DNA sequences of four base pairs facilitate differentiation of herpes simplex virus type 1 strains.

Variation of restriction endonuclease cleavage patterns between herpes simplex virus type 1 (HSV-1) strains was investigated using restriction endonucleases recognizing DNA sequences of four base pairs (4-bp enzymes) (HaeIII, HhaI, Sau3AI). The analysis made feasible identification of variations not heretofore detectable, using enzymes recognizing DNA sequences of six base pairs (BamHI, KpnI, SalI), and proved to be most useful for distinction and classification of HSV-1 strains. Ten of the fifteen strains analysed using 4-bp enzymes were closely related, and were put into group 1, and the other five not so related strains were classed into the non-group 1. The observations suggested a possible common ancestor from which group 1 strains had derived.