Plaque dissociation of herpes simplex viruses: biochemical and biological characters of the viral variants.

Polycaryocytogenic (P) and non-polycaryocytogenic, or aggregating (A), stable variants were selected from a herpes simplex virus type 1 (HSV-1) and from a herpes simplex virus type 2 (HSV 2) which had not been deliberately exposed to known mutagenic agents. The P variant of HSV-1 (FP) differed from the A variant (FA) in polypeptides and glycoprotein patterns, but no gross differences were evident between the two variants of HSV-2 (GP and GA). Each P variant proved more 'specific' than each A variant in immune neutralization tests. At high multiplicity, GP produced polycaryocytes but FP did not. Virulence tests in mice showed FP to be much more virulent than FA but GA to be more virulent than GP. Finally, A and P variants of each type could not be differentiated with respect to thermal resistance of virons, capacity to grow at high temperature, and buoyant density of DNA.