Radiometric detection of herpes simplex viruses

Two radiometric techniques were investigated as possible means of detecting viruses in clinical specimens. The effect of herpes simplex virus on DNA synthesis by monolayers of human embryonic lung fibroblasts was monitored by the incorporation of [ ³H] thymidine or [ ¹²⁵I] iododeoxyuridine ([ ¹²⁵I] IdU). Radiometric results were compared with those obtained from visual examination for cytopathic effects in the same cell line. Cells infected with herpes simplex virus type-2 (HSV-2, 10 ^6.8 virions) showed a marked increase in [ ³H] thymidine incorporation 2-6 hr after infection. Types 1 and 2 herpes simplex virus yielded similar results, with increased incorporation of tracer being observed 72 hr after infection with 10 virions. The [ ³H] thymidine technique was used successfully to assay mouse brains infected with HSV-1. Increased [ ¹²⁵I] IdU incorporation was observed 6 hr after infection with 10 ⁵-10 ^6.8 HSV-1 virions, 24 hr after 10 ⁴ virions, 48 hr after 10 ³ virions, and 72 hr after 10-100 virions. The increased [ ¹²⁵I] IdU incorporation was completely inhibited by preneutralization with immune serum. These radiometric techniques for detection of viral effect on cellular metabolism are simple, objective, and quantitative.