Inhibition of Autographa californica nuclear polyhedrosis virus replication in high-density Trichoplusia ni cell cultures.

Replication of the Autographa californica nuclear polyhedrosis virus was studied in Trichoplusia ni (TN-368) tissue culture cells under cell density conditions which approximated a confluent monolayer (5.7 x 10(5) cells/cm(2) growth surface). These high-density cultures were not refractory to infection but the synthesis of both the occluded and nonoccluded forms of the virus were inhibited greater than 98% when compared to inoculation of low cell density cultures (1.4 x 10(5) cells/cm(2)). The inhibition phenomenon was not due to depletion of a medium component or a diffusable cell-associated factor. The inhibition was reversible and required cell-to-cell contact. Viral-induced protein synthesis studies using 35S-labeled methionine incorporation indicated an 18-hr delay in the synthesis of one of the four early proteins under high cell density conditions. DNA:DNA dot hybridization and 3H-labeled thymidine incorporation studies indicated that cell-to-cell contact reversibly inhibited both cellular and viral DNA synthesis.