Studies on Autographa californica nuclear polyhedrosis virus replication in Spodoptera littoralis cells including virus-induced protein synthesis.

The replication of the Autographa californica nuclear polyhedrosis virus in Spodoptera littoralis cells has been investigated. Various cytopathic changes were detected by light and electron microscopy and progeny enveloped virus particles, some occluded within polyhedra, were later seen in the nucleus of infected cells. Infectious virus was released into the growth medium and increased exponentially from ca. 10 to 24 hours post infection and then slowly increased over the next 4 days. In comparison, virus was released ca. 3.5 hours earlier from Spodoptera frugiperda cells. Total rates of DNA and protein synthesis were drastically reduced during the late stages of virus replication when cell death was occurring. By ca. 18 hours post infection, a clear switch from host to virus induced protein synthesis had occurred and a total of 39 virus-induced polypeptides of M.W. 12 to 120 X 10(3) were detected. These included polyhedrin of M.W. 33 X 10(3), which was particularly prominent during the late stages of virus replication, and a major virus structural protein of M.W. 42 X 10(3).