Inhibition of interferon production by 5-lodo-2-deoxyuridine

Expression of the human cytomegalovirus genome in mouse cells and in human-mouse heterokaryons

Mouse cells with an established human cytomegalovirus (HCMV) infection were fused with susceptible human embryonic fibroblast cells. CMV-specific early antigens could be demonstrated in the cytoplasm and cell-membrane of the heterokaryons. Treatment with 5-iodo-2'-deoxyuridine (IUdR) of the heterokaryons or of the latently infected mouse cells, prior to their fusion with human cells, could induce the appearance of immunoflourescent elements, characterised as late antigens, and of infectious virus. Our data show that the mouse cells, in the latent stage of infection, contain the whole virus genome and that the replication of the virus is controlled by a genetic mechanism of the host cells both in virus-harbouring mouse cells and in heterokaryons.

Cytomegalovirus: conversion of nonpermissive cells to a permissive state for virus replication

Human embryonic kidney cells are epithelioid cells which are normally nonpermissive for in vitro replication of human cytomegalovirus. These cells were converted to a permissive state for the virus by prior treatment with 5-iodo-2'-deoxyuridine. When this method was used, a nonpermissive cell was made permissive to an infecting virus.

Cytomegalovirus replication in cells pretreated with 5-iodo-2'-deoxyuridine

The replication of human cytomegalovirus (CMV) in cells pretreated with 5-iodo-2'-deoxyuridine (IUdR) was studied. Pretreatment of cells with IUdR enhanced several parameters of virus replication. Virus grown in drug-treated cells exhibited a shorter eclipse period and the cells produced more infectious virus sooner than did untreated cells. There was an approximate fivefold increase in virus yield per cell in the drug-treated samples when compared to control cultures. The time required for plaque development was shortened by 6 days in drug-treated cultures. Pretreatment of cells with IUdR also increased plaquing efficiency of the virus by approximately 10-fold. The enhancement of virus replication by IUdR was further demonstrated by varying the multiplicity of infection. In a 7-day period there was a 100-fold increase in sensitivity of the cultures for virus detection when the cells had been previously exposed to IUdR. The data presented indicate the possibility that IUdR interferes with the production of a cellular product inhibitory for CMV replication.