The Ability of Phage Containing 5-Iodo-2′-deoxyuridine-substituted Deoxyribonucleic Acid to Induce Enzymes

Physical and biological consequences of incorporation of antiviral agents into virus DNA

The molecular basis for the antiviral activity is discussed for a variety of nucleoside compounds approved for clinical use in the U.S.A. (5-iodo-2'-deoxyuridine, 5-trifluoromethyl-2'-deoxyuridine, 9-beta-D-arabinofuranosyladenine, 9-(2-hydroxyethoxymethyl)guanine), or in clinical trial (E-5-(2-bromovinyl)-2'-deoxyuridine, 1-(2-deoxy-2-fluoro-beta-D-arabinosyl)-5-iodocytosine, 1-beta-D-ribofuranosyl-1,2,4-triazole-3-carboxamide), or of specific interest to our laboratory (5-iodo-5'-amino-2',5'-dideoxyuridine, 5'-amino-5'-deoxythymidine). The consequence of incorporation of idoxuridine, the 5'-amino analog of thymidine or the 5'-amino analog of idoxuridine into the DNA of herpes simplex virus type 1 on transcription and translation is emphasized.

Effects of nucleoside analogues on the expression of herpes simplex type 1-induced proteins

Exposure of herpes simplex virus type 1 (HSV-1)-infected Vero cells to the nucleoside analogues 5-iodo-5'-amino-2',5'-dideoxyuridine (AIdUrd), 5-iodo-2'-deoxyuridine (IdUrd) or 5'-amino-2',5'-dideoxythymidine (5'-AdThd) resulted in altered expression of HSV-1-induced proteins. Infected cell proteins (ICPs) synthesized in the presence of the nucleoside analogues were compared by sodium dodecyl sulphate (SDS) polyacrylamide gel electrophoresis to ICPs from non-drug-treated cells and it was found that there was no effect on HSV-1-induced alpha proteins but beta and gamma proteins were reduced as much as 60%. There were three exceptions: ICP 35 (Mr = 46,000) and ICP 39 (Mr = 36,000) were not reduced and ICP 36 (Mr = 42,000) was increased during drug treatment. Progeny virions were isolated from drug-treated infected Vero cells and were compared to progeny isolated from control cells with respect to their polypeptide make-up and for their ability to induce HSV-1 proteins in non-drug-treated Vero cells. The progeny virus from drug-treated cells exhibited altered protein patterns on SDS-polyacrylamide gels with respect to control HSV-1. The progeny virions from AIdUrd- or IdUrd- but not from 5'-AdThd-treated cells were defective in their abilities to induce proteins upon subsequent infection of non-drug-treated Vero cells. Two unusual phosphoproteins were detected; one with an apparent molecular weight of 30,000 was induced by progeny virus from AIdUrd-treated cells and another at approximately 69,000 was induced by progeny virus from 5'-AdThd-treated cells.

The effect of 5-iodouracil on the growth and biosynthetic processes of bacteriophage T4td8 in the absence of light

5-Iodouracil (IUra)-substituted progeny bacteriophage T4td8 were grown under conditions such that, upon CsCl equilibrium isopycnic gradient centrifugation, progeny with density distributions about the median similar to that of unsubstituted phage are obtained. In the absence of light a monotonic relationship exists between decreasing progeny viability and increasing percent IUra substitution. IUra is equivalent to thymine as a growth factor on a molar basis, and at concentrations of IUra plus thymine above that required for maximum particle production, the percent IUra substitution in phage DNA is determined by the mole fraction of IUra in the medium. The lethal effects of 5-iodo-2'-deoxyuridine (IdUrd) and IUra are equivalent, and are not produced by a direct effect on the phage particles. At equivalent percent substitution in phage DNA the order of lethality is IUra greater than 5-bromouracil (BrUra) greater than 5-chlorouracil (ClUra). There is no interference with the transfer of thymine from host cell to progeny phage by the presence of IUra in the medium, and IUra affects neither the time of lysis nor the content of phage DNA in the infected cells.