title: Inhibition of vaccinia virus replication by N-(phosphonoacetyl)-L-aspartate: differential effects on viral gene expression result from a reduced pyrimidine nucleotide pool.
abstract: The replication of vaccinia virus was reduced by 3 logs in cells that had been treated before and during infection with a concentration of N-(phosphonoacetyl)-L-aspartate (PALA) which lowered the UTP and CTP to 5 and 20% of controls, respectively, without affecting cell viability. The antiviral activity of PALA was reversed with uridine, indicating that it was entirely due to the diminution in pyrimidine nucleotides. Analysis of viral proteins revealed prolonged synthesis of some early stage species but a drastic reduction in late stage species, even though the nucleotide concentrations remained relatively constant throughout the infection. Although the gene expression pattern resembled that caused by a potent inhibitor of DNA synthesis, viral DNA accumulation was reduced by only 60%. Very little of the DNA made in the presence of PALA was converted to genome length molecules. The effect of PALA on transcription of early genes was complex: there was a twofold increase in the amount of a relatively short mRNA of 500 nucleotides but a two- to threefold decrease in the amount of a 4300-nucleotide mRNA encoding the largest subunit of RNA polymerase. In contrast, PALA severely inhibited the accumulation of viral intermediate and late stage mRNAs. The extreme sensitivity of vaccinia virus to PALA and the differential effects of the drug on viral gene expression result from the cascade mechanism of viral gene regulation.
authors.affiliation: Laboratory of Viral Diseases, National Institute of Allergy and Infectious Diseases, Bethesda, Maryland 20892-0445, USA.
authors.forename: G C
authors.initials: GC
authors.lastname: Katsafanas
authors.forename: J L
authors.initials: JL
authors.lastname: Grem
authors.forename: H A
authors.initials: HA
authors.lastname: Blough
authors.forename: B
authors.initials: B
authors.lastname: Moss
mesh_terms: D000998:Antiviral Agents / Q000494:pharmacology*; D001224:Aspartic Acid / Q000031:analogs & derivatives* / Q000494:pharmacology; D002470:Cell Survival / Q000187:drug effects; D003570:Cytidine Triphosphate / Q000378:metabolism; D012321:DNA-Directed RNA Polymerases / Q000096:biosynthesis; D015967:Gene Expression Regulation, Viral / Q000187:drug effects / Q000502:physiology*; D006367:HeLa Cells; D006801:Humans; D007700:Kinetics; D046911:Macromolecular Substances; D010746:Phosphonoacetic Acid / Q000031:analogs & derivatives* / Q000494:pharmacology; D011742:Pyrimidine Nucleotides / Q000378:metabolism*; D012333:RNA, Messenger / Q000096:biosynthesis; D014158:Transcription, Genetic / Q000187:drug effects*; D014529:Uridine / Q000494:pharmacology; D014544:Uridine Triphosphate / Q000378:metabolism; D014616:Vaccinia virus / Q000187:drug effects* / Q000502:physiology; D014779:Virus Replication / Q000187:drug effects*
chemical_list: D000998:Antiviral Agents; D046911:Macromolecular Substances; D011742:Pyrimidine Nucleotides; D012333:RNA, Messenger; D001224:Aspartic Acid; D003570:Cytidine Triphosphate; C013195:sparfosic acid; D012321:DNA-Directed RNA Polymerases; D010746:Phosphonoacetic Acid; D014544:Uridine Triphosphate; D014529:Uridine