Inhibition of vaccinia virus replication by N-(Phosphonoacetyl)-L-aspartate: Differential effects on viral gene expression result from a reduced pyrimidine nucleotide pool

George C. Katsafanas, Jean L. Grem, Herbert A. Blough, Bernard Moss

Research output: Contribution to journalArticle

4 Scopus citations

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.

Original languageEnglish (US)
Pages (from-to)177-187
Number of pages11
JournalVirology
Volume236
Issue number1
DOIs
StatePublished - Sep 15 1997

ASJC Scopus subject areas

  • Virology

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