Evaluation of the elevation of host cell biosynthesis of deoxynucleosi
de triphosphates (dNTP's) induced by human cytomegalovirus (HCMV) infe
ction as a target for antiviral therapeutics was carried out. The conc
entrations of all four intracellular dNTP's rose rapidly following HCM
V infection, and were markedly above baseline by 8 h post infection (p
.i.). All four deoxynucleoside triphosphates remained elevated above b
aseline for at least 72 h p.i. The effects of inhibitors of the de-nov
o pathway of pyrimidine biosynthesis on HCMV viral replication-were qu
antified by DNA dot blot. AII pyrimidine biosynthesis inhibitors exami
ned inhibited the HCMV DNA replication at concentrations that were non
-toxic to the cell. These drugs were also more effective against HCMV,
which is highly dependent on host denovo synthesis, than against HSV-
1 which encodes enzymes capable of increasing the supply of dNTP's. Th
e antiviral effect of brequinar, an inhibitor of one of the enzymes of
the de-novo pathway (dihydroorotate dehydrogenase), was examined to d
etermine if it coincided with a decrease in dNTP's. HCMV-infected fibr
oblasts and uninfected control cells were treated with a concentration
of brequinar able to inhibit HCMV DNA levels 90%. It was found that b
requinar markedly lowered the levels of dTTP found in treated cells co
mpared to untreated cells in both HCMV-infected and uninfected cells.