Differential effect of phosphonoacetic acid on the expression of Epstein-Barr viral antigens and virus production.

Abstract

The effects of phosphonoacetic acid on cell growth, expression of Epstein-Barr virus antigens, and virus production in human and marmoset lymphoblastoid cell lines have been studied. The drug had no significant effect at concentrations up to 100 jg/ml on cell growth or total cell DNA synthesis. Hi' er doses induced not only a drastic decrease in DNA synthesis and cell growth, but also a dramatic cell enlargement. Immunofluorescence studies showed that >30 jsg/ml of phosphonoacetic acid inhibited viral capsid antigen synthesis without affecting the expression of the nuclear antigen or the spontaneous and 5-iodo-2'-deoxyuridineinduced early antigens. Production of transforming EpsteinBarr virus was also blocked. Inhibition of viral capsid antigen expression and of virus production at low doses was reversible. The (human fibroblast) cells (3). PAA inhibits herpes simplex virus replication by interfering with the DNA polymerase activity (4). It has also been found to inhibit the replication of several other herpes viruses, including cytomegalovirus (5), Marek's disease virus (6), and equine abortus virus (7), and a non-herpes virus, vaccinia virus (8). In this paper we present data which show that PAA inhibits the synthesis of Epstein-Barr (EBV) viral capsid antigens (VCA) and of virus itself at concentrations which have no detectable effect on the synthesis of nuclear antigen (EBNA) and early antigens (EA), or on cellular DNA synthesis and cell proliferation. PAA also has no detectable effect on 5-iodo-2'-deoxyuridine-(IdUrd) or superinfection-induced EA synthesis in the nonproducer Raji cell line. MATERIALS AND METHODSCell Cultures. Lymphoblastoid cell lines B95-8, P3HR-1, nd Raji used in this investigation were obtained from Dr. 7eorge Klein and from Pfizer, Inc. The B95-8 cell line is an EBV-transformed marmoset lymphocyte line which proluces a lymphocyte-transforming virus (9). P3HR-1 and laji are Burkitt's lymphoma-derived lines which produce iontransforming cytopathic EBV (10) and no virus (11), respectively. Cells were routinely maintained in RPMI-1640 medium supplemented with 100 Ag/ml of streptomycin, 100 units/ml of penicillin, 300 jg/ml of glutamine, and fetal calf serum. They were fed every 3-4 days and the concentration was adjusted to 2 to 5 X 105 cells per ml at each feeding. All cultures were kept at 370 in a humidified 5% CO2 incubator.Reagents Cell Growth and DNA Synthesis. For measurement of DNA synthesis, B95-8 cells were seeded in duplicate at 5 X 105 per ml in a total of 3 ml for 48 hr and pulse labeled with 4 .Ci/ml of[3H]dThd (New England Nuclear, specific activity: 13 Ci/mmol) for 1 hr, and radioactivity ip the trichloroacetic-acid precipitable material was assayed in a Beckman liquid scintillation counter. For measurement of growth, cells were seeded in duplicate at 5 X 105 per ml and cultivated for various times. Viable cells were determined by the trypan blue exclusion technique. The effect of PAA on chromosomes was studied in exponentially growing B95-8 cells treated with co...

Structure-activity studies on phosphonoacetate

“…This suggests that the ionic property of the phosphono group is more important than that of the carboxylic group and that at least one ionizable group on phosphono must be available for activity. As expected, diesters [16,17] and triesters [18 to 21] of PAA were not active.…”

“…Phosphonoacetic acid (PAA) has been previously shown to suppress replication of herpes simplex virus (1,19), avian herpesvirus (11), cytomegalovirus (9), Epstein-Barr virus (16,23,27), vaccinia virus, equine abortion virus, and varicella-zoster virus (1,18) in tissue culture. Promising results in the treatment of ocular, cutaneous, and encephalitic herpesvirus infections in mice, hamsters, and rabbits have been documented (4,5,14,17,21,25).…”

Upregulation of STAT3 Marks Burkitt Lymphoma Cells Refractory to Epstein-Barr Virus Lytic Cycle Induction by HDAC Inhibitors

“…2). Phosphonoacetic acid (PAA) was used to block lytic viral DNA replication (40) to reduce the background of newly synthesized viral DNA. After correcting for input, the amount of Zp immunoprecipitated with anti-acetylated H3 antibody from refractory cells was substantially greater than the amount recovered from untreated or lytic cells ( Fig.…”

Effects of Nucleoside Analogs on Epstein-Barr Virus-Induced Transformation of Human Umbilical Cord Leukocytes and Epstein-Barr Virus Expression in Transformed Cells

“…A virally coded DNA polymerase has been shown to be the most likely target for the action of this drug (26,27,33). Phosphonoacetic acid has also been shown to inhibit EBV expression in (30,45,50), and transformation of, human leukocytes (36,46). Unfortunately, host toxicity appears likely to limit the usefulness of phosphonoacetic acid in vivo.…”