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Chemical agents reported to inhibit the growth of various ribonucleic acid and deoxyribonucleic acid viruses were tested against foot-and-mouth disease virus in cell culture. These included Zn2+, aurintricarboxylic acid, polyribocytidylic acid, polyriboinosinic acid, phosphonoacetic acid, and the viral contact inactivator Nmethyl isatin,-thiosemicarbazone alone and with CUSO4. The most effective agent, Zn2+, inhibited foot-and-mouth disease virus production in primary calf kidney cells by 1 log unit at 0.05 mM Zn2+ and completely at 0.50 mM. Zinc was inhibitory even when added late in infection and was nontoxic to uninfected cells as measured by protein and nucleic acid syntheses. Polyacrylamide gel patterns of [IS]methionine-labeled, virus-specific proteins showed increasing amounts of higher-molecular-weight material, in accord with reports that Zn2+ inhibits posttranslational cleavages of other picornavirus precursor polypeptides.Certain antiviral agents (6) have been shown to inhibit the production of foot-and-mouth disease virus (FMDV) in cell cultures (1,7,8). These agents are primarily amino acid, purine, and pyrimidine analogs, as well as substituted thiosemicarbazones. The present report examines the effectiveness of Zn2+, aurintricarboxylic acid (ATA), polyribocytidylic acid, polyriboinosinic acid, phosphonoacetic acid, and N-methyl isatin,8-thiosemicarbazone (methisazone) alone and in conjunction with Cu2+. The most inhibitory of these, Zn2+, is shown to interfere with the cleavage of high-molecular-weight precursors of FMDV-specific proteins, as has been reported for post-translational cleavages of other picornavirus precursor polypeptides (2). MATERIALS AND METHODSCells and media. Primary bovine kidney (BK) monolayer cultures were grown in 4-ounce (120-ml) prescription bottles containing Hanks balanced salts solution (HS), 0.5% lactalbuini hydrolysate, and 6% bovine serum. The chemical agents, unless otherwise noted, were dissolved in HS in 1.0% tris(hydroxymethyl)aminomethane (Tris) buffer (pH 7.5) containing 0.2% glucose, 4 mM glutamine (HS-TB), and basal Eagle amino acids (HS-TB-AA).Viru8. Type A12 strain 119 FMDV was grown in rolling-bottle cultures of a baby hamster kidney (BHK) cell line passage 21, clone 13 in a Tris-buffered modified Eagle medium containing 0.5% lactalbumin hydrolysate, 10% tryptose phosphate, and no serum (9). Virus was concentrated 100-fold by two cycles of precipitation with polyethylene glycol (13), and infectivity was determined by plaque assay in BK cell cultures by using a 0.6% gum tragacanth overlay and crystal violet staining at 48 h (6).Chemicals. Copper sulfate, zinc acetate, and zinc chloride were from standard commercial sources. ATA was from the Aldrich Chemical Co., Milwaukee, Wis., methisazone from Nutritional Biochemicals Corp., Cleveland, Ohio, and polyribocytidylic and polyriboinosinic acids were purchased from Miles Laboratories, Inc., Elkhart, Ind. Phosphonoacetic acid was a gift of Abbot Laboratories, North Chicago, Ill.Inhibition test. The action of th...

Abstract.-The foot-and-mouth disease virus-RNA polymerase complex was released from membrane particulates present in the cytoplasm of infected baby hamster kidney cells. The soluble polymerase complex was fractionated by zonal centrifugation in sucrose gradients. Two polymerase complexes (RNA and protein complex) active in the cell-free system were isolated and had S-rate ranges of 20-70S and 100-300S, respectively. The light polymerase complex contained 20S double-stranded RNA; and the heavy polymerase complex contained a polydisperse, partially RNase-resistant RNA. The cell-free product of these two polymerase complexes was analyzed by zonal centrifugation in sucrose gradients. The light polymerase complex synthesized only 20S doublestranded RNA. The product of the heavy polymerase complex contained no detectable 20S double-stranded RNA and only a peak of single-stranded RNA with S-rate corresponding to 37S viral RNA. A third polymerase complex was isolated with S-rate greater than 300S, and it contained a polydisperse, partially RNase-resistant RNA. This third polymerase complex synthesized both 37S viral RNA and 20S double-stranded RNA in the cell-free system, and it is probably the native polymerase complex still bound to cellular particulates.

POLATNICK, J. (Plum Island Animal Disease Laboratory, Greenport, N.Y.), and HOWARD L. BACHRACH. Production and purification of milligram amounts of foot-and-mouth disease virus from baby hamster kidney cell cultures. Appl. Microbiol. 12:368-373. 1964.-A stable line of baby hamster kidney cells for use in the production of, and subsequent purification of, footand-mouth disease virus (FMDV) was grown in large quantities on the cylindrical surfaces of 2-liter Baxter bottles. The bottles, in round wire cages, were rotated on a three-tiered roller mill. The cells retained their rapid growth characteristics and susceptibility to FMDV in a tris(hydroxymethyl)aminomethane buffer-containing medium which was especially formulated for large-scale work. This medium, without being changed, sustained cell growth for 6 to 7 days to yield confluent layers containing 500 to 750 million cells per bottle. In small-scale virus-growth experiments, harvested fluids contained about 103-8 to 108 8 plaque-forming units (PFU) per ml. This corresponded to a yield of 30 to 50 PFU per cell. In production runs with 190 cultures, the infectious fluids usually contained 107.9 to 109-2 PFTJ per ml, and the mass of essentially pure virus obtained therefrom ranged from 7 to 17 mg concomitant with cumulative infectivity recoveries of about 20%.