Amino acid metabolism in mammalian cell cultures

Characterization of a Tumorlike Antigen in Type 12 and Type 18 Adenovirus-Infected Cells

Gilead, Zvee (University of Pennsylvania, Philadelphia), and Harold S. Ginsberg. Characterization of a tumor-like antigen in type 12 and type 18 adenovirus-infected cells. J. Bacteriol. 90:120-125. 1965.-An antigen that reacts with antibody from type 12 adenovirus tumor-bearing hamsters was identified in extracts of KB cells infected with type 12 or 18 adenovirus. In contrast, viral structural proteins separated by chromatography on diethylaminoethyl-cellulose did not react with the sera from tumorous hamsters. The tumorlike (T) antigen in infected cells was found to be smaller than the viral structural antigens and, therefore, could be separated from them by centrifugation in a linear sucrose gradient. Investigation of the production of the T antigen in virus-infected cells further distinguished it from viral structural proteins by the following properties: (i) the T antigen was first detected 3 to 4 hr after infection, whereas viral antigens were synthesized 17 to 20 hr after infection; and (ii) the T antigen was produced when deoxyribonucleic acid (DNA) biosynthesis was inhibited by 5-fluorodeoxyuridine (10(-6)m), but viral proteins were not synthesized in the absence of viral DNA replication.

KINETICS OF SYNTHESIS OF VARIOUS TYPES OF ANTIGENIC PROTEINS IN CELLS INFECTED WITH PSEUDORABIES VIRUS

Hamada, Chuya (Albert Einstein Medical Center, Philadelphia, Pa.), and Albert S. Kaplan. Kinetics of synthesis of various types of antigenic proteins in cells infected with pseudorabies virus. J. Bacteriol. 89:1328-1334. 1965.-By means of an indirect precipitation test, a determination was made of the rates of synthesis of various types of serologically specific proteins in rabbit kidney cells infected with pseudorabies virus. The rate of synthesis of cell-specific protein decreased after infection. During the early stages of the infective process, proteins which bear no precursor relationship to the viral particles (nonstructural viral proteins) and which cannot be detected in noninfected cells were formed. Almost concurrently with these nonstructural proteins, synthesis of virus precursor proteins began. The synthesis of these proteins preceded the formation of mature virus and continued until the end of the virus growth cycle.

Functional Ribosomal Unit of Gamma-Globulin Synthesis

Nascent protein synthesis is associated with polyribosomes in extracts of lymph node cells removed from hyperimmunized rabbits, if the ribonuclease activity in such extracts is inhibited. Prior treatment of the cells with actinomycin D markedly decreases protein synthesis by polyribosomes.

CYCLOHEXIMIDE: ASPECTS OF INHIBITION OF PROTEIN SYNTHESIS IN MAMMALIAN CELLS

Cycloheximide and acetoxy-cycloheximide specifically inhibit protein synthesis in L-cells growing in suspension culture. In extracts of rat liver, the drugs inhibit transfer of amino acid from soluble RNA to polypeptide. Unlike puromycin, these drugs do not accelerate release of nascent polypeptide chains. The drugs have no effect on protein synthesis in extracts of Escherichia coli.

PLAQUE DIFFERENTIATION AND REPLICATION OF VIRULENT AND ATTENUATED STRAINS OF MEASLES VIRUS

Rapp, Fred (Baylor University College of Medicine, Houston, Tex.). Plaque differentiation and replication of virulent and attenuated strains of measles virus. J. Bacteriol. 88:1448-1458. 1964.-Plaque formation by strains of measles virus in a stable line of African green monkey kidney cells (BSC-1) is characterized by development of large plaques (>1 mm) within 4 days after inoculation of the cultures with the virulent Edmonston strain or by small plaques (<1 mm) after inoculation with the attenuated Edmonston strain of virus. Plaque formation by measles virus is not influenced by iododeoxyuridine, cytosine arabinoside, isatinthiosemicarbazone, streptonigrin, actinomycin D, or mitomycin C. The predominant cytopathic effect observed with both strains is the formation of large, multinucleated giant cells. Development of the giant cells is correlated with development of virus antigen and synthesis of infectious virus. Synthesis of virus is similar at 34 and at 37 C. Appearance of intracellular virus precedes release, and is later in the attenuated virus-infected cells than in cells infected with the virulent strain. With the virulent strain, equal concentrations of intra- and extracellular virus are found but, with attenuated virus, only a small fraction reaches the extracellular fluids, and more than 95% of the newly synthesized virus remains cell-associated.

COLORADO TICK FEVER VIRUS IN CELL CULTURE I

Trent, Dennis W. (University of Oklahoma School of Medicine, Oklahoma City) and L. Vernon Scott . Colorado tick fever virus in cell culture. I. Cell-type susceptibility and interaction with L cells. J. Bacteriol. 88: 702–708. 1964.—Colorado tick fever (CTF) virus was serially propagated in monolayer cultures of L and FL cells. Early passages of virus in FL cells yielded viral titers 10 4 -fold greater than did the corresponding L-cell passages. During L-cell passage number 4, there was a 10 3 -fold increase in the amount of infectious virus produced as compared with virus cultured earlier in this cell line. Viruses from L-cell passages 8 and 12 were identified with specific immune serum to be CTF viruses which were antigenically similar, if not identical, to the mouse-adapted virus. Parallel titrations of mouse-, L cell-, and FL cell-adapted viruses were performed in mice and replicate monolayers of L, FL, HeLa, KB, chick embryo, and cotton rat kidney cells. Cytopathic effects and viral replication were noted in all cultures except HeLa and cotton rat kidney. Cultures of L, FL, and chick embryo cells were as sensitive to infection as were suckling or weanling mice. KB cells were the least susceptible of those cell types examined. In L-cell cultures, 90% of the input virus was adsorbed to the cells during the first 30 min of incubation. The latent period lasted 10 to 12 hr, and was followed by rapid viral synthesis for the next 10 to 24 hr, depending upon the multiplicity of infection. Curves describing exponential increase in cell-associated and cell-released virus were separated by 4 hr. When the maximal total virus titers were reached, 80 to 90% of the virus was released from the cell.