Biochemical studies on adenovirus multiplication

Chromatographic separation, and characteristics of nucleic acids from HeLa cells

The application of the phenol-duponol method to extraction of nucleic acids from HeLa cells is described. Chromatography of the phenol extract on an esterified bovine serum albumin column with a salt gradient of sodium chloride gives separation of soluble RNA, DNA, and two different high molecular RNA fractions. Ultracentrifugation of the DNA eluted from the column gives a sedimentation coefficient (s₂₀^o,w) of 38, which agrees with ultracentrifugation data on the phenol extract. The eluted RNA appears polydisperse at low ionic strength, but at high ionic strength and after alcohol precipitation two fractions with the sedimentation coefficients of 16 and 25 to 29, respectively, were obtained.

Nucleuc acid synthesis in types 4 and 5 adenovirus-infected HeLa cells

Type 4 adenovirus infection of HeLa cells effected a marked increase in synthesis of the saline-soluble DNA fraction, but not the host-cell DNA (the water-soluble fraction). This was demonstrated by the marked increase in specific activity of saline-soluble DNA but not water-soluble DNA when P³²-inorganic phosphate or sodium formate-C¹⁴ was employed. When these isotopes were used to label cells before viral infection rather than during the process of viral propagation, the saline-soluble DNA from infected cells had a specific activity of 10 to 20 per cent less than that of uninfected cells, indicating that the saline-soluble DNA was synthesized both from prelabeled precursors of the cell pools and unlabeled materials from the medium. Saline-soluble DNA began to increase between 10 to 12 hours after viral infection and 3 to 4 hours before appearance of newly propagated infectious virus. The specific activity of the acid-soluble pool of infected cells also increased between 10 to 12 hours after viral inoculation when sodium formate-C¹⁴ was used as a radioisotope. When P³²-inorganic phosphate was utilized, the specific activity of infected-cell RNA was increased approximately the same relative amount as when total RNA was determined chemically; i.e., 30 to 40 per cent. With type 5 adenovirus, not only did a 3- to 5-fold increase in saline-soluble DNA occur, but also an increase was measured in specific activity of RNA when P³²-inorganic phosphate was used.

Synthesis of virus-specific polymers in adenovirus-infected cells; effect of 5-fluorodeoxyuridine

Biochemical synthesis in adenovirus-infected HeLa cells was studied utilizing 5-fluorodeoxyuridine (5-FUDR), a potent inhibitor of deoxyribonucleic acid production. Synthesis of saline-soluble DNA and infectious virus was completely suppressed by addition of the analogue to cells as late as 10 hours after infection. The inhibitory effect of this compound was totally reversed by addition of 10^–6M thymidine to the culture medium. Synthesis of DNA essential for virus production began 10 hours after infection and was completed by 16 hours after infection. These data support the hypothesis that the saline-soluble DNA is a precursor of infectious virus particles. Studies of antigen production indicated that formation of virus-specific proteins was directly dependent upon synthesis of DNA.

A correlative study by electron and light microscopy of the development of type 5 adenovirus. II. Light microscopy

The evolution of the intranuclear lesion produced by type 5 adenovirus in HEp-2 and HeLa cells is described as seen in the light microscope and the bodies formed in the course of the infection characterized histochemically. Some 12 hours after infection acidophilic protein bodies, without appreciable nucleic acid, first appear in the nucleus and coalesce into a network. Within or in association with this material, DNA-containing masses (viral aggregates) are formed which rapidly increase in amount and then coalesce. At the same time, a protein is produced, histochemically different from that of the acidophilic or basophilic structures mentioned, within the infected nucleus, which constitutes a matrix within which regular cytstals of a protein, (presumably non-viral) materialize. These structural and histochemical features are correlated with details which have been observed in parallel studies with the electron microscope.

ELECTRON MICROSCOPIC RADIOAUTOGRAPHY OF HELA CELLS INFECTED WITH ADENOVIRUS

Harford, Carl G. (Washington University, St. Louis, Mo.), and Alice Hamlin. Electron microscopic radioautography of HeLa cells infected with adenovirus. J. Bacteriol. 89:1540-1547. 1965.-Because intracellular particles of adenovirus are not seen by light microscopy, radioautography with tritiated thymidine was carried out with an electron microscope. Reacted grains were present over many nuclei containing viral aggregates, but only 16% of these grains were over the aggregates. Control observations with tritium-labeled bacteria indicated that this low incidence of labeling of viral aggregates could not be attributed to errors of the method. We think that deoxyribonucleic acid (DNA) labeled with tritiated thymidine in these experiments was mainly the excess viral DNA that is known to accumulate in adenovirus-infected cells. We did not exclude the possibility that some cellular DNA was labeled.

Effect of Friend virus infection on the biosynthetic enzymes of phosphatidylcholine biosynthesis in spleen microsomes

The effects of Friend virus infection on phosphatidylethanolamine methyltransferase, phosphatidylmonomethylethanolamine methyltransferase, phosphatidyldimethylethanolamine methyltransferase and choline phosphotransferase in mouse spleen microsomes were investigated 14 days following viral inoculation. There was a significant 9.2 fold increase above control values in the specific activity (pmol phosphatidylcholine formed/min/mg microsomal proteins) of choline phosphotransferase. No stimulation occurred in the activities of phosphatidylethanolamine methyltransferase, phosphatidylmonomethylethanolamine methyltransferase or phosphatidyldimethylethanolamine methyltransferase, the three enzymes involved in the methylation phosphatidylethanolamine (PE) to phosphatidylcholine (PC). The concentration of S-adenosylmethionine (AdoMet) and S-adenosylhomocysteine (AdoHcy), the substrate and physiological inhibitor of transmethylation reactions, respectively, were measured in the spleens of control and viral infected mice. AdoHcy is a competitive inhibitor of the phosphatidylethanolamine methyltransferase. A significant increase in the AdoHcy concentration and the resultant decrease in the AdoMet/AdoHcy ratio are sufficient to prevent stimulation of the transmethylation of PE to PC.

Viral stimulation of choline phosphotransferase in spleen microsomes

Choline phosphotransferase and phosphatidyl ethanolamine methyltransferase enzymatic activities (nmoles phosphatidyl choline/min/mg protein) have been determined in spleen microsomes of Rauscher virus infected balb/c male mice at 5, 10, 14, and 21 days following inoculation of the virus. There is a significant stimulation of the choline phosphotransferase activity in the virus infected spleens with the peak of activity at about 10 days of viral infection. The specific activity of choline phosphotransferase is 10 times that of the phosphatidyl ethanolamine methyltransferase at 10 days of viral infection. There is a 51-fold increase over controls for the total microsomal choline phosphotransferase at 14 days of viral infection and only an 18-fold increase over controls for the phosphatidyl ethanolamine methyltransferase activity. There is a significant (P less than 0.001) increase over controls in the concentration of total phospholipid-P, phosphatidyl choline-P, and phosphatidyl choline-P fractions as separated by argentation chromatography of microsomes from spleens of mice infected with Friend virus of Rauscher virus for 14 days. The choline phosphotransferase and phosphatidyl ethanolamine methyltransferase specific activities in liver microsomes of 14 day Friend and/or Rauscher virus are unaltered during viral infection.

Sarcoma-virus-related RNA sequences in normal rat cells

A rat type C virus spontaneously activated from the NRK (normal rat kidney) cell line was found to have two major size classes of viral RNA subunits sedimenting at 35 and 30 S. Virus-producing cells contained both RNA species, while normal "virus-free" rat cells contained primarily virus-specific 30S RNA species. A DNA transcript, specific for Kirsten sarcoma virus, prepared from virus activated in nonproducer BALB/c cells originally transformed by Kirsten sarcoma virus and rendered specific for the virus by absorption of sequences related to mouse helper virus hybridized only with the 30S RNA species of virus-producing rat cells and normal rat cells. These findings are consistent with the hypothesis that sarcoma-specific nucleic acid sequences in kirsten sarcoma virus emerged through a process that incorporated some portions of 30S RNA species from rat cells (either normal or virus-producing) into the Kirsten leukemia virus during passage in vivo of that virus. The virus designated M-MSV(RaLV), which originally derived from tumor induced by Moloney sarcoma virus (M-MSV) in rats, contained 35S RNA species of rat type C viruses and 30S RNA species specific for both rat and mouse viruses. It appears striking that for these two animal species, sarcoma-virus-specific information resides on a 30S subunit.

Sarcoma and helper-specific RNA tumor virus subunits in transformed nonproducer mouse cells activated to produce virus by treatment with bromodeoxyuridine

A tumor line (58-2T) was established from a slowly growing tumor in a BALB/c mouse inoculated with M58-2 cells. The latter clonal cell line was isolated after bromodeoxyuridine treatment as a flat variant from nonproducer BALB/3T3 cells transformed by the Kirsten sarcoma virus. The 58-2T cells produced type C virus with two discrete virus-specific RNA species. One of the species, which was probably an endogenous virus RNA subunit, had a sedimentation coefficient of 35S as the largest major subunit, and had sequences similar to Rauscher leukemia virus RNA based on nucleic acid hybridization. The other RNA species had 30S as the largest major subunit and corresponded to Kirsten sarcoma virus-specific RNA. These two RNA species formed heterogeneous, 60 to 70S, high-molecular-weight RNA in virions.DNA transcripts (58-2T DNA) from the activated virus contained base sequences complementary to Rauscher leukemia virus and Kirsten sarcoma virus. The Kirsten sarcoma virus-specific DNA sequences (58-2TS) were purified from 58-2T DNA by eliminating RLV-specific sequences.

Detection and localization of virus-specific DNA by in situ hybridization of cells during infection and rapid transformation by the murine sarcoma-leukemia virus

Cytological preparations of interphase nuclei and chromosomes from mouse 3T6 cells prepared at various times after infection with the murine sarcomaleukemia virus complex were hybridized with the [(3)H]DNA product of the viral RNA-directed DNA polymerase. While uninfected nuclei had an average of 4 autoradiographic grains, infected nuclei had 30 grains at 5 hr after infection and 63-65 grains at 11 and 25 hr. Virus-specific grains were localized in the chromocenters of interphase nuclei and were found also in the centromeric heterochromatin region of metaphase chromosomes. These findings provide evidence that the viral RNA-directed DNA polymerase functions to synthesize virus-specific DNA early after infection and that newly synthesized viral DNA rapidly becomes associated with or integrated into specific intranuclear sites.

Mutants of nonproducer cell lines transformed by murine sarcoma virus. 3. Detection and characterization of RNA specific for helper and sarcoma viruses

BALB/3T3 cells transformed by the Kirsten sarcoma virus (nonvirus producer BALB/3T3 cells) and mutant cell lines derived therefrom by treatment with bromodeoxyuridine (BrdU) were analyzed for expression of virus-specific RNA using single-stranded DNA transcripts of Rauscher leukemia virus (RLV), a virus activated in one of the cell lines (58-2T), and Ki-SV-specific DNA transcript; the latter transcript after removal of all sequences cross-reactive with RLV RNA. The Rauscher virus DNA detected multiple copies of viral RNA in virus-producing cells ( approximately 2.5 x 10(3)/cell) whether infected with RLV or activated to produce virus with BrdU. Nonproducer (NP) cells and normal BALB cells showed small numbers of RNA genomes (70-250/cell) and only partial saturation of the transcript. The intracellular RNA sedimented at 35S (main peak) with a variable minor peak at 20S with the exception of one mutant cell, M-43-2 (main peak at 26-27S). The 58-2T transcript reacted preferentially in NP cells and their derivatives with biphasic kinetics suggesting the possibility of sequences specific for the original transforming virus. The size of Ki-SV specific sequences were 30S in mutant cells whether or not complete virus was being produced and independent of in vivo transplantability.

Effect of Sendai virus infection on lipid metabolism in chick embryo fibroblasts

Lipid metabolism in the "abortive" system, Sendai virus-infected primary chick embryo fibroblasts, was examined by using (32)P-orthophosphate, (14)C-glucose, and (14)C-glycerol as precursors. Incorporation of radioactivity from (32)P-orthophosphate and (14)C-glucose into lipid was increased in infected cells. Synthesis of all individual phospholipids was about equally stimulated. There was also evidence for increased lipid synthesis in more productively infected monkey kidney cells. Incorporation of (14)C-glycerol when at a high level in the medium was also increased. However, when this precursor was supplied in minute quantities of high specific activity, incorporation was inhibited. Even though incorporation of radioactivity from (14)C-glucose was stimulated during long labeling periods, the uptake of this precursor during short pulses was inhibited in infected cells. The phenomenon of increased labeling of triglyceride in infected chick cells under certain conditions is discussed, in conjunction with the other effects, in terms of related changes in other virus-infected systems.

Biochemical studies on adenovirus multiplication. 13. Synthesis of virus-specific ribonucleic acid during infection with human adenovirus type 12

The transcription of virus-specific ribonucleic acid (RNA) was studied in KB cells infected with adenovirus type 12 (strain Huie). Viral deoxyribonucleic acid (DNA) synthesis began at 12 to 15 hr after infection, and virus maturation occurred between 20 and 50 hr after infection. The rate of incorporation of (3)H-uridine into RNA per infected cell was stimulated, reaching a maximum of 1.6 times that of uninfected cells at 20 hr after infection. "Early" viral messenger ribonucleic acid (mRNA) constituted 0.1% of RNA synthesized at 11 hr, and "late" viral mRNA constituted 50% of RNA synthesized at 45 hr after infection, as determined by hybridization of viral DNA with labeled RNA from infected cells pulse labeled with (3)H-uridine. The species of virus-specific RNA synthesized at 22 hr after infection (when virus maturation has just begun) and at 45 hr (when virus maturation is nearly complete) were studied further: (i) 22- and 45-hr RNA had the same average guanine plus cytosine content, 47%, (ii) 22- and 45-hr RNA contained mostly the same viral nucleotide sequences, (iii) 45-hr RNA had a five times higher concentration of virus-specific RNA molecules than did 22-hr RNA, and (iv) 22- and 45-hr RNA contained virus-specific nucleotide sequences transcribed from all, or nearly all, of the viral genome.

Synthesis of virus deoxyribonucleic acid during abortive infection of simian cells by human adenoviruses

Rapp, Fred (Baylor University College of Medicine, Houston, Tex.), Lawrence A. Feldman, and Manley Mandel. Synthesis of virus deoxyribonucleic acid during abortive infection of simian cells by human adenoviruses. J. Bacteriol. 92:931-936. 1966.-Inoculation of green monkey kidney cells (GMK) with adenovirus types 2 or 12, under conditions where neither infectious virus was synthesized, resulted in an increase in the uptake of H(3)-thymidine into deoxyribonucleic acid (DNA). Extraction of the DNA from infected cells, followed by identification by isopycnic analysis in CsCl gradients, revealed the presence of virus DNA. Cells infected with adenovirus type 2 yielded DNA giving bands with peak densities of 1.699 g/ml [GMK DNA with 40 moles% guanine + cytosine (GC)] and 1.714 g/ml (adenovirus type 2 DNA with 55 moles% GC). Cells infected with adenovirus type 12 also yielded the GMK DNA and a band at 1.706 g/ml (adenovirus type 12 DNA with 47 moles% GC). The rate of synthesis of adenovirus type 2 DNA in KB cells (productive cycle) and in GMK cells infected only with adenovirus (nonproductive cycle) or with adenovirus and simian virus 40 (adeno-productive cycle) was not significantly different.

Role of ribonucleic acid biosynthesis in multiplication of type 5 adenovirus

Flanagan, John F. (University of Pennsylvania, Philadelphia), and Harold S. Ginsberg. Role of ribonucleic acid biosynthesis in multiplication of type 5 adenovirus. J. Bacteriol. 87:977-987. 1964.-The requirement for ribonucleic acid (RNA) biosynthesis in the multiplication of type 5 adenovirus was investigated by using radioactive phosphorus to label nucleic acids and two pyrimidine analogues, 6-azauridine and 5-fluorouracil or 5-fluorouridine, to inhibit synthesis of functional RNA. The data indicate that biosynthesis of RNA after infection is essential for production of virus-specific deoxyribonucleic acid, virus antigens, and infectious particles. The onset of essential RNA synthesis occurs 8 to 9 hr after virus infection and prior to the biosynthesis of other known virus-induced macromolecules.