Viral DNA in transformed cells. I. A study of the sequences of adenovirus 2 DNA in a line of transformed rat cells using specific fragments of the viral genome

The detection of virus DNA sequences in a herpes type 2 transformed hamster cell line (333-8-9)

Herpes simplex virus type 2 DNA labelled in vitro with 125I has been used as a probe to search for virus DNA sequences in the 333-8-9 line of transformed primary hamster cells and in clines derived from the line. Virus DNA sequences were present when the cells were examined initially but these sequences were lost on subsequent handling. No virus sequences were detected in clones derived from the line. It is suggested that the presence of virus DNA is an unstable characteristic of the cell line and that these sequences may be lost at cell division. The possibility that a small fragment of the genome remains cannot be excluded.

A unique pattern of integrated viral genes in hamster cells transformed by highly oncogenic human adenovirus 12

We have analyzed the viral DNA sequences persisting in HE C19, a clonal line of hamster embryo cells transformed in vitro by human adenovirus 12 (Ad 12), a member of highly oncogenic group A. Saturation-hybridization of in vitro labeled Ad 12 DNA (2-4 x 10(8) cpm/mug) with HE C19 DNA showed that 93-100% of viral DNA sequences are present in the transformed cell. Reassociation of Ad 12 32P-DNA in the presence of HE C19 DNA detected 8 viral genome equivalents per diploid quantity of cell DNA. REannealing each of the six Ad 12 EcoRl restriction DNA fragments with HE C19 DNA indicated that the sequences of each fragment are present in near equimolar quantities, 8-10.5 copies per cell. HE C19 DNA "networks" were prepared and shown to contain the same viral DNA sequences and in the same amounts as present in unfractionated transformed cell DNA; these data provide the first direct evidence that human adenovirus genes are covalently linked to cellular DNA. The presence of most, if not all, of the viral genes was demonstrated also in the Ad 12 hamster tumor cell line, HT-2. The pattern of integrated viral genes in these nonpermissive hamster cells transformed by Ad 12 is different from that described for cells transformed by group C and B human adenoviruses and for SV40.

Preparation of radioiodinated simian virus 40 DNA for use in DNA - DNA reassociation kinetics experiments

A method is described for the preparation of 125I-labelled SV40 DNA. Using this method, SV40 DNA can be routinely labelled to 15 - 10(6) dpm per mug; much higher specific activities are easily obtained by minor modifications of the method. Once incorporated, the radioactive label dissociates from DNA exceedingly slowly at 4 degrees C or at 68 degrees C. Iodinated SV40 DNA is shown to be useful in the quantitation of viral nucleic acid sequences in SV40-transformed 3T3 cells by DNA - DNA reassociation kinetics.

Detection of virus-specific DNA and RNA base-sequences in individual cells transformed or infected by adenovirus type 2

By means of 3H thymidine-labelled adenovirus 2 DNA, adenovirus-specific DNA sequences have been localized in individual nuclei of adenovirus 2- or 12-infected cells, and adenovirus-specific RNA sequences have been detected in the permissive cells as well as in cells transformed by adenovirus type 2. The ability to detect such specific virus RNA base-sequences in particular, by in situ hybridization, should be useful in studying the transcriptional specificities of tumours and neoplasms.

Transcription of the genome of adenovirus type 12. Viral mRNA in productively infected KB cells

In human KB cells productively infected with adenovirus type 12, viral DNA replication starts between 12 and 14h postinfection. Virus-specific, polysome-associated mRNA was investigated early (6-8h) and late (26-28h) after infection. Most of the viral mRNA was polyadenylated and accounted for 0.46% and 24.1% of the mRNA synthesized early and late postinfection, respectively. The viral-specific mRNA isolated both early and late after infection falls into several distinct size-classes, ranging in molecular weights between 0.3X10(6) and 1.5X10(6) for the early RNA and between 0.6X10(6) and 2.3X10(6) for the RNA synthesized late in the infection.

A study of the oncogenicity of adenovirus type 2 transformed rat embryo cells

Rat embryo cells were transformed by adenovirus type 2 at different multiplicities of infection. The oncogenic potential of the resulting transformed lines varied considerably but a relationship was found to exist between transforming virus dose and oncogenicity of the resulting transformed lines. Possible reasons for the considerable variation in oncogenicity of the transformed lines are discussed, giving particular consideration to cellular antigenicity and recent molecular biology studies of adenovirus type 2 transformed cell lines.

Mapping of late adenovirus genes by cell-free translation of RNA selected by hybridization to specific DNA fragments

Cytoplasmic RNA, isolated from cells late after infection by adenovirus type 2 and fractionated by hybridization to specific fragments of adenovirus DNA produced by cleavage with the endonuclease R-EcoRI, was used as template for protein synthesis in cell-free mammalian extracts. Each of the R-EcoRI fragments of DNA selects RNA that encodes specific subsets of the viral polypeptides. From the known order of the R-EcoRI fragments, the following partial map is deduced: (III, IIIa, IVa2, V, P-VII, IX), (II, P-VI), 100K, IV-where the relative order of the components enclosed in parentheses has not yet been determined.

Differential accumulation of virus-specific RNA during the cell cycle of adenovirus-transformed rat embyro cells

In adenovirus type 2-transformed rat embryo cells there is a threefold greater incorporation of [3-H]uridine into virus-specific RNA early in S phase than in late S or G2. This heightened accumulation of labeled RNA is true for both nuclear and cytoplasmic virus-specific labeling. Inhibition of DNA synthesis decreases the virus-specific RNA labeling, whereas reversal of inhibition again allows the elevated level of virus-specific RNA labeling.

Synthesis of complementary RNA sequences during productive adenovirus infection

Liquid RNA.DNA hybridization with separated strands of adenovirus type 2 DNA revealed that late nuclear RNA can hybridize to about 85% of the 1-strand and 10-15% of the h-strand, whereas late cytoplasmic RNA hybridizes to 65-70% and 25% of the l- and h-strand, respectively. With separated strands from the six EcoRI fragments of adenovirus type 2 DNA as probes, it was shown that late nuclear RNA hydridizes to 85-90% of the l-strand from all six EcoRI fragments. Since late cytoplasmic RNA hybridizes to 40-50% of the h-strand from both fragments EcoRI-B and EcoRI-C, complementary viral RNA sequences are synthesized during adenovirus infection. Complementarity between nuclear and cytoplasmic RNA could also be demonstrated by showing that late cytoplasmic RNA which had been preincubated with late nuclear RNA hybridized to a smaller fraction of the h-strand of fragment EcoRI-C than without preincubation. Double-stranded RNA which contains sequences that correspond to at least 60% of the viral genome was isolated from infected cells. However, less than 2% of the newly synthesized late RNA became double-stranded after incubation under annealing conditions, which suggests that RNA derived from one of the strands is present at a low concentration. Accordingly, it was shown that nearly all viral cytoplasmic RNA which is synthesized late after infection is derived from the l-strand.

Localization of adenovirus 2 messenger RNA's to segments of the viral genome defined by endonuclease R-R1

Adenovirus 2 mRNAs synthesized in productive infection were assigned to specific regions of the genome by hybridization to unique fragments of viral DNA. Radioactive viral RNA synthesized early or late in infection was first fractionated by polyacrylamide gel electrophoresis. Eluted RNAs were then tested for complementary hybrid formation with each of the six fragments of adenovirus 2 DNA generated by cleavage with endonuclease R.R1. Early RNA species migrating as 13S, 19S, and 20S RNAs were identified as transcription products of fragments A, B, and D, respectively. In addition to the 13S RNA transcribed from A fragment DNA, 13S RNA also hybridized to the D and E fragment DNAs; 11S RNA annealed to both A and B fragments. The RNA that hybridized to fragment C DNA was heterogeneous in size. Viral RNA synthesized late in infection included 27S, 24S, 19S, and 11S size classes, all of which annealed to A fragment DNA. Additional RNA migrating as 24S hybridized to E and C fragment DNA, and 23S RNA annealed to F fragment DNA. The results of the hybridizations of size fractionated RNAs with viral DNA fragments enabled formation of a partial map of viral mRNAs with respect to the adenovirus 2 genome. Some of the viral RNAs may represent transcripts which overlap R1 cleavage sites, because in at least three instances hybridization revealed viral RNAs which have the same electrophoretic mobility and anneal to fragments that are contiguous on the genome.