Isolation of a nondefective recombinant between adenovirus type 5 and early region 1A of adenovirus type 12.

A nondefective recombinant between adenovirus type 5 (Ad5) and type 12 (Ad12), rc-1 (Ad5 dl312, carrying the Ad12 E1A gene), was isolated from hamster cell foci transformed by a defective recombinant, rcB-1 (dl312, carrying the Ad12 E1 gene). The recombinant rc-1 grew in human embryo kidney and KB cells in the absence of helper and synthesized Ad12 T antigen g, the product of the E1A gene. The genome of rc-1 has a deletion between 79.9 and 82.5 map units of Ad5 dl312 DNA with an insertion of 0.1 to 5.5 map units of Ad12 DNA at the deletion site. The mRNAs of Ad12 E1A were transcribed from the Ad12 E1A promoter, and unusual RNAs were abundantly transcribed from the Ad5 E3 promoter on the opposite strand. The frequency of cell transformation with rc-1 was lower than those with Ad5 and Ad12 wild types.     

Efficient expression of small RNA polymerase III genes from a novel simian virus 40 vector and their effect on viral gene expression.

In the past, simian virus 40 (SV40) has been used as a cloning vehicle to clone foreign genes by substituting portions of the viral genome vital for viral replication. Propagation of these defective viruses required a helper virus and the recombinant viruses obtained could be grown only as a mixture. In this study, we describe a novel nondefective SV40 vector to clone small RNA polymerase III genes. Two small RNA polymerase III genes, an amber suppressor human serine tRNA gene and the adenovirus (Ad) VAI RNA gene, were cloned in the intron region of the large-T antigen gene of SV40 after deleting DNA sequences coding for the small-t polypeptide. The recombinant viruses grew to wild type levels and showed no growth defects. When CV-1p cells were infected with these viruses, the cloned RNA polymerase III genes were expressed at high levels at late times. Interestingly, large amounts VAI RNA in CV-1p cells infected with SV40-VA recombinant virus, did not enhance translation of viral mRNAs significantly but did lead to a 3 to 4 fold increase in the steady state levels of large-T mRNA suggesting a novel function for VAI RNA in SV40 infected monkey cells. Furthermore, VAI mutants which fail to function in Ad infected human cells also failed to enhance the levels of large-T mRNAs in monkey cells infected with SV40. The simple SV40 vector described here may be useful to study the structure and function of small RNA polymerase III genes in the context of a eucaryotic chromosome. In addition, the nondefective recombinant SV40 which expresses the suppressor tRNA gene at high levels may provide a useful helper system to propagate animal viruses with amber mutations in essential genes.     

Oncogenicity by adenovirus is not determined by the transforming region only.

We have constructed a nondefective recombinant virus between the nononcogenic adenovirus 5 (Ad5) and the highly oncogenic Ad12. The recombinant genome consists essentially of Ad5 sequences, with the exception of the transforming early region 1 (E1) which is derived from Ad12. HeLa cells infected with the recombinant virus were shown to contain the Ad12-specific E1 proteins of 41 kilodaltons (E1a) and 19 and 54 kilodaltons (both encoded by E1b). The recombinant virus replicated efficiently in human embryonic kidney cells and HeLa cells, showing that the transforming regions of Ad5 and Ad12 had similar functions in productive infection. After the recombinant virus was injected into newborn hamsters, no tumors were produced during an observation period of 200 days. Thus, despite the fact that all products required for oncogenic transformation in vitro were derived from the highly oncogenic Ad12, the recombinant virus did not produce tumors in vivo. These data show that tumor induction by adenovirus virions is not determined only by the gene products of the transforming region.     

Adenovirus transcription. II. RNA sequences complementary to simian virus 40 and adenovirus 2DNA in AD2+ND1- and AD2+ND3-infected cells.

The genomes of the two nondefective adenovirus 2/simian virus 40 (Ad2/SV 40) hybrid viruses, nondefective Ad2/SV 40 hybrid virus 1 (Ad2+ND1) and nondefective hybrid virus 3 (Ad2+ND3), WERE FORMED BY A DELETION OF ABOUT 5% OF Ad2 DNA and insertion of part of the SV40 genome. We have compared the cytoplasmic RNA synthesized during both the early and late stages of lytic infection of human cells by these hybrid viruses to that expressed in Ad2-infected and SV40-infected cells. Separated strands of the six fragments of 32P-labeled Ad2 DNA produced by cleavage with the restriction endonuclease EcoRI (isolated from Escherichia coli) and the four fragments of 32P-labeled SV40 DNA produced by cleavage with both a restriction nuclease isolated from Haemophilus parainfluenzae, Hpa1, and EcoRI were prepared by electrophoresis of denatured DNA in agarose gels. The fraction of each fragment strand expressed as cytoplasmic RNA was determined by annealing fragmented 32P-labeled strands to an excess of cellular RNA extracted from infected cells. The segment of Ad2 DNA deleted from both hybrid virus genomes is transcribed into cytoplasmic mRNA during the early phase of Ad2 infection. Hence, we suggest that Ad2 codes for at least one "early" gene product which is nonessential for virus growth in cell culture. In both early Ad2+ND1 and Ad2+ND3-infected cells, 1,000 bases of Ad2 DNA adjacent to the integrated SV40 sequences are expressed as cytoplasmic RNA but are not similarly expressed in early Ad2-infected cells. The 3' termini of this early hybrid virus RNA maps in the vicinity of 0.18 on the conventional SV40 map and probably terminates at the same position as early lytic SV40 cytoplasmic RNA. Therefore, the base sequence in this region of SV40 DNA specifies the 3' termini of early messenger RNA present in both hybrid virus and SV40-infected cells.     

Species dependence of the major late promoter in adenovirus type 12 DNA.

In hamster cells human adenovirus type 12 (Ad12) is deficient in DNA replication and late gene expression whereas adenovirus type 2 (Ad2) can replicate. Functions located in the E1 region of the Ad2 or adenovirus type 5 (Ad5) genome can complement the deficiencies of the Ad12 genome in hamster cells, but, infectious viral particles are not produced. We have now investigated the activity of the major late promoter of Ad2 and of Ad12 DNA in human and hamster cells. This promoter governs the expression of most of the late viral functions. We have inserted the major late promoter (MLP) of Ad2 or of Ad12 DNA in front of the chloramphenicol acetyl transferase gene in the pSVO-CAT construct. Upon transfection into uninfected human and hamster cells, the pAd12MLP-CAT construct shows no significant activity; the pAd2MLP-CAT construct exhibits low activity. In Ad12-infected human cells, both constructs are active. These findings support the notion that other viral factors are required for MLP activity of Ad2 or Ad12 DNA in permissive human cells. In Ad2-infected hamster cells, both the pAd2MLP-CAT and the pAd12MLP-CAT constructs are active. Apparently, the Ad12 MLP can be activated by Ad2 functions, as already demonstrated for the entire Ad12 genome in double-infected cells or in Ad2- or Ad5-transformed cells superinfected with Ad12. In Ad12-infected hamster cells, however, the MLP of Ad12 DNA is inactive but that of Ad2 DNA shows activity. Thus the MLP of Ad12 DNA somehow differentiates between cellular auxiliary functions of different species.(ABSTRACT TRUNCATED AT 250 WORDS)     

Studies of Nondefective Adenovirus 2-Simian Virus 40 Hybrid Viruses V. Isolation of Additional Hybrids Which Differ in Their Simian Virus 40-Specific Biological Properties

Four new nondefective adenovirus 2 (Ad2)-simian virus 40 (SV40) hybrid viruses have been isolated. Although these viruses (designated Ad2(+)ND(2), Ad2(+)ND(3), Ad2(+)ND(4), and Ad2(+)ND(5)) were clonal derivatives of the same Ad2-SV40 hybrid population, they differ significantly from each other and from the previously isolated nondefective hybrid, Ad2(+)ND(1), in their biological properties or in the amount of SV40-specific RNA induced during lytic infection.Like Ad2(+)ND(1), Ad2(+)ND(2), and Ad2(+)ND(4) pass serially in both human embryonic kidney (HEK) and primary African green monkey kidney cells. In contrast, Ad2(+)ND(3) and Ad2(+)ND(5) pass serially only in HEK cells. Ad2(+)ND(2) is like Ad2(+)ND(1) in that it induces the SV40 U antigen, but not SV40 T antigen; however, in contrast to the perinuclear SV40 antigen induced by Ad2(+)ND(1), the SV40 antigen induced by Ad2(+)ND(2) is located peripherally in the cytoplasm as well as in the perinuclear region of infected cells. Ad2(+)ND(4) induces both the SV40 T and U antigens. Ad2(+)ND(3) and Ad2(+)ND(5) do not induce serologically detectable SV40 antigens and are distinguished from each other on the basis of the relative quantities of SV40-specific RNA which they induce. The induction of different SV40-specific functions suggests the incorporation of different segments of SV40 DNA within the genomes of the respective hybrid viruses.     

Hybrids of human and monkey adenoviruses (adeno-adeno hybrids) that can reproduce in monkey cells: biological and molecular genetic peculiarities

A highly oncogenic monkey adenovirus SA7(C8) facilitates the reproduction of human adenovirus type 2 (Ad2) in monkey cells. Upon mixed infection of monkey cells with both viruses, these viruses recombine producing defective adeno-adeno hybrids Ad2C8 serologically identical to Ad2 and capable of assisting Ad2 to reproduce in monkey cells. Ad2C8 and Ad2 form an intercomplementary pair inseparable in monkey cells. Unlike oncogenic SA7(C8), Ad2C8 is a nononcogenic virus for hamsters but is able to induce tumor antigens of this virus (T and TSTA). Molecular genetic analysis of 68 clones of adeno-adeno hybrids revealed that the left part of their genome consists of Ad2 DNA, and the right part contains no less than 40% of the viral SA7(C8) genome where E2A, E3, and E4 genes are located. Apparently, the products of these genes contribute to the composition of adenoviral tumor antigens, while the E4 gene is involved in complementation of monkey and human adenoviruses and makes a contribution to host range determination of these viruses.     

Expression of the chloramphenicol acetyl transferase gene in human cells under the control of early adenovirus subgroup C promoters: effect of E1A gene products from other subgroups on gene expression

A hierarchy of dominance has been observed in HeLa cells co-infected with two serotypes of adenovirus belonging to different subgroups. DNA replication and late protein synthesis of one serotype are inhibited by those of the other. The degree of inhibitory effect has the following decreasing order: adenovirus type 3 (Ad3) and Ad7 (subgroup B), Ad9 (D), Ad4 (E), Ad12 (A), Ad2 and Ad5 (C) [Delsert and D'Halluin, Virus Res. 1 (1984) 365-380]. HeLa cells were first transfected with recombinant plasmids carrying Ad5 E2A or E3 promoters fused to the chloramphenicol acetyl transferase gene (cat), and then infected with human Ad belonging to different subgroups. All the serotypes tested were found to be able to stimulate both E2A and E3 promoters. When HeLa cells were co-transfected with either of the previous plasmids, plus a second plasmid carrying the Ad3 E1A region, the same stimulatory effect was observed. However, an inhibitory effect on Ad5 E2A and E3 promoters seemed to occur when both Ad2 E1A (subgroup C) and Ad3 E1A (subgroup B) genes were present together. To determine which one of the early products was responsible for the observed repression effect, and to assign the target on the genome of subgroup C Ad, a plasmid was constructed in which the sequences at the 5' end of the Ad2 E1A region were fused to the structural sequences of the cat gene. In HeLa cells transfected with this plasmid, CAT activity was significantly increased after co-transfection with a plasmid carrying the Ad2 E1A region, but decreased with a plasmid carrying the Ad3 E1A region.(ABSTRACT TRUNCATED AT 250 WORDS)     

cyt gene of adenoviruses 2 and 5 is an oncogene for transforming function in early region E1B and encodes the E1B 19,000-molecular-weight polypeptide

A total of 59 cytocidal (cyt) mutants were isolated from adenovirus 2 (Ad2) and Ad5. In contrast to the small plaques and adenovirus type of cytopathic effects produced by wild-type cyt+ viruses, the cyt mutants produced large plaques, and the cytopathic effect was characterized by marked cellular destruction. cyt mutants were transformation defective in established rat 3Y1 cells. cyt+ revertants and cyt+ intragenic recombinants recovered fully the transforming ability of wild-type viruses. Thus, the cyt gene is an oncogene responsible for the transforming function of Ad2 and Ad5. Genetic mapping in which we used three Ad5 deletion mutants (dl312, dl313, and dl314) as reference deletions located the cyt gene between the 3' ends of the dl314 deletion (nucleotide 1,679) and the dl313 deletion (nucleotide 3,625) in region E1B. Restriction endonuclease mapping of these recombinants suggested that the cyt gene encodes the region E1B 19,000-molecular-weight (175R) polypeptide (nucleotides 1,711 to 2,236). This was confirmed by DNA sequencing of eight different cyt mutants. One of these mutants has a single missense mutant, two mutants have double missense mutations, and five mutants have nonsense mutations. Except for one mutant, these point mutations are not located in any other known region E1B gene. We conclude that the cyt gene codes for the E1B 19,000-molecular-weight (175R) polypeptide, that this polypeptide is required for morphological transformation of rat 3Y1 cells, and that simple amino acid substitutions in the protein can be sufficient to produce the cyt phenotype.     

Hybrids of Human and Monkey Adenoviruses (Adeno-Adeno Hybrids) That Can Reproduce in Monkey Cells: Biological and Molecular Genetic Peculiarities

A highly oncogenic monkey adenovirus SA7(C8) facilitates the reproduction of human adenovirus type 2 (Ad2) in monkey cells. Upon mixed infection of monkey cells with both viruses, these viruses recombine producing defective adeno-adeno hybrids Ad2C8 serologically identical to Ad2 and capable of assisting Ad2 to reproduce in monkey cells. Ad2C8 and Ad2 form an intercomplementary pair inseparable in monkey cells. Unlike oncogenic SA7(C8), Ad2C8 is a nononcogenic virus for hamsters but is able to induce tumor antigens of this virus (T and TSTA). Molecular genetic analysis of 68 clones of adeno-adeno hybrids revealed that the left part of their genome consists of Ad2 DNA, and the right part contains no less than 40% of the viral SA7(C8) genome where E2A, E3, and E4 genes are located. Apparently, the products of these genes contribute to the composition of adenoviral tumor antigens, while the E4 gene is involved in complementation of monkey and human adenoviruses and makes a contribution to host range determination of these viruses.     

Construction of an adenovirus type 7a E1A- vector.

A strategy for constructing replication-defective adenovirus vectors from non-subgroup C viruses has been successfully demonstrated with adenovirus type 7 strain a (Ad7a) as the prototype. An E1A-deleted Ad7a reporter virus expressing the chloramphenicol acetyltransferase (CAT) gene from the cytomegalovirus promoter enhancer was constructed with DNA fragments isolated from Ad7a, an Ad7a recombination reporter plasmid, and the 293 cell line. The Ad7a-CAT virus particle transduces A549 cells as efficiently as Ad5-based vectors. Intravenous infections in a murine model indicate that the Ad7a-CAT virus infects a variety of tissues, with maximal levels of CAT gene expression found in the liver. The duration of Ad7a-CAT transgene expression in the liver was maximally maintained 2 weeks postinfection, with a decline to baseline activity by the week 4 postinfection. Ad7a-CAT represents the first example of a non-subgroup C E1A- adenovirus gene transfer vector.     

Adenovirus E1A gene induction of susceptibility to lysis by natural killer cells and activated macrophages in infected rodent cells.

Rodent cells immortalized by the E1A gene of nononcogenic adenoviruses are susceptible to lysis by natural killer (NK) cells and activated macrophages. This cytolysis-susceptible phenotype may contribute to the rejection of adenovirus-transformed cells by immunocompetent animals. Such increased cytolytic susceptibility has also been observed with infected rodent cells. This infection model provided a means to study the role of E1A gene products in induction of cytolytic susceptibility without cell selection during transformation. Deletion mutations outside of the E1A gene had no effect on adenovirus type 2 (Ad2) or Ad5 induction of cytolytic susceptibility in infected hamster cells, while E1A-minus mutant viruses could not induce this phenotype. E1A mutant viruses that induced expression of either E1A 12S or 13S mRNA in infected cells were competent to induce cytolytic susceptibility. Furthermore, there was a correlation between the accumulation of E1A gene products in Ad5-infected cells and the level of susceptibility of such target cells to lysis by NK cells. The results of coinfection studies indicated that the E1A gene products of highly oncogenic Ad12 could not complement the lack of induction of cytolytic susceptibility by E1A-minus Ad5 virus in infected cells and also could not block induction of this infected-cell phenotype by Ad5. These data suggest that expression of the E1A gene of nononcogenic adenoviruses may cause the elimination of infected cells by the immunologically nonspecific host inflammatory cell response prior to cellular transformation. The lack of induction of this cytolysis-susceptible phenotype by Ad12 E1A may result in an increased persistence of Ad12-infected cells in vivo and may lead to an increased Ad12-transformed cell burden for the host.     

Conditional lethal mutants of adenovirus type 2-simian virus 40 hybrids. II. Ad2+ND1 host-range mutants that synthesize fragments of the Ad2+ND1 30K protein.

Adenovirus type 2 (Ad2) grows 1,000 times less well in monkey cells than in human cells. This defect can be overcome, not only upon co-infection of cells with simian virus 40 (SV40), but also when the relevant part of the SV40 genome is integrated into the adenovirus genome to form an adenovirus-SV40 hybrid virus. We have used the nondefective Ad2-SV40 hybrid virus Ad2+ND1, which contains an insertion of 17% of the SV40 genome, to isolate host-range mutants which are defective in growth on monkey cells although they grow normally on human cells. Like Ad2, these mutants are defective in the synthesis of late proteins in monkey cells. A 30,000-molecular-weight protein (30K), unique to Ad2+ND1-infected cells, can be synthesized in vitro, using Ad2+ND1 mRNA that contains SV40 sequences. 30K is not seen in cells infected with those host-range mutants that are most defective in growth on monkey cells, and translation in vitro of SV40-specific mRNA from these cells produces new unique polypeptides, instead of 30K. Genetic and biochemical analyses indicate that these mutants carry point mutations rather than deletions.     

Two functions encoded by adenovirus early region 1A are responsible for the activation and repression of the DNA-binding protein gene.

Human adenovirus early region 1A (E1A) gene products differentially regulate the expression of early region 2A (E2A) encoding the DNA-binding protein (DBP). In a microinjection system, plasmids containing the DBP gene associated with both its early (map coordinate 75) and late (coordinate 72) promoters, or only with the early promoter, are inefficiently expressed, and the presence of E1A DNA is required for full expression. In contrast, the E2A plasmid in which the DBP gene is associated solely with its late promoter, efficiently produces DBP, the synthesis of which is significantly inhibited by an E1A gene product. To identify which of the E1A products is responsible for either activation or repression of DBP gene expression, two E1A mutants (Ad5hr1 and Ad2/5pm975) have been tested in the microinjection system in the presence of different DBP plasmids containing either one or both promoters. The results obtained indicate that the product encoded by the E1A 13S mRNA is responsible for the stimulation of DBP produced from the early promoter and that the 12S mRNA codes for the product which represses the synthesis of DBP from the late promoter. These results were confirmed using clones in which the E2A early or late promoter was associated to the chloramphenicol acetyltransferase (CAT) gene and assayed for CAT activity after cell transfection in the absence or in the presence of wild-type or mutant E1A plasmids, and we have also shown that this promoter-dependent regulation is reflected in the relative amount of specific DBP mRNA.     

Stimulation of host centriolar antigen in TC7 cells by simian virus 40: requirement for RNA and protein syntheses and an intact simian virus 40 small-t gene function

Simian virus 40 (SV 40) stimulated a host cell antigen in the centriolar region after infection of African green monkey kidney (AGMK) cells. The addition of puromycin and actinomycin D to cells infected with SV40 within 5 h after infection inhibited the stimulation of the host cell antigen, indicating that de novo protein and RNA syntheses that occurred within the first 5 h after infection were essential for the stimulation. Early viable deletion mutants of SV40 with deletions mapping between 0.54 and 0.59 map units on the SV40 genome, dl2000, dl2001, dl2003, dl2004, dl2005, dl2006, and dl2007, did not stimulate the centriolar antigen above the level of uninfected cells. This indicated that an intact, functional small-t protein was essential for the SV40-mediated stimulation of the host cell antigen. Our studies, using cells infected with nondefective adenovirus-SV40 hybrid viruses that lack the small-t gene region of SV40 (Ad2+ND1, Ad2+ND2, Ad2+ND3, Ad2+ND4, and Ad2+ND5), revealed that the lack of small-t gene function of SV40 could be complemented by a gene function of the adenovirus-SV40 hybrid viruses for the centriolar antigen stimulation. Thus, adenovirus 2 has a gene(s) that is analogous to the small-t gene of SV40 for the stimulation of the host cell antigen in AGMK cells.     

Monoclonal antibodies against simian virus 40 tumor antigens: analysis of antigenic binding sites, using adenovirus type 2-simian virus 40 hybrid viruses.

The antigenic binding sites of two monoclonal antibodies are located in the COOH-terminal region (clone 412) and probably in an internal region (clone 7) of simian virus 40 large T antigen. A third monoclonal antibody (clone 122), which has been shown to bind nonviral T antigen, does not react with HeLa cells infected with nondefective adenovirus type 2 (Ad2)-simian virus 40 hybrid viruses Ad2+ND1, Ad2+ND2, or Ad2+ND4.     

Fastidious human adenovirus type 40 can propagate efficiently and produce plaques on a human cell line, A549, derived from lung carcinoma.

Human adenovirus type 40 (Ad40) cannot propagate in conventional established human cell lines such as KB or HeLa cells. However, it has been shown that Ad40 DNA replicates in KB18 cells which express Ad2 E1B genes, suggesting that Ad40 is defective in the E1B gene function in KB or HeLa cells. We show here that Ad40 can propagate and produce plaques on A549 cells which do not contain Ad E1B genes. Our experiments show that the levels of replication of Ad40 DNA and production of infectious Ad40 virus in A549 cells are the same as or higher than those in 293 or KB18 cells. Dot blot analysis shows that the levels of Ad40 E1A and E1B mRNAs expressed in A549 cells at early to intermediate times postinfection are at least 10-fold higher than those in KB or KB18 cells. Northern (RNA) blot analysis shows that large E1B mRNA species (approximately 24S to 26S) are synthesized prior to the onset of DNA replication in A549 cells. No E1B mRNA species are synthesized in KB or KB18 cells at early times postinfection, and no differences in the expression of E1B mRNAs are seen between KB and KB18 cells. The experiment suggests that A549 cells have a cellular factor(s) which activates Ad40 E1B mRNA synthesis and that the E1B mRNA synthesis helps Ad40 propagation. In contrast, Ad40 can propagate in KB18 cells by using Ad2 E1B gene products that are constitutively expressed in this cell line. Furthermore, this result shows that Ad40 cannot propagate in KB cells because of the failure in the expression of E1B genes at early times postinfection.     

Absence of an essential regulatory influence of the adenovirus E1B 19-kilodalton protein on viral growth and early gene expression in human diploid WI38, HeLa, and A549 cells.

Mutations in the gene encoding the adenovirus (Ad) early region 1B 19-kDa protein (the 19K gene) result in multiple phenotypic effects upon infection of permissive human cells. It has been reported, for example, that Ad type 2 (Ad2) and Ad5 with mutations in the 19K gene (19K-defective mutants) have a marked growth advantage compared with wild-type virus in human diploid WI38 cells (E. White, B. Faha, and B. Stillman, Mol. Cell. Biol. 6:3763-3773, 1986), and it was proposed that this host range phenotype stems from the large increase in viral early gene expression reported to occur in the mutant-infected cells. These observations gave rise to the hypothesis that the 19-kDa protein (the 19K protein) normally functions as a negative regulator of Ad early gene expression and growth. We have tested this hypothesis and find that Ad5 and Ad12 wild-type viruses grow as efficiently as their respective 19K-defective mutants, in1 and dl337 and pm700 and in700, in WI38 and other human cell types. Neither the accumulation of E1A cytoplasmic mRNAs nor the synthesis of E1A and other viral early proteins in these cells is altered as a result of these mutations in the 19K gene, and we conclude that the 19K protein does not play an essential role in regulating viral early gene expression or viral growth in human cells.