SV40-adenovirus "hybrid" populations: transfer of SV40 determinants from one type of adenovirus to another

Growth of SV 40, adeno 7 and SV 40-adeno 7 viruses in monkey and human cells at 29 degrees and 37 degrees C

Adeno 7 virus replicated well in human diploid (LEP) cells but only to a low degree in green monkey kidney (GMK) cells at 37 degrees C; it did not replicate in either system at 29 degrees C. At 37 degrees C SV 40 virus replicated well in GMK cells but only moderately in LEP cells; at 29 degrees C it did not replicate in either system. SV 40-adeno 7 hybrid grew in both GMK cells and LEP cells at 37 degrees C. At 29 degrees C this virus replicated in GMK cells but not in LEP cells. While the formation of V-antigen generally corresponded to the infectious virus production in the respective system, considerable differences were encountered in the T-antigens production. Adeno 7 T-antigen was detected earlier and in a higher percentage of GMK cells than in the fully permissive LEP cells and its formation was only slightly influenced by the incubation temperature. SV 40 T-antigen was more efficiently formed in GMK cells than in LEP cells. At 29 degrees C SV 40 T-antigen was only found in GMK cells and was detected later than at 37 degrees C. The difference in the formation of SV 40 T-antigen in GMK cells infected with SV 40 and SV 40-adeno 7 hybrid virus was further analyzed. The results obtained suggest that an early step of the virus-cell interaction, but neither virus attachment nor penetration, was involved.

Studies of nondefective adenovirus 2-simian virus 40 hybrid viruses. IV. Characterization of the simian virus 40 ribonucleic acid species induced by wild-type simian virus 40 and by the nondefective hybrid virus, Ad2 + ND 1

Ad2(+)ND(1), a nondefective adenovirus 2 (Ad2)-simian virus 40 (SV40) hybrid virus, has been previously shown to contain a small segment of the SV40 genome covalently linked to Ad2 deoxyribonucleic acid (DNA). The SV40 portion of this hybrid virus has been characterized by relating the SV40-specific ribonucleic acid (RNA) sequences transcribed from the Ad2(+)ND(1) DNA to those transcribed from the DNA of SV40 itself. RNA-DNA hybridization-competition studies indicate that the SV40 component of Ad2(+)ND(1) consists of some, but not all, of that part of the SV40 genome which is transcribed early, i.e., prior to viral DNA replication, in SV40 lytic infection.

Components of adenovirus-simian virus 40 hybrid viruses

The DNA and protein components of the adenovirus 7-simian virus (SV)40 hybrid virus "E46(+)" have been investigated. The Ad.7-SV40 hybrid DNA genome could be distinguished from nonhybrid Ad. 7 genome on the basis of its molecular weight in an alkaline sucrose gradient. The hybrid genome could also be separated from nonhybrid adenovirus 2 DNA when purified transcapsidant adenovirus 2(+t7) (Ad.7-SV40 DNA within an Ad.2 capsid) was studied. The presence and amount of SV40 DNA in the hybrid virus genome was determined by DNA-RNA hybridization. The results presented suggest: (i) that about 10% of the particles in the E46(+) preparations contained SV40 DNA covalently linked to adenovirus DNA; (ii) that the hybrid virus genome has a molecular weight 10-12% lower than that of nonhybrid virus, consistent with a deletion of adenovirus DNA; and (iii) that the hybrid virus contained only 40-50% of a total SV40 genome. The protein components of the Ad.7-SV40 hybrid virus were examined by acrylamide gel electrophoresis in sodium dodecyl sulfate. No significant quantitative or qualitative differences between the proteins of hybrid and nonhybrid adenovirus were demonstrated.

Isolation of two plaque variants from the adenovirus type 2-simian virus 40 hybrid population which differ in their efficiency in yielding simian virus 40

Studies on the adenovirus type 2-simian virus 40 (SV40) hybrid population demonstrated two genetically stable variants within this population, which were isolated by plaquing in African green monkey kidney cells. These variants were similar in that each induced SV40 T antigen in human embryonic kidney cells and contained similar concentrations of nonhybrid adenovirus type 2 virions and adenovirus-encapsidated particles containing the infectious SV40 genome. These variants differed markedly, however, in their ability to produce SV40 viral antigen in human embryonic kidney cells and the efficiency with which they produce SV40 plaques in monkey cell monolayers. It is postulated that the differences in SV40-yielding efficiency between these variants lie in the nature of the recombinant deoxyribonucleic acid composing the genome of the hybrid particles.

Equilibrium density gradient studies on simian virus 40-yielding variants of the adenovirus type 2-simian virus 40 hybrid population

The simian virus 40 (SV40)-yielding variants of the adenovirus type 2 (Ad.2)-SV40 hybrid (Ad.2(++)) population were studied by means of fixed-angle equilibrium density gradient centrifugation in cesium chloride. The hybrid virions of the Ad.2(++) high-efficiency yielder population banded at densities of 0.004 g/cm(3) lighter than the nonhybrid Ad.2 virions. The degree of separation of the hybrid particles was sufficient to permit greater than 100-fold relative purification by two cycles of centrifugation. Hybrid particles that produce adenovirus plaques in African green monkey kidney cells by two-hit kinetics (one-hit kinetics when assayed on lawns of nonhybrid adenovirus) were not separable from the particles that yield SV40 virus. The hybrid particle in the Ad.2(++) low-efficiency yielder population was not separable from the nonhybrid Ad.2 virions.

Variation in properties of plaque progeny of PARA (defective simian papovavirus 40)-adenovirus 7

One hundred and twelve progeny from double plaque-purified clones were derived from the original PARA (defective simian papovavirus 40)-adenovirus 7 population. These progeny were found to differ in their oncogenic potential in newborn hamsters with progeny from 20 clones not inducing any tumors during 1 year of observation. The varying tumorigenicity of the individual clonal progeny was not related to the titer of PARA (particle aiding replication of adenovirus) in the inoculum. There was a perfect correlation between the tumor antigen content of the tumor cells and the antibody response of the tumor-bearing host. The tumors containing both adenovirus and simian papovavirus 40 (SV40) tumor antigens appeared earlier than those carrying only SV40 tumor antigen. Progeny from clones which induced mixed tumors also produced tumors which contained only SV40 tumor antigen. Three variants of PARA were isolated which induced the synthesis of SV40 tumor antigen in the cytoplasm of infected simian cells; all other clones yielded progeny which induced synthesis of SV40 tumor antigen in the nucleus.

In vitro transformation by adenovirus-simiam virus 40 hybrid viruses. IV. Properties of clones isolated from cell lines transformed by adenovirus 2-simiam virus 40 and adenovirus 12-simiam virus 40 transcapsidant hybird viruses

Clones were isolated from hamster cells transformed by the adenovirus 2-SV40 and adenovirus 12-SV40 transcapsidant hybrid viruses. The clones were characterized with respect to their cytomorphology, virus and antigen content, and the histomorphology of tumors induced by transplantation of the clonal sublines to hamsters. Three different cellular and colonial morphologies were observed. Clones with an SV40 morphology gave rise to tumors predominantly with an SV40 histology, whereas clones with an adenovirus morphology produced typical adenovirus tumors upon transplantation of the transformed cells. Clones which had features of both SV40 and adenovirus transformed cells gave rise to "intermediate" and adenovirus tumors. The results indicate that multiple events occur during transformation and tumorigenesis by the transcapsidant virus populations and provide an explanation for the multiplicity of findings which have been reported with these virus populations.

Variants of defective simian papovavirus 40 (PARA) characterized by cytoplasmic localization of simian papovavirus 40 tumor antigen

Three isolates of PARA (particle aiding replication of adenovirus)-adenovirus 7 out of a total of 112 clonal progeny derived by two successive plaque purifications in green monkey kidney cells (GMK) were found to induce the synthesis of simian papovavirus40 (SV 40) tumor (T) antigen in the cytoplasm of infected cells. The variant viruses induced plaque formation in human embryonic kidney cells which followed one-hit kinetics. In GMK cells, plaque formation followed two-hit kinetics which converted to first-order kinetics in the presence of additional helper adenovirus type 7. Analysis of plaque progeny from human cells showed that the progeny could replicate only in human cells, whereas progeny from monkey cells could multiply in both human and monkey cells. Heterologous human adenoviruses were able to enhance plaque formation by the variant viruses in monkey kidney cells. Neutralization tests indicated that both components of the populations had a type 7 adenovirus capsid. All three viruses were capable of inducing SV40 transplantation immunity in weanling hamsters. These results indicate the three variants are PARA-adenovirus 7 populations. Response of the induction of the synthesis of the cytoplasmic antigen to metabolic inhibitors was the same as for the synthesis of the nuclear SV40 T antigen. Different pools of sera which reacted with the intranuclear SV40 T antigen also detected the cytoplasmic antigen induced by the variant viruses. An adsorption experiment with cells containing either nuclear or cytoplasmic T antigen to remove tumor antibody from hamster sera also indicated that it is probably SV40 T antigen which is responsible for the cytoplasmic reaction. The species of the host cell-human, simian, or rabbit-appeared to play no role in the altered localization of this antigen. It is postulated that these PARA variants are further defective in some virus-mediated transport mechanism which shifts the T antigen from the cytoplasm to the nucleus.

A nondefective (competent) adenovirus-SV40 hybrid isolated from the AD.2-SV40 hybrid population

A new nondefective hybrid virus has been plaque-isolated from the Ad.2-SV40 hybrid population. This virus replicates efficiently with one-hit kinetics in both human embryonic kidney and African green monkey kidney cells, induces an SV40 specific antigen which is detectable by immunofluorescence and complement-fixation using sera from SV40 tumor-bearing hamsters, and produces SV40-specific RNA detectable by DNA-RNA hybridization. The SV40-specific antigen induced by this virus is heat-stable, sensitive to inhibitors of DNA synthesis, serologically different from SV40 T and viral antigens, and is an unrecognized SV40 antigen.

Variation in the oncogenic potential of human adenoviruses carrying a defective SV40 genome (PARA)

The acquisition of the defective SV40 genome by a variety of human adenovirus serotypes by the process of transcapsidation has resulted in the addition of oncogenic potential for newborn hamsters to the previously nononcogenic adenovirus types 1, 2, 5, and 6. These serotypes have previously been grouped together by the high GC content of their DNA. Transcapsidation of the SV40 genome to weakly oncogenic adenovirus types 3, 14, 16, and 21 has failed to increase their oncogenic potential although the parent adenovirus type 7 carrying PARA is highly oncogenic. These serotypes belong to the group possessing a DNA of intermediate GC content. All the PARA-adenovirus populations, even those that were nononcogenic, were able to induce SV40 transplantation immunity and therefore carry the SV40 transplantation marker as well as the marker for synthesis of SV40 tumor or T antigen.

Correlation of immunology and histopathology of tumors induced by defective SV40-adenovirus hybrids

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In vitro transformation by the adenovirus-SV40 hybrid viruses. II. Characteristics of the transformation of hamster cells by the adeno 2-, adeno 3-, and adeno 12-SV40 viruses

Primary weanling hamster kidney cultures were transformed with the adeno 2-SV40, adeno 3-SV40, and adeno 12-SV40 hybrid viruses and with adenovirus type 12. The transformed cell lines which were established were characterized with respect to morphology, virus and antigen content, and chromosome aberrations. The adeno 2 and adeno 3-SV40 hybrid transformed cells had the morphology and T antigen content characteristic of SV40 transformations; cells transformed by the former hybrid had cytogenetic changes typical of SV40-transformed cells as well. The adeno 12-SV40 transformed cells were similar morphologically to adeno 12-transformed cells, contained both the SV40 and adeno T antigens and demonstrated the karyotypic instability of SV40-transformed cells, indicating that both viral genomes are operative in these cells. Although the results indicate that the SV40 genome in hybrids derived from the moderately or nononcogenic adenoviruses supplies the determinants for most of the characteristics investigated, and perhaps for oncogenesis, evidence was presented which suggests that a portion of a nononcogenic adenovirus genome may be integrated in adeno 2-SV40 transformed cells and directs the synthesis of adenovirus T antigens.

Replication of adenovirus type 7 in monkey cells: a new determinant and its transfer to adenovirus type 2

A strain of human adenovirus type 7, adapted to replication in green-monkey kidney cells, requires the interaction of two particles to initiate plaque formation in the simian cells. One particle is a true adenovirion. The second, apparently defective, consists of a genome carrying amonkey-adapting component in an adenovirus capsid; this genome does not express known SV40 determinants. The addition of human adenovirus type 7 that is not adapted enhances the titer and changesconditions for plaque formation by the adapted virus to a one-particle requirement. Addition of nonadapted human adenovirus type 2 as helper virus results in the transfer of the monkey-adaptingcomponent from adenovirus type 7 to adenovirus type 2. The population containing the adenovirus 2 transcapsidant then has the ability to replicate in simian cells.

Susceptibility of human diploid fibroblast strains to transformation by SV40 virus

A quantitative system has been developed for the study of transformation of human diploid fibroblasts in culture by two oncogenic viruses, SV40 and the E46 strain of adeno 7-SV40 "hybrid" virus. Seven of the eleven cell strains derived from human skin biopsies when infected with SV40 (10(9) tissue culture infective doses per milliliter) gave rise to transformed colonies with approximately the same frequency (0.03 percent). Two strains derived from patients with Fanconi's anemia, an autosomal recessive disease associated with a high incidence of chromosome abnormalities and spontaneous neoplasms, gave values more than ten times higher. Two strains from persons heterozygous for this gene were also considerably more susceptible to viral transformation.

Studies of adenovirus-SV40 hybrid viruses. V. Evidence for linkage between adenovirus and SV40 genetic materials

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Interaction of a simian papovavirus and adenoviruses. I. Induction of adenovirus tumor antigen during abortive infection of simian cells

Feldman, Lawrence A. (Baylor University College of Medicine, Houston, Tex.), Janet S. Butel, and Fred Rapp. Interaction of a simian papovavirus and adenoviruses. I. Induction of adenovirus tumor antigen during abortive infection of simian cells. J. Bacteriol. 91:813-818. 1966.-Adenovirus types 2, 7, and 12 undergo an abortive growth cycle in green monkey kidney cells; they induce the formation of adenovirus tumor antigen, but synthesis of adeno capsid antigen and infectious adenovirus was observed only when cultures were concomitantly infected with a simian papovavirus (SV40). Several other viruses, including herpes simplex and measles which replicate in monkey cells, and rabbit papilloma and human wart papovaviruses which do not, failed to stimulate adenovirus replication in the monkey cells. Adenovirus tumor antigen was detected 8 to 10 hr postinfection by immunofluorescent techniques. The antigen induced by adenovirus types 2 and 7 appeared as intranuclear masses; adenovirus type 12 tumor antigen also appeared as cytoplasmic and nuclear flecks. Sera from hamsters bearing tumors induced by adenovirus type 12 cross-reacted with tumor antigens induced by types 2 and 7 but not with antigens induced by SV40.