Phenotypic mixing between N- and B-tropic murine leukemia viruses: Infectious particles with dual sensitivity to Fv-1 restriction

Rein, Alan; Kashmiri, S. V. S.; Bassin, Robert H.; Gerwin, Brenda I.; Duran-Troise, Graciela

doi:10.1016/0092-8674(76)90166-5

Cited by 72 publications

(44 citation statements)

References 15 publications

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“…We first described it as the main feature of the Fv-J gene restriction (19), and it was later confirmed by others (3,40). The Fv-1 gene maps on mouse chromosome 4 (30) and has been shown to require the presence of a viral determinant to operate (21,26). A selective decrease of supercoiled viral DNA has also been observed in newly infected cells treated with ethidium bromide (12), cycloheximide (41), or aphidicolin (13,16), suggesting that newly synthesized protein(s), possibly DNA polymerase a or 8 or both, are required for the formation of these DNA molecules.…”

Section: Discussionmentioning

confidence: 90%

An X-linked gene affecting mouse cell DNA synthesis also affects production of unintegrated linear and supercoiled DNA of murine leukemia virus.

Richter¹,

Ozer²,

DesGroseillers³

et al. 1984

Mol. Cell. Biol.

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To identify specific cellular factors which could be required during the synthesis of retroviral DNA, we have studied the replication of murine leukemia virus in mouse cells temperature sensitive for cell DNA synthesis (M. L. Slater and H. L. Ozer, Cell 7:289-295, 1976) and in several of their revertants. This mutation has previously been mapped on the X chromosome. We found that a short incubation of mutant cells at a nonpermissive temperature (39°C) during the early part of the virus cycle (between 0-to 20-h postinfection) greatly inhibited virus production. This The replication of the RNA genome of retroviruses by reverse transcriptase is a complex process. Linear doublestranded DNA molecules with segmented (+) strand are first synthesized with a redundant sequence at each end, the long terminal repeats (LTR) (for review, see reference 36). LTR are composed of a sequence derived from the 3' end and another one from the 5' end of the RNA genome. The linear DNA molecules mature as nonsegmented, fully doublestranded molecules and appear to be converted in the nucleus into two species of covalently closed circular viral DNAs (20, 32), one shorter species harboring one LTR copy and the larger species harboring two LTR copies (31, 42). Several of these steps seem to be carried out by reverse transcriptase alone or possibly in combination with other virion proteins. Indeed, infectious double-stranded linear viral DNA, as well as circular viral DNA with one LTR copy can be synthesized in vitro by purified virions (1,2,5,6,10). This in vitro reaction, however, does not yield closed circular viral DNA with two LTR copies. Most importantly, the infectivity of viral DNA made in vitro is several orders of magnitude lower than that of viral DNA made early during infection (10,23,28). This suggests that cell factors are required during the reverse transcription process. Other experiments also indicate that the cell provides essential * Corresponding author.factors during some steps of reverse transcription. Serum starvation has been shown to markedly affect the production of unintegrated viral DNA in newly infected avian (7,8,37) or murine (14) cells. Cycloheximide added early after infection prevented the formation of both species of supercoiled viral DNA, suggesting that newly synthesized proteins are required to complete this step (41). The treatment of newly infected murine (4, 13) or avian (16) cells with aphidicolin, an inhibitor of cellular DNA polymerase a (17) and 5 (24), also prevented the formation of supercoiled viral DNA, suggesting that cellular DNA polymerases may be involved at this step of the virus cycle.Although very suggestive, these experiments do not permit one to distinguish between a number of factors possibly affected by the inhibitors. Also, it is not clear whether the effect of these treatments is directly on retroviral DNA synthesis or only indirectly influencing it. It would therefore be helpful to identify the cellular factors required in the reverse transcription process by using cell mutan...

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Section: Discussionmentioning

confidence: 90%

An X-linked gene affecting mouse cell DNA synthesis also affects production of unintegrated linear and supercoiled DNA of murine leukemia virus.

Richter¹,

Ozer²,

DesGroseillers³

et al. 1984

Mol. Cell. Biol.

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“…Formally, reduced virus infection might result from the activity of a restricting factor, like Fv1, or from the absence of a specific factor required for infection. To distinguish between these possibilities, we used an approach similar to one taken in the study of Fv1, in which it was shown that viruses containing mixed N-and B-tropic CA molecules were equally restricted in cells carrying either the n or b alleles of Fv1 (9). We prepared chimeric viruses containing different ratios of N-and B-tropic CA by cotransfection of Nand B-tropic gag-pol expression vectors.…”

Section: N-tropic Virus Ismentioning

confidence: 99%

“…The viral determinants for N-and B-tropism have been shown to be present in the capsid (CA) protein with an arginine at amino acid position 110 specifying N-tropism and a glutamate B-tropism (7). Fv1 is codominant because cells from heterozygous Fv1 n/b animals are not infected by either N-or B-tropic viruses (8) and mixed virus particles containing N and B CA molecules are restricted by either allele (9). Fv1 restriction is not absolute but results in a 50-to 1,000-fold reduction in virus replication (10).…”

mentioning

confidence: 99%

A conserved mechanism of retrovirus restriction in mammals

Towers

Bock

Martin

et al. 2000

Proc. Natl. Acad. Sci. U.S.A.

225

306

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“…1A). Because, after first subcultivation, (27,28) and also by kinetic studies of resistance transfer with cell extracts (10) and by a cell fusion method (7). In contrast, two previous reports put forward the view that Fv-I gene action was at a step beyond viral gene integration (29,30 …”

mentioning

confidence: 99%

Transfection of Fv-1 permissive and restrictive mouse cells with integrated DNA of murine leukemia viruses.

Hsu¹,

Yang²,

Tennant³

et al. 1978

Proc. Natl. Acad. Sci. U.S.A.

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Whole-cell DNA preparations isolated from SC-1 cells chronically infected with N-or B-tropic murine leukemia viruses (MuLV) were tested for infectious activity in an Fv-1n (NIH-3T3) and two Fv-1 b (C57BL/6 and SV-A31) cell cultures. Efficiency of transfection for all DNAs was better in the NIH-3T3 cells than in C57BL/6 or SV-A31 cells; and an [N-tropic MuLVJSC- (Clinton, TN), respectively. All cells used were within 10 passages of the original sources and were grown in Eagle's minimal essential medium containing 10% heat inactivated fetal calf serum, streptomycin (100;g/ml), and penicillin (100 units per ml).DNA Preparations. SC-1 cells were inoculated with N-or B-tropic MuLV at a multiplicity of infection of 1. Forty-eight hours later they showed more than 90% infection by immunofluorescence measurement. After five serial passages in dishes, the chronically infected SC-1 cells were grown to confluency in medium containing hydrocortisone (1 ,uM) and insulin (0.1 international unit/ml) in 6 X 75 cm roller bottles. The cells were harvested by scraping, washed, and used for DNA isolation according to a modification of Marmur's method (12), which includes Pronase digestion, ribonuclease digestion, and extractions with chloroform/isoamyl alcohol, 25:1 (vol/vol), as described (13,11). The final DNA products were dissolved in 15 mM NaCI/1.5 mM Na citrate, pH 7.0, and stored in aliquots at -70°. DNA concentration was measured spectrophotometrically at 260 nm by assuming that 20 A20 units equal 1 mg of DNA. All DNA preparations showed A 2m/A28o ratios of 1.9-2.0.Infectious DNA Assay. The detailed procedure for DNA transfection in mouse cell cultures has been described (11). In this study, all cultures were plated at 2 X 105 cells per 35-mm dish 20 hr prior to DNA inoculation. The cells, with medium removed, were exposed to 0.3 ml of the freshly prepared calcium DNA suspension (14) which contained various doses of sample DNA and also an appropriate amount of calf thymus DNA to maintain a constant DNA concentration of 40 Ag/ml. After 15 min, 3 ml of medium was added and the dishes were placed in a 370 CO2 incubator for an additional 15 hr before DNA was removed by a change to fresh medium. Two to 3 days after DNA inoculation, when the cultures became confluent, the cells were trypsinized and used 1:5 for subculture. Serial Abbreviations: MuLV, murine leukemia virus; PFU, plaque-forming units.

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Phenotypic mixing between N- and B-tropic murine leukemia viruses: Infectious particles with dual sensitivity to Fv-1 restriction

Cited by 72 publications

References 15 publications

An X-linked gene affecting mouse cell DNA synthesis also affects production of unintegrated linear and supercoiled DNA of murine leukemia virus.

An X-linked gene affecting mouse cell DNA synthesis also affects production of unintegrated linear and supercoiled DNA of murine leukemia virus.

A conserved mechanism of retrovirus restriction in mammals

Transfection of Fv-1 permissive and restrictive mouse cells with integrated DNA of murine leukemia viruses.

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