Mechanism of restriction of murine leukemia viruses varies between different strains of Fv‐1 n mice

Kiggans

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

et al. 1980

Production of various forms of nonintegrated viral DNA was measured in cultured mouse cells carrying different Fv-1 alleles early after infection with N-tropic or B-tropic retroviruses. Quantitative analyses were performed by agarose gel electrophoresis, transfer to diazobenzyloxymethyl-paper, and molecular hybridization. In permissive infection of Fv-n cells (NIH Swiss and DBA mouse strains) with N-tropic virus and of Fv-1 b cells (BALB/c and C57BL/6 strains) with B-tropic virus, form III (double-stranded linear) DNA first appeared at 3-4 hr and reached a maximum at 8-10 hr; two form I (closed circle) DNAs appeared at 7-8 hr and reached a maximum at or beyond 12 hr. In the two Fv-1 b cells infected with N4ropic virus and in DBA (Fv-1 n) cells infected with B-tropic virus, formation of the two form I DNAs was quantitatively restricted but formation of form III DNA was unaltered. In Fv-1" NIH Swiss mouse embryo cells infected with B-tropic virus, the level of form III DNA was markedly depressed and hence the two form I DNAs were not detectable. In C57BL/6 cells as well as in DBA/2 cells 12 hr after infection, the quantity of form III DNA varied directly with the amount of restricted virus, whereas the quantity of form I DNA varied according to the square of the amount of restricted virus. The significance of these results for understanding the molecular basis of retrovirus replication and its restriction by the Fv-1 gene is discussed. The importance of the mouse Fv-1 gene locus in controlling infection by N-and B-tropic retroviruses has been well recognized in both animal studies and cell culture studies (1-5). This locus, mapped on chromosome 4 of the mouse (6), is presumably responsible for the production of specific inhibitor molecules in the cytoplasm of the cell (7-9). Inactivation of the restricted virus particles appears to be mediated by a virus protein, possibly the p30 core protein (10), which serves as a "target" for the Fv-1 gene product (11,12). However, the precise molecular mechanism of Fv-1 gene restriction is still unknown. Results of various previous investigations (13)(14)(15)(16)(17)(18)(19)(20) indicate that Fv-1 restriction occurs intracellularly at an early step of the virus replication cycle. Of particular significance are the observations (i) that, in Fv-1 restricted infection, the quantity of the cellgenome integrated viral DNA is markedly decreased whereas the formation of nonintegrated viral DNA appears to be unaffected (17-18), and (ii) that transfection by infectious integrated viral DNA is not restricted by the Fv-1 locus of the cell (19,20). These data imply that Fv-1 restriction may occur at or prior to the step of viral DNA integration.In the present study, we quantitatively measured the production of double-stranded linear and circular forms of viral DNA in Fv-1 permissive and restrictive cells early after infection with N-and B-tropic murine retroviruses. The results demonstrate that mouse cells may be assigned to either of two classes with regard to their ability to re...

Section: Resultsmentioning

confidence: 48%

Synthesis and circularization of N- and B-tropic retroviral DNA Fv-1 permissive and restrictive mouse cells.

Kiggans

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

et al. 1980

Journal of General Virology

“…; 1974), permissive to both N-and B-tropic MuLV; DBA (Benjers et al, 1979), which contains the Fv-1 n gene, rendering it permissive to N-tropic MuLV and restrictive to B-tropic MuLV; Balb/3T3, which contains the Fv-1 b gene, rendering it permissive to B-tropic MuLV and restrictive to N-tropic MuLV. As illustrated in Table 1, MuLV from chromosome-treated cells exhibited a titre on Balb/3T3 cells which was more than 100-fold lower than that observed on 3T3FL or DBA cells.…”

Section: Chromosome-mediated Transfer Of Mul V Genes To Nih/3t3 Cellsmentioning

confidence: 99%

Transfer of Murine Leukaemia and Murine Sarcoma Virus Genetic Information by Transfection with Isolated Metaphase Chromosomes

Levin

Hughes²,

Graeter

et al. 1982

Self Cite

SUMMARYChromosome-mediated transfer of murine leukaemia (MuLV) and murine sarcoma (MuSV) virus genetic information to uninfected recipient cells was investigated. Metaphase chromosomes from AKR MuLV-infected SC-1 mouse cells were incubated with NIH/3T3 cells. After several passages (1 to 3 weeks), infectious virions exhibiting reverse transcriptase activity and the characteristic host range of ecotropic, N-tropic AKR virus appeared in the supernatant fluids of the treated cells. Restriction endonuclease analysis of genomic DNA from transfected cells indicated that AKR proviral DNA was associated with the high molecular weight DNA of the host. These results demonstrate that the AKR MuLV genome can be stably transferred to uninfected recipient cells via isolated metaphase chromosomes. Although AKR virions are not able to infect heterologous cells, chromosomemediated transfection resulted in the establishment of productive AKR MuLV infection in mink cells. Thus, the use of chromosomes to transfer virus genes can circumvent the natural host restriction barrier. In other experiments, it was shown that normal NIH/3T3 cells were transformed after exposure to metaphase chromosomes isolated from an MuSV-infected, non-producer line. Foci were detected 14 to 21 days after chromosome treatment and were shown to contain true viral transformants since transforming virus was produced after superinfection with MuLV.

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

“…(6) showing that NIH Swiss mouse cells may possess an additional gene that appears to modify the Fv-1 gene of these cells. This modified Fv-1 gene effect renders these cells even more restrictive than can be accounted for purely on the genotype of the ,Fv-l/' locus (2).…”

mentioning

confidence: 99%

Host restriction of Friend leukemia virus: gag proteins of host range variants.

Duttagupta¹,

Soeiro²

1981

The host response to murine ecotropic leukemia viruses is mainly controlled by the mouse Fv-1 gene. This locus controls virus replication at. an-intracellular stage and prevents provirus integration. Biological studies suggest that the Fv-1 effector molecule recognizes at least one virion structural'protein.We have produced host range variants of B-tropic Friend murine leukemia virus in order to study the primary structure ofpotential viral target proteins. Our results show that conversion of B-tropism to NB-tropism is associated with changes inthe primary structure of three gag proteins-pI5, p1l, and p30. These results suggest that host range conversion is due to a recombinational event, presumably between the parental virus and an endogenous murine virus. They alsoopen the possibility that p12 and p30 may be involved in host range restriction.The response ofthe mouse to infection by ecotropic murine leukemia viruses is controlled by several genes, but one, the Fv-1 locus, predominates (1). This gene, which maps to chromosome 4, exists in two allelic forms, Fv-1 and Fv-lb. NIH Swiss mice represent the prototype of the homozygous N-genotype (Fv-1l1'), and BALB/c mice represent the homozygous B-genotype Using a combined genetic and biochemical analysis, Hopkins and colleagues (17) showed that there is a correlation between the major viral core protein p30 and viral host range. Similar studies revealed a lack of such a relationship for the envelope protein gp69/70 or the core protein p15. In addition, Gautsch et al. (18) demonstrated by tryptic peptide pattern that the primary structure ofp30 was specific for the viral host range. Furthermore, structural changes in the 5' end ofthe genome-that is, in the general region of the gag gene which includes p30-have been found to correlate with host variation (19).We have isolated a series of NB-tropic variants in order to study possible structural changes that might be produced in genome or protein. Our 2320The publication costs ofthis article were defrayed in part by page charge payment. This article must therefore be hereby marked "advertisement" in accordance with 18 U. S. C. §1734 solely to indicate this fact.Abbreviations: MuLV, murine leukemia virus; MSV, murine sarcoma virus; F-MuLV, Friend MuLV.