Restriction of moloney murine leukemia virus replication in moloney murine sarcoma virus-infected cells

The ts1 mutant of Moloney murine leukemia virus (MoMuLV) induces a neurodegenerative disease in mice, in which glial cells are infected by the retrovirus but neurons are not. ts1 infection of primary astrocytes, or of the immortalized astrocytic cell line C1, results in accumulation of the ts1 gPr80 env envelope protein in the endoplasmic reticulum (ER), with ER and oxidative stress. Notably, only about half of the infected astrocytes die in these cultures, while the other half survive, continue to proliferate, and continue to produce virus. To determine how these astrocytes survive ts1 infection in culture, we established a chronically infected subline of the living cells remaining after the death of all acutely infected cells in an infected C1 cell culture (C1-ts1-S). We report here that C1-ts1-S cells proliferate more slowly, produce less virus, show reduced H 2 O 2 levels, increase their uptake of cystine, and maintain higher levels of intracellular GSH and cysteine compared to acutely infected or uninfected C1 cells. C1-ts1-S cells also upregulate their thiol antioxidant defenses by activation of the transcription factor NF-E2-related factor 2 (Nrf2) and its target genes. Interestingly, despite maintenance of higher levels of intracellular reduced thiols, C1-ts1-S cells are more sensitive to cystine deprivation than uninfected C1 cells. We conclude that some ts1-infected astrocytes survive and adapt to virus-induced oxidative stress by successfully mobilizing their thiol redox defenses.

Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

See 1 more Smart Citation

Astrocytes Survive Chronic Infection and Cytopathic Effects of thets1 Mutant of the Retrovirus Moloney Murine Leukemia Virus by Upregulation of Antioxidant Defenses

Qiang

Kuang

Liu

et al. 2006

“…Cells. Viruses were propagated in mouse TB cells, a thymus bone marrow cell line derived from CFW/D mice (1), and assayed on 15F cells, a murine-sarcoma-positive, leukemia-negative (S+L-) cell line (22). NIH 3T3 cells were used for transfection experiments.…”

Section: Methodsmentioning

confidence: 99%

The neurovirulent determinants of ts1, a paralytogenic mutant of Moloney murine leukemia virus TB, are localized in at least two functionally distinct regions of the genome

Yuen¹,

Tzeng²,

Knupp³

et al. 1986

To better understand the molecular mechanism involved in retrovirus tsl-induced paralytic disease in mice, we constructed a panel of recombinant viruses between tsl and the wild-type viruses Moloney murine leukemia virus (MoMuLV) and MoMuLV-TB, a strain of MoMuLV. These recombinant viruses were constructed in an attempt to identify the sequence(s) in the genome of tsl which contains the critical mutation(s) responsible for the neurovirulence of tsl. Two functionally distinct sequences in the genome of tsl were found to be responsible for its paralytogenic ability. One of these sequences, the 0.77-kilobase-pair XbaI-BamHI (nucleotides 5765 to 6537) fragment which encodes the 5' half of gp7O and 11 base pairs upstream of the env gene coding sequence, determines the inability of tsl to process Pr8Oenv. The other sequence, the 2.30-kilobase-pair BamHI-PstI (nucleotides 538 to 8264 and 1 to 567) fragment, which comprises nearly two-thirds of the env gene, the long terminal repeat, and the 5' noncoding sequence, determines the enhanced neurotropism of tsl. Replacement of any one of these two regions with the homologous region from either one of the two wild-type viruses resulted in recombinant viruses which either totally failed to induce paralysis or induced a greatly attenuated form of paresis in some of the infected mice.

“…A thymus-bone marrow (TB) cell line derived from CFW/D mice (1) was used for propagation of both MoMuLV and the tsl mutant as described by Wong et al (23). 15F, a nontransformed, nonproducer, sarcoma-positive, leukemianegative (S+L-) cell line (28), was used to determine virus titers. All cell lines were cultured in Dulbecco modified Eagle medium (DMEM) supplemented with 10% heat-inactivated fetal bovine serum and containing 50 ,ug of gentamicin per ml of medium.…”

Section: Methodsmentioning

confidence: 99%

ts1, a Paralytogenic mutant of Moloney murine leukemia virus TB, has an enhanced ability to replicate in the central nervous system and primary nerve cell culture

Wong¹,

Knupp²,

Yuen³

et al. 1985

A temperature-sensitive mutant of Moloney murine leukemia virus TB (MoMuLV-TB), tsl, which is defective in intracellular processing of envelope precursor protein (Pr80e"v), also possesses the ability to induce hind-limb paralysis in infected mice. To investigate whether tsl has acquired neurotropism and to determine to what extent it can replicate in the central nervous system, we compared viral titers in the spleen, plasma, spinal cord, and brain throughout the course of infection of mice infected with tsl and parental wild-type (wt) MoMuLV-TB. In both the tsl-and wt-inoculated mice, the concentrations of infectious virus recovered from the plasma and spleen increased rapidly and reached a plateau by 10 days postinfection (p.i.). In contrast, virus concentrations in the spinal cord and brain of tsl-inoculated mice increased gradually and reached a titer comparable to that in the spleen and exceeding that in the plasma only at 25 to 30 days p.i. At this time, the virus titer was-200x greater in tsl-infected spinal cord tissue and-20x greater in tsl-infected brain tissue than in the same wt-infected tissues. Paralysis became evident at 25 to 30 days p.i. in tsl-inoculated mice, whereas the wt-inoculated mice were normal. In addition, a substantial amount of Pr80e"v was detected in the spinal cords of tsl-inoculated mice compared with that found in the spinal cords of wt-inoculated mice. The infectious virus isolated from tsl-infected nerve tissue was found to possess the characteristic phenotype of the tsl virus. Microscopic lesions of tsl-inoculated mice at 30 days p.i. consisted of vacuolar degeneration of motor neurons and spongy change of white matter in the brain stem and spinal cord. Similar but less severe lesions were observed in wt-inoculated mice. With primary cultures of central nervous system tissue we showed that tsl can infect and replicate in both neuron and glial cells. In contrast, although wt MoMuLV-TB replicated in glial cell-rich culture, viral replication was barely detectable in neuron-rich culture.