Regulation of Moloney murine leukemia virus replication in chronically infected cells arrested at the G0/G1 phase

Abstract

The replication of Moloney murine leukemia virus (MMuLV) in chronically infected mouse cells arrested at the GO/Gl phase of the cell cycle by different procedures was investigated. MMuLV production was inhibited in glutamineand isoleucine (Gln-Ile)-deprived GO/Gl cells. In contrast, butyric acid treatment, which efficiently arrested the cells at the GO/Gl phase of the cell cycle, did not inhibit MMuLV production. Furthermore, the inhibition of MMuLV production caused by either Gln-Hle deprivation or by interferon (IFN) treatment was overcome by butyric acid treatment. Thus, the replication of MMuLV could be dissociated from cell proliferation. The inhibition of MMuLV production in Gln-lle-deprived cell cultures was compared to the inhibitory effect of IFN, which is known to affect budding and release of the virus. Rates of MMuLV protein synthesis were not affected in both the IFN-treated and Gln-Ile-deprived cells. However, processing of the viral polyprotein Pre65919 into p30 was blocked in the Gln-Ile-deprived cells. Furthermore, whereas in IFN-treated cells, MMuLV accumulated on the cell surface and could be released upon treatment with trypsin, in Gln-Ile-deprived cells, no virions were released by such treatment. These results indicate that in cells arrested by Gln-Ile deprivation, MMuLV is inhibited at a posttranslation step. This step appears to precede the anti-MMuLV block induced by IFN.

Human primary T lymphocytes have a low capacity to amplify MLV-based amphotropic RCR and the virions produced are largely noninfectious

“…Reportedly, RCR production is higher in cycling cells than in stationary cells. [14][15][16] No effect was observed from the presence of IFNg Ab, either on the total titer of viral particles or on the fraction of infectious viral particles. As in the previous experiment, the fraction of infectious particles was extremely low, at best 0.1% for donor 9.…”

“…Thus, each cell type was cultured under conditions most suitable for that cell type to remain in log phase, since RCR is best produced by cells growing in log phase. [14][15][16] After the indicated culture time periods, supernatant was harvested and residual cells and cell debris were removed by centrifugation at 500 g for 5 min. Then the supernatant was filtered through a 0.45 mm filter and aliquots were stored at À801C till further use.…”

Therapeutic effects of D‐aspartic acid β‐hydroxamate (DAH) on friend erythroleukemia

“…human tumors; among these, N-(phosphonacety1)-L-aspartic acid (PALA) and L-2-amino-3-(N-hydroxy-N-nitrosamino) propionic acid (L-alanosine) have undergone phase-I and -11 trials in several centers in the USA (Ardalan and Singh, 1987;Morton et al, 1987). Furthermore, glutamine is required for the in vitro production of the Moloney (Gloger et al, 1985;Gloger and Panet, 1986) and Rauscher (Roberts and McGregor, 1989) murine leukemia viruses; depletion in glutamine and asparagine is of therapeutic benefit in mice infected with the Rauscher and Friend leukemia viruses (Roberts and McGregor, 1991).…”