- Volume 7, Issue 3, 1970
Volume 7, Issue 3, 1970
- Articles
-
-
-
Genetic Resistance of Fowl to MH2 Reticuloendothelioma Virus
More LessSUMMARYComparison of the properties of MH2 reticuloendothelioma virus with known subgroup A, B and C strains of Rous sarcoma virus indicated that it belongs to subgroup C of avian tumour viruses.
The Reaseheath R line of chickens was highly resistant to MH2 virus, and tests on crosses between this line and the susceptible Reaseheath W line were consistent with the hypothesis that a single autosomal recessive gene controls resistance to MH2 virus.
-
-
-
-
Encephalomyocarditis Virus Multiplication in the Presence of Pyronine *
More LessSUMMARYPyronine at non-toxic concentrations greatly reduced the yield of encephalomyocarditis virus produced by Krebs ascites cells. The inhibition was greatest when pyronine was added 2 hr after infection and was less when the dye was added later. It also decreased when the dye was added shortly before infection. It could be reversed by removing pyronine from infected cells less than 2 hr after treatment. In the presence of the dye, synthesis of virus RNA was inhibited; the residual singlestranded RNA synthesized was not infectious and had abnormal sedimentation characteristics. Infectious double-stranded virus RNA was synthesized normally for 3 hr after infection and was inhibited later. Both virus and cellular protein synthesis were inhibited by pyronine. A possible explanation for these results could be the modification of the template activity of double-stranded virus RNA due to intercalation of pyronine between the base pairs.
-
-
-
Effect of Prolonged Interferon Treatment on Mouse Embryonic Fibroblasts Transformed by Murine Sarcoma Virus
More LessSUMMARYBalb/c mouse embryonic fibroblasts were transformed in vitro by the murine sarcoma virus (MSV) (moloney strain). These cells have a disorderly growth pattern. When grown in soft agar 61 % of them formed colonies. They contained ‘C’ type MSV particles and the transplantation antigen of the murine leukosis group of viruses. After 200 passages with interferon in the tissue culture medium, a cell line (MSV-IF+) emerged. This cell line recovered orderly growth and only 0·5% of the cells gave rise to colonies in soft agar. It contained about ten times more ‘C’ type particles than the original MSV cells. These particles harboured the MSV and leukaemia genome. The cells also retained the group and transplantation antigens. MSV-IF+ cells were completely resistant to exogenous interferon. When challenged with Newcastle disease virus they produced about ten times more interferon than the original MSV cells. Newcastle disease virus did not induce a refractory state to further interferon induction. When challenged five times every 48 hr the cells always produced a significant amount of interferon. It was postulated that this MSV-interferon cell line, unlike the original cell population, was not able to produce or use a repressor of interferon synthesis. In addition, the transformed cells recovered, to some degree, properties of the original normal cells.
-
-
-
Serum Accessory Factors in the Measurement of Arbovirus Neutralization Reactions
More LessSUMMARYFactors in normal serum which enhance Semliki Forest virus neutralization by specific immune guinea-pig serum have been demonstrated in a range of normal domestic and laboratory animals. The factors alfecting the in vitro assay system for accessory factors have been determined and enhancement of neutralization by normal guinea-pig serum in other virus/cell systems has been demonstrated. Accessory factors are denatured by various physical and chemical procedures but survive freeze-drying. The effect of ageing on accessory factors in vivo in normal and germ-free rats and rabbits and in normal calves, lambs, guinea-pigs and mice revealed marked species differences but showed no difference between normal and germ-free animals of the same species. There was no correlation between haemolytic complement and accessory factor levels present in a serum, except in rats, although the two complexes had several properties in common.
-
-
-
The Refractory State after Induction of Interferon with Double-stranded RNA
More LessSUMMARYAfter a first exposure to single-stranded polyriboinosinic and polyribocytidylic acids, which initiates interferon production, rabbit kidney cultures become refractory for about 3 days to further stimulation with polyriboinosinic and polyribocytidylic acids. However, when polyriboinosinic and polyribocytidylic acids are left in contact with the cells for several days, the interferon response is not restored to normal, as appears from a gradually decreasing production rate and a decreasing responsiveness to a higher dose. This is interpreted as indicating that refractoriness is not merely due to exhaustion of interferon precursors, but also to a blocking of denovo synthesis of interferon or interferon precursors. Small doses of polyriboinosinic and polyribocytidylic acids which did not induce measurable interferon, but which did stimulate resistance to virus, caused a hyper-reactivity to a second exposure to a high dose of polyriboinosinic and polyribocytidylic acids. It was concluded that in rabbit kidney cells, refractoriness is not correlated with the antiviral state resulting from stimulation of the interferon mechanism.
-
-
-
The Effects of Ultraviolet Irradiation on Mycobacteriophages and their Infectious DNAs
More LessSUMMARYMycobacteriophages D4, D29, D29A and D32, their isolated DNAs and their host, Mycobacterium smegmatis, atcc 607, are highly resistant to u.v. irradiation. Infective DNA appeared more resistant than intact phage but this difference was in part due to shielding by the greater u.v. absorbency of the DNA solutions. It was, however, also due to the occurrence of non-reversible u.v. damage to phage protein. D29, D29A and D32 and their DNAs showed two-component dose-survival curves, D4 and its DNA were inactivated exponentially, while M. smegmatis showed a non-linear semilog curve with a distinct shoulder in the low-dose region. M. smegmatis possesses a mechanism for reversing u.v. damage to the bacterial genome and to the genome of infecting phage by photoreactivation. Specific dark-repair mechanisms were not identified, except in the case of a significant level of acriflavin-sensitive host-cell reactivation demonstrated for D29. The observed enhancement of survival of heavily irradiated D29 and D4 by pretreatment of the assay bacteria with iodoacetate was interpreted as evidence that a delay of growth and division of the host, and/or a delay of phage replication, contributed indirectly to a dark-repair mechanism.
-
-
-
The Role of DNA Synthesis in Virus Replication and the Morphological Transformation of Normal Mouse Embryo Cells by MSV (moloney)
R. Bather and A. LeonardSUMMARYMorphological transformation of normal mouse embryo cells by murine sarcoma virus (moloney) and subsequent development of murine sarcoma virus growth were investigated using cytosine arabinoside (ara-C) and X-irradiation. Inhibition of DNA synthesis, cell division and transformation by ara-C were all reversible by deoxycytidine. The susceptibility of mouse embryo cells to infection and morphological transformation was most sensitive to ara-C during the first 6 hr after the virus-cell encounter. Sensitivity decreased with time, and by 24 to 48 hr virtually all infected cells had become transformed and completed the virus growth cycle, despite ara-C treatment. Irradiation of transformed, virus-producing cells with either 5000 R or 100,000 R had little effect on the ability of infected cells to produce murine sarcoma virus 24 hr later, and about 10% irradiated cells were still producing virus after 48 hr. Radiation survival and heat (37 °) inactivation data for murine sarcoma virus (moloney) are presented. The results indicate that the successful infection and morphological transformation of normal mouse embryo cells by murine sarcoma virus (moloney) requires a DNA synthetic event immediately after the virus-cell encounter and, that once initiated, successful virus growth no longer depends on DNA synthesis.
-
Volumes and issues
-
Volume 105 (2024)
-
Volume 104 (2023)
-
Volume 103 (2022)
-
Volume 102 (2021)
-
Volume 101 (2020)
-
Volume 100 (2019)
-
Volume 99 (2018)
-
Volume 98 (2017)
-
Volume 97 (2016)
-
Volume 96 (2015)
-
Volume 95 (2014)
-
Volume 94 (2013)
-
Volume 93 (2012)
-
Volume 92 (2011)
-
Volume 91 (2010)
-
Volume 90 (2009)
-
Volume 89 (2008)
-
Volume 88 (2007)
-
Volume 87 (2006)
-
Volume 86 (2005)
-
Volume 85 (2004)
-
Volume 84 (2003)
-
Volume 83 (2002)
-
Volume 82 (2001)
-
Volume 81 (2000)
-
Volume 80 (1999)
-
Volume 79 (1998)
-
Volume 78 (1997)
-
Volume 77 (1996)
-
Volume 76 (1995)
-
Volume 75 (1994)
-
Volume 74 (1993)
-
Volume 73 (1992)
-
Volume 72 (1991)
-
Volume 71 (1990)
-
Volume 70 (1989)
-
Volume 69 (1988)
-
Volume 68 (1987)
-
Volume 67 (1986)
-
Volume 66 (1985)
-
Volume 65 (1984)
-
Volume 64 (1983)
-
Volume 63 (1982)
-
Volume 62 (1982)
-
Volume 61 (1982)
-
Volume 60 (1982)
-
Volume 59 (1982)
-
Volume 58 (1982)
-
Volume 57 (1981)
-
Volume 56 (1981)
-
Volume 55 (1981)
-
Volume 54 (1981)
-
Volume 53 (1981)
-
Volume 52 (1981)
-
Volume 51 (1980)
-
Volume 50 (1980)
-
Volume 49 (1980)
-
Volume 48 (1980)
-
Volume 47 (1980)
-
Volume 46 (1980)
-
Volume 45 (1979)
-
Volume 44 (1979)
-
Volume 43 (1979)
-
Volume 42 (1979)
-
Volume 41 (1978)
-
Volume 40 (1978)
-
Volume 39 (1978)
-
Volume 38 (1978)
-
Volume 37 (1977)
-
Volume 36 (1977)
-
Volume 35 (1977)
-
Volume 34 (1977)
-
Volume 33 (1976)
-
Volume 32 (1976)
-
Volume 31 (1976)
-
Volume 30 (1976)
-
Volume 29 (1975)
-
Volume 28 (1975)
-
Volume 27 (1975)
-
Volume 26 (1975)
-
Volume 25 (1974)
-
Volume 24 (1974)
-
Volume 23 (1974)
-
Volume 22 (1974)
-
Volume 21 (1973)
-
Volume 20 (1973)
-
Volume 19 (1973)
-
Volume 18 (1973)
-
Volume 17 (1972)
-
Volume 16 (1972)
-
Volume 15 (1972)
-
Volume 14 (1972)
-
Volume 13 (1971)
-
Volume 12 (1971)
-
Volume 11 (1971)
-
Volume 10 (1971)
-
Volume 9 (1970)
-
Volume 8 (1970)
-
Volume 7 (1970)
-
Volume 6 (1970)
-
Volume 5 (1969)
-
Volume 4 (1969)
-
Volume 3 (1968)
-
Volume 2 (1968)
-
Volume 1 (1967)