The presence of ecotropic murine leukemia virus (MuLV) in mice designated SJL/J-(v+) (SJL/J mice with a high level of MuLV) was studied. Isoenzyme analysis of several genetic markers done to exclude any cross contamination showed concordance with SJL/J markers. Most adult mice expressed high titer N-tropic virus In the tall; spleen, thymus gland, and kidney were seldom positive, and liver was negative. The time course of appearance of Infectious ecotropic MuLV in tails of individuals 10-40 days old indicated that mice might be grouped into two classes according to the earlier or later activation of virus. This pattern had a dear-cut litter distribution. Lymphomatous tissue usually contained a lower virus content than did normal tissue from mice of the same age, as indicated by a 10-fold decrease In the number of both infectious centers and XC plaque-forming units per tumor tissue homogenate. Normal thymus glands of tumor-bearing mice exhibited an analogous decrease in virus titers, whereas thymus glands from old mice expressed high MuLV levels. The high virus phenotype was dominantly expressed in F1 hybrids of several strains. Infectious virus was detectable in spleens of 50% of the segregant first backcross (Bc1) populatipn (DBA/2 × SJL) × DBA/2, Indicating that one dominant gene was responsible for the expression of high levels of virus. The progeny of 11 MuLV-positive Bc1 males or females mated to DBA/2 was also distributed into two classes, with a 1:1 ratio between virus-positive (51) and virus-negative (53) mice. The number of infectious centers in F1, Bc1, and second backcross populations suggested that no additional major genetic Influences regulate virus expression. Recovery of virus from tail tissue of many F1 and Bc1 hybrids, however, was lower in titer as was the percentage of positive mice. No close correlation between high virus phenotype and three coat color markers (d, a, b) was found. © 1979 Oxford University Press. All rights reserved.
Age dependence and genetics of expression of ecotropic murine leukemia virus in SJL/J mice.
DE ROSSI, ANITA;
1979
Abstract
The presence of ecotropic murine leukemia virus (MuLV) in mice designated SJL/J-(v+) (SJL/J mice with a high level of MuLV) was studied. Isoenzyme analysis of several genetic markers done to exclude any cross contamination showed concordance with SJL/J markers. Most adult mice expressed high titer N-tropic virus In the tall; spleen, thymus gland, and kidney were seldom positive, and liver was negative. The time course of appearance of Infectious ecotropic MuLV in tails of individuals 10-40 days old indicated that mice might be grouped into two classes according to the earlier or later activation of virus. This pattern had a dear-cut litter distribution. Lymphomatous tissue usually contained a lower virus content than did normal tissue from mice of the same age, as indicated by a 10-fold decrease In the number of both infectious centers and XC plaque-forming units per tumor tissue homogenate. Normal thymus glands of tumor-bearing mice exhibited an analogous decrease in virus titers, whereas thymus glands from old mice expressed high MuLV levels. The high virus phenotype was dominantly expressed in F1 hybrids of several strains. Infectious virus was detectable in spleens of 50% of the segregant first backcross (Bc1) populatipn (DBA/2 × SJL) × DBA/2, Indicating that one dominant gene was responsible for the expression of high levels of virus. The progeny of 11 MuLV-positive Bc1 males or females mated to DBA/2 was also distributed into two classes, with a 1:1 ratio between virus-positive (51) and virus-negative (53) mice. The number of infectious centers in F1, Bc1, and second backcross populations suggested that no additional major genetic Influences regulate virus expression. Recovery of virus from tail tissue of many F1 and Bc1 hybrids, however, was lower in titer as was the percentage of positive mice. No close correlation between high virus phenotype and three coat color markers (d, a, b) was found. © 1979 Oxford University Press. All rights reserved.
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