We investigated the role of the Moloney helper virus, Moloney murine leukemia virus (Mo-MuLV), in cell transformation and tumor induction by the defective Abelson murine leukemia virus (Ab-MuLV). A molecular clone of Ab-MuLV (P160 strain) was transfected into the tA2 packaging cell line, and helper virus-free Ab-MuLV(qk2) was harvested from the supernatant medium. Ab-MuLV(f2) was as efficient as helper virus-containing Ab-MuLV(Mo-MuLV) in the transformation of primary bone marrow cells in vitro.Inoculation of weanling BALB/c mice with induced nonthymic pre-B-cell lymphomas with high efficiency and short latency (28 days). Adult BALB/c mice were less sensitive to tumor induction by a factor of 100. Ab-MuLV(q2) did not induce tumors in weanling C57BL/6 mice, unlike (24). C57BL/6 nu/nu mice were obtained from Norman Drinkwater (University of Wisconsin) and maintained by brother-sister mating. Mice were anesthetized and inoculated through the retroorbital sinus vein with 0.1-0.5 ml of tissue culture supernatant. Mice were observed three times a week for lymphadenopathy, paraplegia, or cathexia for a period of 3 months after infection.Viruses and Cells. The Ab-MuLV (P160 strain) proviral clone pAB4 was recovered in X CH4A from an Ab-MuLVinduced tumor cell line, E102 (25), DNA library and characterized in our laboratory. Ab-MuLV(Mo-MuLV) was recovered from harvests of supernatant fluids of NIH 3T3 cells cotransfected with 1 Ag of pAB4 and 2 pug of Mo-MuLV-Mov3 (26) proviral clones. Ab-MuLV(qi2) was harvested from supernatants of morphologically transformed cell clones of t2 cells (1)
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ABL-MYC, a recombinant murine retrovirus that expresses v-abl and c-myc, rapidly induces transplantable mono-or oligoclonal plasmacytomas in BALB/c mice. To determine if the targets for trnsformation of this retrovirus are antigen-committed B lymphocytes and to explore this system as an alternative technique for producing antigenspecific monoclonal antibodies, plasmacytomas were induced in mice that had beep immunized with two different types of immunogens, hen egg white Iysozyme and sheep red blood cells.The maority of these plasmacytomas secreted immunogenspecific antibodies. Plasmacytomas induced in unimmunized mice did not react with hen egg white lysozyme or sheep red blood cells. The specific antibodies were comparable in concentration, specificity, and affinity to monoclonal antibodies obtained with conventional hybridoma technology, but, in addition to IgGs and IgMs, they included specific IgA antibodies, which are rare among splenic-derived hybridomas. Our results demonstrate that a principal target for ABL-MYC is an antigen-committed B Iymphocyte. In addition this procedurem provides an alternative method for the production of monoclonal antibodies, without a requirement for heterocaryon formation by cell fusion techniques.Plasmacytomas typically arise with a mean lhtency of 240 days in up to 60%o of mice from susceptible strains (e.g.,
Molecular analysis has shown that the majority of Abelson murine leukemia virus (Ab-MuLV)-induced primary thymomas represent transformed y/8 thymocytes.
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