RNA from noninfectious virions produced by two established clonal -lines of sarcoma positive-leukemia negative (S+L-)-transformed 3T3 cells has been characterized. RNA from virions or nucleoids of S+L--(C243) cells consisted of three to four sizes: +44 S (6%), 28 S (17%), 18 S (38%), and <18 S (39%). 28S Genomes of RNA tumor viruses have been studied extensively. Nondissociated genomes (-60-70 S), which can be dissociated to smaller RNAs (c30-40 S), have been isolated from sarcoma-leukemia complexes as well as leukemia viruses of murine (1), avian (2, 3), feline (4), and other RNA tumor viruses (5). Genomes (-60-70 S) of transforming and nontransforming variants of Rous sarcoma virus (RSV) dissociate primarily into "a" and "b" subunits, respectively (6).The wild-type isolate of murine Moloney sarcoma virus (MSV) and avian RSV generally consisted of complexes containing sarcoma virus with an excess of leukemia virus (7,8), with the noticeable exceptions of the following avian RNA tumor viruses: B-RSVa(O), B-RSV3(O), SR-RSV, PR-RSV, and B-77 (6, 9).With the isolation and characterization of the sarcoma positive-leukemia negative (S+L-)-transformed 3T3 particleand antigen-producing cells (10, 11), as well as the sarcoma positive-helper negative (S+H -)-transformed hamster "producer" cells (12, 13), it became possible to characterize the genome from S-+fL-murine virions, as has been done for avian RNA tumor viruses (9). This research was initiated to characterize the RNA of S+L-virions.

Specific antibodies to the RNA-dependent DNA polymerase (reverse transcriptase) of murine type C viruses have been isolated from the renal glomeruli of both leukemic and nonleukemic AKR mice where they presumably had been deposited as immune complexes. The antibodies were shown to have sedimentation coefficients of 26 S to 28 S and 5 S to 7 S on sucrose rate zonal centrifugation. Inactivation with monospecific antisera to various mouse immunoglobulins identified antibodies as being in both immunoglobulin (IGM) and IgG classes. In addition, these antibodies only reacted with the reverse transcriptase from murine and feline type C viruses, but not the polymerase from avian myeloblastosis virus (AMV). Our results provide additional evidence for the lack of immunological tolerance and demonstrate the presence of another immune complex system in AKR kidneys.

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