Wallace P. Rowe

Isolation of a cytopathogenic agent from human adenoids undergoing spontaneous degeneration in tissue culture.

Summary 1. From the present evidence it appears that an unidentified, possibly new, tissue culture cytopathogenic agent has been isolated repeatedly from human adenoids undergoing spontaneous degeneration in tissue culture. The filter ability and the inability to cultivate the agent on bacteriological media and to demonstrate organisms in stained tissue culture preparations would indicate that the agent belongs to the group of viruses or rickettsial It is tentatively proposed to designate the agent as the “adenoid degeneration agent”, abbreviated as “A.D. agent”. 2. That the agent is derived from the adenoid tissue rather than from the nutrient media is indicated by the fact that some adenoids and all human embryonic tissues cultivated in the identical media and at the same time have not undergone degeneration, although they are susceptible to infection with the agent; also, repeated attempts to isolate the agents from adenoid cultures not demonstrating degeneration have been uniformly unsuccessful. 3. Further investigation is in progress to determine the relation of the agent to the adenoids and to study their possible role in human disease; particularly upper respiratory infections.

Clonal cell lines from a feral mouse embryo which lack host-range restrictions for murine leukemia viruses.

Abstract Tissue culture cell lines highly sensitive to both N- and B-tropic host-range variants of mouse-tropic murine leukemia virus (MuLV) were derived by clonal selection from a feral mouse embryo cell culture line. The clonal lines are more sensitive than standard assay cultures, particularly for isolating naturally occurring N- and B-tropic MuLV from tissue extracts. Also, they can support the replication of xenotropic MuLV to a limited extent. The host-range patterns of N- and B-tropic viruses are not altered by serial passage in the sensitive cells. It is presumed that these cell lines lack the Fv -1 gene function, and it is suggested that Fv -1 may have a much broader inhibitory effect than previously recognized.

Studies of genetic transmission of murine leukemia virus by AKR mice. II. Crosses with Fv-1 b strains of mice.

AKR mice, which regularly contain infectious murine leukemia virus, were mated with four Fv-1n strains of mice which show little or no expression of virus. F1, F2, and first and second backcross generation hybrids were tested for virus in tail tissue at 2 and 6 wk of age. The segregation data indicate that the AKR mouse contains two unlinked, autosomal, chromosomal loci, either of which suffices to induce detectable levels of infectious virus in Fv-1n progeny by 6 wk of age. One of the loci (tentatively referred to as V1) is on linkage group I, 25–30 map units from the locus for albino; the gene order tentatively appears to be N1-c-Hbb.

Nonproducer clones of murine sarcoma virus transformed BALB3T3 cells

Abstract A continuous line of BALB c embryo cells can be transformed by murine sarcoma virus (MSV). Of twenty foci selected at limiting MSV dilution, eighteen release both MSV and murine leukemia virus (MuLV). Two focus-derived lines, however, show no physical or biological evidence of virus production and contain no evidence of antigens of the murine sarcoma-leukemia complex. These lines have altered properties in tissue culture and in vivo and are morphologically indistinguishable from virus releasing MSV-transformed mouse lines. The addition of “helper” MuLV results in the rescue of the MSV genome with host range and neutralization characteristics of the MuLV used to rescue it. These findings show that virus production and release is not necessary for the maintenance of the transformed state in mouse cells and suggest that MSV is capable of initiating transformation without MuLV. In the nonproducer lines the sarcoma genome can be passed from cell to daughter cell for over 100 cell generations in the absence of any detectable virus expression. A preliminary report of some of these findings has been presented ( Aaronson, 1970a ).

Noninfectious ARK mouse embryo cell lines in which each cell has the capacity to be activated to produce infectious murine leukemia virus

Abstract When cells of AKR mouse embryos were grown in tissue culture, only one cell in 250,000 to one in 12,000,000 produced murine leukemia virus within the first few days in culture. By 2.5 weeks in culture, 12–100 times this many cells had spontaneously begun to produce virus. By planting cultures with small numbers of AKR embryo cells, it was possible to obtain two cell lines which contained no detectable virus-producing cells for more than 60 serial transfers, despite exhaustive tests for virus and virus products. However, these lines and all 10 clonally derived sublines have the capacity to produce virus, either spontaneously or after certain experimental manipulations, including X-ray or ultraviolet irradiation, and transformation by SV40 virus. Activation of virus appears to be a very low-frequency event. These findings indicate that the majority, and probably all, of the cells in the AKR cell lines carry the full viral genome in an unexpressed form, and by extrapolation suggest that this is true of all AKR cells.

Rapid viral induction of plasmacytomas in pristane-primed balb-c mice.

Strain BALB/c mice were injected intraperitoneally with 0.5 milliliter of pristane, and 39 to 56 days later they were infected with Abelson murine leukemia virus, which is a lymphosarcomagenic variant of Moloney virus. Fifty-eight percent of the mice developed lymphosarcoma, and 28 percent developed immunoglobulin-producing plasmacytomas within 20 to 93 days (77 to 149 days after the pristane injection). Two of 57 control mice developed plasmacytomas at days 138 and 166 after a single injection of pristane; no plasmacytomas were found in mice treated with virus alone.

Effect of interferon on exogenous, endogenous, and chronic murine leukemia virus infection.

Abstract The effect of purified mouse interferon on the replication of AKR mouse leukemia virus (MLV) in a clonal line of AKR cells was studied, with emphasis on comparing the effect of interferon on the replication of exogenous virus, activation of endogenous virus by IdUrd, and production of virus by chronically infected cells. It was found that interferon inhibited replication of virus in all three systems. Interferon did not abort exogenous infection or virus induction by IdUrd, but only delayed appearance of infectious virus. Virus production by chronically infected cells also was suppressed in the presence of interferon; however, after removal of interferon, rapid recovery of virus production occurred. Under conditions where interferon treatment inhibited virus yield as measured both by infectious virus and virion-associated reverse transcriptase activity, no significant inhibition of synthesis of virus specific (gs) antigen was observed (as measured by immunofluorescence and radioimmunoassay for p30 protein). These results indicate that unlike its effect on the majority of viruses, interferon does not inhibit MLV by a general inhibition of viral protein synthesis; rather, it appears to inhibit one or more of the later steps in MLV replication which occur after the expression of viral gs antigen. The interferon block of acute exogenous or IdUrd-induced endogenous infection appeared to occur prior to virus assembly, resulting in a marked decrease in the number of free and cell-associated particles. In the chronic infection, however, the interferon treatment only partially prevented assembly and release of virus particles, but these had markedly reduced infectivity.

Genetic mapping of a murine leukemia virus-inducing locus of akr mice.

The chromosomal location of one of the two murine leukemia virus-inducing loci of AKR mice has been determined. The locus, which appears to be the integrated genome of the virus, is designated Akv-1, and is on linkage group 1, 12 map units from Gpi-1, with gene order c-Gpi-1-Akv-1. This identification of a closely linked gene whose phenotype is independent of virus expression should facilitate analysis of the biologic importance of the Akv-1 locus.

Protective effect of pre-irradiation on lymphocytic choriomeningitis infection in mice.

Summary 1. 300 r total body x-irradiation given to adult mice one to 4 days prior to intracerebral or intraperitoneal infection with LCM virus, produced a marked increase in survival and diminution in objective evidence of the infection. 2. The growth curve of the virus after intracerebral inoculation was identical in the irradiated and non-irradiated groups. After intraperitoneal infection with a viscerotropic strain there appeared to be a slightly lower virus titer in the pooled organs of the irradiated as compared with the non-irradiated mice.

Qualitative and quantitative studies of AKR-type murine leukemia virus sequences in mouse DNA.

Utilizing a single-stranded [3H]DNA probe highly representative of AKR viral 70S RNA, we have performed association kinetics experiments with cellular DNA in vast excess from 3 high-, 5 low- and 4 non-virus-yielding mouse strains. Our hybridization studies indicate that in the strains so far tested, the complete genome of the AKR-type MLV is present in the DNA of the embryos of both high- and low-virus-yielding mouse strains, while DNA of non-virus strains contains only a part of the genome. Furthermore, at least two populations of virus-specific DNA sequences can be identified (more abundant and less abundant species) according to their rate of association. Low-virus-yielding mouse strains contain a smaller number (1-2 copies) of the less abundant species, and thus a lower number of complete viral genome than do high-virus strains (3-4 copies). Non-virus-yielding strains are lacking these less abundant sequences in their genome. DNA from wild Mus musculus also contained viral sequences, the sample tested showing association kinetics identical to the non-virus-producing strains. Thus there is a good correlation between completeness of the AKR-type MLV genome in cellular DNA and the capacity of the cells to release AKR-type MLV. Mice of a non-virus-yielding strain made partially congenic for the AKR virus-inducing locus Akv-1 contained the complete virus genome, confirming that this locus consists of structural genes of the virus.