Janet W. Hartley

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.

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.

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.

Seroepidemiologic studies of coronavirus infection in adults and children.

Abstract McIntosh, K. A. Z. Kapikian, H. C Turner, J. W. Hartley, R. H. Parrott and R. M. Chanock. (Lab. of Infectious Diseases, NIAID, NIH, Bethesda, Md. 20014) Sero-epidemiologic studies of coronavirus infection in adults and children. Amer. J. Epid., 1970, 97: 585–592-A seroepidemiologic study of infection by coronavirus strains 229E, OC38, OC43, and mouse hepatitis virus (MHV) strain A-59, is described. In adults with upper respiratory disease, two “outbreaks” of coronavirus infection occurred, one during the winter of 1965–1966 associated with complement fixing (CF) antibody responses to OC38, OC43 and MHV, and the other during the following winter associated with CF antibody responses to 229E. In hospitalized children, infection with 229E was rare; infection with OC38, OC43, and MHV occurred less often in hospitalized children with lower respiratory tract disease (3.5%) than in a control group with non-respiratory tract disease (8.2%). The limitations of the CF test using available coronavirus antigens are discussed.

A major genetic locus affecting resistance to infection with murine leukemia viruses. IV. Dose-response relationships in Fv-1-sensitive and resistant cell cultures.

The resistance to N- and B-tropic viruses controlled by the murine genetic locus Fv-1 was studied by dose-response analyses, using infectious center plating onto sensitive cells to determine the number of virus-producing cells. Three components contributing to the reduced plaquing efficiency on Fv-1 resistant cells were identified. First, the dose-response relations in Fv-1 resistant cells showed multiple-hit kinetics; most virus strains showed 2-hit kinetics, but the Gross Passage A virus gave 3-hit kinetics. This hitness factor is considered to represent the basic effect of Fv-1. Second, in many instances only a small fraction of Fv-1 resistant cells receiving the minimum required number of hits actually became virus producers. Third, only a fraction of the virus-producing cells registered as plaques when left in situ with resistant cells, due to the relative inefficiency of subsequent cycles of infection. Strain DBA/2 cells differed from those of other Fv-1n strains in showing only the hitness component. Fv-1nb hybrid cells showed multiple-hit dose-response curves with both N- and B-tropic viruses. Once infection has been established, virus yield from sensitive and resistant cells is similar.

Serotype composition of the adenovirus group.

Summary Seven additional adenovirus serotypes of human origin have been established, including a subtype of type 7, designated 7a. Also, 3 additional adenovirus types of simian origin are reported. It is suggested that the adenovirus group be divided into strains of human, chimpanzee, and monkey origin, with separate series of type numbers.

High-throughput retroviral tagging for identification of genes involved in initiation and progression of mouse splenic marginal zone lymphomas

Human B-cell lymphomas are frequently associated with specific genetic changes caused by chromosomal translocations that activate proto-oncogenes. For lymphomas of mice expressing murine leukemia virus, mutagenic proviral insertions are thought to play a similar role. Here we report studies designed to determine whether specific retroviral integration sites might be associated with a specific subset of mouse B-cell lymphomas and if the genes associated with these sites are regularly altered in expression. We studied splenic marginal zone lymphomas (MZL) of NFS.V+ mice that are unusual in exhibiting frequent progression from low to high grade, potentially allowing assignment of cancer genes to processes of initiation and progression. We used inverse PCR to clone and analyze 212 retroviral integration sites from 43 MZL at different stages of progression. Sixty-two marked common integration sites and included 31 that had been marked previously. Among the new common integration sites, seven were unique to MZL. Using microarrays and real-time quantitative PCR analysis, we defined differential patterns of gene expression in association with disease progression for Gfi1, Sox4, Brca2, Snf1lk, Nfkb1, Pou2af1, Prdm1, Stat6, and Blnk. Heightened expression of Gfi1 distinguishes MZL from other lymphoma types. The combined use of proviral tagging and analyses of gene expression thus provides a powerful approach to understanding of genes that collaborate in tumorigenesis.

Expression of infectious murine leukemia viruses by RAW264.7 cells, a potential complication for studies with a widely used mouse macrophage cell line

The mouse macrophage-like cell line RAW264.7, the most commonly used mouse macrophage cell line in medical research, was originally reported to be free of replication-competent murine leukemia virus (MuLV) despite its origin in a tumor induced by Abelson MuLV containing Moloney MuLV as helper virus. As currently available, however, we find that it produces significant levels of ecotropic MuLV with the biologic features of the Moloney isolate and also MuLV of the polytropic or MCF class. Newborn mice developed lymphoma following inoculation with the MuLV mixture expressed by these cells. These findings should be considered in interpretation of increasingly widespread use of these cells for propagation of other viruses, studies of biological responses to virus infection and use in RNA interference and cell signalling studies.

Accelerated Appearance of Multiple B Cell Lymphoma Types in NFS/N Mice Congenic for Ecotropic Murine Leukemia Viruses

Spontaneous lymphomas occur at high frequency in NFS.V+ mice, strains congenic for ecotropic murine leukemia virus (MuLV) proviral genes and expressing virus at high titer. In the present study, a total of 703 NFS.V+ lymphomas were studied by histopathology, immunophenotypic analysis, immunoglobulin heavy chain or T cell receptor β chain rearrangements, and somatic ecotropic MuLV integrations; 90% of the lymphomas tested were of B cell lineage. Low-grade tumors included small lymphocytic, follicular, and splenic marginal zone lymphomas, while high-grade tumors comprised diffuse large-cell (centroblastic and immunoblastic types), splenic marginal zone, and lymphoblastic lymphomas. Comparison of mice of similar genetic background except for presence (NFS.V+) or absence (NFS.V−) of functional ecotropic MuLV genomes showed that NFS.V− clonal lymphomas developed at about one-half the rate of those occurring in NFS.V+ mice, and most were low-grade B cell lymphomas with extended latent periods. In NFS.V+ mice, clonal outgrowth, defined by Ig gene rearrangements, was associated with acquisition of somatic ecotropic proviral integrations, suggesting that, although generation of B cell clones can be virus independent, ecotropic virus may act to increase the rate of generation of clones and speed their evolution to lymphoma. The mechanism remains undefined, because only rare rearrangements were detected in several cellular loci previously associated with MuLV insertional mutagenesis.

Mouse hepatitis virus infection as a highly contagious, prevalent, enteric infection of mice.

Summary Mouse hepatitis viruses were readily isolated, by a variety of technics, from pooled feces of weanling mice of the majority of colonies tested. The infection was highly contagious to contacts from a non-infected mouse stock. Evidence is presented that contact infection with hepatitis viruses produced high mortality in infant mice of the non-infected stock.