Article

Complement fixation and tissue culture assays for mouse leukemia virus

Authors:
To read the full-text of this research, you can request a copy directly from the authors.

No full-text available

Request Full-text Paper PDF

To read the full-text of this research,
you can request a copy directly from the authors.

... We have utilized this virion-associated RDP activity in determining viremia in feral mouse populations by assaying this enzyme activity in particulate fractions of mouse sera. The results were compared with other existing methods such as complement fixation tests (10) of spleen extracts and competitive radioimmunoassays (3) of sera for the 30,000-molecular-weight (p30) internal antigen of the virus and assays for infectious virus in sera by induction of complement fixation p30 antigen in cell cultures (COMUL test) (10). It was shown earlier that about 85% of normal adult mice of a natural colony (LC) of wild mice (Mus musculus) have high titers of infectious type C viruses in their viscera and sera (5,6), whereas the remaining 15% of adult LC mice have little or no detectable infectious virus. ...
... We have utilized this virion-associated RDP activity in determining viremia in feral mouse populations by assaying this enzyme activity in particulate fractions of mouse sera. The results were compared with other existing methods such as complement fixation tests (10) of spleen extracts and competitive radioimmunoassays (3) of sera for the 30,000-molecular-weight (p30) internal antigen of the virus and assays for infectious virus in sera by induction of complement fixation p30 antigen in cell cultures (COMUL test) (10). It was shown earlier that about 85% of normal adult mice of a natural colony (LC) of wild mice (Mus musculus) have high titers of infectious type C viruses in their viscera and sera (5,6), whereas the remaining 15% of adult LC mice have little or no detectable infectious virus. ...
... Portions ( 10 p,Ci (18 Ci/mmol); and 2 ,ug of (dT),......poly(rA). The reactions were incubated at 37°C for 1 h in small test tubes covered with Parafilm and then cooled in ice bath. ...
Article
Full-text available
Assay of particulate reverse transcriptase activity in the sera from feral mice naturally infected with type C virus provides a sensitive and rapid procedure for the determination of in vivo virus infection. The results compare well with assays for infectious virus and with complement fixation or competitive radio-immunoassays for the p30 internal antigen of the virus.
... We have utilized this virion-associated RDP activity in determining viremia in feral mouse populations by assaying this enzyme activity in particulate fractions of mouse sera. The results were compared with other existing methods such as complement fixation tests (10) of spleen extracts and competitive radioimmunoassays (3) of sera for the 30,000-molecular-weight (p30) internal antigen of the virus and assays for infectious virus in sera by induction of complement fixation p30 antigen in cell cultures (COMUL test) (10). It was shown earlier that about 85% of normal adult mice of a natural colony (LC) of wild mice (Mus musculus) have high titers of infectious type C viruses in their viscera and sera (5,6), whereas the remaining 15% of adult LC mice have little or no detectable infectious virus. ...
... We have utilized this virion-associated RDP activity in determining viremia in feral mouse populations by assaying this enzyme activity in particulate fractions of mouse sera. The results were compared with other existing methods such as complement fixation tests (10) of spleen extracts and competitive radioimmunoassays (3) of sera for the 30,000-molecular-weight (p30) internal antigen of the virus and assays for infectious virus in sera by induction of complement fixation p30 antigen in cell cultures (COMUL test) (10). It was shown earlier that about 85% of normal adult mice of a natural colony (LC) of wild mice (Mus musculus) have high titers of infectious type C viruses in their viscera and sera (5,6), whereas the remaining 15% of adult LC mice have little or no detectable infectious virus. ...
... Portions ( 10 p,Ci (18 Ci/mmol); and 2 ,ug of (dT),......poly(rA). The reactions were incubated at 37°C for 1 h in small test tubes covered with Parafilm and then cooled in ice bath. ...
... To investigate further the relationship between G1x and GCSA expression and infection of cells by naturally occurring MULV, we examined a number of ecotropic and xenotropic MuLV isolates for their ability to induce these antigens in vitro. Induction of Glx expression was found to be a type-specific property of some but not all ecotropic MuLVXs which had previously been classified as Gross-AKR type on the basis of virus neutralization tests (17,18,22). The measurement of GCSA expression indicated that a system of multiple antigenic determinants was probably involved with characteristics of both type and group specificity. ...
... These cells were recloned prior to use in these experiments. ME cells were prepared from embryos in day 14 to 16 ofgestation (17) and stored prior to use at -196°C. Pregnant NIH/Swiss and BALB/c mice were kindly provided by W. P. Rowe. ...
... The phenotype of partial GCSA absorption (GCSA+) is discussed below. Three G1xIGCSA phenotypes (Glx++/GCSA++ Glx-I GCSA++, and GQx++/GCSA+) were observed with viruses that had previously been grouped as Gross-AKR type on the basis of virus neutralization data (17,18,22), allowing further subdivision of this class of MuLV's. Within the ecotropic class of MuLV's, only the FMR subgroup had the G,X-/GCSA+ phenotype; such a result for GCSA is consistent with the previously reported partial absorption of GCSA antiserum by FMR leukemia cells (33). ...
... Factors considered in adapting the XC assay to microplates were (i) the seeding densities of MEF and XC cells and (ii) the intensity of UV exposure of virus-infected MEF cells. Infection of semiconfluent monolayers of MEF cells with Mulv has been shown to result in higher titers than Mulv titrated on confluent monolayers of MEF cells (1,3). In additon, Rowe et al. showed that the density of XC cells and the dose of UV used to treat Mulv-infected cultures were critical factors in achieving the highest titer for Mulv by the XC cell plaque assay (5). ...
... Table 1 shows that titers of Moloney leukemia virus (MLV) obtained in microplates did not appear to differ when the cell densities employed varied from 1.6 x 102 to 6.3 x 102 MEF cells per microwell and from 4.5 x 103 to 9.0 X 104 XC cells per microwell. However, 3.15 x 104 MEF cells per well yielded lower titers of MLV. ...
Article
The XC cell assay employed in in vitro titration of murine leukemia viruses was modified for use as a semi-micro procedure.
... Serological analyses have been an important tool for the identification and classification of murine leukemia viruses (MuLVs). In early studies, the reactivity of different antisera with MuLVs led to the detection of antigens restricted to particular types of MuLVs (e.g., exogenous ecotropic MuLVs) or of antigens which were shared among larger groups of MuLVs (e.g., exogenous ecotropic MuLVs and endogenous ecotropic and xenotropic MuLVs) (15,18,20,23,24,49,53). Antisera which were reactive with particular types of MuLVs frequently neutralized virus infectivity and were found to be directed predominantly toward antigens of the viral envelope proteins (18,23,36,38,52,56), while antisera with broad specificity reacted predominantly with viral core proteins (15,18,20,40,49). ...
... In early studies, the reactivity of different antisera with MuLVs led to the detection of antigens restricted to particular types of MuLVs (e.g., exogenous ecotropic MuLVs) or of antigens which were shared among larger groups of MuLVs (e.g., exogenous ecotropic MuLVs and endogenous ecotropic and xenotropic MuLVs) (15,18,20,23,24,49,53). Antisera which were reactive with particular types of MuLVs frequently neutralized virus infectivity and were found to be directed predominantly toward antigens of the viral envelope proteins (18,23,36,38,52,56), while antisera with broad specificity reacted predominantly with viral core proteins (15,18,20,40,49). With the advent of monoclonal antibody (MAb) technology, a much more precise antigenic characterization of MuLVs became possible such that different virus types, and even very closely related isolates of the same virus type, could be distinguished (5,6,30,32,37). ...
Article
Full-text available
Anepitope common toallclasses ofmurine leukemia viruses (MuLVs) was detected byreactivity ofMuLVs with aratmonoclonal antibody (MAb)termed 83A25. Theantibody isoftheimmunoglobulin G2aisotype and was derived after fusion ofNS-1myeloma cells withspleen cells fromaFischer ratimmunized witha Friend polytropic MuLV.Theantibody reacted withnearly allmembersoftheecotropic, polytropic, xenotropic, and amphotropic classes ofMuLVs.Unreactive viruses were limited totheFriendecotropic MuLV,Rauscher MuLV,andcertain recombinant derivatives ofFriend ecotropic MuLV.Thepresenceofan epitope common tonearly allMuLVsfacilitated adirect quantitative focal immunofluorescence assayforMuLVs,including the amphotropic MuLVsforwhichno direct assayhadbeenpreviously available. Previously described MAbs whichreactwithallclasses ofMuLVs havebeenlimited tothosewhichreactwithvirion core or transmembrane proteins. Incontrast, protein immunoblot andimmunoprecipitation analyses established that theepitope reactive withMAb 83A25resides intheenvelope glycoproteins oftheviruses. Structural comparisons ofreactive andnonreactive Friend polytropic viruses localized theepitope near thecarboxyl terminus oftheglycoprotein. Theepitope served asatarget forneutralization ofallclasses ofMuLV withMAb 83A25. Theefficiency ofneutralization varied withdifferent MuLV isolates butdidnotcorrelate withMuLV interference groups.
... At various time periods (up to 63 days), depending on the virus tested, each group and five uninoculated control mice were sacrificed, and 10% (wt/vol) spleen extracts were tested for MLV-gs antigen in complement fixation versus 4 U of antisera reactive against the MLV-gs antigen (6). (1). Complement fixation at antigen dilutions of 1:2 or greater was scored positive; the mean infectious dose per 0.1 ml was calculated for the SPAT assay, and the mean tissue culture infectious dose per 0.1 ml was calculated for the CoMuL assay. ...
Article
A test is reported for the in vivo detection of the replicative ability of murine leukemia viruses (MLV) in the BALB/c mouse strain. Growth in the spleen was assayed by the complement-fixation assay for MLV group-specific antigen after injection of newborn mice. Low doses of laboratory-derived and wild-type MLV from cell-culture and animal-grown sources were detected as early as 7 to 14 days postinoculation. The sensitivity of this in vivo test compared favorably with in vitro assays for MLV. In vivo detection of MLV replication was correlated with long-term oncogenicity.
... MuLV CF Antigen.--The complement-fixation (CF) method for the detection of CF antigens with murine leukemia virus (MuLV) group and type speeificities is described elsewhere (17,18). The rat antisera used in the CF test were transplanted lymphomas or sarcomas induced respectively by murine leukemia viruses or the Moloney strain of murine sarcoma virus (19), and were selected for antibody specificity with respect to MuLV antigens and for absence of nonspecific reactions with extracts of normal tissues of various mouse strains. ...
Article
The pathogenesis of the spontaneous glomerulonephritis of NZB and (NZB x NZW) F1 hybrid mice is related at least in part to the formation of natural antibody against antigens of the G (Gross) system, and apparently to the deposition in the glomeruli of immune complexes of G natural antibody with G soluble antigen (GSA), type-specific antigen specified by wild-type Gross leukemia virus. G natural antibody and GSA are detectable in the acid-buffer eluate of the kidneys of NZB mice during the course of the glomerulonephritis. (NZB x NZW) F1 hybrid mice develop glomerulonephritis and produce GSA and free G natural antibody earlier in life than do NZB mice. The proteinuria manifestation of the gomerulonephritis of (NZB x NZW) F1 hybrid mice becomes increasingly prevalent as GSA undergoes immune elimination from the circulation. Gross leukemia virus-specified antigens together with bound immunoglobulins are located in the glomerular lesions of (NZB x NZW) F1 hybrid mice, both in the mesangium as observed in NZB mice and also in the wall of the peripheral capillary loops of the glomeruli.
... Complement Fixation.--The tests were conducted in the laboratory of Dr. R. J. Huebnet (National Cancer Institute) according to a technique previously described (19). ...
Article
Gross virus-induced lymphoma cells express strong virus-associated (Gross murine leukemia virus [G-MuLV]) antigens and are consistently rejected when grafted in normal adult syngeneic rats. By contrast, similar grafts are tolerated and allowed to grow progressively by rats that have been injected at birth with deaggregated G-MuLV antigens. However, the tolerance induced by this procedure is only partial as the grafted lymphoma cells lose their G-MuLV membrane antigens. These cells showing an antigenic disjunction, with negative membrane and positive cytoplasmic G-MuLV antigenic expression, become transplantable in normal-nonconditioned adult recipients. By further grafting, the expression of cytoplasmic G-MuLV antigens is similarly lost while the lymphoma cells substantially increase their transplantability, rate of growth, and capacity for metastasis.
Article
Gel filtration, with Sephadex G-200, was utilized to obtain Friend virus (FV) from infected spleen homogenate. Highly infectious and immunologically active material was eluted as a large initial protein peak, whereas hemoglobin and other noninfectious materials were found in two subsequent peaks. Fractions that made up the first peak were reactive in serological tests with antiserum towards FV. Formalinized fractions from the first peak, when combined with Freund's complete adjuvant, were able to protect mice against subsequent FV challenge. Further purification of antigen was carried out by sucrose gradient ultracentrifugation.
Article
This report describes morphological transformations observed approximately 6 weeks after treatment of Rauscher leukemia virus (RLV) infected rat embryo (RE) cells with various levels of 7,12-Dimethylbenz(a)-anthracene (DMBA) for 7 days. Uninfected cells treated with DMBA and RLV-infected RE cells untreated with DMBA failed to show any evidence of transformation. When stained with Giemsa, the foci of transformed cells consisted of randomly oriented criss-crossing spindle-shaped cells, having much more rapid replication rates than the untreated and untransformed RE cells. The transformed cells were more resistant to the toxicity of DMBA than were the untransformed RE cells. Local subcutaneous sarcomas were produced when the transformed cells were transplanted into newborn rats, whereas the infected or DMBA-treated untransformed cells produced no tumors. Cells derived from the tumors, when re-established in tissue culture, like the tumor tissue itself contained group-specific (GS) complement-fixing antigens characteristic of the murine leukemia-sarcoma virus complex and the C-type RNA particles. These results, which showed that both chemical and virus were required for transformation, suggest that the C-type RNA viral genome of RLV provided specific oncogene information for the malignant transformation.
Article
Lymphoblastoid cell lines were derived from patients with active systemic lupus erythematosus by allowing spontaneous transformation of peripheral B lymphocytes (B cells) harboring endogenous Epstein-Barr virus or by superinfecting peripheral lymphocytes with exogeneous Epstein-Barr virus. Results of extensive studies aimed at identifying type C oncornaviruses in these lymphoblastoid cells were entirely negative by electron microscopy, DNA-DNA hybridization, reverse transcriptase assays, and cocultivation experiments. These results do not support the postulated association of oncornavirus infection in human systemic erythematosus.
Article
The prevalence of C-type RNA tumor-virus gs antigen and infectious virion expression was determined at various ages throughout the life span of the BALB/cCr mouse. The incidence of gs antigen was low (2.5%) prior to 6 months of age, but increased progressively to 71% in mice over 24 months of age. The incidence of infectious virus isolated in mouse embryo cell culture was low (10%) prior to 6 months of age, but rose rapidly after 6 months of age and remained relatively stable (varying from 46% to 62%) throughout the remainder of life. Eighteen of nineteen isolations made prior to 1 year of age were made on NIH Swiss mouse embryo cells as opposed to BALB/c mouse embryo cells (1/19). In older mice, isolations on BALB/c cells increased, but only after 24 months of age were isolation rates higher than on NIH Swiss cells. Isolations from the spleens of mice with malignancies were somewhat more frequent than from spleens of mice which were normal or had histologically benign tumors.
Article
Non-producer (NP) human cells induced by the Kirsten sarcoma virus were characterized. These morphologically altered NP cells produced neither infectious virus nor complement-fixing antigens of the murine sarcoma—leukemia virus complex. The NP cells did not release RNA-dependent DNA polymerase and type-C virus particles with a density of approximately 1.15 g/ml in sucrose gradients by 3H-uridine labelling. The NP cells produced tumors when transplanted subcutaneously into athymic nude mice. The tumor cells re-established in culture resembled the original NP cells, were confirmed as human cells by karyological analysis and were also found to be “nonproducer”. The sarcoma virus genome in NP cells could be rescued not only by co-cultivation with “helper virus”-releasing cells but also by superinfection with helper type-C viruses. Murine (Rauscher, Ki-MuLV, AT-124 and two other xenotropic viruses), feline, RD-114 and Simian (woolly monkey and baboon) type-C viruses possessed the ability to rescue the sarcoma genome from NP cells but not AKR leukemia virus. In addition, the feline leukemia virus titer obtained by the rescuing technique in NP cells was the same as those obtained in feline embryo and NP cells by CF induction assay.
Article
Guinea-pig embryo cells were transformed in vitro by the Kirsten strain of mouse sarcoma virus (Ki-MSV). The transformed cells were found to release infectious virus continuously and produced high titers of group-specific, complement-fixing antigen characteristic of the murine leukemia—sarcoma virus complex. Foci of transformed cells were similar in appearance to those obtained with Ki-MSV in mouse and rat cells. The transformed cells produced RNA-dependent DNA polymerase and type-C virus particles with a density of approximately 1.15 g/ml in sucrose gradients by 3H-uridine labelling. The transformed cells from one line produced tumors when transplanted into newborn guinea-pigs. A number of focus-derived clonal lines and “normal cells” derived from infected cells were isolated and characterized. All the focus-derived lines were found to be MSV producers. The Ki-MSV grown in guinea-pig cells replicated efficiently in guineapig and NRK cells but very poorly in mouse cells. A non-cytopathic type-C virus-producing line (clone No. 2) was isolated. A non-focus-forming virus grown in guinea-pig embryo cells (clone No. 2) rescued infectious MSV by direct cocultivation with Ki-MSK non-producer NRK cells. The rescued MSV virus was neutralized by Ki-MSV antiserum and produced foci readily in mouse, rat and guinea-pig cells.
Article
Changes in titers of antibodies to protein and glycoprotein antigens of bovine leukemia virus (BLV) were investigated by immunodiffusion in two groups of cattle. In one group of cattle (10 head) which developed enzootic bovine leukosis during the observation period of 3 years, seven showed a gradual increase in antibody titers following a period of level antibody titers that persisted for several months to several years. The titer was finally eight to 32 times higher than the initial titer. The remaining three showed little change in titer. Of the 10 animals with tumors, three showed a decrease in the titer when they were in extremis. In contrast, in the second group of cattle (110 head), which were infected with BLV subclinically, the change in the titers during 1 and 3 years ranged from no change to four times the lowest titer that was observed during the period. Of the cattle which had a low level of antibody to one of the BLV antigens, a few became negative reactors to the respective antigen.
Article
Mice were immunized with tissue-cultured or formalin-inactivated murine leukemia virus preparations and challenged with active virus or with the virus-induced leukemic cells from established tissue culture lines. Although the virus obtained from the tissue-culture system had a low leukemogenic potential, its immunizing capacity was equal to that of the inactivated leukemic spleen filtrate virus. All preparations afforded protection against challenge with virus as well as with cells. Transplantation immunity was further demonstrated by the marked inhibition of spleen colony formation by the leukemic cells in preimmunized lethally irradiated mice. IMMUNITÉ DE TRANSPLANTATION ET SUPPRESSION DE LA FORMATION DE COLONIES DANS LA RATE PAR IMMUNISATION AU MOYEN DE PREPARATIONS DE VIRUS DE LA LEUCEMIE DE LA SOURIS (FRIEND) Des souris ont été immuniskes au moyen de prkparations de virus de la leucey'mie murine cultivt sur tissu ou inactivk par le formol et PprouvPes ensuite soit avec le virus actif soit avec des cellules leuctmiques d'origine virale provenant de IignPes e'tablies en culture de tissu. Bien que Ie virus obtenu a partir de la culture tissulaire n'ait eu qu'un faible pouvoir leuckmogkne, sa capacitP imniunisante Ptait Pgale a celle du virus inactivt' obtenu par Jiltrat de rate IeucPmique. Toutes les prkparations ont confPrC une protection contre I'Ppreuve ejectuke aussi bien avec le virus qu'avec Ies cellules. L'immunite de transplantation a PtP Pgalement mise en tvidence par ('inhibition marquPe de la formation de colonies dans la rate par Ies cellules leucdmiques chez des souris prtimmunistes ic une irradiation Ittale.
Article
Twenty four per cent of our specific pathogen free BALB/c female control mice and 9% of control males developed lymphoid moplasias Three fourth of the neoplasms were reticulosarcomas type B (Hodgkin's like lesions)Without change in the proportion of reticulosarcomas the tumor incidence was tripled by infecting newborn BALB/c mice with 0.05 ml 5 times concentrated subcellular extracts of reticulosarcomas, doubled by injecting 105 XC units of either of two leukemia type viruses recently isolated from BAIB/c mice, and tripled by grafting 104 cells from leukemia virus infected syngeneic secondary embryonic fibroblast cultures. Intrathymic inoculation gave the same result as subcutaneous administration 4 four log reduction tn virus given dose s.c. only lowered the tumor incidence slightly.The mean latent period was 13 months following inoculation of cell free virus preparations and 8 month after injection of infected tissue culture fibroblasts. Adult mice receiving onus did not show enhanced tumor incidence.
Article
The S+L− cell lines derived from Swiss mouse 3T3FL cells transformed by Moloney murine sarcoma virus (M-MSV) in the absence of mouse-tropic murine leukemia virus (MuLV) produce type-C viral particles which are not infectious for a variety of mammalian cells. A rescuable MSV genome is present in such cell lines. We report here that preparation of particles spontaneously released from S+L− cells contain MSV which, upon coinfection with MuLV, is capable of transforming SC-1 cells, a cloned line derived from wild-mouse embryo. This transforming virus is tentatively designated as murine sarcoma virus-zero (MSV-Z). No productive infection can be detected following infection with MSV-Z alone but, in the presence of MuLV, infection of SC-1 cells with MSV-Z results in replication of MSV(MuLV) and MuLV. Exposure of S+L− cells to 5-iododeoxyuridine increases the titer of transforming virus up to 400-fold, but we have detected no comparable increase in reverse transcriptase activity or number of physical particles. No replicating MuLV or xenotropic murine oncornavirus was detected after chemical induction. The peak of transforming activity of MSV-Z is found at a buoyant density 1.15 g/cm3 in sucrose gradients. MSV-Z cannot be induced from S+L− reverant cell lines. Sensitivity to MSV-Z transformation appears to be limited to the SC-1 cell line although some activity was detected upon infection of NRK cells. Based on glycoprotein interference and neutralization tests, the viral envelope of MSV-Z is distinct from the previously described murine C-type oncornaviruses.
Article
A study was made on the effect of human interferon (HuIFN) on the synthesis and release of type D viruses (MPMV and SMRV) by chronically infected human lines. Interferon at concentrations of 50 IU/ml lead to an inhibition of the extracellular virus production by about 50%-80% as measured by virus-associated reverse transcriptase activity, by metabolic labeling of the virus with (3H) uridine or (3H) amino acids, or by electron microscopy counting of particles. The profiles of intracellular viral proteins, as visualized by radioimmunoprecipitation and electrophoresis, were not different in control or IFN-treated cells and the yield of intracellular protein p27 stayed unchanged or was slightly increased. Electron microscopy of thin sections taken from the control and IFN-treated cells revealed no difference in any subcellular structures including that of the viruses. However, electron microscopic examination of IFN-treated cells showed an increased number of either budding particles and intracytoplasmic precursors (two- to five-fold) or mature virus particles (four- to ten-fold) on the cell surface of the IFN-treated cells. These results indicate that IFN inhibits further developments of MPMV and SMRV replication as was described for type C and B retroviruses.
Article
The XC cell assay employed in in vitro titration of murine leukemia viruses was modified for use as a semi-micro procedure.
Article
Major virion low-molecular-weight polypeptides were isolated from the Moloney strain of murine leukemia virus (type C) by agarose chromatography in 6M guanidine hydrochloride and were shown to have molecular weights of 15,000 (p15), 12,000 (p12), and 10,000 (p10) by their elution volumes and by their relative mobilities in sodium dodecyl sulfate-polyacrylamide gels. Each polypeptide could be iodinated and employed in double antibody radioimmunoassay procedures. All three polypeptides demonstrated a high degree of type-specificity in serologic immunoprecipitation analysis and in corresponding competition immunoassays. The p15 was immunologically distinct from other viron polypeptides including p12 and p10; the p12 and p10 were highly related to each other but not to other virion polypeptides and were even more type-specific than the p15 in serologic tests. Competition immunoassays with p15 and p10 indicate that the Moloney strain of MuLV is only a distant relative of the Friend-Rauscher group. The combined use of the Kirsten and Moloney low-molecular-weight polypeptide immunoassays suggest that xenotropic viruses constitute yet another group(s) of murine leukemia virus with distinct type-specific antigens, further expanding an already heterogeneous group of mouse type C viruses.
Article
A membrane antigen from RBL-5 leukemic cells that was solubilized and partially purified is further characterized in this study. This soluble antigen is capable of immunizating syngeneic hosts to reject neoplastic cells and thus resembles TSTA. It also induces cytotoxic antibody in syngeneic hosts capable of specifically lysing RBL-5 cells in vitro. RBL-5, however, releases infectious virus (RLV); it was necessary therefore to rule out virus or structural virion antigens as the effective immunogen. Infectious virus was not detectable in our initial crude membrane (CM) material, nor in the papain-solubilized CS or the G-150 Sephadex-chromatographed fraction. Virus-neutralizing antibody was not detected, under stringent assay conditions, in the syngeneic anti-CM sera. Antigen preparations CM, CS and the chromatographeal fractions F1, F2 and F3 were assayed in a complement-fixation test against brood-reacting antisera capable of detecting virus envelope antigen and gs antigen and against syngeneic antisera. Although our antigen preparations were positive for virion antigens, CS and F2 contained an antigen that reacted only with syngeneic antiserum. These same fractions were those reactive as immunogens. On the basis of these data, it is postulated that a cellular membrane component, other than viral, functions as TSTA.
Article
The polypeptides of reticuloendotheliosis virus (REV) were separated by gel filtration in the presence of guanidine hydrochloride. The eight peaks obtained by gel filtration were then analyzed by polyacrylamide gel electrophoresis and four appeared to contain single polypeptides. The material identified as p29 was used to prepare antiserum. This protein constitutes the major internal non-glycosylated polypeptide in the virion. Double immunodiffusion indicated that the antiserum was specific for p29. Using this antiserum, cross-reactivity was demonstrated between REV, chick syncytial virus, duck infectious anemia virus, and spleen necrosis virus. Antiserum to p29 failed to cross-react with Rous sarcoma virus. This indicates that p29 is a group-specific antigen shared by the viruses of the REV complex. A microcomplement fixation test was developed with this antiserum that will be useful in the quantitation of REV and the identification of other members of this newly defined group.
Article
Viral growth curves of N- and B-tropic murine leukemia viruses (MuLVs) were measured at varying multiplicities of infection (m.o.i.) on Fv-1-sensitive and -resistant cells. Both Fv-1-dependent and Fv-1-independent effects on the appearance of progeny virus were observed. At low m.o.i., growth curves in productively infected Fv-1-resistant cells were identical to those in Fv-1-sensitive cells with a latent period of 24–30 hr; under these conditions the virus-releasing Fv-1-resistant cells are doubly infected and show growth kinetics similar to those of the singly infected Fv-1-sensitive cells. The length of the viral latent period in both Fv-1-sensitive and -resistant cells was inversely related to m.o.i. and appeared to correlate with the fraction of multiply infected cells in a given population. The average yield per infected cell increased stoichiometrically as a function of m.o.i.
Article
Gross murine leukemia virus is the etiologic agent of spontaneous leukemias of AKR mice. Despite the persistence of the Gross virus throughout their life, these mice are not immunologically tolerant to the virus. Specific antibodies to Gross antigens can be detected in the kidney where they have been deposited in the glomeruli, apparently in the form of Gross antigen-antibody complexes.
Article
This report concerns a cell surface antigen (GIX; G = Gross) which exhibits mendelian inheritance but which also appears de novo in cells that become productively infected with MuLV (Gross), the wild-type leukemia virus of the mouse. In normal mice, GIX is a cell surface allo-antigen confined to lymphoid cells and found in highest amount on thymocytes. Four categories of inbred mouse strains can be distinguished according to how much GIX antigen is expressed on their thymocytes. GIX- strains have none; in the three GIX+ categories, GIX3, GIX2, and GIX1, the amounts of GIX antigen present (per thymocyte) are approximately in the ratios 3:2:1. A study of segregating populations derived mainly from strain 129 (the prototype GIX3 strain) and C57BL/6 (the prototype GIX- strain) revealed that two unlinked chromosomal genes are required for expression of GIX on normal lymphoid cells. The phenotype GIX+ is expressed only when both genes are present, as in 129 mice. C57BL/6 carries neither of them. At one locus, expression of GIX is fully dominant over nonexpression (GIX fully expressed in heterozygotes). At the second locus, which is linked with H-2 (at a distance of 36.4 ± 2.7 units) in group IX (locus symbol GIX), expression is semidominant (50% expression of GIX in heterozygotes); gene order T:H-2:Tla:GIX. As a rule, when cells of GIX- mice or rats become overtly infected with MuLV (Gross), an event which occurs spontaneously in older mice of certain strains and which also commonly accompanies malignant transformation, their phenotype is converted to GIX+. This invites comparison with the emergence of TL+ leukemia cells in TL- mouse strains which has been observed in previous studies and which implies that TL- → TL+ conversion has accompanied leukemic transformation of such cells. So far the only example of GIX- → GIX+ conversion taking place without overt MuLV infection is represented by the occurrence of GCSA-:GIX+ myelomas in BALB/c (GCSA:GIX-) mice. Unlike the other Gross cell surface antigen described earlier, GCSA, which is invariably associated with MuLV (Gross) infection and never occurs in its absence, GIX antigen sometimes occurs independently of productive MuLV infection; for example, thymocytes and some leukemias of 129 mice are GCSA-:GIX+, and MuLV-producing sarcomas may be GCSA+:GIX-. The frequent emergence of cells of GIX+ phenotype in all mouse strains implies that the structural gene coding for GIX antigen is common to all mice. There is precedent for this in the TL system, in which two of the Tla genes in linkage group IX appear to be ubiquitous among mice, but are normally expressed only in strains of mice carrying a second (expression) gene. It is not yet certain whether either of the two segregating genes belongs to the MuLV genome rather than to the cellular genome. This leaves the question whether MuLV may have a chromosomal integration site still debatable. But there is a good prospect that further genetic analysis will provide the answer and so elucidate the special relationship of leukemia viruses to the cells of their natural hosts.
Article
STANLEY et al. reported the production of a lymphoma (2731/L) in Prince Henry (PH) mice after inoculation with spleen cells from a PH mouse with chronic (272 days) reovirus type 3 infection1. They suggested a relationship between reoviruses and the tumour. From recent data on the prevalence of murine leukaemia virus in most mouse strains2, we would conclude that lymphomas induced in mice can, with considerable certainty, be attributed to murine leukaemia (C-type RNA) viruses in the passage materials. We have therefore tested for the presence of a murine leukaemia virus in the 2731/L tumour as well as other mouse lymphomas developing after various procedures (Table 1) in Stanley's PH line.
Article
An antigen specific for mouse leukemia viruses (MLV) was isolated in highly pure form from Friend virus after Tween 80-ether treatment. Its purity was demonstrated by electrophoresis, analytical ultracentrifugation, and serological tests. Serologically identical antigens are present in Rauscher virus as well as Gross virus and a mouse leukemia virus contained in L cell cultures. The group-specific antigen of Friend virus is a strongly basic protein, having a molecular weight of about 26,000 daltons. The amino acid composition of this component was likewise determined.
Thesis
The Fvl gene controls the sensitivity of murine cells to the retrovirus Murine Leukemia Virus (MLV). This inhibition of viral replication is called restriction. Restriction is specific, with different alleles of Fvl having different activities against individual subclasses of MLV. Fvl has homology with certain murine endogenous retroviruses, and has a putative Major Homology Region (MHR) which is a domain found in the capsid protein of most exogenous retroviruses. The aim of my PhD project was to further investigate the mechanism of Fvl restriction. This thesis initially describes the development of a fast, transient assay to test Fvl function using two colour FACS analysis. Using this assay, the regions of Fvl necessary for restriction of MLV were investigated. First, stop codons were introduced into Fvl to demonstrate that Fvl functions as protein rather than RNA. Then, mix-and-match mutants were generated by shuffling the major alleles of the gene about the three positions at which they differ. Residues 358 and/or 399 were also mutated to alanine for each mutant, to study specificity further. A variety of mutations were then introduced into the Fvl gene, producing both N- and C-terminus deletions, internal deletions throughout the coding region, and point mutations in the putative MHR domain of Fvl. These Fvl derivatives were all tested for activity. A significant fraction of the Fvl protein was not required for restriction, however retention of an intact MHR and domains toward the N- and C-termini was essential. Binding specificity appeared to be a combinatorial property of a number of residues within the C-terminal portion of Fvl. Certain mutations were also found to affect the localisation pattern of the protein. Finally, this thesis includes studies to determine the effect of mutations on the solubility of Fvl. Bacterially-expressed full length Fvl is highly insoluble, complicating future biochemical and structure analysis of the Fvl-MLV interaction. All Fvl mutants tested were as insoluble as wild-type, but initial attempts to purify Fvl protein using a baculovirus expression system look promising.
Chapter
Although it has been known for many years that certain viruses have something to do with tumor induction, in most instances there has been no specific evidence that the individual tumor cell had been directly transformed by a given virus. This sort of evidence was available only in the case of those RNA viruses, such as the avian leukoses, where the infected transformed cell continues to produce infectious virus. In the DNA virus-induced tumors, which are frequently free of infectious virus, there was no easy, direct way of establishing the etiological relationship. However, with the discovery in recent years that virus-induced tumors contain specific new antigens, a ready means of identification became available. There is good reason to believe that these antigens will be present in all virus-induced tumors, since one type or another has been found in all classes of tumors thus far adequately examined.
Chapter
Folgende Grunde und Gesichtspunkte rechtfertigen gerade auch im Hinblick auf den eigentlichen Zweck der experimentellen Krebsforschung, namlich der Krebsbekämpfung beim Menschen zu dienen, eine ausfuhrlichere Darlegung der murinen Leukamien und der sie verursachenden (onkogenen) Viren: 1) In den letzten Jahrzehnten — seit der wichtigen Entdeckung des Virus der lymphatischen Leukamie der Maus durch L. GROSS (1951) — wurde eine Vielzahl weiterer Leukämieviren bei der Maus nachgewiesen, die bei dieser Tierart und z.T. auch bei der Ratte hamatologisch sehr differente Leukämietypen (myeloische, retikulare, erythroblastische Leukämien) verursachen.
Chapter
In the past 80 years since the first recognition of viruses, now known as retroviruses, basic tenets or dogmas about these infectious agents have been stated. Many of them have been challenged and reversed by the constant acquirement of new information on their biologic properties and diversified functions. Ten dogmas in retrovirology have been selected for discussion. By reviewing the new developments in retrovirology, one can appreciate changes that occur in basic scientific truths and the need to constantly challenge dogmas to test their validity and applicability.
Article
The RNA-containing tumor viruses have been the objects of a surge of investigational activity during the past few years. This activity emanates from a conviction that cancer in man may be a direct consequence of infection by RNA tumor viruses, and it was prompted by the discovery of enzymes (reverse transcriptases) which have forced a conceptual change in notions about the transfer or exchange of genetic information among eukaryotic cells.
Chapter
Type C RNA viruses are a distinct class of vertebrate viruses which share a common morphology, protein composition, and viral life cycle, have single-stranded RNA as their viral genome, and contain an RNA-directed DNA polymerase (reverse transcriptase).
Chapter
Of the molecular changes associated with neoplastic transformation, the expression of tumour antigens has been the subject of special interest in recent years largely on account of the immunotherapeutic and diagnostic possibilities which their existence appears to raise1,2. These entities are frequently described as ‘neoantigens’ because the determinants are new with respect to the host at the time when the neoplasm appears. However tumour cells frequently possess several antigens, detectable by different techniques, which vary in respect of specificity, cellular location and biological function. Certain of these may be expressed at other stages of development of the whole organism, or at different levels of tissue differentiation so that the concept of ‘neoantigen expression’ needs to be qualified accordingly.
Article
This report concerns a cell surface antigen (GIX; G = Gross) which exhibits mendelian inheritance but which also appears de novo in cells that become productively infected with MuLV (Gross), the wild-type leukemia virus of the mouse. In normal mice, GIX is a cell surface allo-antigen confined to lymphoid cells and found in highest amount on thymocytes. Four categories of inbred mouse strains can be distinguished according to how much GIX antigen is expressed on their thymocytes. GIX- strains have none; in the three GIX+ categories, GIX3, GIX2, and GIX1, the amounts of GIX antigen present (per thymocyte) are approximately in the ratios 3:2:1. A study of segregating populations derived mainly from strain 129 (the prototype GIX3 strain) and C57BL/6 (the prototype GIX- strain) revealed that two unlinked chromosomal genes are required for expression of GIX on normal lymphoid cells. The phenotype GIX+ is expressed only when both genes are present, as in 129 mice. C57BL/6 carries neither of them. At one locus, expression of GIX is fully dominant over nonexpression (GIX fully expressed in heterozygotes). At the second locus, which is linked with H-2 (at a distance of 36.4 ± 2.7 units) in group IX (locus symbol GIX), expression is semidominant (50% expression of GIX in heterozygotes); gene order T:H-2:Tla:GIX. As a rule, when cells of GIX- mice or rats become overtly infected with MuLV (Gross), an event which occurs spontaneously in older mice of certain strains and which also commonly accompanies malignant transformation, their phenotype is converted to GIX+. This invites comparison with the emergence of TL+ leukemia cells in TL- mouse strains which has been observed in previous studies and which implies that TL- → TL+ conversion has accompanied leukemic transformation of such cells. So far the only example of GIX- → GIX+ conversion taking place without overt MuLV infection is represented by the occurrence of GCSA-:GIX+ myelomas in BALB/c (GCSA:GIX-) mice. Unlike the other Gross cell surface antigen described earlier, GCSA, which is invariably associated with MuLV (Gross) infection and never occurs in its absence, GIX antigen sometimes occurs independently of productive MuLV infection; for example, thymocytes and some leukemias of 129 mice are GCSA-:GIX+, and MuLV-producing sarcomas may be GCSA+:GIX-. The frequent emergence of cells of GIX+ phenotype in all mouse strains implies that the structural gene coding for GIX antigen is common to all mice. There is precedent for this in the TL system, in which two of the Tla genes in linkage group IX appear to be ubiquitous among mice, but are normally expressed only in strains of mice carrying a second (expression) gene. It is not yet certain whether either of the two segregating genes belongs to the MuLV genome rather than to the cellular genome. This leaves the question whether MuLV may have a chromosomal integration site still debatable. But there is a good prospect that further genetic analysis will provide the answer and so elucidate the special relationship of leukemia viruses to the cells of their natural hosts.
Article
Cell surface antigens expressed by cells transformed in vivo by FBJ virus, a wild type murine sarcoma virus (MSV) complex derived from a spontaneously arising sarcoma in a CF1 mouse, have been studied by indirect membrane immunofluorescence (MIF). Using mouse antisera raised by immunization of syngeneic CBA mice with transplanted FBJ sarcomata an antigen common to all FBJ tumours was detected which was also present on Gross (G) antigen positive tissues, viz. leukaemic and preleukaemic AKR lymphoid cells, but absent from the tissues of mice of G negative strains. Failure to demonstrate antigenic cross-reactivity in reciprocal MIF tests using FBJ immune sera and antisera to MSV-H (Harvey), an MSV isolate of Friend-Moloney-Rauscher (FMR) sub-group specificity, established the virus type-specificity of antigens expressed by sarcoma cells transformed by the respective MSV. The presence of a cellular antigen with G specificity on FBJ sarcoma cells was confirmed in tests with aged exbreeding C57B1 antisera containing naturally occurring G antibody lacking significant virus neutralizing activity. However, evidence for a “sarcoma-non-leukaemia” antigen on cells transformed by MSV-FBJ was not obtained since absorption studies failed to reveal any specificity on FBJ sarcoma cells which was not also present on AKR leukaemic tissues. It is suggested that the major humoral component of the immune response to FBJ sarcoma cells is evoked against antigens specified by the associated non-pathogenic leukaemia virus (MLV-FBJ) and the relationship of antigens demonstrated by MIF to those detected previously by complement fixation (CF) and tumour rejection tests is discussed.
Article
RD cells, line 2, derived from a human rhabdomyosarcoma were used for these studies3. The FeLV was derived from an interference end point dilution beyond the focus forming end point of the Gardner-Arnstein strain of feline sarcoma virus in beagle cells4. The virus stock, in thirteenth passage in beagle cells, contained approximately 103 (
Article
Antibody titers to protein (p) and glycoprotein (gp) antigens of bovine leukemia virus were studied by the immunodiffusion test in two groups of cattle. One group showed evidence of enzootic bovine leukosis (BL+ cattle), whilst the second group, possessing antibodies to gp antigen, were adjudged as subclinical cases (BL−). All 165 BL− and 97% (108/111) BL+ cattle possessed antibodies to gp antigen but those to p antigen were evident in only 67% BL− cattle in contrast to 89% in BL+ cattle. Mean antibody titers to both antigens were statistically higher in BL+ cattle.
Article
Spontaneous AKR Gross leukemias permanently produced Graffi virus if the cells had been repeatedly passaged in Graffi-virus-infected mice. Only one of 10 Graffi-virus-infected Gross leukemias investigated appeared to be immunologically indistinguishable from Graffi leukemias. Its cells contained the Graffi-virus-induced surface antigens as demonstrated by the phenomenon of tumor-specific transplantation resistance in vivo and by immunofluorescence and absorption tests in vitro. The original leukemias transplanted independently did not contain these antigens.
Article
The question that whether the unit of malignancy is a gene, or an organism that grows in highly specialized protoplasmic environments, or a molecule that multiplies by virtue of integral chemical union with a molecule of protoplasm, remains unanswered. The question of whether leukemia in the mouse is caused by either genetic or viral mechanisms has taken on a new meaning with the recognition of host genetic constitution with the viral infection in leukemogenesis. The chapter covers the early studies of murine leukemia and the genetic control of friend virus susceptibility and naturally occurring leukemia viruses. It also discusses the h2 linked genetic control of leukemogenesis and the other genes responsible for leukemogenesis. Infection with ontogenic viruses is complex and malignancy is not an inevitable result of tumor virus infection; many specific events affect the interaction of leukemia virus with cells, leading to leukemogenesis.
Article
The properties of a C-type virus from mouse myeloma cells (MMCV) are described. The virus was isolated in 3T3 cell cultures, but the infected cells did not transform nor did they produce abnormal proteins. MMCV acted as a helper in the rescue of murine sarcoma viral (MSV) genome from transformed non-producing mouse and hamster cells. The pseudotype virus formed (MSV-MMCV), transformed mouse and rat cells in culture, and induced rhabdomyosarcoma when inoculated into neonatal BALB/c-mice. However, newborn mice inoculated with MMCV did not develop any tumours. MMCV was found to share the group specific antigen of the murine leukaemia sarcoma viruses, but contained a type specific viral antigen which was not neutralized by anti-MSV-H serum.Mouse cells chronically infected with MMCV were resistant to superinfection and transformation by different pseudotypes of MSV (MSV-H, MSV-FLV, MSV-FLV and MSV-MMCV).
Article
INFECTION of susceptible mouse cells in culture with murine leukaemia viruses (MLV) does not cause any observable change in cellular morphology, even though continuous virus replication in these cells can often be demonstrated. Complement-fixation1 and fluorescent antibody2 techniques as well as interference3 or potentiation4 of focus formation by ``defective'' murine sarcoma viruses have all been used successfully to detect and to quantitate in vitro infection of mouse cell cultures with MLV. These techniques, however, are less than ideal because they involve special reagents and lengthy incubation, or because they are relatively insensitive, Klement et al.5 have shown that the XC cell line6, derived from a rat tumour induced by the Prague strain of Rous sarcoma virus, undergoes syncytium formation when present in mixed cultures together with MLV-infected mouse cells. This phenomenon of mixed culture cytopathogenicity has been used to develop a plaque assay for murine leukaemia viruses in mouse cell cultures (unpublished observations of W. P. Rowe et al.).
Article
A number of ecotropic and xenotropic murine leukemia viruses were examined for their ability to induce the GIX antigen and Gross cell surface antigen (GCSA) in tissue culture fibroblasts. GIX appears to be a constituent of murine leukemia virus gp70; a molecular characterization of GCSA has not yet been reported. Antigen induction was measured by the ability of productively infected cells to absorb cytotoxic activity from the standard GIX- and GCSA-typing antisera. Cells infected by ecotropic viruses displayed four distinct phenotypes GIX:+/GCSA++, GIX-/GCSA++, GIX++/GCSA+, and GIX-/GSCA+; cells infected by xenotropic viruses were either GIX-/GCSA+ or GIX-/GCSA-. GIX induction appeared to be a type-specific property of some but not all Gross-AKR type ecotropic viruses. Differences in the degree of absorption of the GCSA antiserum by ecotropic virus- and xenotropic virus-infected cells indicated that GCSA may comprise multiple antigenic determinants.
Article
Sera of hamsters bearing large primary or transplanted subcutaneous fibrosarcomas induced by the Schmidt-Ruppin (S-R) strain of Rous sarcoma virus contain complement-fixing (CF) antibodies reactive not only with the homologous virus, but also with antigens of other avian leucosis viruses. Using this group-specific reaction, a complement fixation test (the COFAL test) was developed for the specific detection and assay of viruses of the avian leucosis group; the test appears to be at least as sensitive and useful as the resistance-inducing factor (RIF) interference procedure.Virus was assayed by inoculating decimal dilutions of virus into chicken embryo fibroblast cultures grown in petri dishes or in roller tubes and testing the inoculated cultures for the development of CF viral antigens. End points for virus assays were obtained in petri dish cultures after one or two cell transfers and also in roller tube cultures without cell transfers. In both systems, virus diluted 10−4 to 10−5 was detected within 10 days of virus inoculation and final titration end points were often reached within 2 weeks. Rous-associated virus (RAV) was readily demonstrated in the Bryan strain but not in the S-R strain of Rous sarcoma virus. The test was effective in demonstrating naturally occurring avian lymphomatosis virus.
Article
A disease with the characteristics of a leukemia has been found to be serially transmissible in adult Swiss mice by means of cell-free filtrates. Thus far, the disease has been transmitted through twenty-six serial passages with filtrates as well as cell suspensions. The agent readily passes through Selas 03, Berkefeld N, and gradocol membrane filters—these last having an average pore size of 220 mµ. Filtrates remain stable when stored for long periods at –70°C. or when lyophilized. Splenic tissue containing the agent, which was subjected to massive doses of x-ray (50,000 r),—far more than sufficient to kill the cells,—show undiminished infectivity. The agent is inactivated by heating to 56°C. for 30 minutes and by exposure to ether or formalin. The disease can be transmitted to adult Swiss mice or DBA/2 mice, but not to adult PRI, C3H, A, C57B1/6, or F1(C58 x BALB) mice. Intraperitoneal, subcutaneous, intracerebral, and intramuscular injections are all effective.
Article
Several strains of a new virus (RV) have been isolated from rat tumors under conditions which suggest that it may be a latent agent in these animals. The virus is characterized by its ability to multiply and to cause a marked cytopathogenic effect (CPE) in rat embryo cells in tissue culture. The virus is associated with a hemagglutinin for guinea pig red cells, and circulating antibodies against these strains have been found in a number of laboratory and wild rats, suggesting that it is widely disseminated. Viral antibodies were detected in a germ-free rat, suggesting that the agent may be vertically transmitted. The virus resembles SE polyoma virus in a number of respects, including heat stability, resistance to ether, agglutination of red cells without spontaneous elution and the destruction of red cell receptors by cholera vibrio filtrates containing receptor-destroying enzyme (RDE). The virus differs from SE polyoma virus in that there is no detectable antigenic relationship and the agent does not grow in mouse embryo tissue nor does it cause tumors or other detectable pathology on inoculation into rats. However, the resemblances suggest that the two agents may represent mouse and rat variants of a similar class of virus agent.
Article
Mice inoculated with the Moloney strain of mouse lymphoid-leukemia virus showed marked diminution of spleen weight response to infection with Friend leukemia virus given 3 to 4 weeks later.
The WM1-B strain of Friend virus was originally recovered from mice which had been inoculated with WM1 virus. The question of relationship between the two strains was examined.Antisera prepared in stock C3H mice against either WM1-B or WM1 virus neutralized WM1-B virus but not WM1 virus. Q.I.M.R. mice infected with WM1 virus were resistant to superinfection with WM1-B virus. These two findings indicated that a relationship existed between some component of the WM1 line and the leukaemogenic component of the WM1-B line.By treatment of WM1-B virus with C3H antiserum to WM1 virus, a strain of WM1 virus was obtained which did not produce antibodies to WM1-B virus in C3H mice and did not protect Q.I.M.R. mice against challenge with WM1-B virus, but which did produce the lymphoid hyperplasia typical of WM1 virus infection. This pure WM1 strain was still free of relationship to WM1-B virus at the 8th passage.The original WM1 line therefore contained two viruses. One (WM1 virus) caused lymphoid hyperplasia in Q.I.M.R. mice, while the other (an avirulent variant of WM1-B virus) caused no signs but was detectable by means of neutralization and protection tests.Seventeen wild mice were studied virologically. Strains of virus resembling pure WM1 virus were isolated from two wild mice, and an avirulent strain related to WM1-B virus was obtained from a third, while both viruses were isolated from three other wild mice.These results support the view that WM1 virus and the avirulent form of WM1-B virus are distinct.It was concluded that an avirulent virus, which is apparently related to Friend virus, occurs in wild mice in Queensland.
Article
RAUSCHER virus induces a characteristic malignant hæmopathy when inoculated into adult or new-born mice of various strains, mainly that of BALB/c (ref. 1). In order to handle a system which would give a good production of virus in vitro, we cultured cells taken from various organs of animals inoculated with Kauscher virus several days previously. Among the organs tested, we obtained valuable results with cultures of young mice kidneys. The kidney always being spared during the course of Rauscher leukæmia, this production of virus is worth while mentioning.
A virus (WM1 strain) was isolated from a wild house mouse, Mus musculus. It was infective for suckling and weaned mice inoculated intraperitoneally, but not for laboratory Rattus norvegicus, guinea-pigs, rabbits or chick embryos.A prolonged chronic infection resulted, with normal blood picture, persistent viraemia, moderate splenomegaly and general enlargement of lymph nodes, which were sometimes massive. Most infected mice died within 11½ months.Microscopically, the splenomegaly was seen to be due to hyperplasia of both red and white pulp, while enlargement of lymph nodes was essentially due to medullary hyperplasia, with plasma cells prominent. Four of 79 infected weaned mice examined at random within 11½ months had developed neoplasms of the lymph nodes, while none was seen in any of the 87 control mice examined in the same period. However, two of 17 control mice had neoplasms of lymph nodes at 18 months.The virus passed through Gradocol membranes with average pore diameter of 320 mμ. lt was sensitive to ether, formalin, and heating at 56° C. for 30 minutes, but remained viable at −60° C. and after lyophilization, and was resistant to 5 p.c. ethanol at 4° C. for 24 hours.
Article
A newly isolated, highly potent murine leukemogenic virus induced a dual type of disease in 90 to 100 percent of mice of different strains. The disease was characterized by rapid and extreme proliferation of predominantly erythrocytic and leukocytic elements as early as 7 days postparenteral inoculation. Within 15 days after inoculation of newborn or adult mice, 50 to 100 percent developed palpable spleens. Fifty percent of the animals, with spleens weighing 30 to 50 times those of normal mice, died within 25 to 35 days. In mice that survived, the erythrocytopoiesis was followed by the development of lymphocytic leukemia beginning 30 to 45 days after inoculation. Leukemic tissues transplanted with ease and killed 100 percent of the recipients. An intense viremia occurred in infected mice at least as early as 16 days after inoculation. The virus extracted from plasma or from leukemic tissues was of such potency that a 10⁻⁷ dilution of the test material induced the disease in 50 percent of the recipients within 95 days. Virus particles measuring 100 mμ were seen in thin sections of plasma pellets and in malignant lymphoblasts from spleen. Osborne-Mendel rats, 8 different inbred strains of mice, and random-bred Swiss mice, were all highly susceptible. The virus was stable to lyophilization, −70° C, formalin, and was not neutralized by antiserum prepared against the murine leukemia viruses of Friend, Moloney, or Schoolman-Schwartz. The ratio of mice responding with erythrocytopoiesis only to those developing erythrocytopoiesis plus lymphoid leukemia was influenced by the infecting dose of virus and by the strain and age of the recipients.
  • H Ginsburg
  • L Sachs
Ginsburg, H., and L. Sachs, Virology, 13, 380 (1961);
  • E A Mirand
  • J T Grace
Cancer Inst., 27, 1153 (1961); ibid., 28, 1391 (1962). 4Osato, T., E. A. Mirand, and J. T. Grace, Jr., Nature, 201, 52 (1964).
  • A E Moore
  • Unio Acta
  • Intern
Moore, A. E., Acta, Unio Intern. Contra Cancrum, 19, 273 (1963).
personal communication. 17 Pope
  • T Wv Ward
16 Ward, T. WV., personal communication. 17 Pope, J. H., Austral. J. Exptl. Biol., 41, 349 (1963).
  • P S Sarma
  • H C Turner
  • R J Huebner
9 Sarma, P. S., H. C. Turner, and R. J. Huebner, Virology, 23, 313 (1964). 10 Rauscher, F. J., J. Natl. Cancer Inst., 29, 515 (1962). 11 Friend, C., J. Exptl. Med., 105, 307 (1957).