Showing papers on "Virus published in 1971"
TL;DR: A papova-like virus has been cultivated from the brain of a case of progressive multifocal leucoencephalopathy complicating Hodgkin's disease, suggesting that it is a new papovavirus.
1,554 citations
TL;DR: The isolation of a new papovavirus from the urine of a renal allograft recipient with ureteric obstruction is described and this virus is not identical with any of the previously described members of the polyoma subgroup.
1,371 citations
TL;DR: Herpes simplex virus establishes a persistent, latent infection in spinal ganglia after mice have recovered from posterior paralysis and is replicated when these ganglia are explanted and maintained as organ cultures in vitro.
Abstract: Herpes simplex virus establishes a persistent, latent infection in spinal ganglia after mice have recovered from posterior paralysis. Infectious virus is replicated when these ganglia are explanted and maintained as organ cultures in vitro.
586 citations
TL;DR: It is indicated that the full genome of murine leukemia virus is present in an unexpressed form in all AKR cells and provide a potentially powerful technique for activating leukemia virus genomes in other cell systems.
Abstract: Cells of embryos of the high leukemic mouse strain AKR can be grown in culture as virus-negative cell lines However, these lines and clonal sublines uniformly have the capacity to initiate synthesis of murine leukemia virus Exposure of the cells to 5-iododeoxyuridine or 5-bromodeoxyuridine induced synthesis of virus in as high as 01 to 05 percent of the cells; many of the cells were producing virus as soon as 3 days after initiation of treatment Induction of virus by these drugs is several orders of magnitude greater than that obtained with any other treatment tested These studies indicate that the full genome of murine leukemia virus is present in an unexpressed form in all AKR cells and provide a potentially powerful technique for activating leukemia virus genomes in other cell systems
559 citations
TL;DR: Each clone of BALB/c mouse embryo cells that has been tested can be induced to form C-type virus, which contains a complete copy of the genetic information for making the murine RNA tumor viruses.
Abstract: Each clone of BALB/c mouse embryo cells that has been tested can be induced to form C-type virus. The individual cells therefore contain a complete copy of the genetic information for making the murine RNA tumor viruses.
398 citations
TL;DR: It is shown that the infectious RNA occurs in the form of several species with molecular weights ranging from 2.5 × 10 4 to 1.1 × 10 5 daltons, and the term “viroid” is proposed to designate potato spindle tuber “virus” RNA and other RNAs with similar properties.
393 citations
TL;DR: The genetic locus described appears of major significance in the biology of murine leukemia and has no effect on growth of certain laboratory-passaged leukemia viruses which propagate equally well on embryo cells of all mouse strains, F1, and backcross hybrids.
Abstract: Previous studies have indicated that all naturally occurring murine leukemia viruses propagate significantly more efficiently on embryo cells of either NIH Swiss or BALB/c mice. Studies of the plaquing efficiency of representative viruses on embryo cells of various inbred and hybrid mice indicate that the pattern of sensitivity of the cells is genetically determined. All of 23 strains tested were found to resemble either NIH Swiss (N-type) or BALB/c (B-type) with respect to plaquing efficiency of these viruses. Virus growth on embryo cells derived from (N-type x B-type)F1 hybrids indicated dominance of resistance to both types of viruses. Backcross hybrid studies indicated that a single locus is the primary determinant of the host-range patterns observed. This locus has no effect on growth of certain laboratory-passaged leukemia viruses which propagate equally well on embryo cells of all mouse strains, F1, and backcross hybrids. Though other genetic and nongenetic factors influence viral growth or expression in vitro and in vivo, the genetic locus described appears of major significance in the biology of murine leukemia.
364 citations
TL;DR: It is shown that the XC cell line, 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, which has been used to develop a plaque assay for murine leukaemia viruses in mouse cell cultures.
Abstract: 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.).
349 citations
TL;DR: The available evidence suggests that protein 2, which is found in much larger amount in infected cells than in the mature virion, is cleaved at the plasma membrane to yield proteins 5 and 6, which are the last proteins to appear at the Plasma membrane.
325 citations
TL;DR: Comprehensive surveillance of acute lower respiratory illnesses of children seen in apediatric group practice was maintained for 67 months in Chapel Hill, North Carolina, and consistent patterns have been observed in the clinical manifestations, seasonal occurrence, and age and sex distribution of infections.
264 citations
TL;DR: The case for the possible association of EBV with Burkitt's lymphoma (BL) and nasopharyngeal carcinoma (NPC) rests mainly on the observation that patients with these diseases have significantly higher EBV antibody titres than matched controls from the same region.
Abstract: THE discovery of Epstein and Barr1 of an antigenically and biologically unique herpes-like virus (EBV) in cultured cells derived from Burkitt's lymphoma aroused much speculation regarding the possible aetiological role of this agent in human lymphoproliferative diseases. Serological and clinical data provided strong evidence for the causal relationship between EBV and infectious mononucleosis2. The case for the possible association of EBV with Burkitt's lymphoma (BL) and nasopharyngeal carcinoma (NPC) rests mainly on the observation that patients with these diseases have significantly higher EBV antibody titres than matched controls from the same region3. Similar findings, however, were also reported in patients with sarcoidosis4 and systemic lupus erythematosus5.
TL;DR: Analyses of the polypeptide composition of three influenza viruses, X-31,X-7F1, and AO/BEL/42, and of the isolated antigenic components of these viruses are reported.
TL;DR: The DNA polymerase of murine leukaemia virus has been purified and can be separated physically from enzymes with some similar properties that are present in normal cells.
Abstract: The DNA polymerase of murine leukaemia virus has been purified and can be separated physically from enzymes with some similar properties that are present in normal cells. Chromatographic and immunological methods have made it possible to identify the viral enzyme in virus-transformed cells.
TL;DR: A cell surface antigen 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, and which invites comparison with the emergence of TL(+) leukemia cells in TL(-) mouse strains.
Abstract: 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.
TL;DR: A large number of kirsten sarcoma virus-transformed mouse and rat cell foci has been isolated, and from these many non-producer clonal lines have been derived and characterized.
Abstract: Summary
Kirsten sarcoma virus induces foci of morphologically altered cells in rat, mouse, and human cells in tissue culture. The kirsten sarcoma virus stock contains two viruses; one forming foci and the other plaques on XC cells. The sarcoma virus particle transforms cells in the absence of murine leukaemia virus but requires murine leukaemia virus for its replication. The high susceptibility of human cells to transformation by kirsten sarcoma virus is related to a function provided to the sarcoma virus by murine leukaemia virus. A large number of kirsten sarcoma virus-transformed mouse and rat cell foci has been isolated, and from these many non-producer clonal lines have been derived and characterized.
TL;DR: Although this study associates elevated EBV titers with those factors relating to a poor prognosis in patients with Hodgkin's disease, the data do not distinguish between an etiologic role for EBV and that of a passenger virus which produces high titers as a result of the disease process.
Abstract: Sera from 63 patients with Hodgkin's disease and 42 patients of comparable age with other lymphomas were tested for antibody to Epstein-Barr virus (EBV) by indirect immunofluorescence. The geometric mean titer (GMT) of EBV antibody in the patients with Hodgkin's disease was significantly higher (1:367) than the GMT of the other lymphoma patients (1:132) and 85 normal controls (1:90). Higher EBV titers in untreated patients with Hodgkin's disease were associated with a longer duration of symptoms, more advanced disease, shorter survival, and a histologic picture of lymphocyte depletion. Treated patients had significantly higher titers than untreated patients. When the same sera were tested for antibody to 4 other herpes viruses (herpes simplex type I and type II, cytomegalovirus, and varicella), no differences in titer between patient and control groups were found. Although this study associates elevated EBV titers with those factors relating to a poor prognosis in patients with Hodgkin's disease, the data do not distinguish between an etiologic role for EBV and that of a passenger virus which produces high titers as a result of the disease process.
TL;DR: Results of tissue culture studies were parallel to results of studies in vivo and indicate that the F-S virus is N-tropic and theF-B virus is NB- Tropic.
Abstract: The N-B locus affecting tissue culture infectivity with naturally occurring murine leukemia viruses appears to be identical to the Fv-1 locus described for sensitivity to Friend leukemia virus. Results of tissue culture studies were parallel to results of studies in vivo and indicate that the F-S virus is N-tropic and the F-B virus is NB-tropic. Inbred and partially congenic mouse strains sensitive at Fv-1 show N-type sensitivity; strains resistant at Fv-1 show B-type sensitivity. The Fv-2 locus does not appear to exert significant effect in tissue culture. Knowledge of N-B type has been useful in predicting Fv-1 sensitivity.
Journal Article•
TL;DR: Resistance to extensive infection in both studies, and resistance to illness in the second study, appeared to be correlated with high levels of nasal wash antibody, but not with the level of serum antibody.
Abstract: Volunteers were inoculated with a low (102.7 pfu), or 200-fold higher dose (105.0 pfu) of respiratory syncytial virus (RSV). The low dose infected 100% of the men but did not produce illness; the level of virus replication and the magnitude of the subsequent antibody response were inversely correlated with the level of nasal secretory neutralizing antibody prior to infection. The high dose infected only 53% of the men (9 of 17); five of the infected men became ill. Two of the men who excreted virus apparently resisted experimental inoculation and acquired infection secondarily by contact with infected men. The differences in rates of infection between the two studies were minimized if only those men who had extensive infection (virus excretion τ; 102.5 pfu or significant antibody responses) were considered. Resistance to extensive infection in both studies, and resistance to illness in the second study, appeared to be correlated with high levels of nasal wash antibody, but not with the level of serum antibody.
TL;DR: This work has demonstrated that RNA-DNA hybrids have been demonstrated to occur as intermediates in this reaction and single stranded DNA is generated as an early reaction product, which is then replicated to give a double stranded DNA product.
Abstract: DURING replication of RNA tumour viruses, the genetic information contained in the viral RNA seems to be transferred to DNA1,2. Studies on the enzymatic activities present in the virus particles suggest that this transfer is mediated by an RNA dependent DNA polymerase3,4. RNA-DNA hybrids have been demonstrated to occur as intermediates in this reaction5 and single stranded DNA is generated as an early reaction product6, which is then replicated to give a double stranded DNA product6–8. The mechanism by which the single stranded DNA is displaced from the RNA template is, however, not known.
TL;DR: Some human milk contains particles physically identical to the mouse mammary tumour virus, which could serve as a model in the study of human breast cancer.
Abstract: Some human milk contains particles physically identical to the mouse mammary tumour virus. Tumorigenesis in the mouse could serve as a model in the study of human breast cancer.
TL;DR: Several other picornaviruses that failed to induce interferon in L cells, human embryonic lung cells, or monkey kidney cells did induceInterferon when these cells had been primed by homologous interferons, and priming appears to be a function ofinterferon separable from its antiviral activity.
Abstract: No interferon is made by L cells when they are infected with MM virus. However, several thousand units of interferon are produced when interferon-treated L cells are infected with MM virus. We call the conversion of cells, from nonproducers to producers, priming. The time required for cells to become fully primed is dependent on the interferon concentration with which they are incubated. Primed cells produced interferon earlier than normal cells stimulated by other inducers. Cells which were exposed to interferon in the presence of inhibitors of protein synthesis became fully primed yet developed no virus resistance. Also, primed cells produced interferon in response to low concentrations of polyriboinosinic acid · polyribocytidylic acid that did not induce interferon in normal cells. Therefore, priming appears to be a function of interferon separable from its antiviral activity. Several other picornaviruses that failed to induce interferon in L cells, human embryonic lung cells, or monkey kidney cells did induce interferon when these cells had been primed by homologous interferons.
TL;DR: Observations indicate that the occurrence of NT viruses in stocks of helper-independent avian sarcoma viruses is not the result of passage in gs positive chicken cells, rather the NT viruses appear to be spontaneous segregants of sarcomA viruses.
TL;DR: Intracerebral inoculation of newborn and 5-week-old mice with Zika virus resulted in an early and marked enlargement of astroglial cells with patchy destruction of the pyriform cells of Ammon's horn.
Abstract: Intracerebral inoculation of newborn and 5-week-old mice with Zika virus resulted in an early and marked enlargement of astroglial cells with patchy destruction of the pyriform cells of Ammon's horn. Replication of the virus was demonstrated in both neurones and astroglial cells. New virions appeared to be formed within networks of endoplasmic reticulum. The similarity of these ultrastructural observations to those obtained fromin vivo studies of other group B arboviruses is contrasted with the widely differing findings fromin vitro studies.
TL;DR: O differs from the common type of helper virus by its greater physical instability, its poor ability to interfere with related viruses, and its dependence on RSV(O) in the infection of quail cells, suggesting that RAV-O plays an essential role in the replication of RSVs in gs negative cells and that it is also involved in the reproduction of RSV
TL;DR: The simultaneous assay of the reverse transcriptase and 60S to 70S RNA of oncogenic RNA viruses is described, increasing the certainty with which a positive outcome can be interpreted.
Abstract: The simultaneous assay of the reverse transcriptase and 60S to 70S RNA of oncogenic RNA viruses is described. The virus can be detected at low concentrations in biological fluids containing enzymatically active cell fragments or other contaminants. The fact that two features diagnostic of the oncornaviruses are used in the tests increases the certainty with which a positive outcome can be interpreted.
TL;DR: Evidence is provided that inside the axons a transport of materials directed disto-proximally all the way to the nerve cell body exists, and that a spread of virus in endoneurial spaces or by propagation in Schwann cells is of minor importance.
Abstract: Suckling mice were inoculated intradermally with herpes simplex virus into the sole of the hind foot. Titrations for infective virus from different levels of the sciatic nerve, dorsal ganglia, and spinal cord showed that virus was already present in the spinal cord two days after inoculation, and before virus could be recovered from the examined levels of the sciatic nerve. Ligatures, freezing, and local treatment with colchicine of the sciatic nerve could prevent the spread of infection. The ultrastructural features of nerves soaked with mitosis inhibitors are described. Extensive changes with ultimate collapse of axons and disintegration of myelin sheaths were found, while the Schwann cells showed no obvious degenerative changes and the endoneurial spaces were wide. It is considered that the infectious agent travels inside the axons to the CNS, and that a spread of virus in endoneurial spaces or by propagation in Schwann cells, as recently has been suggested, is of minor importance. The study seems to provide evidence that inside the axons a transport of materials directed disto-proximally all the way to the nerve cell body exists.
TL;DR: A single mutant was defective in the synthesis of viral DNA, viral structural antigens, and viral particles, and this mutant stimulated cell DNA synthesis at the restrictive temperature and complemented the other two functional groups of mutants.
Abstract: Ten temperature-sensitive mutants of simian virus 40 have been isolated and characterized in permissive cells. The mutants could be divided into three functional groups and two complementation groups. Seven mutants produced T antigen, infectious viral deoxyribonucleic acid (DNA), and structural viral antigen but predominantly the empty shell type of viral particles. Two mutants produced T antigen and infectious viral DNA, but, although viral structural protein(s) could be detected immunologically, no V antigen or viral particles were found. These two functional groups of mutants did not complement each other. A single mutant was defective in the synthesis of viral DNA, viral structural antigens, and viral particles. T antigen could be detected in infected cells by fluorescent antibody but was reduced by complement fixation assay. This mutant stimulated cell DNA synthesis at the restrictive temperature and complemented the other two functional groups of mutants.
TL;DR: Extracellular rabbitpox virus released naturally from infected cells differed antigenically from intracellular virus released by artificial disruption of cells, and should be used as the test virus in titrations of neutralizing antibody if these are to assess the protective activity of an antiserum.
Abstract: Summary
Extracellular rabbitpox virus released naturally from infected cells differed antigenically from intracellular virus released by artificial disruption of cells. Intracellular virus was neutralized by antiserum prepared against live rabbitpox virus and by antiserum against inactivated vaccinia virus. In contrast, extracellular virus was neutralized only by rabbitpox antiserum. The antibodies responsible for the neutralization of intracellular and extracellular virus could be absorbed separately from rabbitpox antiserum. Morphologically, extracellular virus differed from intracellular virus in possessing an outer envelope. This envelope was probably the site of the virus antigen characteristic of extracellular virus, and fluorescent antibody staining of infected cells suggested that it was derived from the modified host cell membrane. Antibody directed against extracellular virus was responsible for the ability of rabbitpox antiserum to control the spread of rabbitpox virus in tissue culture and probably for its ability to protect rabbits from rabbitpox infection. Extracellular virus should therefore be used as the test virus in titrations of neutralizing antibody if these are to assess the protective activity of an antiserum.
TL;DR: A transformed clone has been selected which still is strongly contact inhibited in spite of producing SV40 T-antigen and having rescuable virus information, but has gained one of the growth properties associated with virus-transformation, the ability to grow in factor-free medium.