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Biomedical subjects

J G Stevens

Publications and source records attributed to J G Stevens.

At least 73 records · Page 4Linked to original sources
PubMed1983

Physical location of a herpes simplex virus type-1 gene function(s) specifically associated with a 10 million-fold increase in HSV neurovirulence.

In this paper we present a technique developed to physically locate the HSV-1 gene(s) which restore neurovirulence to a non-neurovirulent HSV intertypic recombinant described in the preceding report. In brief, tissue culture cells are co-transfected with unit length RE6 DNA and restriction endonuclease fragmented HSV-1 (strain 17 Syn+) DNA. In this way, random recombinations between RE6 and 17 Syn+ are produced. An in vivo enrichment in mouse brains is then employed to select recombinants which have incorporated the HSV-1 gene(s) associated with neurovirulence. In each of five cases where neurovirulent recombinants were isolated by this procedure, restriction enzyme and Southern DNA transfer analysis revealed that HSV-1 information from 0.71 to 0.83 map units had been incorporated into the RE6 genome. Confirmation of the role of this portion of the genome for HSV neurovirulence was obtained by similar cotransfection and in vivo rescue experiments performed with an electrophoretically purified HSV-1 DNA fragment which encompasses this region. Subsequent genome structure analysis of neurovirulent recombinants generated by this procedure revealed that only type-1 information from 0.71 to 0.83 map units had been incorporated into RE6. Thus an HSV-1 gene function(s) which resides in this region of the viral DNA is associated with a 10 million-fold increase in the neurovirulence of the virus. Potential applications of this in vivo selection technique are discussed.

Animals↗
PubMed1983

Restricted replication of herpes simplex virus in spinal ganglia of resistant mice is accompanied by an early infiltration of immunoglobulin G-bearing cells.

In an attempt to define the nature of the difference in the susceptibility of C57BL/6 (resistant) and A/J (susceptible) mice to herpes simplex virus type 1, we initiated a study of virus progression through the nervous system. After inoculation of virus in a rear footpad, C57BL/6 mice were found to be more than 500-fold more resistant, but resistance did not extend to pseudorabies virus. In additional investigations, it was found that the virus was selectively restricted at the level of spinal ganglia in C57BL/6 mice. No intrinsic difference in the ability of this tissue from either mouse strain to replicate virus was found. However, by 4 days after infection, morphological investigations indicated that a mononuclear cell infiltrate was present surrounding infected neurons and satellite cells both earlier and in greater numbers in the ganglia of C57BL/6 mice. Immunohistochemical methods showed that most of these cells did not express Thy 1.2 antigen, but the vast majority bore immunoglobulin G. The mechanism by which these infiltrating cells could restrict virus spread is discussed.

Animals↗
PubMed1983

Replication at body temperature selects a neurovirulent herpes simplex virus type 2.

A prototype strain of herpes simplex virus type 2 (HG-52) replicated at 31 degrees C was avirulent when inoculated intracranially into mice. This property was not altered after serial passage of the agent at 31 degrees C, but the virus became virulent after passage at 37.5 degrees C. The selection was not merely for an agent which replicated more efficiently at the higher temperature, but for viruses with enhanced capacity to replicate in the brains of mice. Virulent descendants of plaque-purified avirulent stocks were obtained in each instance attempted.

Animals↗
PubMed1982

Variable-sized free episomes of Shope papilloma virus DNA are present in all non-virus-producing neoplasms and integrated episomes are detected in some.

The state of rabbit (Shope) papilloma virus DNA in virus-induced nonproducing tumors on domestic rabbits was investigated. Virus-specific sequences were resolved into many distinct bands by one-dimensional agarose gel electrophoresis. Two-dimensional gel electrophoresis, CsCl/propidium iodide density equilibrium centrifugation, partial digestion with a restriction endonuclease, and S1 nuclease digestion permitted us to identify the bands as free viral episomes representing circular molecules of increasing size. In some tumors (both papillomas and carcinomas), up to 25% of the virus-specific DNA was linear and comigrated with cellular DNA. Integration of at least some of these sequences was suggested by the detection of viral-cellular junction bands in one tumor after digestion of DNA with EcoRI and Sal I, enzymes that cut Shope DNA once. Finally, the physical states of viral DNA in papillomas and carcinomas were found to be similar, although free episomes were generally larger in carcinomas.

Animals↗
PubMed1982

Activation of latent murine cytomegalovirus in vivo and in vitro: a pathogenetic role for acute infection.

Many cytomegalovirus (CMV) infections result from activation of virus previously latent in the host. Murine models of latent CMV infection have been developed in which latent virus can be activated in vivo by immunosuppression or by coculture of splenic lymphocytes in vitro. In the present study, latent murine CMV (MCMV) could be activated from lymphocytes of mice regardless of genetic strain, age at time of virus inoculation, or use of syngeneic or allogeneic fibroblasts for coculture. After intraperitoneal inoculation, virulent virus was activated from lymphocytes more often than attenuated MCMV (69% vs. 20% of lymphocyte cocultures were positive, respectively). Latent MCMV was not detected in lymphocytes after subcutaneous inoculation of weanling mice but could be activated from mice infected subcutaneously as newborns. The absence of latent infection in the lymphocytes of the mice that had been inoculated as weanlings was due to lack of virus replication in the spleen during acute infection.

Animals↗
PubMed1982

Two colinear and spliced viral transcripts are present in non-virus-producing benign and malignant neoplasms induced by the shope (rabbit) papilloma virus.

The nature of Shope virus-specific RNA was investigated in non-virus-producing Shope (rabbit) papilloma virus-induced benign and malignant domestic rabbit tumors and in a cell line derived from the VX-7 transplantable carcinoma. RNA transfer (Northern) blot analysis of polyadenylated RNA isolated from whole cell extracts of all three sources was resolved into two major bands of 1.3 and 2.0 kilobases. Two additional minor bands of 3.5 and 4.8 kilobases could be seen in some analyses. RNA of the VX-7 cell line was further separated into nuclear, cytoplasmic, and polysomal fractions. The cytoplasmic fraction only contained the 1.3- and 2.0-kilobase species, and virus-specific RNA was found to be associated with polysomes. The two major transcripts present in VX-7 cells were mapped by hybridization of RNA transfer blots with subgenomic probes, and the results indicated that both transcripts are spliced and are most likely colinear. Our results are consistent with the suggestion that the two viral transcripts are necessary for induction and maintenance of the neoplasms.

Animals↗
PubMed1981

Marek's disease: a natural model for the Landry-Guillain-Barré syndrome.

The early lesions of Marek's disease in chickens are indistinguishable from those of the Landry-Guillain-Barré syndrome in human beings. Because of these similarities, and since the etiological agent (a herpesvirus) is known, Marek's disease can be meaningfully exploited as a model of the Landry-Guillain-Barré syndrome. Recent work in our laboratories has shown that the agent establishes latent infections in neuronal supporting cells and that affected birds mount cellular and humoral immunological reactions to peripheral nerve and myelin. Based on these findings, a working hypothesis for the pathogenesis of the disease is presented.

Animals↗
PubMed1981

Modification by adoptive humoral immunity of murine cytomegalovirus infection.

The effects of specific antiviral antibody on several aspects of infection with murine cytomegalovirus (CMV) were examined. Administration of immune serum 24 hr before subcutaneous inoculation of 10(5) plaque-forming units of murine CMV prevented detectable viral replication in the tissues of 92% of animals. Protection was associated with the immune globulin fraction and not with normal serum or heterologous antiviral serum. However, the development of latent murine CMV infection was not prevented by prior administration of antibody since immunosuppression with antilymphocyte serum and cortisone 16 weeks later unmasked dormant virus in 17 of 20 animals. In normal animals murine CMV-immune serum administered six days after acute virus infection had been initiated did not influence the outcome; however, in immunosuppressed mice, virus dissemination during acute infection was substantially reduced by specific antibody. These results demonstrate a significant effect of humoral immunity on the course of experimental CMV infection.

Animals↗
PubMed1981

Marek's disease as a model for the Landry--Guillain--Barré syndrome: latent viral infection in nonneuronal cells accompanied by specific immune responses to peripheral nerve and myelin.

In the chicken, Marek's disease virus (MDV) induces a demyelinating peripheral neuropathy that, early in the course of the disease, is histopathologically indistinguishable from that seen in the Landry--Guillain--Barré syndrome in man. A continuing role for a productive infection in the pathogenesis of this disease is unlikely, since neither MDV nor MDV antigens can be characteristically detected in nerves or spinal ganglia examined at necropsy. The authors investigated the possible role of a latent viral infection by explanting and maintaining in vitro the sciatic nerves and spinal ganglia from diseased birds. In these tissues, viral specific products were induced and detected by immunofluorescence and ultrastructural methods early after explanation in well-isolated Schwann cells, satellite cells, and lymphocytes. Later, virus was detected in fibroblasts, macrophages, and neoplastic lymphoblastoid cells. Neurons and myelinating Schwann cells, in contrast, did not replicate the agent. Specific cell-mediated and humoral immune responses to chicken peripheral nerve and peripheral nerve myelin were demonstrated early in the course of the disease. When considered relative to potential pathogenetic mechanisms, these results suggest that Marek's disease neuropathy is initiated by the establishment of a latent viral infection in neuronal supporting cells. A specific immune response to viral-induced antigens on these cells could, in turn, result in subsequent demyelination.

Animals↗
PubMed1980

No measles virus genetic information detected in multiple sclerosis--derived brains.

Measles virus nucleotide sequences were searched for in diseased and normal-appearing white matter from brains of four multiple sclerosis victims. At the level of sensitivity established, 2.5 to 7.8 measles virus genome-equivalents of RNA, or 4.9 genome-equivalents of putative DNA per diploid cell quantity of DNA, could have been detected. At these levels, no measles virus genetic information was found in any of the four brains.

Adult↗
PubMed1980

Latency competence of thirteen HSV-1 temperature-sensitive mutants.

Thirteen temperature-sensitive (ts) mutants of HSV-1 were analysed for their capacity to establish latent infections in the brains of mice. Eleven of the mutants could be classified as latency-positive or -negative; two could not be assigned to either group. Leakiness of mutants in the brain and differences in particle/infectivity ratios were found not to play a role in the results. Ts+ revertants of selected latency-negative mutants regained the capacity to establish latent infections, indicating that it was the ts lesion in these agents which was involved in latency. Ultrastructural studies of neuroblastoma cells infected with various mutants and maintained at the restrictive temperature showed that no absolute correlations could be made between capacity to establish latent infection and synthesis of various morphologically identifiable virus products. Finally, from a comparison of latency characteristics with previously established polypeptide phenotypes of mutants it was concluded that one immediate early and one or more later virus functions are necessary for establishment and/or maintenance of the latent state.

Animals↗
PubMed1979

Multiple copies of Shope virus DNA are present in cells of benign and malignant non-virus-producing neoplasms.

In an initial efforts to characterize the virological basis of neoplasia in the Shope papilloma-carcinoma system, the extent to which the viral genome is present in non-virus-producing benign and malignant tumors in domestic rabbits was established. Employing nick-translated radioactive viral DNA purified from productively infected papillomas on cotton tail rabbits as a probe, it was found that (i) papillomas, primary carcinomas, and metastatic carcinomas contain 10 to about 100 copies of the viral genome per diploid cell equivalent of DNA and (ii) viral DNA is present in detectable amounts in essentially all neoplastic cells. These results are consistent with the suggestion that continued presence of the viral genome is necessary for induction and maintenance of malignant as well as benign neoplasms.

Animals↗
PubMed1979

Pathogenesis of reactivated latent murine cytomegalovirus infection.

Sixteen weeks after inoculation, murine cytomegalovirus (MCMV) can no longer be detected in the tissues of mice. However, a 2-week course of immunosuppression with antilymphocyte serum and cortisone acetate results in reactivation and dissemination of the latent virus in all animals. In this study of reactivation, MCMV was first detected in the liver, usually during the first week of immunosuppression, and virus replication was shown to be restricted to hepatocytes. Subsequently, a viremia occurred, with spread of infection to other organs. The highest titers of virus were reached in salivary glands in which replication occurred in serous acinar cells. In the lung, virus-specific abnormalities were difficult to detect because of superimposed bacterial and fungal infections. However, interstitial pneumonitis could be produced when cortisone acetate was deleted from the immunosuppressive regimen. Although the site of virus latency has not been defined, this model system will be useful for study of reactivation of latent cytomegalovirus infection.

Animals↗