Biomedical subjects

E Cash

Publications and source records attributed to E Cash.

27 records · Page 2Linked to original sources

PubMed1991

Role of the humoral immune response in resistance to Theiler's virus infection.

Theiler's virus, a murine picornavirus, persists in the central nervous system of susceptible strains of mice, causing chronic inflammation and demyelination in the white matter of the spinal cord. Resistant strains, however, clear the virus and do not develop late disease. In this study, we compared the characteristics of T and B lymphocytes in C57BL/6 (resistant) and SJL/J (susceptible) mice 1 week after intracerebral infection. We detected a marked increase of the number of immunoglobulin M (IgM)-secreting cells in the spleens of C57BL/6 detected a marked increase of the number of immunoglobulin M (IgM)-secreting cells in the spleens of C57BL/6 mice (but not in those of SJL/J mice), which correlated with higher levels of serum IgM antiviral antibodies. The role of the humoral response in virus clearance and resistance was demonstrated by a marked decrease in the number of infected spinal cord cells in SJL/J mice after passive transfer of serum from infected C57BL/6 donors. The B-cell response was found to be partly T cell independent. These results suggest an important role of the early humoral immune response in resistance to Theiler's virus-induced disease.

Animals↗

PubMed1989

Characterization of B lymphocytes present in the demyelinating lesions induced by Theiler's virus.

Theiler's virus, a murine picornavirus, persists in the central nervous system of SJL/J mice and causes inflammation and demyelination in the white matter of spinal cord. We isolated inflammatory cells from the central nervous system of infected animals and studied their functions in vitro. Flow microfluorimetry analysis showed the presence of all major lymphocyte subsets, namely CD4+ and CD8+ T cells as well as B lymphocytes. B lymphocytes were activated in vitro and the antigenic specificity of secreted Ig was determined by immunoblotting. Secreted Ig reacted strongly with viral capsid proteins VP1 and VP2 and had neutralizing activity. They reacted also with two nonviral white matter components which were present only in infected animals. Therefore, it is likely that Igs secreted at the site of infection play a role in limiting virus spread. It is also possible that virus induced autoreactive antibodies participate in demyelination.

Animals↗

PubMed1988

Minus-strand RNA synthesis in the spinal cords of mice persistently infected with Theiler's virus.

Theiler's virus, a murine picornavirus, causes a chronic neurological disease characterized by primary demyelination in SJL/J mice. The lesions are very reminiscent of those of multiple sclerosis. Theiler's virus persists in oligodendrocytes and to a lesser extent in astrocytes and macrophages throughout the disease. Viral RNA and capsid protein syntheses are minimal in these cells. This restriction could play a central role in the mechanism of virus persistence. By quantitating plus- and minus-strand RNAs in infected central nervous system cells, we showed that RNA replication was blocked at the level of minus-strand RNA synthesis.

Animals↗

PubMed1986

Quantitative in situ hybridization using initial velocity measurements.

In situ hybridization can be used to quantitate viral RNA at the single cell level by measuring levels of hybridization after saturation hybridization with an excess of cDNA probe has been achieved (1,2). In this paper we describe an alternative approach which consists in measuring the initial hybridization rate using a low concentration of cDNA probe and a short hybridization time. Under these conditions, we obtained a linear relationship between the number of autoradiographic grains and the number of viral genomes per cell in the range of 600 to 60,000 copies per cell of a 7-kb RNA genome. This approach allows an accurate measurement of copy number in a range for which saturation in situ hybridization is very difficult to achieve.

Autoradiography↗

PubMed1986

Quantitation, with a new assay, of Theiler's virus capsid protein in the central nervous system of mice.

We developed a quantitative assay for antigens at the single-cell level. Tissue sections were reacted with a primary antibody, a biotinylated secondary antibody, or 35S-streptavidin. Binding of streptavidin to cells was quantitated by microscopic autoradiography. We showed that the number of autoradiographic grains was proportional to the amount of antigen per cell. With this assay, we studied the synthesis of Theiler's virus capsid proteins VP1, VP2, and VP3 in permissive BHK cells grown in vitro and in mouse central nervous system (CNS) cells during a persistent infection. We found that synthesis of the three capsid proteins was restricted in mouse CNS cells. Restricted virus replication could play a major role in the persistence of Theiler's virus in mouse CNS cells.

Animals↗

PubMed1985

Theiler's virus RNA and protein synthesis in the central nervous system of demyelinating mice.

We studied Theiler's virus RNA and capsid protein synthesis in sections of mouse spinal cord using in situ hybridization coupled to immunoperoxidase. We found that the majority of infected cells contain 100 to 500 viral genomes and no detectable capsid antigens. Similarly, baby hamster kidney (BHK) cells, which are permissive to Theiler's virus, do not synthesize capsid if they contain less than 1000 viral genomes. Our results demonstrate that virus multiplication is restricted in vivo at the level of RNA replication. They suggest that RNA restriction is sufficient to explain the lack of capsid antigen synthesis.

Animals↗

PubMed1985

Detection of picornavirus sequences in nervous tissue of amyotrophic lateral sclerosis and control patients.

We used in situ hybridization to look for picornavirus ribonucleic acid (RNA) sequences in frozen sections of central nervous system (CNS) tissue of amyotrophic lateral sclerosis (ALS) and control patients. Using reconstruction experiments, we concluded that 30 copies of viral RNA per cell could be detected with the assay. RNA which hybridized to DNAs complementary (cDNAs) to both poliovirus and Theiler's virus was found at several levels in the CNS of 2 patients, 1 ALS patient, and 1 control. In transverse sections of the spinal cord, these sequences predominated in cells of the anterior horns. We assessed the specificity of hybridization by several criteria: no hybridization was observed with heterologous visna virus cDNA probes; hybridization was abolished by pretreatment of the sections with ribonuclease; chemography artifacts were ruled out; and the results were reproduced in three independent experiments. We concluded that RNA molecules, possibly belonging to a picornavirus having sequences in common with poliovirus and Theiler's virus, were present in the CNS of these 2 patients. On the other hand, 14 cases of classic ALS, 2 cases of Guamanian parkinsonian dementia, and 5 controls had negative results. However, the presence of picornavirus sequences in our series could be underestimated because in many cases autolysis times were 10 hours or longer.

Amyotrophic Lateral Sclerosis↗

PubMed1984

Simultaneous in situ detection of viral RNA and antigens.

We have combined in situ hybridization and immunocytochemistry to detect RNA and proteins in the same cell. We envision a wide range of applications for this method, and, as one example, we show that viral genomes and capsid antigens can be detected simultaneously in paraffin sections of the central nervous system of mice infected with Theiler's virus, the causative agent of a slow demyelinating disease.

Animals↗

PubMedDate not supplied

Desensitization of the antigen receptor primes B cells for activation by superstimulatory influenza virus.

Interaction of the B cell receptor (BCR) with non-immunogenic receptor ligands can induce a specific state of B cell unresponsiveness as a result of receptor desensitization. Provided it is maintained over time, BCR desensitization may provide the molecular basis for clonal anergy. Using an in vitro model of anti-Ig-mediated BCR desensitization, we assessed the susceptibility of desensitized "anergic" B lymphocytes to activation by B cell superstimulatory influenza virus hemagglutinin (HA). Rabbit anti-mouse Ig antibodies (whole Ig molecule or F(ab')(2)-fragments) totally abolished the response of murine B cells to HA, when added simultaneously with the virus. Pretreatment with the same antibodies, however, yielding a complete unresponsiveness to a subsequent challenge with normally mitogenic anti-Ig reagents, even enhanced the subsequent proliferative response to HA. By contrast, HA-mediated high-rate immunoglobulin synthesis was suppressed after desensitization. BCR-desensitized, HA-stimulated B cells exhibited a hyperexpression of various activation markers (B7, major histocompatibility complex class II, CD25) and served as potent antigen-presenting cells (APC) in a polyclonal model for T lymphocyte activation. These observations suggest a possible scenario for the breaking of natural B cell tolerance, where infections with B cell superstimulatory viruses may lead to the clonal expansion of receptor desensitized, functionally silenced B lymphocytes in vivo.

Animals↗