Analysis of the Fv1 alleles involved in the susceptibility of mice to lactate dehydrogenase-elevating virus-induced polioencephalomyelitis.

Development of polioencephalomyelitis in mice infected with lactate dehydrogenase-elevating virus (LDV) requires expression of N-tropic ecotropic MuLV retroviruses. 129/Sv mice are resistant to N-tropic MuLV expression and therefore do not develop LDV-induced polioencephalomyelitis. The Fv1 gene determines the susceptibility to retrovirus replication. We sequenced the open reading frame of the Fv1nr allele of 129/Sv mice. It differs by only one nucleotide, modifying one amino acid in the encoded protein, from the Fv1n allele of susceptible AKR and C58 animals. We excluded that the resistance of 129/Sv mice to LDV-induced polioencephalomyelitis resulted from the absence of endogenous N-tropic retrovirus, by infecting (129/Sv x C58/J) F1 animals. Therefore it is possible that the amino acid that defines the Fv1nr allele is responsible for resistance of 129/Sv mice to N-tropic MuLV expression and to LDV-induced polioencephalomyelitis.

Is there a causal link between hepatitis B vaccination and multiple sclerosis?

After the publication of case reports of hepatitis B vaccinees with onset or relapse of multiple sclerosis (MS), followed by a media-driven scare campaign in France, the perception that hepatitis B vaccine causes MS has developed. This has led to a fall in the acceptance of hepatitis B vaccination particularly in French-speaking communities which was accelerated by court decisions in favour of vaccination "victims" and the suspension of routine vaccination of pre-adolescents in French schools as a "precautionary measure". This situation has arisen in spite of the absence of scientific data to support a causal link between vaccination and multiple sclerosis. In this article, initially written to inform and reassure employees of one of the vaccine manufacturers, the epidemiological importance of hepatitis B and current knowledge on the aetiology of MS are described. All available data that may throw light on the hypothesis that hepatitis B vaccination is causally linked to MS was reviewed. The conclusion reached on the basis of available data is that the most plausible explanation for the observed temporal association between vaccination and MS is that it is a coincidental association. It is now important to rebuild public confidence in hepatitis B vaccine as well as in vaccination in general.

[Viral infection of the central nervous system: from experimental model to human application]. / Infection virale du système nerveux central: du modèle expérimental à l'application humaine.

The Daniel's strain of Theiler's virus, a murine picorna virus, induces a neurological disease characterized by an acute encephalomyelitis, followed by a persistent infection of the white matter. This late demyelinating disease is studied as a model for multiple sclerosis because of its chronicity and similarity to the histology of the lesions. This mouse model of viral infection allows a review of the various major aspects of the immune response to an infection of the central nervous system. The observation that inbred strains of mice differ in their susceptibility to the demyelinating disease provided the base for genetic studies that were informative for the involved functional immunological mechanisms. A locus in the H-2D region of the major histocompatibility complex was shown to control susceptibility to the persistent infection, leading to approach the key role of CTLs. Non-H-2 genes were also implicated, one of which was mapped close to the IFN-gamma locus on chromosome 10. The key role of IFN-gamma was demonstrated, and led to a further investigation of the function of the potential producers of this cytokine, namely NK, CD8+, and CD4+ Th1 cells. Finally, non-immune factors were also shown to play a role in resistance. A personal view of the antiviral immune responses emerged from this review.

The Th1/Th2 balance does not account for the difference of susceptibility of mouse strains to Theiler's virus persistent infection.

Theiler's virus causes a persistent infection with demyelination that is studied as a model for multiple sclerosis. Inbred strains of mice differ in their susceptibility to viral persistence due to both H-2 and non-H-2 genes. A locus with a major effect on persistence has been mapped on chromosome 10, close to the Ifng locus, using a cross between susceptible SJL/J and resistant B10.S mice. We now confirm the existence of this locus using two lines of congenic mice bearing the B10.S Ifng locus on an SJL/J background, and we describe a deletion in the promoter of the Ifng gene of the SJL/J mouse. We studied the expression of IFN-gamma, IL-2, IL-10, and IL-12 in the brains of SJL/J mice, B10.S mice, and the two lines of congenic mice during the first 2 wk following inoculation. We found a greater expression of IFN-gamma and IL-2 mRNA in the brains of B10.S mice compared with those of SJL/J mice. Also, the ratio of IL-12 to IL-10 mRNA levels was higher in B10.S mice. However, the cytokine profiles were the same for the two lines of resistant congenic mice and for susceptible SJL/J mice. Therefore, the difference of Th1/Th2 balance between the B10.S and SJL/J mice is not due to the Ifng locus and does not account for the difference of susceptibility of these mice to persistent infection.

Expression of costimulatory molecules and cytokines in CSF and peripheral blood mononuclear cells from multiple sclerosis patients.

We amplified the mRNA for cytokines in peripheral blood mononuclear cells (PBMC) and cerebrospinal fluid (CSF) cells from 18 multiple sclerosis (MS) patients and 21 other neurological patients, using the reverse transcription polymerase chain reaction (RT-PCR). Radioactive hybridization of the amplified DNA allowed quantitation of mRNA levels. Expression of tumor necrosis factor (TNF)-alpha, interferon (IFN)-gamma and interleukin (IL)-10 mRNA was elevated in CSF cells from MS patients. IFN-gamma and IL-10 mRNA levels were higher in MS patients than in other inflammatory neurological diseases. mRNA coding for transforming growth factor (TGF)-beta was detectable in the majority of cases, with higher expression in CSF cells of MS and other inflammatory neurological diseases than in noninflammatory controls, and higher expression in PBMC of MS patients than in all other cases. In many MS patients both proinflammatory and immunoregulatory cytokine messages were detected in the CSF compartment without correlation with the clinical activity of the disease. In contrast, mRNA for the costimulatory molecule B7.1 was only detected in the CSF cells of some MS patients, who showed clinical signs of acute relapse at the time of the spinal tap.

B7-1 (CD80), B7-2 (CD86), interleukin-12 and transforming growth factor-beta mRNA expression in CSF and peripheral blood mononuclear cells from multiple sclerosis patients.

Costimulatory molecules B7-1 (CD80) and B7-2 (CD86) are differently involved in T cell stimulation. In chronic experimental autoimmune encephalomyelitis (EAE) model of multiple sclerosis (MS), B7-1 was preferentially involved in pathophysiology of relapses. We used reverse transcription polymerase chain reaction (RT-PCR) to amplify the mRNA coding for these molecules in cerebrospinal fluid (CSF) cells and peripheral blood mononuclear cells (PBMC) from 18 MS patients and 21 other neurological patients. In CSF cells of MS cases, B7-1 mRNA was only detected in some patients who showed clinical signs of acute relapse at the time of the spinal tap, while B7-2 mRNA was widely detectable without difference between active or stable MS and controls. mRNA coding for transforming growth factor-beta (TGF-beta) was detectable in the majority of cases, with higher expression in CSF cells of MS and other inflammatory neurological diseases (OIND) than in noninflammatory controls, and higher expression in PBMC of MS patients than in all other cases. Finally, mRNA coding for interleukin (IL)-12p40 was only detected in a very few number of MS and inflammatory cases. These findings were related to previous detection of other cytokines in the same cases, showing relationships in CSF cells between high expression of B7-1, IL-12p40 and TNF-alpha.

Data on cytokine mRNA expression in CSF and peripheral blood mononuclear cells from MS patients as detected by PCR.

Reverse transcription polymerase chain reaction (RT-PCR) was used to amplify the mRNA coding for different cytokines in peripheral blood mononuclear cells (PBMC) and cerebrospinal fluid (CSF) cells from 18 multiple sclerosis (MS) patients as compared with 21 other neurological patients. mRNA levels were quantitated by radioactive hybridization of the PCR products. Expression of tumor necrosis factor (TNF)-alpha, interferon (IFN)-gamma, and interleukin (IL)-10 mRNA was elevated in CSF cells of MS patients. In many MS patients, both proinflammatory and immunoregulatory cytokine messages were detected in the CSF compartment. Such immune reactivity of CSF cells, as opposed to PBMC, was not associated with higher clinical activity of the disease. Expression of the B7.1 accessory molecule mRNA was similarly investigated. In the CSF, it was detected only in some clinically active MS cases and in other inflammatory diseases.

Viruses and multiple sclerosis.

Animal models illustrate how viruses and host genetic factors may interact to cause immune-mediated demyelination. Similar mechanisms may take place in at least some forms of multiple sclerosis, a disease that is histopathologically heterogeneous. No 'multiple sclerosis virus' has been found yet, although recent data on human herpesvirus-6 antigens in multiple sclerosis brain warrant further investigation. Multiple sclerosis associated retrovirus, a recently described retroviral sequence isolated from multiple sclerosis material, is a member of the endogenous retrovirus-9 family. The association between the expression of this virus associated retrovirus and multiple sclerosis is only tentative.

Lymphocytic choriomeningitis virus-induced alterations of T helper-mediated responses in mice developing autoimmune hemolytic anemia during the course of infection.

The effect of LCMV on CD4+ T lymphocytes was analyzed in C3HeB/FeJ mice after infection with the Docile strain of this virus. Our results indicated that LCMV triggers: i) an inhibition of Th2 lymphocyte differentiation induced by concomitant immunization with a nonviral protein antigen; ii) a depression of T helper-dependent antibody responses elicited by such an immunization; and iii) a CD4+ cell-mediated proliferation of spleen cells leading to increased interleukin-4 and interferon-gamma message expression and IgG2a-restricted total immunoglobulin secretion. Taken together, these results indicate that LCMV profoundly affects CD4+ cell-mediated immune responses in infected animals. Such modulations of T-helper functions may explain the preponderance of IgG2a in the antierythrocyte autoimmune response induced by the virus in C3HeB/FeJ mice.

Diagnosis and clinical management of neurological disorders caused by cytomegalovirus in AIDS patients. European Union Concerted Action on Virus Meningitis and Encephalitis.

Cytomegalovirus (CMV) infections are common and severe complications of HIV infection. The virus involves the nervous system, causing encephalitis, polyradiculomyelitis and peripheral neuropathies. Due to their limited sensitivity, traditional virological approaches, such as virus isolation or antigen detection in the CSF are useful only in limited instances, e.g. CMV polyradiculopathy. The aetiological diagnosis of these disorders relies on the analysis of cerebrospinal fluid by PCR and quantitative PCR may be important to establish the extent of CNS lesions and to monitor the efficacy of antiviral treatments. CMV is susceptible to various antivirals, including ganciclovir, foscarnet and cidofovir. CMV infections of the nervous system, in particular encephalitis, however, show only a poor response to standard treatments. Drug combination treatments i.e. ganciclovir plus foscarnet, are currently under evaluation in clinical trials.

Cytokine mRNA expression in CSF and peripheral blood mononuclear cells in multiple sclerosis: detection by RT-PCR without in vitro stimulation.

We amplified the mRNA for cytokines in peripheral blood mononuclear cells (PBMC) and cerebrospinal fluid (CSF) cells from 18 multiple sclerosis (MS) patients and 21 other neurological patients, using reverse transcription polymerase chain reaction (RT-PCR). A radioactive hybridization of the amplified DNA allowed quantitation of mRNA levels. Expression of tumor necrosis factor (TNF)-alpha, interferon (IFN)-gamma and interleukin (IL)-10 mRNA was elevated in CSF cells of MS patients. IFN-gamma and IL-10 mRNA levels were higher in MS patients than in other inflammatory neurological diseases. In many MS patients, both proinflammatory and immunoregulatory cytokine messages were detected in the CSF compartment. Such immune reactivity in CSF, as opposed to the peripheral compartment, did not correlate with the clinical activity of the disease.

IL-4-independent regulation of in vivo IL-9 expression.

We focused on the role of IL-4 in the regulation of the Th2 cytokine IL-9. In vivo, IL-9 mRNA was detected in lymph nodes after immunization with soluble Ags. IL-9 expression preceded that of IL-4, and was not affected in IL-4 knockout mice. In contrast, a significant decrease of IL-9 message was observed in IL-10-deficient mice, indicating a role for this cytokine in the induction of IL-9 production. Treatment with anti-CD4 Ab and analysis of purified CD4 cells confirmed that IL-9 was produced by CD4+ cells. Moreover, similarly to what has been reported for IL-4, IL-9 message induction was strongly decreased by infection with lactate dehydrogenase-elevating virus. IL-9 mRNA was also detected after in vivo stimulation with anti-CD3 Ab. In this model, IL-9 expression followed that of IL-4, but was not reduced in IL-4-deficient mice. This contrasts with in vitro stimulation in which, as reported in humans, IL-9 expression in lymphocytes incubated with anti-CD3 Ab and costimulatory molecules appeared as a late event, and was partly dependent on IL-4. In vitro IL-9 secretion was reduced significantly by addition of anti-IL-4 Ab, as well as in lymphocytes from IL-4 gene-deficient mice. Taken together, our results indicate that the Th2 cytokine IL-9 can be expressed by both IL-4-dependent and -independent pathways.

Specific diagnostic methods for herpesvirus infections of the central nervous system: a consensus review by the European Union Concerted Action on Virus Meningitis and Encephalitis.

BACKGROUND: Herpesvirus infections of the central nervous system are often severe but are fortunately rare. The incidence of these infections has however, increased in recent years as a consequence of an increase in the number of immune-compromised individuals. New diagnostic procedures have improved our ability to diagnose these infections and herpesviruses may yet be implicated as the cause of further neurological diseases with no known aetiology. Methodological standards for selection and evaluation of patient materials are essential to the provision of reliable diagnosis, yet few studies have addressed this important issue. OBJECTIVES: To describe and define methodological standards and reference methodology for diagnosis of herpesvirus infections of the CNS. STUDY DESIGN: Information gathered by literature review. RESULTS: Only for herpes simplex encephalitis is there sufficient data to allow the definition of reference methodology. Good methodological standards exist but few studies have adhered to these standards. As methods for the detection of specific intrathecal antibody synthesis are well established yet under-used in diagnostic virology, the principle of these measurements is reviewed in some detail. CONCLUSIONS: Herpesvirus infections of the CNS are of increasing importance. High quality, multi-centre studies are needed to establish the value of the new diagnostic test procedures if further improvement in the diagnostic sensitivity and specificity of these procedures is to be achieved.

The detection of intrathecal synthesis of anti-herpes simplex IgG antibodies: comparison between an antigen-mediated immunoblotting technique and antibody index calculations. European Union Concerted Action on Virus Meningitis and Encephalitis.

The detection of intrathecal antibody synthesis was compared by the calculation of antibody indices (AI) derived from ELISA techniques with the detection of virus-specific oligoclonal IgGs by an antigen-mediated capillary blot technique. Twenty-seven paired serum and cerebrospinal fluid (CSF) samples were examined from 15 immunocompetent patients with herpes simplex virus encephalitis (HSE) diagnosed by PCR on early CSF samples. These techniques were also applied to paired samples from 20 multiple sclerosis (MS) patients, 10 patients with other inflammatory neurological diseases and 10 patients with non inflammatory neurological disorders. There was a good correlation between the results obtained by AI and those obtained by immunoblotting, especially in HSE (2 discordant results out of 27). Discrepancies were more frequent (25%) in MS patients where a "polyspecific" reaction characterized by low affinity antibodies is known to occur. Some of the discrepancies could, in part, be due to serological cross-reaction with varicella zoster virus.

Encephalitis in immunocompetent patients due to herpes simplex virus type 1 or 2: determination by polymerase chain reaction and detection of intrathecal virus-specific oligoclonal antibodies.

Serum and cerebrospinal fluid (CSF) of 13 patients have been examined to confirm and precise the diagnosis of herpes simplex virus encephalitis (HSVE). By amplifying the DNA with a nested polymerase chain reaction (PCR), we could demonstrate the herpetic origin of these cases of encephalitis. DNA of HSV type 1 or type 2 was directly identified and differentiated, by the use of both type-specific primes in the same reaction. The primer sequences were chosen in the glycoprotein D region for HSV type 1, and in the glycoprotein G region for HSV type 2. Only one case was due to the latter. In all but one cases, an immunoaffinity-mediated capillary blotting study was also performed. This technique showed the occurrence of oligoclonal CSF-specific IgG bands, while the antigen-driven immunoblotting demonstrated intrathecal production of oligoclonal anti HSV antibodies. In most of the cases, repeated CSF analysis allowed us to study the sequential detection of viral DNA and of intrathecal synthesis of virus-specific IgG in relation to the clinical course. All the patients were treated with acyclovir. In one case, a relapse was clinically suspected, but the PCR remained negative.

The infection of mouse by Theiler's virus: from genetics to immunology.

Theiler's virus is a picornavirus of mouse which causes an acute encephalomyelitis followed by a persistent infection of the white matter of the spinal cord with chronic inflammation and demyelination. This late disease is studied as a model for multiple sclerosis. Inbred strains of mice differ in their susceptibility to persistent infection and demyelination. Resistant strains clear the infection after the acute encephalomyelitis. This observation is the basis of genetic studies which we used as a thread for this review. The H-2D locus has a major effect on susceptibility. The H-2Db gene is involved in a fast and intense CTL response which confers resistance. The Tcrb locus is also implicated, although there is no proof that the susceptibility gene in this region codes for the T-cell receptor. A complete screen of the genome uncovered the role of the Ifng locus and led to the demonstration that IFN-gamma limits viral spread in the white matter. The roles of NK cells and B cells in limiting the infection are discussed. CD4+ T cells participate both in protection against the infection and in demyelination. Finally, the effect of non-immune factors in resistance is illustrated by mice with mutations in the MBP or PLP gene.

Involvement of CD4+ cells in the protection of C58 mouse against polioencephalomyelitis induced by lactate dehydrogenase-elevating virus.

Immunosuppression, occurring naturally with aging, or experimentally after cyclophosphamide treatment or irradiation, is required for the development in C58 mice infected with lactate dehydrogenase-elevating virus (LDV) of a severe polioencephalomyelitis that is caused by viral destruction of anterior horn neurons. Here it is shown that depletion of T helper lymphocytes by administration of an anti-CD4 antibody was followed by a progressive paralysis typical of polioencephalomyelitis in C58/J mice inoculated with a neurovirulent strain of LDV. Although it was clear that other cell subsets are also required to assure complete protection of genetically-susceptible mice, our results show that T helper lymphocytes play a major role in the prevention of LDV-induced polioencephalomyelitis. The mechanisms by which these cells confer this protection remain however to be determined.

The role of laboratory investigation in the diagnosis and management of patients with suspected herpes simplex encephalitis: a consensus report. The EU Concerted Action on Virus Meningitis and Encephalitis.

As effective therapies for the treatment of herpes simplex encephalitis (HSE) have become available, the virology laboratory has acquired a role of primary importance in the early diagnosis and clinical management of this condition. Several studies have shown that the polymerase chain reaction (PCR) of CSF for the detection of herpes simplex virus type 1 (HSV-1) or type 2 (HSV-2) DNA provides a reliable method for determining an aetiological diagnosis of HSE. The use of PCR in combination with the detection of a specific intrathecal antibody response to HSV currently represents the most reliable strategy for the diagnosis and monitoring of the treatment of adult patients with HSE. The use of these techniques has also led to the identification of atypical presentations of HSV infections of the nervous system and permits the investigation of patients who develop a relapse of encephalitic illness after an initial episode of HSE. A strategy for the optimal use of the investigative laboratory in the diagnosis of HSE and subsequent management decisions is described.

The anti-Hu syndrome: a clinical and immunological study of 7 cases.

The authors describe the clinical and biological data of seven patients with anti-Hu antibodies. Six of them displayed a small cell lung carcinoma (SCLC), but no cancer was detected in the 7th patient in spite of an extensive workup. The clinical heterogeneity of the anti-Hu syndrome is emphasized. The major symptoms were linked to a severe sensory neuropathy in three cases, to cerebellitis in two cases, to dysautonomia in one case, and to gastro-intestinal pseudo-obstruction in one case. One patient also displayed EMG abnormalities characteristic of the Lambert-Eaton myasthenic syndrome. Two patients developed opsoclonus or ocular flutter associated with severe confusion in the late stage of their disease. In four patients, the neurological signs and symptoms preceded the discovery of the SCLC, and in two cases the initial detection of anti-Hu antibodies prompted the successful search for this tumor. Immunopathological events injuring the peripheral and central nervous system are briefly discussed.