P. Monteyne

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.

Diagnosis and clinical management of neurological disorders caused by cytomegalovirus in AIDS patients

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.

Natural killer cell activation after infection with lactate dehydrogenase-elevating virus.

Early after infection, lactate dehydrogenase-elevating virus (LDV) alters the immune system by polyclonally activating B lymphocytes, which leads to IgG2a-restricted hypergammaglobulinaemia, and by suppressing the secretion of Th2 cytokines. Considering that these alterations may involve cells of the innate immune system and cytokines such as interferon-gamma (IFN-gamma), we analysed the effect of LDV on natural killer (NK) cells. Within a few days of infection, a strong and transient NK cell activation, characterized by enhanced IFN-gamma message expression and cytolysis, was observed. LDV triggered a large increase in serum IFN-gamma levels. Because NK cells and IFN-gamma may participate in the defence against virus infection, we analysed their possible role in the control of LDV titres with a new agglutination assay. Our results indicate that neither the activation of NK cells nor the IFN-gamma secretion affect the early and rapid virus replication that follows LDV inoculation.

Inhibition by lactate dehydrogenase-elevating virus of in vivo interleukin 4 production during immunization with keyhole limpet haemocyanin.

Interleukin 4 (IL-4) and gamma interferon (IFN-gamma) gene expression in lymph node cells from mice immunized with keyhole limpet haemocyanin in the presence of complete Freunds adjuvant was analysed by polymerase chain reaction. This immunization clearly induced the expression of IL-4 message, whereas IFN-gamma message was only slightly increased. A concomitant infection with lactate dehydrogenase-elevating virus drastically decreased IL-4 expression whereas IFN-gamma message was not modified. Analysis of the kinetics of cytokine production indicated that the virus did not induce a mere change in the timing of lymphokine production, but a persistent inhibition of IL-4.

Recurrent meningitis and encephalitis associated with herpes simplex type 2: demonstration by polymerase chain reaction.

Pierre Mollaret described his first case of benign recurrent meningitis in 1928. About 50 years later, he wrote that nothing could be added to the original description and that the etiology remained to be discovered [1]. However, thanks to new technologies such as immu-noblotting and polymerase chain reaction (PCR) it is now sometimes possible to demonstrate the infectious origin of such syndromes. We describe a patient who developed seven episodes of meningitis and encephalitis. These episodes were found to be associated with herpes simplex type 2 (HSV 2) infection. The male patient, born in 1924, had a history of recurrent meningitis and meningoencephalitis between 1974 and 1992. In 1974, 1975 and in February 1979, he was admitted to another hospital for episodes of ‘aseptic meningitis’ with rapid recovery. He was first admitted to our center in May 1979 with fever, headache, drowsiness, and a stiff neck. There were no genital vesicles, and no history of genital herpes was reported. CT brain scan revealed only slight diffuse atrophy. Lumbar puncture showed a high protein level and 960 cells/mm with 59% lymphocytes (table 1). He recovered spontaneously and rapidly. In December 1988, he was admitted for a similar episode with the same symptoms in addition to aphasia and agitation. The EEG displayed abundant diffuse slow activity with anterior predominance. He recovered in 2 days, and developed another similar episode in November 1989. In December 1992, he was hospitalized with fever, aggressiveness and disorientation. His language was inadequate and the patient became confused. The EEG was diffusely slow and irregular with discharges of large slow 5and 6-waves. As in previous episodes, he recovered rapidly. The principal results of CSF analysis are summarized in table 1. In all the samples, immunoblotting demonstrated oligoclonal IgG bands with similar patterns for both CSF and sera. Moreover, some additional CSF-restricted IgG bands were detected. An immunoaf-finity-blotting technique revealed a polyclonal pattern of anti-HSV antibodies present in both serum and CSF, also with some additional

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

Abstract 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-γ 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.

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.

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.