Viral infections and demyelinating diseases

Demyelinating strain of mouse hepatitis virus infection bridging innate and adaptive immune response in the induction of demyelination

The presence of immunoglobulin oligoclonal bands in the cerebrospinal fluid of Multiple Sclerosis (MS) patients supports the hypothesis of an infectious etiology, although the antigenic targets remain elusive. Neurotropic mouse hepatitis virus (MHV) infection in mice provides a useful tool for studying mechanisms of demyelination in a virus-induced experimental model of MS. This study uses Affymetrix microarray analysis to compare differential spinal cord mRNA levels between mice infected with demyelinating and non-demyelinating strains of MHV to identify host immune genes expressed in this demyelinating disease model. The study reveals that during the acute stage of infection, both strains induce inflammatory innate immune response genes, whereas upregulation of several immunoglobulin genes during chronic stage infection is unique to infection with the demyelinating strain. Results suggest that the demyelinating strain induced an innate-immune response during acute infection that may promote switching of Ig isotype genes during chronic infection, potentially playing a role in antibody-mediated progressive demyelination even after viral clearance.

Neurotropic Coronavirus Infections

Neurotropic strains of the mouse hepatitis virus (MHV) cause a range of diseases in infected mice ranging from mild encephalitis with clearance of the virus followed by demyelination to rapidly fatal encephalitis. This chapter discusses the structure, life cycle, transmission, and pathology of neurotropic coronaviruses, as well as the immune response to coronavirus infection. Mice infected with neurotropic strains of MHV have provided useful systems in which to study processes of virus- and immune-mediated demyelination and virus clearance and/or persistence in the CNS, and the mechanisms of virus evasion of the immune system.

Microglia-mediated neuroinflammation is an amplifier of virus-induced neuropathology

Microglia, the major resident immune cells in the central nervous system (CNS) are considered as the key cellular mediators of neuroinflammatory processes. In the past few years, microglial research has become a main focus in cellular neuroimmunology and neuroinflammation. Chronic/remitting neurological disease such as multiple sclerosis (MS) has long been considered an inflammatory autoimmune disease with the infiltration of peripheral myelin-specific T cells into the CNS. With the rapid advancement in the field of microglia and astrocytic neurobiology, the term neuroinflammation progressively started to denote chronic CNS cell-specific inflammation in MS. The direct glial responses in MS are different from conventional peripheral immune responses. This review attempts to summarize current findings of neuroinflammatory responses within the CNS by direct infection of neural cells by mouse hepatitis virus (MHV) and the mechanisms by which glial cell responses ultimately contribute to the neuropathology on demyelination. Microglia can be persistently infected by MHV. Microglial activation and phagocytosis are recognized to be critically important in the pathogenesis of demyelination. Emerging evidence for the pathogenic role of microglia and the activation of inflammatory pathways in these cells in MHV infection supports the concept that microglia induced neuroinflammation is an amplifier of virus-induced neuropathology.

Microglia play a major role in direct viral-induced demyelination

Microglia are the resident macrophage-like populations in the central nervous system (CNS). Microglia remain quiescent, unable to perform effector and antigen presentation (APC) functions until activated by injury or infection, and have been suggested to represent the first line of defence for the CNS. Previous studies demonstrated that microglia can be persistently infected by neurotropic mouse hepatitis virus (MHV) which causes meningoencephalitis, myelitis with subsequent axonal loss, and demyelination and serve as a virus-induced model of human neurological disease multiple sclerosis (MS). Current studies revealed that MHV infection is associated with the pronounced activation of microglia during acute inflammation, as evidenced by characteristic changes in cellular morphology and increased expression of microglia-specific proteins, Iba1 (ionized calcium-binding adaptor molecule 1), which is a macrophage/microglia-specific novel calcium-binding protein and involved in membrane ruffling and phagocytosis. During chronic inflammation (day 30 postinfection), microglia were still present within areas of demyelination. Experiments performed in ex vivo spinal cord slice culture and in vitro neonatal microglial culture confirmed direct microglial infection. Our results suggest that MHV can directly infect and activate microglia during acute inflammation, which in turn during chronic inflammation stage causes phagocytosis of myelin sheath leading to chronic inflammatory demyelination.

Coronavirus pathogenesis

Coronaviruses infect many species of animals including humans, causing acute and chronic diseases. This review focuses primarily on the pathogenesis of murine coronavirus mouse hepatitis virus (MHV) and severe acute respiratory coronavirus (SARS-CoV). MHV is a collection of strains, which provide models systems for the study of viral tropism and pathogenesis in several organs systems, including the central nervous system, the liver, and the lung, and has been cited as providing one of the few animal models for the study of chronic demyelinating diseases such as multiple sclerosis. SARS-CoV emerged in the human population in China in 2002, causing a worldwide epidemic with severe morbidity and high mortality rates, particularly in older individuals. We review the pathogenesis of both viruses and the several reverse genetics systems that made much of these studies possible. We also review the functions of coronavirus proteins, structural, enzymatic, and accessory, with an emphasis on roles in pathogenesis. Structural proteins in addition to their roles in virion structure and morphogenesis also contribute significantly to viral spread in vivo and in antagonizing host cell responses. Nonstructural proteins include the small accessory proteins that are not at all conserved between MHV and SARS-CoV and the 16 conserved proteins encoded in the replicase locus, many of which have enzymatic activities in RNA metabolism or protein processing in addition to functions in antagonizing host response.

Coronavirus pathogenesis

Coronaviruses infect many species of animals including humans, causing acute and chronic diseases. This review focuses primarily on the pathogenesis of murine coronavirus mouse hepatitis virus (MHV) and severe acute respiratory coronavirus (SARS-CoV). MHV is a collection of strains, which provide models systems for the study of viral tropism and pathogenesis in several organs systems, including the central nervous system, the liver, and the lung, and has been cited as providing one of the few animal models for the study of chronic demyelinating diseases such as multiple sclerosis. SARS-CoV emerged in the human population in China in 2002, causing a worldwide epidemic with severe morbidity and high mortality rates, particularly in older individuals. We review the pathogenesis of both viruses and the several reverse genetics systems that made much of these studies possible. We also review the functions of coronavirus proteins, structural, enzymatic, and accessory, with an emphasis on roles in pathogenesis. Structural proteins in addition to their roles in virion structure and morphogenesis also contribute significantly to viral spread in vivo and in antagonizing host cell responses. Nonstructural proteins include the small accessory proteins that are not at all conserved between MHV and SARS-CoV and the 16 conserved proteins encoded in the replicase locus, many of which have enzymatic activities in RNA metabolism or protein processing in addition to functions in antagonizing host response.

A mechanism of virus-induced demyelination

Myelin forms an insulating sheath surrounding axons in the central and peripheral nervous systems and is essential for rapid propagation of neuronal action potentials. Demyelination is an acquired disorder in which normally formed myelin degenerates, exposing axons to the extracellular environment. The result is dysfunction of normal neuron-to-neuron communication and in many cases, varying degrees of axonal degeneration. Numerous central nervous system demyelinating disorders exist, including multiple sclerosis. Although demyelination is the major manifestation of most of the demyelinating diseases, recent studies have clearly documented concomitant axonal loss to varying degrees resulting in long-term disability. Axonal injury may occur secondary to myelin damage (outside-in model) or myelin damage may occur secondary to axonal injury (inside-out model). Viral induced demyelination models, has provided unique imminent into the cellular mechanisms of myelin destruction. They illustrate mechanisms of viral persistence, including latent infections, virus reactivation and viral-induced tissue damage. These studies have also provided excellent paradigms to study the interactions between the immune system and the central nervous system (CNS). In this review we will discuss potential cellular and molecular mechanism of central nervous system axonal loss and demyelination in a viral induced mouse model of multiple sclerosis.

Pathogenesis of murine coronavirus in the central nervous system

Murine coronavirus (mouse hepatitis virus, MHV) is a collection of strains that induce disease in several organ systems of mice. Infection with neurotropic strains JHM and A59 causes acute encephalitis, and in survivors, chronic demyelination, the latter of which serves as an animal model for multiple sclerosis. The MHV receptor is a carcinoembryonic antigen-related cell adhesion molecule, CEACAM1a; paradoxically, CEACAM1a is poorly expressed in the central nervous system (CNS), leading to speculation of an additional receptor. Comparison of highly neurovirulent JHM isolates with less virulent variants and the weakly neurovirulent A59 strain, combined with the use of reverse genetics, has allowed mapping of pathogenic properties to individual viral genes. The spike protein, responsible for viral entry, is a major determinant of tropism and virulence. Other viral proteins, both structural and nonstructural, also contribute to pathogenesis in the CNS. Studies of host responses to MHV indicate that both innate and adaptive responses are crucial to antiviral defense. Type I interferon is essential to prevent very early mortality after infection. CD8 T cells, with the help of CD4 T cells, are crucial for viral clearance during acute disease and persist in the CNS during chronic disease. B cells are necessary to prevent reactivation of virus in the CNS following clearance of acute infection. Despite advances in understanding of coronavirus pathogenesis, questions remain regarding the mechanisms of viral entry and spread in cell types expressing low levels of receptor, as well as the unique interplay between virus and the host immune system during acute and chronic disease.

Experimental optic neuritis induced by a demyelinating strain of mouse hepatitis virus

Optic neuritis (ON), an inflammatory demyelinating optic nerve disease, occurs in multiple sclerosis (MS). Pathological mechanisms and potential treatments for ON have been studied via experimental autoimmune MS models. However, evidence suggests that virus-induced inflammation is a likely etiology triggering MS and ON; experimental virus-induced ON models are therefore required. We demonstrate that MHV-A59, a mouse hepatitis virus (MHV) strain that causes brain and spinal cord inflammation and demyelination, induces ON by promoting mixed inflammatory cell infiltration. In contrast, MHV-2, a nondemyelinating MHV strain, does not induce ON. Results reveal a reproducible virus-induced ON model important for the evaluation of novel therapies.

Demyelinating and nondemyelinating strains of mouse hepatitis virus differ in their neural cell tropism

Some strains of mouse hepatitis virus (MHV) can induce chronic inflammatory demyelination in mice that mimics certain pathological features of multiple sclerosis. We have examined neural cell tropism of demyelinating and nondemyelinating strains of MHV in order to determine whether central nervous system (CNS) cell tropism plays a role in demyelination. Previous studies demonstrated that recombinant MHV strains, isogenic other than for the spike gene, differ in the extent of neurovirulence and the ability to induce demyelination. Here we demonstrate that these strains also differ in their abilities to infect a particular cell type(s) in the brain. Furthermore, there is a correlation between the differential localization of viral antigen in spinal cord gray matter and that in white matter during acute infection and the ability to induce demyelination later on. Viral antigen from demyelinating strains is detected initially in both gray and white matter, with subsequent localization to white matter of the spinal cord, whereas viral antigen localization of nondemyelinating strains is restricted mainly to gray matter. This observation suggests that the localization of viral antigen to white matter during the acute stage of infection is essential for the induction of chronic demyelination. Overall, these observations suggest that isogenic demyelinating and nondemyelinating strains of MHV, differing in the spike protein expressed, infect neurons and glial cells in different proportions and that differential tropism to a particular CNS cell type may play a significant role in mediating the onset and mechanisms of demyelination.

Detection and typing of BKV, JCV, and SV40 by multiplex nested polymerase chain reaction

A multiplex nested polymerase chain reaction (PCR) method was developed for detecting and differentiating simultaneously the DNA of polyomaviruses JC, BK, and SV40 in a single tube. In the first amplification step the same set of primers was used to amplify a conserved DNA region of the large T antigen gene of JCV, BKV, and SV40. The second round was carried out using a set of primers designed to obtain products of different size for each related virus. Subsequently, the sensitivity of the multiplex nested PCR was maximized by optimizing parameters such as primer, magnesium, and dNTP concentrations. The sensitivity of the method ranged between 1 and 10 copies of the polyomavirus genome. The assay was then used for detecting polyomavirus DNA in urine, serum, and biopsy specimens from renal transplant recipients. Based on the results obtained, the multiplex nested PCR developed in our study represents a useful tool for supporting the diagnosis of polyomavirus infection and could be used for epidemiological purposes and to better define the role of polyomaviruses in human pathology.

Multiplex polymerase chain reaction for the simultaneous detection and typing of polyomavirus JC, BK and SV40 DNA in clinical samples

A novel multiplex nested PCR (nPCR) method was developed for detecting and differentiating simultaneously the DNA of polyomaviruses JC, BK and SV40 in a single tube. In the first amplification step the same set of primers were used to amplify a conserved DNA region of the large T antigen gene of JCV, BKV and SV40. The second round of multiplex nPCR was carried out using a set of primers designed to render products of different size for each related virus. The thermocycling parameters and concentration of each reaction component were optimised systematically to achieve optimal specificity and sensitivity for the nPCR assay. The sensitivity of the method ranged between one and 10 copies of polyomavirus genome. Cerebrospinal fluid (CSF) was examined from AIDS patients with clinical and neuroradiological evidence of progressive multifocal leukoencephalopathy (PML) and CSF from AIDS patients with other neurological alterations. Urine specimens from bone marrow transplant recipients affected by haemorrhagic cystitis were also tested. The results obtained suggest that the assay is a good tool for supporting the diagnosis of polyomavirus infection and could be used for epidemiological purposes and in other studies in order to define better the role of polyomaviruses in human disease.

Herpesviruses--a rationale for antiviral treatment in multiple sclerosis

In multiple sclerosis (MS), the extensive and long lasting search for viruses or other pathogens has hitherto failed to identify a common etiological agent. However, the beneficial effects by interferon-beta treatment in MS, although suggested to depend mainly on immunomodulation, might lend support to a viral involvement in the pathogenesis. The human herpesviruses have attracted interest since their recurrent modes of infection share some similarity with the relapsing-remitting course of MS, most members are readily detected within the brain, and several of these viruses may induce demyelination within the central nervous system in human hosts as well as in animal models. Accumulated diagnostic and epidemiological data are compatible with a role for the herpesviruses as possible cofactors rather than etiological agents, and recent studies showing early neuronal damage in MS patients focus attention on the neurotropic alpha-herpesviruses. Antiviral treatment trials with safe and effective drugs such as valaciclovir offer a possibility of testing the hypotheses concerning herpesviral involvement in MS.

Dorsal root ganglia may be reservoirs of viral infection in multiple sclerosis

There are presently two competitive theories that attempt to explain the etiology of multiple sclerosis (MS). Briefly summarized, they are: 1. An infection, probably of viral type, may attack the oligodendroglia of the central nervous system; or, 2. An autoimmune process may begin with an infection of the peripheral lymphatic immune system, producing antibodies that cross the blood-brain barrier, leading to myelinoclasia. Since 1935, research has been directed toward myelin of the central nervous system and the myelin sheaths of peripheral nerve; however, dorsal root and cranial sensory ganglia (DRG) have apparently not been studied. The present hypothesis states that an infectious agent (probably viral) finds privileged sanctuary in the dorsal root and cranial sensory ganglia (DRG): thereafter periodically invading the spinal cord, brain, or peripheral nerve. Previously reported erratic spinal fluid viral titers and cultures can be explained by differences in the anatomy of the DRG in which there is a variable and limited contact of spinal fluid with sensory ganglia. Clues to this hypothesis were noted by the author during routine neurological examinations of patients with MS, in which sensory signs and symptoms were frequently encountered. This clinical observation has also been reported by others who found such symptoms in 75% of MS patients, ranking second only to incoordination.

Multiple sclerosis: the role of puberty and the pineal gland in its pathogenesis

Epidemiological studies demonstrate that the incidence of multiple sclerosis (MS) is age-dependent being rare prior to age 10, unusual prior to age 15, with a peak in the mid 20s. It has been suggested that the manifestation of MS is dependent upon having passed through the pubertal period. In the present communication, I propose that critical changes in pineal melatonin secretion, which occur in temporal relationship to the onset of puberty, are intimately related to the timing of onset of the clinical manifestations of MS. Specifically, it is suggested that the fall in melatonin secretion during the prepubertal period, which may disrupt pineal-mediated immunomodulation, may stimulate either the reactivation of the infective agent or increase the susceptibility to infection during the pubertal period. Similarly, the rapid fall in melatonin secretion just prior to delivery may account for the frequent occurrence of relapse in MS patients during the postpartum period. In contrast, pregnancy, which is associated with high melatonin concentrations, is often accompanied by remission of symptoms. Thus, the presence of high melatonin levels may provide a protective effect, while a decline in melatonin secretion may increase the risk for the development and exacerbation of the disease. The melatonin hypothesis of MS may explain other epidemiological and clinical phenomena associated with the disease such as the low incidence of MS in the black African and American populations, the inverse correlation with sun light and geomagnetic field exposure, the occurrence of relapses in relation to seasonal changes and fluctuations in mood, and the association of MS with affective illness and malignant disease. Therapeutically, this hypothesis implies that application of bright light therapy or the use of other major synchronizers of circadian rhythms such as sleep deprivation or application of external weak magnetic fields may be beneficial in the treatment and/or prophylaxis of relapses in the disease.

On the membrane cytopathology of mouse hepatitis virus infection as probed by a semi-permeable translation-inhibiting drug

Previous studies of the membrane fusion process have permitted the characterization of membrane permeability changes concomitant with MHV-induced cytopathology. One indication of membrane permeability in MHV-infected cells is their sensitivity to translation inhibition by the normally impermeable amino-glycoside, hygromycin B (Macintyre, G., Wong, F. and Anderson, R. (1989) J. Gen. Virol. 70, 763-768). In the present study, we examine the hygromycin B sensitivity of acutely infected mouse fibroblast L-2 cell and macrophage cultures as well as persistently infected mouse fibroblast LM-K cell cultures. The results suggest that membrane permeability alterations (as indicated by hygromycin B sensitivity) are a common feature of these MHV infections. Hygromycin B "cured" persistently infected LM-K cells as indicated by the absence of detectable virus antigen by immunofluorescence and by the absence of infectious virus even after removal of the drug or co-cultivation with untreated L-2 cells. The results argue against the maintenance of MHV infection by a mechanism involving latently or non-cytolytically infected cells. We conclude therefore that at least one mechanism for MHV persistence depends on virus propagation by cytolytic infection of a small, dynamically changing, fraction of the total cells present in culture.

Leukoencephalopathy among native Indian infants in northern Quebec and Manitoba

We report 14 cases of a severe familial leukoencephalopathy among native North American Indian infants in northern Quebec and Manitoba. Affected infants have hypotonia and mild motor delay, followed by seizures, hypotonia or spasticity, eye deviation, and abnormal posture during a febrile illness around 6 months of age. Death follows a rigid, vegetative state that manifests days to months after disease onset and is marked in some cases by prominent autonomic disturbances, blindness, and cessation of head growth. Symmetrical hemispheric white matter lucencies and diffuse hypomyelination of the cerebral hemispheres and brainstem are the radiological and pathological hallmarks. This disease differs from the known diseases of cerebral myelin. An autosomal recessive pattern of inheritance awaits statistical confirmation. The proposed cause is a delay in development or abnormal turnover of central nervous system myelin.

Perivascular demyelinization of cochlear neurons in two neonates

Localized perivascular demyelinization of the peripheral processes of cochlear neurons was observed in surface preparations of the osseous spiral lamina in two neonates, one a premature infant with erythroblastosis fetalis, the other a full-term infant with cyanotic congenital heart disease. In both cases the cause of the demyelinization was unknown. Both infants had severe edema as a result of congestive heart failure and anoxia. The serum bilirubin level in the erythroblastotic child appeared too low to have caused injury to the nerve fibers. The demyelinization was most striking in the lower half of the basal turn. It was observed only in the immediate vicinity of meandering stretches of capillaries as they crossed the nerve fibers. In the premature infant there was hair cell loss throughout the cochlea; in the other there was no hair cell loss, but a malformed labyrinth of the Mondini type.

Progressive multifocal leukoencephalopathy in a case of acquired immune deficiency syndrome

The case of a 40-year-old homosexual male with A.I.D.S. (Acquired Immune Deficiency Syndrome) and P.M.L. (Progressive Multifocal Leukoencephalopathy) is described. The importance of a brain biopsy for diagnostic procedures, especially in the case of a patient with A.I.D.S. is stressed. The diagnosis P.M.L. has been made by means of light- and electronic microscopical examination, and the presence of JCV-DNA in the brain tissue has been confirmed by dot hybridization. Various antiviral treatments did not show any effect on the course of the P.M.L.

Replication of murine coronaviruses in somatic cell hybrids between murine fibroblasts and rat schwannoma cells

The replication of the murine coronaviruses MHV3 and JHM has been studied in somatic cell hybrids formed between murine fibroblast L2 cells which support lytic infections with both these agents, and rat RN2 Schwannoma cells which support the replication of JHM in a temperature-sensitive, persistent manner but are restrictive to the replication of MHV3. The results described in this report indicate that the totally permissive state is dominant over the persistent or restricted state since the hybrid cells permit the replication of both these viral agents in a lytic manner.

Peripheral blood T and B lymphocyte subpopulations in Bell's palsy

A prospective clinical, virological and immunological study was performed on 25 consecutive Bell's palsy (BP) patients. Multiple cranial nerve involvement was found in 15 patients. A significant decrease in the peripheral blood T lymphocyte percentage as well as an increase in B lymphocyte percentage (p less than 0.001) were found in 13 of the BP patients during the first 24 days from the clinical onset of the paralysis. No correlation was found between the peripheral blood lymphocyte subpopulations and the patient's age, sex, degree of paralysis or recovery rate. No changes were detected in the levels of immunoglobulins (IgG, IgM), complement (C3, C4) and antiviral antibodies to herpes simplex and zoster, EBV, cytomegalic virus, adenovirus, influenza and mumps. The clinical and immunological data of BP show a similar pattern to those of Guillain-Barre syndrome suggesting that BP may be an antoimmune demyelinating cranial polyneuritis which may be caused by a preceding viral infection.

Oligodendrocyte infection and demyelination produced in mice by the M9 mutant of Semliki Forest virus

Intraperitoneal inoculation with the M9 mutant of Semliki Forest virus caused focal demyelinating encephalomyelitis in weanling BALB/c and C57BL/6 mice. Demyelination was more severe in BALB/c than in C57BL/6 mice. Virus particles were seen in oligodendrocytes in areas of myelin vacuolation 5 and 7 days post inoculation (DPI). Oligodendrocytes containing virus in BALB/c mice showed hypertrophy and vacuolar degeneration. There was a mononuclear cell infiltrate and lymphocytes and necrotic cells were present in vacuoles in myelin sheaths. Demyelinating plaques containing macrophages laden with myelin debris were most prominent 14 DPI when virus was cleared from the brain. Remyelination of the central type occurred 28 DPI in BALB/c mice. These findings indicate that direct virus-induced injury to oligodendrocytes has a major role in the initiation of inflammation and demyelination in this model system.

Adoptive transfer of EAE-like lesions from rats with coronavirus-induced demyelinating encephalomyelitis

Viruses have been found to induce inflammatory demyelinating lesions in central nervous system (CNS) tissue of both animal and man, either by natural infections or after vaccination. At least two different pathogenic mechanisms have been proposed for these changes, a cytopathic viral infection of oligodendroglia cells with subsequent cell death, and a host immune reaction against virus and brain antigens. We now report the occurrence of cell-mediated immune reactions against basic myelin proteins in the course of coronavirus infections in Lewis rats. Infection of rats with the murine coronavirus JHM leads to demyelinating encephalomyelitis developing several weeks to months postinfection. Lymphocytes from these diseased Lewis rats can be restimulated with basic myelin protein (BMP) and adoptive transfer of these cells leads to lesions resembling those of experimental allergic encephalomyelitis (EAE) in recipients, which can be accompanied by a mild clinical disease. This model demonstrates that a virus infection in CNS tissue is capable of initiating an autoimmune response which may be of pathogenic importance.

Etiology and pathogenesis of monophasic and relapsing inflammatory demyelination - human and experimental

The close similarity of the CNS lesions in cr-EAE and MS renders this model especially valuable for the study of pathogenetic factors, leading to the formation of inflammatory demyelinated plaques. Recent evidence indicates, that various immune reactions, directed against different CNS antigens cooperate in the formation of the plaques. Furthermore it is discussed, that a combination of virus infection and autoimmunity may result in similarity structured lesions. It is thus propose that multiple different etiologic factors (autoimmune as well as exogenous events) may lead to the clinical pathohistological syndrome of multiple sclerosis.

Virus-induced demyelination in herpes simplex virus-infected mice

Herpes simplex virus (HSV) infection of the mouse trigeminal ganglia and the brain stem is associated with demyelination of axons in the central part of the trigeminal root and inflammatory cell infiltration and perivascular demyelination in the brain stem. Cyclophosphamide (CPA) treatment prior to or soon after HSV inoculation caused increased axonal spread of infective virus from the peripheral site of inoculation, more widespread and severe demyelination and increased mortality, suggesting that by CPA the virus invasion of the CNS was facilitated. A direct cytocidal effect of HSV on myelinating cells seemed one plausible explanation for the demyelination. Influence on demyelination at late stages of infection by cytotoxic immune reactions are not excluded by the results reported but seemed not to dominate the picture. Schwann cells from the peripheral part of the nerve root invaded demyelinated areas in the brain stem and remyelinated the axons.

Coronavirus 229E susceptibility in man-mouse hybrids is located on human chromosome 15

Human coronavirus 229E, n enveloped, RNA-containing virus, causes respiratory illness in man and is serologically related to murine coronavirus JHM, which causes acute and chronic demyelination in rodents. 229E displays a species-specific host range restriction whose genetic basis was studied in human-mouse hybrids. 229E replicated in human WI-38 cells but not in three mouse cell lines tested (RAG, LM/TK-, and A9). Human coronavirus sensitivity (HCVS) was expressed as a dominant phenotype in hybrids, indicating that mouse cells do not actively suppress 229E replication. HCVS segregated concordantly with the human chromosome 15 enzyme markers mannose phosphate isomerase (MPI) and the muscle form of pyruvate kinase (PKM2), and analysis of hybrids containing an X/15 translocation [t(X;15)(p11;q11)] localized HCVS to the q11 leads to qter region of chromosome 15. HCVS might code for a specific surface receptor, allowing 229E to be absorbed to and received within the host cell.

RNA and polypeptide homology among murine coronaviruses

Using a 32P complementary DNA (cDNA) prepared against the A59 nucleocapsid protein messenger RNA, we have investigated the extent of homology between A59 and four other strains of murine hepatitis virus (MHV). Analysis by hybridization kinetics of the annealing between A59 [32P]cDNA and infected cell RNA from the other four MHV strains demonstrated 70–80% homology. By gel transfer analysis, the A59 [32P]cDNA was able to detect subgenomic-size virus-specific RNAs in cells infected with all of the five MHV strains. A similar pattern of seven viral RNAs was detected in cells infected with A59, MHV-1, MHV-3, and JHM. In contrast, cells infected with MHV-S contained seven virus-specific RNAs, of which only the two smallest species comigrated with RNAs from the other four strains. The results suggest that as previously shown with A59 (S. Cheley, R. Anderson, M. J. Cupples, E. C. M. Lee Chan, and V. L. Morris (1981) Virology , 112, 596–604), all MHV strains tested encode a nested set of subgenomic RNAs. Analysis of [35S]methionine-labeled viral proteins by SDS-polyacrylamide gel electrophoresis revealed that each strain of MHV specified four major viral polypeptides with apparent molecular weights very similar to those previously reported for the E2, N, El, and PEI polypeptides of A59. The strong degree of interstrain homology among the five MHV strains investigated was confirmed by comparative chymotryptic peptide mapping of the viral N proteins. A majority of the chymotryptic peptides from each of the [35Sknethionine-labeled N proteins was found to coelute by high-performance liquid chromotography. Moreover, this technique of peptide mapping indicated a particularly strong relatedness between MHV-1 and MHV-S and among MHV-3, JHM, and A59.

Measles virus nucleotide sequences: detection by hybridization in situ

A tritium-labeled probe that detects measles virus nucleotide sequences was hybridized in situ to cells infected with measles virus and to sections of brain tissue from patients with subacute sclerosing panencephalitis and from patients with multiple sclerosis. The measles virus genome was detected in many cells in subacute sclerosing panencephalitis where this virus would have been missed by methods such as immunofluorescence. Measles virus sequences were also found in two foci in one of four cases of multiple sclerosis. This refined method of hybridization in situ, which can be useful in the search for covert virus infections of man, provides evidence that viruses may be involved in multiple sclerosis.

Induction of antimyelin and antioligodendrocyte antibodies by vaccinia virus. An experimental study in the mouse

The appearance of serum antibodies binding to specific brain antigens was monitored in mice inoculated intracerebrally with a dermotropic or a neurotropic strain of vaccinia virus. Antibodies were measured with a binding assay using [125I]protein. A. Inoculation with the neurotropic strain caused an induction of serum antibodies binding to the myelin membrane, the myelin basic protein and oligodendrocytes while no induction of binding antibodies to neurons was observed. The dermotropic strain failed to elicit the formation of binding antibodies to brain antigens.

Herpes simplex polyganglionitis

Evidence suggests that many cranial nerve syndromes, such as migraine headache, acute vestibular neuronitis, globus hystericus, carotidynia, acute facial paralysis (Bell's palsy), and Meniere's disease, are caused by the neurotropic herpes simplex virus (HSV). Because transitory cranial nerve dysfunction during acute HSV infection can be asymptomatic but often occurs in conjunction with mucocutaneous vesicles, we tested five subjects with herpes labialis for cranial nerve dysfunction. Four of the subjects had hypesthesia of the trigeminal nerve (which recurred in two); four, hypesthesia of the glossopharyngeal nerve; and two, hypesthesia of the second cervical nerve. Three of the subjects had positional or spontaneous nystagmus (which recurred in one); one of the subjects had a unilateral, decreased caloric response of 50%. Unilateral weakness of the cricothyroid muscle or the palate occurred in three of the subjects (and recurred in one). Volitional electromyograms were normal in all the subjects, but two of the subjects had increased facial nerve latency (which recurred in one). Similar findings of an acute, transitory nature should suggest to the clinician a viral polyganglionitis caused by HSV infection.

Ménière's disease as a form of cranial polyganglionitis

Although endolymphatic hydrops is generally considered to be the most prominent factor in the etiology and pathology of Ménière's disease, we have concluded that this condition more probably represents a polyganglionitis caused by the herpes simplex virus with secondary hydrops changes. The wide range of symptoms occurring in the Ménière's disease complex is illustrated in seven selected cases which support this conclusion. Vestibular nerve section can stabilize hearing and relieve episodic vertigo by removing the locus of viral infection and precluding recurrent activation.

An unusual form of measles meningoencephalitis. A report of two cases

Two patients are reported with a chronic progressive illness characterized by dementia, ataxia and spasticity. There were no myoclonic jerks and both had normal electroencephalograms (EEG). Pathological findings in three brain biopsies were those of viral meningoencephalitis with perivenous demyelination. Serological data in both patients indicated the presence of measles virus infection. Intracytoplasmic structures resembling measles virus nucleocapsids were found in the brain biopsy of one patient. Immunofluorescent staining showed antibody in the temporal lobe biopsy of both patients. It is suggested that these patients are examples of a chronic form of measles meningoencephalitis hitherto undescribed.

Electron microscopic studies of cerebrospinal fluid sediment in demyelinating disease

Cerebrospinal fluid specimens from 31 patients with multiple sclerosis (MS) and 2 with progressive multifocal leukoencephalopathy (PML) were subjected to ultracentrifugation, and the resulting pellets were examined in an electron microscope. Cell types seen in the pellets included lymphocytes, occasional plasma cells, polymorphonuclear leukocytes, monocytes, eosinophils, lipid-laden macrophages, and fibroblasts. The most interesting noncellular elements were extracellular myelin fragments, recognizable by their characteristic alternation of major dense lines and intraperiod lines. Myelin fragments were seen in the CSF from 7 of 9 patients with MS in exacerbation involving areas other than the optic nerve. These fragments were not observed in 4 specimens from patients with acute attacks manifested by optic neuritis. Myelin fragments were present in 1 of the 2 patients with PML. These observations indicate that a portion of the myelin destruction seen in MS and PML occurs extracellularly, with release of myelin fragments and degradation products into the CSF.

Carcinomatous encephalomyelopathy in conjunction with encephalomyeloradiculitis

A man, aged 63, had an illness which lasted 11 months from onset with pain under the left costal margin which radiated to the epigastrium, until his death from cardiac failure. His symptoms consisted principally of parasthesias and proximal weakness of both upper and lower extremities with atrophy of the shoulder and pelvic girdles. He developed pyramidal tract signs, became euphoric, emotionally unstable and mentally retarded. There was no clinical evidence of cerebellar dysfunction. Bronchogenic carcinoma was suspected from a tomograph of the thorax, but, in spite of extensive clinical and laboratory studies, the diagnosis was verified only postmortem. The CSF cell count was high at first but diminished as the disease progressed. Muscle biopsies revealed chronic generalized denervation without signs of myopathy. Neuropathologically, encephalomyeloradiculoneuritis concentrated on the spinal cord was combined with severe rarefaction of the ganglion cells of the anterior horns and with bilateral degeneration of the lateral pyramidal spinocerebellar and posterior tracts. A more diffuse process was obvious in the anterolateral tracts of the lumbar region. Polyneuropathy concentrated in the distal region was accompanied by slight inflammatory reaction in the sciatic nerve. Cerebellocortical degeneration which exceeded physiological age-related rarefaction was also present. The findings are discussed in relation to the literature.

Polystyrene balls as the solid-phase of a double-antibody radioimmunoassay for human serum albumin

Polystyrene balls have been incorporated as the solid-phase of a model double-antibody radioimmunoassay for human serum albumin. Purified IgG from the secondary antiserum is adsorbed on the 6.4 mm diameter balls. The solid-phase secondary antibody is then used to separate primary antibody bound iodinated antigen from unbound antigen. The secondary antibody coated polystyrene balls are easily prepared and manipulated; several hundred sample dilutions can readily be processed in a single assay. Assay background values of 1.5% or less are consistently obtained without extensive or special washing procedures.

Absence of imune deficiencies in a case of progressive multifocal leukoencephalopathy

Progressive multifocal leukoencephalopathy (PML) is a rare disease related to a slow virus infection of the central nervous system; it is usually seen in patients who have impaired immunologic function. The present patient with biopsy-proved PML was found to have no demonstrable defects in either cellular or humoral immunity as assessed by multiple parameters. Thus, it appears that PML may occur in the presence of intact immune responses.

Solid-phase radioimmunoassay of rubella virus immunoglobulin G and immunoglobulin M antibodies

A solid-phase radioimmunoassay method has been developed for the detection of rubella virus-specific immunoglobulin G (IgG) and IgM antibodies in human serum specimens. Purified rubella virus was adsorbed onto polystyrene balls, and antibodies that attached to the virus-treated balls were detected by subsequent binding of 125I-labeled anti-human gamma or anti-human mu immunoglobulins. A total of 77 serum specimens were tested. Binding ratios between positive and negative sera were as high as 22 in the IgG assay but rarely exceeded 3 in the IgM assay. The sensitivity of the IgG assay was found to be 16 to 256 times higher than that of the rubella virus hemagglutination inhibition test. The IgG radioimmunoassay can be readily adopted for routine diagnostic use. The IgM radioimmunoassay, however, due to its lower sensitivity, must be modified before being routinely applied.