Acute multiple sclerosis: electron-microscopic evidence for and against a viral agent in the plaques

Viral Infection at the Blood-Brain Barrier in Multiple Sclerosis: – An Ultrastructural Study of Tissues from a Uk Regional Brain Bank

Although viral infections are often invoked as environmental factors in the aetiology and pathogenesis of multiple sclerosis (MS) it is only recently that a specific, indirect, cytokine-mediated mechanism for triggering of relapses during viral infections has been demonstrated. It is not yet clear however whether this indirect mechanism can account for all reported viral associations with the aetiopathogenesis of MS. A direct causal role of central nervous system (CNS) viral infection in MS has largely been discounted following repeated failures to demonstrate virus within the oligodendrocyte-myelin unit In the light of increasing evidence of blood-brain barrier (BBB) dysfunction in MS and to further explore the issue of possible viral involvement in MS, an ultrastructural search for viruses was undertaken in the CNS microvasculature, in autopsy and biopsy tissue from human CNS primary demyelinating diseases, including MS (20 cases), idiopathic monophasic CNS demyelinating disease (Mdemy, four cases) and metabolic or immunopathological demyelinating disease (two cases). For comparison, tissues from CNS viral disease in which demyelination is a major feature (nine cases) were examined in the same way. Control CNS tissues (nine cases) from a range of other neurological and non-neurological diseases were also examined. Outside the MS and Mdemy groups, morphological evidence of virus associations with the BBB were found only in the acute and subacute viral encephalitides (three cases subacute sclerosing panencephalitis, one case of Herpes encephalitis) and in one case of disseminated Cytomegalovirus infection. In a small proportion of MS and Mdemy cases, particles resembling either adenovirus (one case of MS) or paramyxovirus (one case of MS, one case of Mdemy) were found in the vicinity of microvessels. In each case a different cell type or extracellular compartment was involved and an exact correlation between the virus particles and the demyelinating lesions could not be demonstrated. Furthermore, corroborative clinical or laboratory evidence of current CNS infection in these primary demyelinating disease cases was available only from the single positive Mdemy case and not from the two cases of MS. This and other previously published evidence from MS (which implicated a Coronavirus) and other diseases highlights the potential vulnerability to viral infection of cells associated with the BBB. Furthermore it is concluded that the detection rate of such infections in pathological tissue could underestimate their true frequency. A possible role of transient virus-BBB interactions in triggering focal inflammation, BBB breakdown and demyelination in some cases of MS and parainfectious demyelinating disease cannot be discounted.

A specific viral cause of multiple sclerosis: One virus, one disease

"Multiple sclerosis is an autoimmune disease," is heard so often that it is widely accepted as fact by the current generation of students and physicians. Yet, although it is undisputed that multiple sclerosis (MS) is immune mediated, an autoimmune mechanism remains unproven. Immune-mediated tissue damage can also result from viral infections in which the host immune response is directed to viral rather than self proteins, or as a consequence of nonspecific or bystander immune responses that change the local cytokine environment. Increasing evidence suggests that poorly controlled host immune responses account for much of the tissue damage in chronic infections, and it has been postulated that a similar mechanism may underlie many chronic diseases with features suggestive of an infectious causative factor, including MS. A recent study suggesting that oligodendrocyte death accompanied by microglial activation is the primary event in new MS lesion formation, rather than lymphocyte infiltration, could change the current mindset almost exclusively focused on autoimmunity. This review presents the rationale for considering MS a single disease caused by one virus, as well as the anticipated pattern of a persistent central nervous system infection, the application of Koch's postulates to viral discovery in MS as the causative agent, and tissue culture-independent genotypic approaches to viral discovery in MS.

Light and electron microscopical studies of the immunoperoxidase staining of multiple sclerosis plaques using antisera to a feline-derived agent and to galactocerebroside

Antibodies have been raised to two agents (CCA147 and MV631) that were isolated from central nervous tissue of cats. The cells co-cultivated with these agents are characterized by the presence of cytoplasmic inclusions consisting of 16-18 nm diameter tubular elements morphologically similar to inclusions seen in a demyelinating condition in cats and to inclusions described as 'curved linear profiles' in multiple sclerosis (MS) plaques. The peroxidase-labelled antibodies to CCA147 and MV631 stain these inclusions in MS plaques as well as small virus-like particles. The antisera do not stain normal white matter either in MS or non-MS brain tissue. The staining reaction of one agent is blocked by pretreatment with antisera to the other agent and also by pretreatment with MS sera but not by normal human sera. Peroxidase-labelled antibody to galactocerebroside stains normal myelin and myelin debris within MS plaques but does not stain the 'curved linear profiles' that are stained by the labelled antibodies to the feline-derived agents. The results show that the 'curved linear profiles' described in MS plaques are not myelin degradation products, but are comparable to the nucleocapsids of morbilliviruses. In addition, the small virus-like particles are morphologically similar to morbillivirus virions. The results are discussed with particular emphasis on the features of the morbilliviruses, canine distemper and measles viruses.

Diagnostic virology using electron microscopic techniques

This chapter illustrates the development of the use of electron microscopy in viral diagnosis. The field covered is confined to medical viral diagnosis, but parallel developments have taken place in both veterinary and botanical fields and techniques derived from both these sources are also included where relevant. It is reported that the scanning transmission mode of operation, which can induce image contrast changes electronically, may enhance studies with unstained sections and perhaps facilitate thin section immune electron microscopy (IEM). The application of negative stain IEM has been particularly useful for the study of the antigenic nature of some of the newly discovered noncultivable viruses. Viral antigens can also be detected in thin sections of infected cells by IEM with suitably labeled specific antibodies. Confirmation of viral infection by electron microscopy on tissues originally processed for light microscopy is also frequently useful.

Measles antibodies, kappa-lambda light chain distribution and immunoglobulins in serum, cerebrospinal fluid and brain of a patient affected with multiple sclerosis

The serum, cerebrospinal (CSF) and brain of a patient (NAG) affected with multiple sclerosis (MS) were examined for measles antibodies with CF and HI techniques, and the kappa-lambda light chain ratios of all samples available were evaluated, kappa-lambda populations of the matched serum, CSF and brain specimens were all lambda-predominant and in agreement with each other; the light chain distribution f the brain specimens confirmed previous findings [3]. Only the serum immunoglobulins showed significant measles antibody titers, but slightly increased measles antibody titers were also observed in ventricular plaques. The amount of immunoglobulin G (IgG) synthesized per day by the central nervous system (CNS) was estimated. The IgG synthesis in CNS NAG (11.6 mg/day) was above the upper limit of the normal range (3.3 mg/day), but apparently there was no positive correlation between the intracerebral IgG synthesis and specific anti-measles IgG.

The fine structure of the CNS in multiple sclerosis. I. Interpretation of cytoplasmic papovavirus-like and paramyxovirus-like inclusions

During an electron microscopic study of the white matter in multiple sclerosis (MS), spheroidal reticular particles were found both in MS and in control brains. These particles have previously been described in the brain in MS and in brain-derived cell cultures in subacute sclerosing panencephalitis. In both cases they were interpreted as papovaviruses, but in size, morphology and distribution they are identical to the reticulosomes and related particles which occur as proteinaceous artefacts in a variety of tissues and in subcellular fractions. Inclusions in endothelial cell cytoplasm, previously reported from the CNS in MS as paramyxovirus similar to measles, have also been found in the present study. The were present both in MS and in control brains and are identified as "rod-shaped tubular bodies", normally occurring organelles of endothelial cells. The necessity for a cautious interpretation of virus like inclusions in emphasized.

Intranuclear filaments in a soft tissue sarcoma

Intranuclear filaments aggregating into rodlike structures were found in cells of an undifferentiated soft tissue sarcoma in a child. Similar structures have been uncommonly described in human neoplasms, and uncertainties exist concerning the nature of the inclusion bearing cells in previous reports. The filaments were found to be resistant to mild trypsin digestion. Review of the pertinent literature indicates that these structures may represent the structural manifestation of a highly specialized functional state, rather than a degenerative phenomenon or an artifact. A certain selectivity of occurrence has also been noted. It is therefore plausible to speculate that intranuclear filaments may eventually constitute a morphologic criterion of interest for new tumor classifications.

Immunocytochemical studies for the localisation of measles antigens in multiple sclerosis plaques and measles virus-infected CNS tissue

Actively demyelinating central nervous system (CNS) lesions from a patient with acute multiple sclerosis (MS) were tested for measles antigens using peroxidase-conjugated antimeasles antibody. No evidence of measles antigens was found. Similarly reacted tissue from 2 patients with chronic MS also revealed no evidence of measles antigens. Identically treated and simultaneously tested measles-infected CNS cultures and human SSPE brain tissue stained strongly for measles antigens. The possible reasons underlying the failure to detect measles antigens in MS are discussed.

Intracisternal virus-like particles in brain of a multiple sclerosis patient

Doughnut-shaped particles, 55-65 nm in diameter, were revealed by electron microscopy in the cisterns of the rough endoplasmic reticulum of cells from an active lesion in autopsied brain tissue from a multiple sclerosis patient. The morphology of the particles closely resembled that of coronaviruses.

Lysolecithin fusion of cells from multiple sclerosis patients with Vero cells

Investigations were performed on cell cultures derived from patients with multiple sclerosis (MS) in order to trace a possible virus infection as a cause of the disease. Cell cultures were established from one brain autopsy specimen and four lymph node biopsies from MS patients. Lymphocytes from 28 MS patients and six healthy controls were used for fusion or cocultivation experiments, either immediately after isolation or after mixed lymphocyte cultures (MLC). Lysolecithin fusion and cocultivation experiments were made with Vero cells and with, respectively: cultured brain cells, lymph node cells and lymphocytes from MS patients. Electron microscopical examination revealed intranuclear filamentous structures in 5 per cent of the cells in primary cultures of MS brain and lymph node and in control skin organ cultures. Multinucleated cells were found in six out of 19 cocultures of Vero cells and MS lymphocytes preincubated for 2 days at 37 degrees C. The cultures were tested for the presence of viruses, i.e. measles virus and virus producing hemadsorption with human type O and/or guinea pig erythrocytes and virus against which the MS patients showed serum FA-antibodies. No virus antigen could be demonstrated in the cells.

Pathology of the human spinal ganglia in varicella-zoster virus infection

Spinal ganglia from a patient who died on the 6th day of varicella infection were examined by immunofluorescence and electron microscopy, and were compared with spinal ganglia from a patient dying on the 17th day of herpes zoster infection. In herpes zoster, typical intranuclear inclusion bodies were found in neurons, satellite cells and fibroblast-like cells of the ganglia, which contained numerous naked virus particles. In varicella, few changes were found by light microscopy but viral antigen was detected in a few neurons and satellite cells by immunofluorescence. Electron microscopy revealed scattered virus particles near the nuclear membrane of a neuron, satellite cells and capsular cells and enveloped particles in the cytoplasm of satellite cells. The particles in the nuclei were mostly naked virions with specific crescent-like inner-nuclear structure; those in the cytoplasm had complete and incomplete envelopes and showed pleomorphism. A "virus-like" intranuclear filament found in mononuclear cells in herpes zoster and a "plexiform vermicellar array" found in the nuclei of neurons in varicella are at present considered to be non-specific nuclear changes caused probably by viral infections.

Multiple sclerosis and parainfluenza 1 virus. History of the isolation of the virus and expression of phenotypic differences between the isolated virus and Sendai virus

54 cultures were established from brain tissue obtained 2-3 hrs after death from 1 case of multiple sclerosis and 30 cultures from another case. Following fusion with indicator cells in the presence of lysolecithin, a parainfluenza type 1 virus (6/94 virus) was isolated from cultures representing one plaque area in the first case and one plaque area in the second case. A cell line chronically infected with the 6/94 virus has been maintained for more than 100 passages in vitro. A close relationship to the Sendai Hemagglutinating Virus of Japan (HVJ) is indicated from RNA-RNA hybridization and the patterns of electrophoretic mobilities of viral polypeptides. Conversely, differences in optima for growth-requirement temperatures, hemolytic activity and the capability to fuse mammalian cells, distinguishes 6/94 virus and HVJ as distinct phenotypic entities of a closely related genotype.

Pathology of the early lesion in multiple sclerosis

Ideas concerning the nature of multiple sclerosis continue to be strongly influenced by the unusual morphology of the disease. A review of classic histology studies, however, reveals that there is less agreement than might be supposed concerning several important histiological features of the early lesion. Electron microscopy of brain biopsies, of immersion fixed autopsy tissue and of autopsy tissue fixed by early in situ brain perfusion suggests that the mechanism of demyelination in multiple sclerosis may be an unusual one that involves a progressive reduction in the number of myelin lamellae around nerve fibers in the vicinity of cells of uncertain origin that contain filamentous and multilamellated cytoplasmic inclusions unlike the usual pleomorphic inclusions seen in myelin phagocytes. Lymphocytes are not directly involved in this process but are observed to contact the inclusion material following its delivery to the Virchow-Robin spaces. The putative neurogenic or viral antigen in multiple sclerosis may be contained in this material. The occurrence of filamentous nuclei in early lesions fixed by immersion is an unrelated phenomenon, which may be an autolytic or drug induced artifact although this has not yet been established.

Virus antibody levels in the cerebrospinal fluid from patients with optic neuritis

Virus antibody levels were studied in the cerebrospinal fluid (CSF) of 58 patients with optic neuritis and 58 control patients with no indication of multiple sclerosis (MS) or infectious disorders of the central nervous system (CNS). The specimens were tested against three different structural components of measles virus with measles hemagglutination inhibition (HI), measles hemolysis inhibition (HLI) and gel precipitation (GP) tests. Measles antibodies occurred in 62 per cent of CSF specimens from patients with optic neuritis, and 21 per cent of the controls. In the specimens from patients with optic neuritis, the positive rate figures were: for rubella HI test 35, parainfluenza-1 HI 16, and Epstein-Barr virus immunofuorescence (IF) 53 per cent. The frequencies in the control group were 10, 10 and 26 per cent, respectively. Serum/CSF antibody ratios below 80 occurred in measles tests in 45 per cent of patients with optic neuritis and 16 per cent of the control group. Some patients with optic neuritis (but none from the control group) had a reduced serum/CSF antibody ratio in more than one measles antibody test, The patients with optic neuritis had a higher frequency of low serum/CSF albumin ratios indicating blood brain barrier damage, There were, however, several patients with a normal serum/CSF albumin ratio but low serum/CSF immunoglobulin G and measles antibody ratios. This supports the hypothesis that local production of measles antibodies takes place in CNS in some patients with optic neuritis as well as in MS patients. The CSF specimens were further tested against 12 other viruses and mycoplasma pneumoniae complement fixation, but there were no positive specimens. New CSF specimens were taken from five patients during optic neuritis, and from seven patients later on during the follow-up because of the appearance of new neurological symptoms. There were no changes in virus antibody levels, except for two patients with an increase of measles virus antibody titres.

Intranuclear "paramyxovirus-like" material in multiple sclerosis, adreno-leukodystrophy and Kuf's disease

Detailed comparative ultrastructural examination of multiple sclerosis (MS) plaques, inflammatory CNS lesions from adreno-leukodystrophy(A-LD), tissue from a case of chronic granulomatous meningitis, biopsy samples of necrotic cerebral cortex and CNS tissue from a case of Kuf's disease (adult-type ceroid lipofuscinosis), has revealed that the intranuclear filamentous material previously thought to be related to a viral infection in MS is a non-specific finding. These intranuclear strands were, however, found in greatest frequency in the acute lesions of MS and were absent from chronically demyelinated areas. The macrophages, lymphocytes and fibrocytes containing filamentous material in the nuclei were mainly perivascular. In A-LD, some macrophages in active lesions contained similar nuclei, and in Kuf's disease they were present in some glial cells in the cerebral cortex.

Analysis of a viral agent isolated from multiple sclerosis brain tissue: characterization as a parainfluenzavirus type 1

A virus originally isolated from cell cultures obtained by lysolecithin-induced fusion of human multiple sclerosis brain cells with CV-1 cells has been analyzed for its antigenic, RNA, and polypeptide compositions, and for selective biological properties. Our findings establish that this isolate, designated 6/94 virus, contains a 50S RNA genome and is, as yet, indistinguishable from Sendai virus in its antigenic and total polypeptide compositions. Despite these similarities, the 6/94 and Sendai viruses differ in certain phenotypic properties. 6/94 virus is markedly less cytocidal for chick fibroblasts, especially at 37 C and, after beta-propiolactone inactivation, it possesses a greater capacity for cell fusion and a lower toxicity than does comparably treated Sendai virus. In addition, 6/94 virus shows greater hemolytic activity.