Virological studies with multiple-sclerosis brain tissues

The landscape of extrapulmonary manifestations of human parainfluenza viruses: A systematic narrative review

Human parainfluenza virus (HPIV) infection is associated with every kind of respiratory tract illnesses, including the common cold, laryngotracheobronchitis (i.e. croup), tracheobronchitis, bronchiolitis, and pneumonia, in both children and adults. Although HPIVs are common respiratory pathogens, there are increasing reports about extrapulmonary manifestations of HPIVs infection. Each of the HPIVs could produce infection of other organs (central nervous system, heart, myocardium, etc.) in all age groups who are either immunocompetent or immunocompromised. This review aimed at summarizing the available data on clinical manifestations of HPIV infection outside the respiratory tract from 1961 to 2020. The findings support the possibility of extrapulmonary infections that were thought to be due to rare host genetic or immunologic defects in infected patients. These findings highlight the fact that extrapulmonary dissemination of HPIV can occur, but the association is not clearly demonstrated. Our data support the hypothesis that HPIV infection is one of the possible causes of these alterations and may even be the direct cause in some cases.

Virus-Induced Demyelination: The Case for Virus(es) in Multiple Sclerosis

Multiple Sclerosis (MS) is the most common demyelinating disease of man with over 400,000 cases in the United States and over 2.5 million cases worldwide. There are over 64,000 citations in Pubmed dating back as far as 1887. Much has been learned over the past 129 years with a recent burst in therapeutic options (mostly anti-inflammatory) with newer medications in development that are neuroprotective and/or neuroreparative. However, with all these advancements the cause of MS remains elusive. There is a clear interplay of genetic, immunologic, and environmental factors that influences both the development and progression of this disorder. This chapter will give a brief overview of the history and pathogenesis of MS with attention to how host immune responses in genetically susceptible individuals contribute to the MS disease process. In addition, we will explore the role of infectious agents in MS as potential “triggers” of disease. Models of virus-induced demyelination will be discussed, with an emphasis on the recent interest in human herpesviruses and the role they may play in MS disease pathogenesis. Although we remain circumspect as to the role of any microbial pathogen in MS, we suggest that only through well-controlled serological, cellular immune, molecular, and animal studies we will be able to identify candidate agents. Ultimately, clinical interventional trials that either target a specific pathogen or class of pathogens will be required to make definitive links between the suspected agent and MS.

Parainfluenza viruses

Human parainfluenza viruses (HPIV) were first discovered in the late 1950s. Over the last decade, considerable knowledge about their molecular structure and function has been accumulated. This has led to significant changes in both the nomenclature and taxonomic relationships of these viruses. HPIV is genetically and antigenically divided into types 1 to 4. Further major subtypes of HPIV-4 (A and B) and subgroups/genotypes of HPIV-1 and HPIV-3 have been described. HPIV-1 to HPIV-3 are major causes of lower respiratory infections in infants, young children, the immunocompromised, the chronically ill, and the elderly. Each subtype can cause somewhat unique clinical diseases in different hosts. HPIV are enveloped and of medium size (150 to 250 nm), and their RNA genome is in the negative sense. These viruses belong to the Paramyxoviridae family, one of the largest and most rapidly growing groups of viruses causing significant human and veterinary disease. HPIV are closely related to recently discovered megamyxoviruses (Hendra and Nipah viruses) and metapneumovirus.

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 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.

Virus antibody levels in serum specimens from patients with optic neuritis and from matched controls;

Virus antibody levels in serum specimens taken in acute and convalescent phases from 77 patients with optic neuritits were tested by measles hamagglutination inhibition (HI), measles hemolysis inhibition (HLI), rubella HI, parainfluenza-1 HI, Epstein-Barr immunofluorescence (IF), and against 11 other viruses and mycoplasma pneumoniae with the complement fixation (CF) technique. The virus antibody levels were indicated to be usually very stable, and a fourfold change in virus antibody levels was demonstrated in only eight patients. The virus antibody levels were compared with specimens from two carefully selected control groups. The first control group consisted of 71 healthy persons matched in age, sex and place of residence with the patients with optic neuritis. The other control group consisted of 58 patients with various neurological diseases other than multiple sclerosis (MS) or infectious diseases of the central nervous system. The patients with optic neuritis had significantly higher measles antibody titres than the two control groups in both measles HI and measles HLI tests. Also in 33 patients with optic neuritis of unknown cause, the measles antibody levels were higher than in the control groups. On the other hand, various other antibody tests showed no statistically significant differences between patients with optic neuritis and the control group.

Multiple sclerosis-induced reduction in the yield of a mouse cell line

Cultures of a mouse cell line (PAM) were treated with 71 multiple sclerosis (MS) and 45 non-MS samples. Of the cultures treated with MS material, 80 percent (58) showed a reduction in cell yield (compared to untreated controls) of at least 20 percent by the third passage after inoculation. The MS samples were from 40 MS cases, and a total of 36 cases yielded at least one positive sample. The agent responsible for the decrease was not limited to nervous tissue, but was also found in serum, cerebrospinal fluid, spleen, kidney, and lymph node of MS patients. Positive samples were present at every stage of the disease. None of the non-MS samples yielded cell counts significantly different from untreated controls. The non-MS category included 12 samples from healthy individuals, 13 assorted non-central nervous system disease samples, and the following central nervous system disease samples: six subacute sclerosing panencephalitis, three Huntington's chorea, two Parkinsonism, six amyotrophic lateral sclerosis, one stroke, one encephalopathy, and one epilepsy. Brain homogenates from mice inoculated with MS tissues elicited the decrease, whereas brain homogenates from mice inoculated with non-MS samples did not.

Reduced cell yields of mouse cell line cultures after exposure to homogenates of multiple sclerosis tissues

The total cell yields in cultures of a mouse cell line termed "PAM" were reduced markedly after exposure to multiple sclerosis (MS) homogenates. The reductions were noted as early as the second subcultivation. The effect was produced by eight of eight MS brain homogenates and three of three MS spleen homogenates; the samples were from 10 MS cases. The reduction in total cell yields (compared to medium-treated cultures) was not observed after exposure to homogenates, six brain and two spleen, from eight non-MS cases. The effect was produced by the 50-nm filtrate of a pool of MS brain homogenates. Five of the MS-inoculated cultures were maintained for 18 subcultivations, and the reduction in total cell yields persisted throughout the series. The capacity to induce the reduction in cell yields was present in cell-free lysates from five of five MS cultures at passage 18, as was the capacity to cause a decrease in the polymorphonuclear neutrophils in the peripheral blood of mice. Calculation of the dilution effect (at least 10(18)-fold) that had occurred by the end of the passage series proved that the factor(s) causing the cell change in culture and the polymorphonuclear neutrophil change in mice had replicated in PAM cells.