Multiple Sclerosis & CoronaVirus

Human CoronaViruses (HCoV) cause common colds but can also infect Neural cell cultures.

To provide definitive experimental evidence for the NeuroTropism and NeuroInvasion of HCoV and its possible association with Multiple Sclerosis (MS).

We have performed an extensive search and characterization of HCoV RNA in a large panel of human Brain autopsy samples.

Very stringent reverse transcription-PCR with two primer pairs for both Viral strains (229E and OC43).

Combined with Southern hybridization, was performed on samples from 90 coded donors with various Neurological Diseases (39 with MS and 26 with other Neurological Diseases) or normal controls (25 patients).

We report that 44% (40 of 90) of donors were positive for 229E and that 23% (21 of 90) were positive for OC43.

A statistically significant higher prevalence of OC43 in MS patients (35.9%; 14 of 39) than in controls (13.7%; 7 of 51) was observed.

Sequencing of Nucleocapsid protein (N) Gene amplicons revealed point mutations in OC43.

Some consistently found in three MS patient Brains and one normal control but never observed in laboratory Viruses.

In situ hybridization confirmed the presence of Viral RNA in Brain Parenchyma, outside blood vessels.

The presence of HCoV in human Brains is consistent with NeuroInvasion by these respiratory pathogens.

Further studies are needed to distinguish between opportunistic and disease-associated Viral presence in human Brains.

DeMyelination is the pathologic hallmark of the human Immune-mediated Neurologic Disease Multiple Sclerosis, which may be triggered or exacerbated by Viral infections.

Several experimental animal models have been developed to study the mechanism of Virus-induced DeMyelination, including CoronaVirus Mouse Hepatitis Virus (MHV) infection in mice.

The envelope spike (S) GlycoProtein of MHV contains determinants of properties essential for Virus-host interactions.

However, the molecular determinants of MHV-induced DeMyelination are still unknown.

To investigate the mechanism of MHV-induced DeMyelination, we examined whether the S Gene of MHV contains determinants of DeMyelination and whether DeMyelination is linked to Viral persistence.

Using targeted RNA recombination, we replaced the S Gene of a DeMyelinating Virus (MHV-A59) with the S Gene of a closely related, nonDeMyelinating Virus (MHV-2).

Recombinant Viruses containing an S Gene derived from MHV-2 in an MHV-A59 background (Penn98-1 and Penn98-2) exhibited a persistence-positive, DeMyelination-negative phenotype.

Thus, determinants of DeMyelination map to the S Gene of MHV.

Furthermore, Viral persistence is insufficient to induce DeMyelination, although it may be a prerequisite for the development of DeMyelination.

Multiple Sclerosis (MS) is an Immune-mediated DeMyelinating Disease that could be triggered by a Viral infection.

CoronaViruses induce an MS-like disease in rodents, are NeuroInvasive in humans and can infect primary cultures of human Astrocytes and Microglia.

Infection of the human Astrocytic cell line U-373MG by the OC43 strain of human CoronaVirus caused an upregulation of IL-6, TNF-, and MCP-1 mRNA expression.

This Virus also modulated the activity of Matrix MetalloProteinases-2 and -MMP-9 and augmented Nitric Oxide production in both U-373MG cells and the human Microglial cell line CHME-5.

Thus, a CoronaViral infection of Glial Cells could lead to the production of inflammatory molecules that have been associated with Central Nervous System pathologies such as MS.

Multiple Sclerosis (MS) is an Inflammatory DeMyelinating Neurological Disease in which Autoreactive T-Lymphocytes sensitized to Myelin components of the Central Nervous System are postulated to contribute to PathoGenesis.

The possible relevance of molecular mimicry between a Human CoronaVirus and the Myelin Basic Protein component of Myelin in the generation of this AutoImmune reaction was evaluated.

Myelin Basic Protein- and virus-reactive T-Cell lines were established from 16 MS patients and 14 healthy donors and shown to be mostly CD4⁺.

In contrast to healthy donors, several T-Cell lines isolated from MS patients showed cross-reactivity between Myelin and CoronaVirus Antigens.

Overall, 29% of T-Cell lines from MS patients (10 donors) but only 1.3% of T-Cell lines from normal control subjects (2 donors) showed an HLA-DR-restricted cross-reactive pattern of Antigen activation.

After in vitro selection with either Myelin Basic Protein or human CoronaVirus strain 229E Antigens.

Moreover, reciprocal reactivities were only observed in MS patients (4 donors).

This establishes molecular mimicry between a common Viral Pathogen, such as this human CoronaVirus, and Myelin.

As a possible ImmunoPathological mechanism in MS and is consistent with the possible involvement of more than one infectious Pathogen as an environmental trigger of disease.

Human CoronaViruses, represented by the two prototype strains HCV-OC43 and HCV-229E, are important human respiratory Pathogens, also associated with Necrotizing Enterocolitis.

Two previous studies, one describing the electron microscopic observation of doughnut-shaped particles, resembling CoronaViruses, in a PeriVascular inflammatory Lesion of Brain tissue taken at autopsy from a Multiple Sclerosis patient.

The other one reporting the isolation of CoronaViruses from the Brains of two Multiple Sclerosis patients, suggested the possible association between CoronaViruses and human DeMyelinating Diseases.

We analyzed polyadenylated RNAs extracted from CerebroSpinal Fluid of twenty randomly selected Multiple Sclerosis patients and ten patients with other Neurological Diseases:

Medullary Atrophy, Parkinson's Disease, PolyNeuropathy, Senile Dementia, Headache and Toxic PolyNeuropathy) by reverse transcription and polymerase chain reaction searching for HCV-OC43 and HCV-229E sequences.

By hybridization analysis of amplification products, we detected HCV-OC43 polyadenylated RNAs in ten specimens of patients with Multiple Sclerosis.

Furthermore, we found positive hybridization signals for HCV-OC43 in the other Neurological Diseases, except for the Toxic PolyNeuropathy specimen.

Positivity for HCV-229E was observed in seven specimens of Multiple Sclerosis CerebroSpinal Fluid; one Headache CerebroSpinal Fluid and the Medullary Atrophy specimen also resulted positive for HCV-229E.

Moreover, using a solid phase technique, we report for the first time the sequence of a cDNA fragment derived from RNA extracted from CerebroSpinal Fluid of Multiple Sclerosis patient, belonging to the open reading frame which codes for the HCV-OC43 nucleoprotein N.

Furthermore, cDNA sequences revealed the presence of a mixed Viral population.

Acute MonoSymptomatic Optic Neuritis (AMON) may be an initial symptom of Multiple Sclerosis (MS). CoronaViruses have been implicated in the etiology of MS.

The objective of the present study was to look for CoronaViral RNA in AMON, which could be present in the initial stages of the development of MS.

Material And Methods
Spinal Fluids from 37 patients with AMON and 15 surgical control patients with protrusion of the InterVertebral Disk.

Were assayed with a nested multiplex polymerase chain reaction with primers specific for human CoronaViruses strain (HCV) 229E and OC43.

Results
Four patients and 1 control were positive for HCV-229E. No evidence of HCV-OC43 was found.

The frequency of positive samples was low and there was no statistical difference between AMON and controls.

Conclusion
This study does not provide evidence for an etiological role of human CoronaViruses in Acute MonoSymptomatic Optic Neuritis.