Table 1.
Viruses Implicated in MS: Virus, Disease Involvement, and Association with MS
| Virus | Disease involvement | Association with MS |
|---|---|---|
| EBV, HHV-4, lymphocryptovirus Double-stranded (ds) DNA virus, neurotropic Tropism: B cells, epithelial cells Cell latency: memory B cells |
Infectious mononucleosis, Hodgkin and non-Hodgkin’s lymphoma, Burkett’s lymphoma, gastric and nasopharyngeal cancer, hairy cell leukemia, MS | Mononucleosis predisposes to MS, reduced activity of EBV-specific cytotoxic T cells (e.g., exhausted) in MS patients, EBV seropositive-epidemiological studies, virus present in MS brain, EBV prolongs the lifespan of B cells |
| HHV-6, roseolovirus dsDNA, neurotropic Tropism: broad; hematopoietic and epithelial cells Cell latency: lymphocytes and monocytes |
Exanthema subitum (roseola infantum) and pneumonitis, MS | Present in MS plaques, reactivation during relapses, high levels found in oligodendrocytes and areas of demyelination, elevated levels are found early in MS and during relapses/exacerbations, anti-HPV IgG and IgM titers are reported to predict relapses |
| CMV, betaherpesvirinae dsDNA, neurotropic Tropism: broad; hematopoietic cells, smooth muscle, monocytes, epithelial and endothelial cells, fibroblasts, connective tissue Cell latency: cells of the myeloid lineage |
Retinitis, hepatitis, colitis, pneumonia, encephalitis, MS | Both detrimental and beneficial properties reported, large meta-analysis MS versus controls did not yield a conclusive link between CMV and MS |
| Varicella zoster virus (VZV), HHV-3 dsDNA, neurotropic Tropism: mononuclear cells Cell latency: sensory ganglia |
Chickenpox, shingles, MS | Virus is present during relapses, recent studies failed to show an increased risk of MS associated with varicella or zoster infections |
| HERV-W Tropism: cells of the nervous system, syncytiotrophoblast layer of the placenta Cell latency: multiple |
MS, diabetes, autoimmune arthritis, and schizophrenia. In most cases the observed expression profiles of specific HERV-W sequences have not led to a definitive association with human disease pathology | Present in infiltrating macrophages and activated MS lesions, MSRV Env protein is detected in blood of active MS patients, drives the expression of proinflammatory cytokines, reduces myelin protein, expression and kills oligodendrocyte precursors |