Myelin viral

Interferon beta-la (AVONEX , Rebif ), interferon beta-lb (Betaferon ), and interferon beta (Fiblaferon ) are applied in multiple sclerosis to reduce both frequency and severity of disease incidents and for the treatment of severe viral infections. In multiple sclerosis, DFN- 3 proteins modulate the destruction of myelin in the cause of the autoimmune reaction. 

Other acquired disorders affecting myelin in humans may be secondary to viral infections, neoplasias or immunosuppressive therapy 646... 

Other acquired disorders affecting myelin in humans may be secondary to viral infections, neoplasias or immunosuppressive therapy. Acute disseminated encephalomyelitis, also called postinfectious or postimmunization encephalitis, represents a group of disorders usually of mixed viral-immunological etiology. The condition is most commonly related to a spontaneous viral infection, of which major examples are measles, smallpox or chickenpox [1,2]. 

Polyneuritis is a disorder of the peripheral nerves. It involves damage to the myelin sheath. The condition is due to inflammation of the axonal membrane caused by viral or bacterial attack, i.e. an antoimmnne disease. Guillain-Barre syndrome is one form of polynenritis and is an example of an autoimmune disease caused by immune mimicry in response to a bacterial or viral antigen. It is discnssed in Chapter 17. 

Several other diseases exist which can destroy the myelin sheath. Many are a result of viral infections or the body s immune response to a bacterial infection. Guillain-Barre syndrome causes numbness and paralysis starting at the extremities radiating into the trunk of the body where it can cause complete respiratory collapse. Guillain-Barre has occurred in senior citizens who have been given flu vaccinations. The virus used in the vaccination may be attenuated (diminished in virility but not "killed") and still be capable of causing an infection. 

ADEM acute disseminated encephalomyelitis is an immune mediated disease of brain. It is brief but significant and results in direct myelin damage. It usually occurs following a viral infection or vaccination (commonly for measles, mumps or rubella), but it may also appear spontaneously. 

Shaw, S. Y., Lawson, R. A., and Lees, M. B., Analagous amino acid sequence in myelin proteolipid and viral proteins, FEBS Lett., 207, 266, 1986. 

In the autoimmune theory (Fig. 53-1), MS results from an autoimmune attack against self-myelin or self-oligodendrocyte antigens. The actual mediator of myelin destruction has not been established, but this activity has been attributed to the action of macrophages, killer T cells, lymphokines, antibodies, or a combination of these elements. T-helper cells (CD4+) appear to be key initiators of myelin destruction in MS. These autoreactive CD4+ cells are activated in the periphery, perhaps following a viral infection, and express adhesion molecules on their surfaces that allow them to attach and roll along the endothelial cells that constitute the blood-brain barrier (BBB). These... 

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