MG Vaccine Development
J. Edwin
Blalock, Ph.D.
Like humans, dogs can spontaneously develop MG. The clinical features of the disease are quite similar and include fatigue upon exercise and problems with swallowing. Canine MG is diagnosed based on acetylcholine receptor (AChR) antibody (Ab) levels and electromyograms As with the human disease, myasthenic dogs are treated with Mestinon and Glucocorticoids. Because of the similarities of the disorder, and as an important step toward a human clinical trial, we are in the process of evaluating a therapeutic vaccine in dogs with MG.
The vaccines are peptides that are designed to mimic key parts of disease-causing Ab (B cell vaccine) and T cell receptors (T cell vaccine) that attack AChR. Immunization with the peptides produces Ab that bind to and inactivate B cells producing AChR Ab and T cells reactive with AChR. The end result is that the AChR Ab response is ablated. The remarkable feature of the treatment is that it specifically blocks the disease-causing AChR Ab response without affecting desirable Ab or T cells.
At the present time, 11 out of 11 dogs that are enrolled in the
study and are people’s pets have shown diminished AChR Ab levels as a
result of one or more vaccinations. Of
these, 6 out of 6 dogs that have completed the prescribed course of
vaccinations now have AchR Ab levels that are normal and no longer require
Mestinon nor glucocorticoids. Depending
on the date of entry of a particular animal into the study, certain
animals have been in remission from months to five years.
These results suggest that we may have a lasting therapy for canine
MG and indicate that a clinical trial in humans is warranted in the near
future.
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