An improved vaccine against paratuberculosis?

For her Dr .med. vet. degree at the Norwegian School of Veterinary Science, Ólöf G. Sigurðardóttir studied and described early inflammatory changes in the intestines of goats with paratuberculosis, in order to better understand the development of the disease. She also investigated the routes of infection of paratuberculosis in the intestine.

Paratuberculosis is caused by the bacterium Mycobacterium avium subsp. paratuberculosis, which is related to the tuberculosis bacterium. While tuberculosis in man causes pneumonia, paratuberculosis produces inflammation in the intestine in ruminants. In Norway, paratuberculosis is primarily a disease of goats. After infection, inflammation develops in the intestine and slowly progresses, gradually leading to wasting, reduced yield, and eventually death.

Our present vaccines keep the frequency of the disease at a low level, but do not protect goats against infection with the paratuberculosis agent. Newer vaccines can provide improved protection against the disease if they can stimulate the local defensive mechanisms that exists in the intestine, and especially if they utilise the same pathways of infiltration as does the bacterium.

“My studies have shown that the paratuberculosis bacterium invades the intestine through specialised cells in the mucous membrane of the intestine. These cells are located in regions of the intestine that are important for the immunological surveillance of the intestinal tract. Inflammation with paratuberculosis develops in these regions and gradually spreads throughout the intestine.

If future vaccines are absorbed through these same specialised cells, they will be able to initiate local, effective means of defence in the intestine and will therefore be able to protect ruminants against paratuberculosis”, says Ólöf G. Sigurðardóttir.

On April 22, 2007, Ólöf G. Sigurðardóttir defended her thesis for the degree of Doctor Medicinae Veterinariae, entitled “Paratuberculosis in goats – a study of the uptake of Mycobacterium avium subsp. paratuberculosis and pathology of early subclinical infection”.