VIDO-InterVac scientists advance cattle disease research

TAYLOR BOROWETZ

The International Development Research Centre is funding researchers in Saskatchewan and Kenya to develop an effective vaccine against a bacterial disease that kills up to half of the animals infected: contagious bovine pleuropneumonia (CBPP).

The team from the University of Saskatchewan’s Vaccine and Infectious Disease Organization-International Vaccine Centre (VIDO-InterVac) has been working with colleagues in Africa at the Kenya Agricultural and Livestock Research Organization, International Livestock Research Institute, and the Kenya Veterinary Vaccines Production Institute. They have been collaborating on the project since 2012.

VIDO-InterVac focuses their research on the mitigation of infectious diseases that affect both human and animal health.

CBPP is caused by Mycoplasma mycoide mycoides (MCC) , a microorganism that lives in ruminants — cattle, deer, sheep, giraffes, antelope and their relatives. MCC are impervious to harsh environmental changes and cause a lethal respiratory disease. If an animal does not succumb to CBPP itself, it will remain infected and is capable of spreading the disease. Cattle are infected by inhaling the droplets disseminated from the coughing of those carrying CBPP. The disease can also be passed from a mother cow to her fetus.

Once found worldwide, CBPP was eliminated from most countries through vaccination and destroying infected herds. In the United States in 1879 there was a widespread outbreak so severe that the British government blocked U.S. cattle exports to Britain and Canada. This prompted the U.S. to set up the Bureau of Animal Industry to eradicate the disease, in which it was successful.

Despite being widely eradicated from North America and Europe, CBPP is still found in Africa. According to Andrew Potter, director of VIDO-InterVac and professor of veterinary microbiology, it causes up to $2 billion in economic losses annually there and primarily affects small farmers.

Potter said in an email to the Sheaf that the disease is also of concern from an international trade perspective, since animals from areas where the disease is endemic cannot be moved to other countries, either within Africa or elsewhere. He said because animals move relatively freely in pastoralist communities, this can be problematic.

While vaccines for CBPP do exist, Potter pointed out multiple problems with their use in an African setting. First, he said the vaccines consist of live organisms and would require refrigeration in order to be stable. Second, the vaccine causes immunity for a short period of time, so animals must be repeatedly immunized.

Potter said their approach has been to combine computational methods to mine the genome of MCC strains for potential vaccine components, and then produce these components using recombinant DNA technology for vaccine testing. The team has now tested over 60 proteins for their vaccine potential in Africa and has identified eight that have the potential to be developed further. He said they have been working with their colleagues in Kenya in order to produce these vaccines at economical levels and test their effectiveness under field conditions.

Their greatest breakthrough was the identification of the protective vaccine components — a discovery that has eluded other researchers in the field, Potter said.

“Given the nature of CBPP and the economic losses associated with the disease, we believe that the vaccine formulation we have developed in collaboration with our Kenyan colleagues will have a significant benefit for small scale pastoralists in Africa and will ultimately allow freer movement of animals,” said Potter.

However, whether or not a vaccine will actually be useful depends on a multitude of other factors. He said the team in Kenya is leading work on socio-economic issues including uptake of the vaccine, gender issues, regulatory issues and overall acceptability by farmers.

“Ultimately, the importance of the work will be measured by the sustainability and profitability of holders of livestock in the region,” Potter said.

“We believe that we will be able to contribute to control of the disease in the short term, and in the longer term can look at potential eradication of the disease from Sub-Saharan Africa as has been accomplished in other parts of the world.”