The virus that causes African swine fever has both direct and tickborne life cycles. It has a large, complicated genetic structure with some genes similar to those that govern the host's immune response. Social and political factors also enter into vaccine development. In some cases, the disease may not be widespread enough to make vaccine development and production cost-effective. In others, a vaccine may make it difficult to determine whether an animal has naturally contracted the disease of concern or merely received vaccine.
Diagnostic complications can have serious impacts on trade.
The key to overcoming these challenges is to gain increasingly detailed knowledge about disease agents and the animals they affect. During the last decade, researchers worldwide have shifted their focus to understanding and manipulating specific proteins rather than entire disease organisms. At ARS' National Animal Disease Center , for example, scientists have been able to use biotechnology to remove virulence proteins from the bacterium, Pasteurella haemolytica , which is involved in causing shipping fever of calves. Injecting the modified P. haemolytica into cattle induces an immune response and prevents the disease. At the Southeastern Poultry Research Laboratory , researchers have developed a vaccine using only the hemagglutinin protein from avian influenza virus rather than the whole virus.