What is the difference between Type I and Type II BVD viruses?
Again, this is a difference between strains or biotypes of this virus. Certain parts of the viruss genetic code are different between type I and type II BVD. This difference does not equate to virulence or the ability to cause disease or death. There are type II BVD viruses that cause severe disease and those type II viruses that cause very mild disease. The same holds for type I BVD virus strains. As more research is done to sequence the genetic code of BVD biotypes, this type of classification may become too complicated to use. It is also important to understand that both type I and type II BVD viruses have CPE and non-CPE forms, and in both instances the non-CPE form is the more natural and more common situation in cattle.
