Sequencing of BVDV Strains Isolated From Persistently Infected Alpacas

Principal investigator:

John D. Neill, PhD
National Animal Disease Center, Ames, Iowa

Bovine viral diarrhea virus is a common and important viral pathogen in cattle. It causes disease involving the respiratory, digestive and reproductive systems as well as negatively impacting the immune system, allowing the development of secondary infections. It is becoming increasingly clear that BVDV also plays a role in disease in alpacas. BVDV–specific antibody titers are routinely found in alpaca and cria persistently infected (PI) with BVDV. BVDV infection in adult alpacas is not associated with severe disease. However, BVDV infection of the fetus results in PI crias that can result in severe health problems. Often, crias found to be persistently infected are unthrifty and generally unhealthy. Indications of persistent infection include respiratory infections, chronic health problems, small stature and slow growth. These PI cria can also continue to spread the virus, causing acute infections as well as infecting pregnant animals, thus continuing the cycle. Additionally, it was recently shown that changes in the BVDV genomic RNA occur most rapidly in the persistently infected animal and not in acute infections as previously believed. We found nucleotide and amino acid changes that may improve or enhance replication of the virus in the alpaca host. The birth of a PI cria is probably the major source of rapid change and further adaptation of BVDV to alpaca, underscoring the importance of testing herds for the presence of BVDV and prevention of establishment of PI infections.