Attenuated vaccines can recombine to form virulent field viruses
http://www.sciencemag.org/content/337/6091/188.abstract
Vaccine-associated acute polyneuropathy resembling Guillain-Barré syndrome in a dog
http://www.mendeley.com/research/vaccineassociated-acute-polyneuropathy-resembling-guillainbarr-syndrome-in-a-dog/
Viral status and antibody response in cattle inoculated with recombinant bovine leukemia virus-vaccinia virus vaccines after challenge exposure with bovine leukemia virus-infected lymphocytes
http://www.ncbi.nlm.nih.gov/pubmed/8725805
