Abstract: | Neutralizing antibodies against bovine viral diarrhea virus (BVDV) were detected in sera of Iowa farm sows, their piglets derived by hysterectomy and in specific-pathogen-free (SPF) pigs in a closed herd. No antibodies against BVDV were detected in sera of 134 fetal pigs from 67 sows in an Iowa slaughter-house. Neutralizing antibodies against BVDV or hog cholera virus, produced experimentally in SPF pigs, were demonstrated to be due to different antigens rather than to a common antigen, although slight cross-neutralization reactions sometimes occur. |