The transmissible spongiform encephalopathy agents: concerns and responses of United States regulatory agencies in maintaining the safety of biologics.

Regulatory agencies responsible for protecting public health must be concerned with reducing or preventing opportunities for exposure of humans and animals to the agents of transmissible spongiform encephalopathies (TSEs), especially bovine spongiform encephalopathy and Creutzfeldt-Jakob disease. The United States Food and Drug Administration (FDA) has taken precautionary actions to assure that regulated products are free of such infectious agents, from both animal and human sources, including the issuing of a regulation and a number of guidance documents. With regard to TSEs, the materials of greatest concern to FDA's Center for Biologics Evaluation and Research have been bovine gelatin, tallow derivatives and serum, as well as human-derived products and excipients including blood, blood components and plasma derivatives. A number of newer issues regarding TSEs now confront agencies responsible for protecting public health. It would be of great help to have standard reference materials available to assist in the diagnosis of the diseases and to detect the infectious agents.