Polio vaccine and retroviruses.

In this paper we consider the main steps in the process of manufacture of oral polio vaccine and assess the probable clearance factor for HIV retrovirus at each step. We conclude that the processes employed would have eliminated retrovirus contamination for all practical purposes.

Karyology and tumorigenicity testing requirements: past, present and future.

At the present time, karyology and tumorigenicity are applied to primary, diploid, and continuous cell systems in an uneven and inappropriate manner, largely for historical reasons. It is a significant anomaly that such rigorous requirements are applied only to diploid cells when, of all three cell types, they represent the category with the least potential problems. During the 1992 presidential campaign in the U.

Viral safety of blood derivatives: an overview.

The causes of past accidental viral transmissions associated with blood derivatives are reviewed briefly, as are the safety procedures instituted in Europe on the basis of viral validation studies. A comprehensive five-class classification system for delineating viral risk according to source material and comparative viral safety is presented. Newly emerging viruses are briefly discussed in view of the viral safety of blood products.