How are test article cells, master, or production seed stocks evaluated using electron microscopy techniques?

Test articles from cell banks and production seed stocks are prepared for ultra-thin sectioning, following standard written protocols, and are then examined for the presence of virus or other microbial contaminants in the transmission electron microscope at high magnifications.

This assay allows for the determination and identification of viruses present within, or secreted from, the cells used to produce biopharmaceuticals.