[+] Earle's salts, L-glutamine Medium 199 is often used in vaccine production, virology, and for the culture of various non-transformed cells. It was originally developed as the result of efforts to create a fully defined, animal origin-free medium. Long-term use of this medium requires serum supplementation. All components are animal origin-free. [+] Earle's salts, L-glutamine Medium 199 is often used in vaccine production, virology, and for the culture of various non-transformed cells. It was originally developed as the result of efforts to create a fully defined, animal origin-free medium. Long-term use of this medium requires serum supplementation. All components are animal origin-free.