Purification of a Chimeric Simian – Human Immunodeficiency Virus-Like Nanoparticle from HEK293 Cell Culture

Abstract

Increasing demands for quality, identity and high expression rates have been the driving forces for the development of new expression systems over the last 10 years. In the future, human cell systems will range among leading tech- nologies for expression and production of human therapeutic proteins. Primary human amniocytes obtained by routine amniocentesis have been immortalized by adenoviral E1/pIX functions. CEVEC’s Amniocyte Production (CAP) cells are of non-tumor origin, they are immortalized by a function not oncogenic in human, and they are from ethically accepted source of origin. Moreover, the development of CAP cells follows relevant guidelines and is completely documented. Starting from several hundred transformed cell lines, two CAP cell lines have been selected based on growth stability, performance in permanent and transient protein expres- sion and capacity of growth in suspension. CAP cells grow as single cell suspension in chemically defined serum-free medium. CAP cells have been tested for per- manent expression of reference proteins like human alpha-1 antitrypsin (hAAT), erythropoietin and human IgG1, very high protein expressing cell lines have been obtained. The hAAT expressed in CAP cell lines was fully glycosylated and sia- lylated. In addition, CAP cells show very high transfection efficiency, a major requirement for efficient transient expression of protein. Thus, we have developed a new expression system based on human amniocytes which offers significant advan- tages over existing production technologies, like a human glycosylation pattern or other post-translational modifications and high permanent and transient protein expression.