Spodoptera frugiperda (the fall armyworm caterpillar) and the duck are gradually replacing the chicken as the creature of choice for vaccine production. New cell-culture techniques and, particularly, recombinant technologies, are bringing faster production cycles and higher purity yields, according to researchers who will present their insights at the Bharatbook conference on “Vaccine Manufacturing” next month in London.
Protein Sciences is about to commercialize its FluBlok™ seasonal flu vaccine, which was developed through a baculovirus protein-expression technology that uses insect cells as host cells. The Spodoptera frugiperda insect cell line (expresSF+® cells) grows in suspension culture in the absence of serum. “We will have one of the first products made in insect cells licensed in the U.S.,” reports Clifton McPherson, Ph.D., director of quality control. GlaxoSmithKline was the first, using a different insect virus.
“We use a recombinant baculovirus in which a highly expressed gene is replaced with the hemagglutinin gene, and this recombinant baculovirus is used to infect expresSF+ cells,” Dr. McPherson explains. Using an insect cell line also reduces the potential of cross-over infections, as few viruses can infect both insects and humans.
Although chicken and egg technologies have been widely used for decades, they are expensive and have certain production issues. Namely, “the influenza virus is adapted to grow in eggs,” Dr. McPherson says. In contrast, “ours can be a perfect match for the virus in the wild.”
Protein Sciences’ technology is also scalable. The company is in the process of scaling up from 500 L batches using the same bioreactors used for mAbs. It’s also safe, he adds. “We never handle live virus. We start with RNA or with the gene sequence.”
The same technology used for FluBlok is also being used to develop a pandemic vaccine called PanBlok™ that is in Phase II trials in partnership with UMN Pharma and with support from BARDA in the U.S.
PanBlok is based on a purified recombinant hemagglutinin antigen from the H5N1 avian influenza. Protein Sciences is working to speed pandemic response with the goal of producing 50 million doses within six months of an outbreak. Protein Sciences’ technology allows for a rapid response, and the production volume is more assured because recombinant technology is not limited by egg production concerns.