Tight Control for the Seasonal Influenza Vaccines Production

Seasonal flu vaccines production, using ultracentrifugation for viral particle separation, can be considerably improved by using a K-Patents Refractometer. The fractionation of viral rich material can be controlled using the K-Patents Pharma refractometer. The different fractions with viral rich and disposable material are separated based on their sucrose density gradients.

Influenza vaccines require continuous production as they are reformulated each year to match the circulating strain(s) of virus anticipated in the upcoming season. The vaccines expire at the end of each influenza season.

Upstream Process

Flu vaccines are manufactured using chicken eggs or vats of animal cells to grow the virus. Both techniques have refractometer application at the purification stage (downstream process). The typical automated vaccine manufacturing process begins with chick eggs. A seed ampoule is used to inoculate the eggs. This is followed by incubation period during which the virus grows. After three days eggs are harvested with an automated vacuum system followed by a clarification process.

Virus Particle Separation in Zonal Centrifugation

At the downstream process extensive filtration and concentration steps yield a concentrate, which is loaded onto a zonal ultracentrifuge. The centrifuge separates virus and other particles into discrete zones on the basis of their different sedimentation rates. With this technique, a centrifuge tube, which contains a continuous liquid (a sucrose density gradient) is prepared. The density gradient is loaded into the rotor. A sucrose gradient may consist of layers decreasing from 70% sucrose to 20% sucrose in 10% increments.

The centrifuge tube is accelerated slowly so that the transition from rest to a horizontal position occurs. The particles sediment radially into the gradients of increasing density. They eventually band (iso-pycnically) in cylindrical zones, where the gradient density equals the particle's buoyant density.

After the separation, the tubes are decelerated to rest and the gradients are recovered as a series of discrete fractions. Fractions are collected using a small peristaltic pump or air pressure according to sucrose density gradients measured by K-Patents Pharma Refractometer. A recommended measurement system consists of Pharma refractometer sensor PR-23-AC-HSS-GP-SC-EP with a pharma mni flow cell PMFC-HSS-H04 and an indicating transmitter DTR.