Fast method for preparing flu vaccine: Use bioreactors instead of chicken eggs

Manon Cox will be conferred with a PhD at Wageningen University, Netherlands, on 9 December on the strength of a thesis on this subject.

The prompt availability of sufficient suitable vaccine is always a problem when facing the outbreak of a flu epidemic. At the moment, it takes three to six months to produce a vaccine to counter a new strain of flu virus using chicken's eggs. Moreover, there is no possibility of expanding production capacity in the event of a pandemic as the limited availability of fertilised chicken's eggs needed for production inevitably becomes an insurmountable problem.

Cox's new process demonstrates that it is possible to make a vaccine available in commercial quantities within 45 days. The new production method makes use of a baculovirus that multiplies only inside insect cells, and which cannot spread in vertebrates. The insect cells produce huge quantities of so-called HA proteins, which mobilise the immune system into fighting the flu virus.

The aspect that most slows down the production of vaccine according to the conventional method is the need for fertilised chicken eggs. Furthermore, this creates extra problems if the flu virus is also capable of infecting birds (as was the case in the Netherlands in 2003), as the egg production often grinds to a halt. In addition, the vaccines produced are not suitable for people with an egg allergy. The new production process using insect cells can be used on a large scale, at all times and simultaneously at various locations throughout the world. The process can easily be adapted to new influenza strains and enhance pandemic preparedness.

Meanwhile, the new production process has already been put through clinical trials involving three different strains of flu virus in 460 healthy people. None of the test subjects injected with the vaccine developed symptoms of flu, while 4.6% of those taking part in the control group contracted the disease naturally. Three follow-on studies involving approximately 3,000 people showed no striking or frequent side-effects. The vaccine also appears to protect people from influenza viruses that have undergone genetic changes and in more than 50% of cases, it results in better antibody production than the flu vaccines currently available.

Vaccines for the flu virus contain the HA protein (haemagglutinin) which, once in the bloodstream, puts the body in a state of high alert. The protein also stimulates the production of flu-specific antibodies. The same protein is found on the surface of a flu virus. When a vaccinated person encounters a flu virus , the antibodies produced attach to the proteins on the surface of the virus and inactivate the virus.