By Ben Hirschler
LONDON, Nov 25 (Reuters) - An experimental vaccine based on a molecule related to DNA protects animals against influenza and may one day offer an ultra-rapid way to develop new shots for humans, German scientists reported on Sunday.
Assuming it also works in people, the new approach could allow commercial flu vaccines to be designed and manufactured in weeks rather than months.
Making vaccines quickly is critical in fighting flu, particularly during a pandemic when health authorities and drugmakers are in a race to keep up with mutating strains of virus.
Flu vaccines have traditionally been produced in chicken eggs, a tricky and lengthy process. More recently some firms have started using animal cell cultures, with Novartis on Nov. 20 winning the first U.S. approval for such a product.
Both approaches, however, still involve virus cultivation, which can result in variable yields and production delays.
The new vaccine developed by Lothar Stitz of Friedrich-Loeffler-Institut and colleagues uses a quicker approach. It is made solely of messenger RNA (mRNA) - a single-stranded molecule that carries information telling cells which proteins to make.
"The only thing we need is the sequence of the relevant genes," Stitz said. "It's a new option and it doesn't take long to do."
His team vaccinated mice, ferrets and pigs with an mRNA vaccine and found that the immune response was similar or better than that found with conventional vaccines. What is more, the new vaccines showed high efficacy in very young and very old animals, which can be a problem with current flu shots.
Reporting their results in the journal Nature Biotechnology, the scientists calculated that a completed vaccine could be produced within six to eight weeks of the genetic code of a flu virus strain being published.
In contrast growing vaccines in fertilised chicken eggs can take up to six months, while using cell cultures may reduce that by up to eight to 10 weeks.
Another potential advantage of mRNA vaccines is the fact that they do not need to be refrigerated.
A human vaccine based on the research is still years away, since extensive clinical trials will be needed to test safety and efficacy, and the job of taking the work forward now rests with CureVac, a privately owned biotech company.
CureVac, backed by billionaire German investor and business software firm SAP's co-founder Dietmar Hopp, is already developing a therapeutic mRNA vaccine for prostate cancer in human trials.
The firm also has a vaccine for lung cancer in development and is working on prophylactic vaccines against several unnamed infectious diseases in a collaboration with Sanofi.
Sanofi is a major supplier of flu vaccines, along with Novartis and GlaxoSmithKline.