Speedy flu vaccine on the cards

2005-11-01 15:23

Washington - A new genetic technique developed by US and Japanese scientists could help drug firms produce a vaccine for the deadly strain of bird flu more quickly, researchers said in a specialised magazine.

The improved "reverse genetics" technique makes the disarmed viruses that are the seed stock for producing large quantities of flu vaccine, said the study's co-author, Yoshihiro Kawaoka of the University of Wisconsin.

It could assist in the rapid manufacture of a vaccine for the virulent H5N1 strain of avian flu, which has killed more than 60 people in Asia since late 2003.

The new method, stemming from a technique Kawaoka developed in 1999, makes it easier to produce a seed virus in monkey kidney cells, which, like tiny factories, churn out millions of copies of the disarmed virus for vaccines.

The genetically altered virus is then seeded into chicken eggs to generate the vaccine used in inoculations, the researchers said in this week's issue of the Proceedings of the National Academy of Science.

Monkey kidney cell lines are routinely used to make seed strains for vaccine production because they are not known to carry any unknown infectious agents and do not cause tumours.

According to Kawaoka, "application of the new system may be especially advantageous in situations of outbreaks of highly pathogenic avian influenza viruses".

The method devised by Kawaoka and his colleagues reduces the number of plasmids - a type of DNA molecule found in bacteria - required to introduce viral genes into the monkey kidney cell lines, speeding up the process.

Scientists fear that the deadly H5N1 strain could mutate with a human variety of flu to produce a virulent form of the virus transferable between people, potentially sparking a pandemic.

The production of a vaccine can take months, depending on how quickly new strains are identified, genetically disarmed and subsequently generated in the lab.

- AFP