An egg-free vaccine to combat H5N1?

[2 February 2006 - 00h00]
[mis à jour le 2 February 2006 à 11h19]

Americans have developed a new type of vaccine against H5N1 based on a virus responsible for the common cold. Successfully tested against mice, it is not like traditional anti-flu vaccines produced from embryonic eggs. So this is a major development.

At the CdC in Atlanta and at Purdue University in West Lafayette, Indiana, Dr Sambhara and Dr Mittal genetically modified an adenovirus to produce a type H5NA hemagglutinin. They injected this into a group of mice, while others simply received saline solution. All were then contaminated with strains of the H5N1 virus taken from cases reported in Vietnam in 2003 and 2004.

The authors observed that despite a relatively low level of anti-bodies, the mice treated with the virus “were not dead and had not lost weight”, which was tantamount to saying that they were immunised. The new product will not act in the same way as traditional anti-flu vaccines. It will in particular result in the production of specific T lymphocytes “which help to eliminate the virus”.

A close observer, Dr Luc Hessel, Director of European Medical Affairs at Aventis Pasteur-MSD – the biggest global producer of vaccines – underlined the fact that “this is a very sophisticated technique. It will be useful only in the long-term since we do not yet know whether it can be applied to humans. However, this study is very promising since it releases us at last from the concept of a virus culture”.

We should point out that traditional anti-flu vaccines are made from the embryonic eggs of hens. This is a tried and tested technique, of course, but not without constraints. It involves a vaccine manufacturing period of from four to six months. For a very good reason: it is necessary to have four billion embryonic eggs in order to produce 1.2 billion doses! This imposes a serious constraint as regards the ability of the manufacturers to react. Particularly since H5N1 is highly pathogenic in hens, so that mass availability of such eggs could be compromised. Source: The Lancet, Vol.367, No 9508 - Photo FAO/3312

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