[LUM#2] Viruses that do us good

[LUM Magazine] - Published on March 29, 2016 in Science-Society

It treats infections without the need for antibiotics. Long forgotten, phagotherapy could well be back in the spotlight.

They have saved millions of lives. What are they? Antibiotics: drugs that have revolutionized medicine since the discovery of penicillin by Alexander Flemming in 1928. But yesterday's heroes have lost their lustre. Today, the finger is pointed at them: their excessive use over decades is responsible for the emergence of multi-resistant bacteria, on which they no longer have the slightest effect...

Resistance

A worrying situation for Michael Hochberg, researcher at the Institut des sciences de l'évolution in Montpellier : " Today, it is estimated that an antibiotic is only really effective for 5 to 10 years. During this time, very few new molecules are discovered ". How will we fight bacteria tomorrow? Perhaps with an old-fashioned weapon: bacteriophage viruses. " These natural enemies of bacteria attach themselves to their outer envelope, pierce their cell wall and inject their genetic material. They then multiply inside their host, causing it to die," explains Oliver Kaltz, also a researcher at Isem.

These "phages" had their heyday after their discovery by the Frenchman Felix d'Hérelle in 1917. They are still used today in some Eastern European countries such as Georgia and Poland, but fell into oblivion in Western countries after the 1940s. The cause? The rise of antibiotics, then considered the absolute weapon against all bacterial infections. " Today, antibiotics have reached an impasse, prompting renewed interest in phagotherapy ", explain the researchers.

Wise viruses

Whereas antibiotics attack the bacteria they encounter fairly indiscriminately - including the "good" bacteria that make up our intestinal flora - phages are discerning: each virus generally targets a specific bacterium. " Phage therapy is tailor-made, whereas antibiotic therapy is ready-to-wear ," says Oliver Kaltz. Another advantage of this targeted therapy is that it limits the emergence of resistance. " A bacterium mutates and becomes resistant to a phage? It too will mutate to overcome the resistance. This is what we call a co-evolutionary process", emphasize the Isem researchers, who are studying this co-evolutionary process in the laboratory and its possible importance for phage therapy.

Phage therapy could thus help combat bacteria that are multi-resistant to antibiotics, for which no effective treatment is available. "Some French doctors have used phages to treat patients with hopeless cases, sometimes with spectacular results ," explains Oliver Kaltz.

Could phages one day replace our good old antibiotics? For the researchers, the answer is no: " the idea is rather to develop a therapy combining bacteriophages and antibiotics to increase the effectiveness of the treatment ". This would also considerably reduce the need for these drugs, thereby limiting the emergence of antibiotic resistance.

Legal fog

The benefits of phage therapy are beginning to be seen by public authorities: in a 2012 report, the Centre d'analyse stratégique, a French institution for expertise and decision-making, proposed " clarifying the regulatory status of phage therapy and setting up a research program to evaluate its therapeutic potential ".

Yet the road to phage therapy remains fraught with pitfalls. " Phagotherapy is not taught in medical schools and remains unknown to most practitioners ", say the researchers. And despite official recommendations, its regulatory status remains obscure. " Viruses are alive and do not consist of a simple, well-defined active molecule. Under European legislation, therefore, they do not have the same status as a chemical drug", explains Oliver Kaltz. So they don't attract the same level of interest from the pharmaceutical industry. " All the more so as these living organisms cannot be patented," adds Michael Hochberg.

In the absence of a clear status, it remains difficult to obtain authorization to test the efficacy of phagotherapy, deplore the researchers. However, the situation is beginning to improve with the arrival of the first clinical trials (see box). The next few years will be decisive for the revival of a therapy that is virtually forgotten, but so promising.

Key words : LUM#2, LUM Magazine, Medicine, Research, Health