keskiviikkona, toukokuuta 31, 2006

Faageissa lääketieteen tulevaisuus?

Bakteriofaagit olivat kuuminta hottia lääketieteessä 1920- ja 1930-luvulla. Niitä käytettiin koleraan ja punatautiin. Sitten tuli Sir Flemingin penisilliini ja bakteriofaagit vaipuivat unholaan. Lähes kaikkialla muualla paitsi Venäjällä (Neuvostoliitossa).

Venäjän surkean taloustilanteen ja heikon lääketieteellisen tason (länsimaisin silmin katsottuna) takia bakteriofaageja käytettiin runsaasti sairauksien hoidossa antibioottien esiinmarssista huolimatta. Vielä tänä päivänä venäläinen lääketiede uskoo näihin faageihin. Ja hyvä niin, sillä hattu kourassa länsimaiset tiedemiehet tulevat tutustumaan faagihoitoihin nyt kun bakteerikannat ovat tulleet vastustuskykyisiksi antibiooteille. Ne tiedemiehet, jotka Stalin jätti henkiin, voivat nyt osoittautua hyvinkin merkittäviksi henkilöiksi.

Miten on mahdollista, että faagihoitoa käytetään edelleen Venäjällä?
1. Se on edullinen hoitomuoto
2. Se on tehokas hoitomuoto
3. Venäläiset tiedelehdet kirjoittavat faagihoidoista, länsimaiset eivät

Wikipedia: For various reasons, not least the impermeability of the Russian language to Western researchers, Russian advances in the field remain relatively unknown in the West. There is an extensive library and research centre at the Tbilisi Institute in Georgia. Phage therapy is today a widespread form of treatment in countries that were formerly members of the Soviet Union.

Raha tässäkin näyttelee suurta roolia. Faagihoito on tekniseltä toteutukseltaan niin yksinkertaista, että se länsimainen lääkeyritys, joka ensimmäisenä toteuttaa kalliin faagihoitojen kontrolloidun koesarjan (5-10 vuoden projekti) saa nähdä jäljittelijöiden tulvan. Itse bakteriofaagin vaikutustapaa ("virus syö bakteerit kuoliaaksi") ei voi patentoida ja mahdolliset faageja käyttävät hoitomenetelmät täytyy nähdäkseni perustaa tähän mekanismiin. Faageihin liitetyt kemialliset muutokset ovat patentoitavissa.

So, why do American patients need to go to all the way to [Russian] Georgia for treatment? For starters, in their natural state phages are hard to patent, the route by which drug companies lock up future profits. The first company to spend millions of dollars to prove that a particular phage is safe could allow its competitors to capitalize on the results. As important is the difficulty of regulation. There are two ways that phages are currently used in the former Soviet Union, and both pose problems from the point of view of the Food and Drug Administration. At the Tbilisi phage center, phages are personalized: You send your bacterial sample to the lab, and it's either matched up with an existing phage or a phage is cultured just for you. In the United States, by contrast, drugs are mass produced, which makes it easier for the FDA to regulate them. Phages are also sold over-the-counter in Georgia. People take the popular mixture piobacteriophage, for example, to fight off common infections including staph and strep. These phage mixtures are updated regularly so they can attack newly emerging bacterial strains. In the United States, the FDA would want the phages in each new concoction to be gene sequenced, because regulations require every component of a drug to be identified. To do so would entail prohibitively expensive and lengthy clinical trials. In the early years of phage research in the United States, says former National Institutes of Health scientist Carl Merril, bacteriophages allegedly killed more people than they cured. Phages are culled from dirty, wet places—the first was found in the Ganges River—a recipe for infection unless you know what you're doing. And some kinds of phages—called lysogenic phages—are potentially dangerous, because they sometimes carry genes that cause bacteria to release toxins. So, there is reason for caution.Despite the caveats, a number of phage biotechnology firms have recently opened up in the United States and also in countries like Canada and Israel. Phage biologists point out we know much more about phage biology now than when the viruses were first discovered. Methods of using phages for treatment, from distillation to identification, have improved significantly since then. Clinicians worldwide also report that patients using phages have had good recovery rates and minor or fleeting side effects. Evergreen State College professor Elizabeth Kutter, who collaborates closely with Eliava researchers in Georgia and heads an international phage conference each year, is working with others to find ways to commercialize phages that could sidestep some of the problems with patenting and regulation. Flu vaccine offers one instructive possibility. Like over-the-counter phages, the vaccine is updated regularly with the most recent strain of flu virus—without requiring FDA approval each time. There are already multiple uses for phages without FDA approval. A promising area is American agriculture and livestock, which is regulated by the less stringent United States Department of Agriculture. Domestic scientists are looking at ways in which phages could kill bacteria before they cause infection (rather than fight an infection after it has begun). Alexander Sulakvelidze, an assistant medical professor at the University of Maryland and a co-founder of the phage R&D company Intralytix, awaits federal approval for a phage-based wash for meat and produce that protects against food poisoning. Vincent Fischetti, a professor at the Rockefeller Institute, is designing a phage-based enzyme solution that can be sprayed into the noses and mouths of hospital and nursing-home patients. Fischetti and researchers in Tbilisi are also experimenting with using phages to detect anthrax and cholera in the case of a terrorist attack. Using phages to treat infections at home, on the other hand, for the moment seems unlikely. One company recently tried to open a phage center in Tijuana but was deterred by the Mexican government. Phages might be offered someday at clinics on Native American reservations, as a casinolike quirk of legislative autonomy. But for now, U.S. patients at a loss for options may decide that Tbilisi is close enough.

Lue myös juttuni Lääketieteen lyhyt oppimäärä.

: Slate, 30.5.2006 (Daria Vaisman: The Soviet Method for attacking infection that we can learn from)