Monday, August 05, 2013

Virus to treat bacteria.

In 1917, a Canadian-born physician, Felix d’Herelle was investigating an outbreak of dysentery among the French soldiers, fighting the First World War. The microbes were killing the French soldiers in droves, not only invading their torn flesh, but also their food and water. As part of the analysis, Herelle passed the stool of the soldiers through a filter. The filters pores were so fine, that not even the bacteria that caused the dysentery, known as ‘Shigella’ could slip through. Herelle then took the filtered fluid and mixed it with a fresh sample of Shigella bacteria and spread it in a petri dish.

As the Shigella began to grow, Herelle noticed strange clear spots starting to form in their colonies. Herelle concluded that they were viruses, which were infecting and killing bacteria. Herelle, named these viruses, bacteriophages, meaning eaters of bacteria. Today they are known as phages for short. Scientists were aware of viruses that attacked human, plants and animals. But the concept of bacteria-infecting viruses was so strange and so new that some scientists refused to accept it. The debate on the subject raged for years. Only in 1940’s, when the electron microscope was invented and scientist could visually see the lunar lander like phages, was their presence accepted. On his part though, Herelle did not wait for the debate over phages to end before he began to use them to cure the patients. Herelle noticed that as the levels of phages in the stool climbed, the soldiers started to recover from dysentery. Herelle realised that phages were actually killing the bacteria and if he gave his patients extra phages, he could eliminate diseases faster. To ensure that the phages themselves were safe, Herelle swallowed some and injected some phages into his skin and suffered no ill effects. His phage therapy helped people recover from dysentery, cholera and bubonic plague. Heller developed phage-based drugs that were sold by the company that’s now known as L’Oreal, to treat skin wounds and cure intestinal infections. By 1940’s the phage craze had come to an end, the idea of using live viruses as medicine had made many doctors uneasy. Also in 1930’s antibiotics were discovered, which cured infections faster and unlike phage, were just artificial chemicals. Herelle died in 1949, but his dream of phage therapy was kept alive by a Soviet Institute named Eliava Institute in Tbilisi (presently in Georgia). With antibiotic resistant bacteria on the loose, advocates of phage therapy are back in news. Advocates of phage therapy contend that as bacteria evolve to resist new drugs, the phages too can evolve to fight back. Now 90 years after Herelle first encountered bacteriophages, these viruses may finally be ready to become part of modern medicine. 

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