“Do you have a favourite virus?” A strange question, borderline offensive to many. Surely this cannot include potentially fatal viruses such as those that cause flu (influenza), AIDs (retroviruses) and cancer (HPV)! As I sneeze twice and blow my nose before I even finish this paragraph, I curse the common cold virus. Doesn’t everybody hate viruses?
But secretly I have a favourite and being an extremely shallow person, it became my favourite upon seeing its 10,000 times amplified image and before knowing what it did…. the bacteriophage “bacteria eater”! This group of viruses includes the T4 phage which looks like an alien nano-machine with its needle-like legs, coiled lower body and diamond-shaped upper body enclosing its genetic material, DNA. Their shape and genetic material (DNA/RNA) varies between phages.
Each different phage invades specific bacteria in a process known as the lytic cycle. They land on its cell surface and the real similarity with sci-fi begins with a parasite-style alien invasion. The phage injects its genetic material into its target and this integrates with the bacteria’s chromosome. With a mechanism worthy of Mulder and Scully, the bacteria are tricked into making new viruses inside it. Once the new viruses are fully formed, the final phase of the lytic cycle takes place, the lysis of the bacteria which is killed as it bursts open releasing the next alien attack! So these phages have significantly more than good looks!
But could this be a tiny superhero in disguise? The increasing antibiotic resistance by ‘superbugs’ was evident this week with new strains of E. coli infecting thousands in Europe and a new strain of MRSA found in the UK, Denmark and Dublin hospitals. New ways to treat E. coli infection were explored in a New Scientist article on Wednesday. These include therapies aimed at bacteria toxins which have led to kidney damage in the recent E. coli outbreak, vaccinations against specific proteins which allow E. coli to invade the gut and the use of my favourite, bacteriophages, being tested by a UK company to shut down bacterial DNA.
This gave me renewed hope in the potential of bacteriophages. Because antibiotics have been used as the jack of all trades for the last number of years, phage therapy is years behind where it could be. This became obvious when researching for this blog earlier this week. The search terms “bacteriophage”, “phage” and “bacteriophage therapy” led to very few recent articles in major journals (such as Nature, Science, Cell and PNAS) in relation to using phages to treat bacterial infection.
The most recent study I could find was in 2009 in PNAS. Some bacteria such as the new strain of E. coli can’t be treated by most available antibiotics as they react to them by producing more toxin in a reaction called SOS. This study found that the use of phages could enable antibiotic treatment by suppressing the bacteria’s SOS reaction. Ironically, as released at 9pm yesterday by Nature News, the genes in the current E. coli outbreak responsible for the release of toxin are phage genes that have integrated into the bacteria’s chromosome which activate once the SOS reaction begins. So phages also have an extremely dark side!
Before phages could be a viable treatment option, many problems need to be ironed out such as potential immune responses to the virus and the use of different phages for each strain of bacteria which results in high expense rather than the usual broad-spectrum antibiotic model. But perhaps it’s time to end the longstanding chemical vs. bacteria war and let biological warfare begin.
Maybe being shallow isn’t such a bad thing. Looks can kill…. or cure!
Photo: Wikimedia Commons