The virtues of viruses

Bacteriophages, or phages, where first discovered in the late 19th century. They are viruses that infect and kill a specific type of bacteria and will therefore never infect human cells. These viruses can be found everywhere, in fact, they are even found within our bodies (e.g. in the gut). French-Canadian scientist Felix d’Herelle first came up with the term ‘bacteriophage’, which is a combination of ‘bacteria’ and ‘phagein’, meaning ‘to eat’ in Greek. He devised the name after seeing holes appear in a bacterial ‘lawn’ (see picture below) he infected with these bacteriophages, so it looked like they were eating the bacteria.

Currently I’m working on a project that’s looking into the role of phages in the gut and their interaction with the residing bacteria. Phages are used in a lot of applications and have a huge potential that’s yet to be explored.

The high specificity of these phages, or in other words, their ability to infect and kill only one specific type of bacteria, makes them very useful in a wide range of applications.

Firstly, phages can be used to treat infectious diseases. Shortly after their discovery, phages were used to treat a variety of bacterial infections. They consequently became a very useful tool in the pre-antibiotic era. The same scientist that named the bacteriophages, d’Herelle, was also the first scientist to develop the use of phages in clinical therapies, using them to treat bacterial dysentery. His therapies were soon picked up by pharmaceutical companies, with the predecessor of the French cosmetic giant L’oréal being one of the first companies to market a range of phage-based products: bacté-coli-phage (against E. coli), bacté-staphy-phage (against Staphylococcus), etc. Unfortunately, phage therapy had a very low effectiveness, often due to their inappropriate use, such as in non-bacterial diseases, or in situations where the phage preparation was inactivated very fast after application. This together with the rise of antibiotics eventually led to the downfall of phage therapy. However, now in the upcoming post-antibiotics era, we might have some use for them again.

Secondly, phages can also be used in the food industry. Bacteria can be ingested via contaminated food where they can cause disease (with highly uncomfortable symptoms), and sometimes even death, with the most famous food-borne pathogens being: Campylobacter, Salmonella, Listeria and E. coli. In 2011 the Centre for Disease Control (CDC) identified approximately 48 million cases of food poisoning in the USA alone, of which 3000 were fatal. Phages can play an important role here in reducing these numbers. In fact, several phage products have already been approved in this industry. The phages are applied at different stages of food processing: livestock (orally), food preparation equipment and the end product that’s delivered to the store. Just imagine the phages being sprayed onto a working surface and killing all the bacteria!

But wait, there’s more, phages can also bind and disaggregate proteins called: β-amyloid and α-synuclein plaques, which can be found in the brains of patients with Alzheimer’s or Parkinson’s disease, potentially giving them a therapeutic role in these diseases. Additionally, phages can be useful to deliver anti-cancer drugs selectively to the location of the cancer.

In short, phages have a wide range of biological applications and will probably play an ever more important role in the post-antibiotic era. Without a doubt, everyone will eventually have phage based ointments and lotions in our medicine cabinets and kitchens.

Gwendoline Deslyper