We are living through a pandemic that has affected millions of people, broken countless health systems and economies, and shattered the reputation of viruses. I do not mean that before we met SARS-CoV-2, viruses were saints of our devotion. Society already recognized them as responsible for diseases such as measles, hepatitis and AIDS. Today, however, the fear and rage against these microbes seem greater than ever.
Here I will try to clarify that not all viruses are bad. In fact, in our laboratory we work with viruses that may one day save our lives. They are called bacteriophages.
Before explaining what makes bacteriophages our allies, I will review three of their similarities to other viruses:
Its structure is quite simple. They are just a few strands of genetic material protected by a shell made of proteins.Advertisement
It is difficult to consider them alive. By themselves, viruses are unable to multiply. They need to attack and hijack a cell.
They are very picky. Each virus is capable of infecting only a very small and specific type of cells.Advertisement
The main difference lies in this last characteristic. Bacteriophages cannot infect human cells. They exclusively kill bacteria.
Bacteria and antibiotic resistance
Bacteria are microscopic organisms too, but they are much more complex than viruses. Although they are responsible for a wide range of infections, they are of particular concern in the hospital environment.
The vast majority of healthcare-associated infections are caused by bacteria – from surgical wound infections to those of the urinary tract and bloodstream. When a hospitalized patient acquires a bacterial infection, their chances of dying increase dramatically.
Until a couple of decades ago, bacterial infections weren’t worrisome. With the proper dose of the correct antibiotic, patients began a rapid recovery.
One of the biggest threats the world is facing today is antibiotic resistance. Bacteria have become capable of resisting even our most powerful antibiotics. We need new strategies to help patients with these infections. This is where bacteriophages come in.
Phagotherapy: the enemy of my enemy is my friend
It would look like a scene out of a science fiction movie.
A hospitalized patient suffers from a generalized bacterial infection. He is in intensive care, in a coma, and his doctors have exhausted possible antibiotic treatments. The prognosis is grim.
One last hope: the medical team proposes to administer billions of viruses directly to the patient’s circulation. But not just any virus: bacteriophages that have been carefully selected in the laboratory to kill the bacteria that are infecting the patient.
After a few days of treatment, the patient wakes up. Viruses are winning the battle against bacteria. The enemy of my enemy is my friend.
In the last five years, multiple variations of this story have been published in major scientific journals. Cases include infections in the bones, prostheses, implants, and wounds, as well as pneumonia, sepsis, and urinary tract infections. Even the most dangerous and resistant bacteria, according to the World Health Organization, have succumbed in specific cases to bacteriophages.
Ancient, versatile and promising allies
Although phage therapy recently celebrated its first centenary, our interest in it has grown exponentially in the last decade, mainly due to the emergence of antibiotic resistance. A new wave of discoveries has made it clear that bacteriophages are versatile and promising allies.
For example, in January we published our observation of bacteria that can become resistant to phage therapy. We report, however, that when they do, they lose the resistance they used to have to various antibiotics. We conclude that with the correct bacteriophages we can put bacteria between a rock and a hard place. Combining bacteriophages with antibiotics could extend our therapeutic arsenal.
On the other hand, research groups are exploring the design of bacteriophage cocktails. By mixing several viruses in a single preparation, we can improve their spectrum of action.
Others study specific proteins produced by bacteriophages. Using just these proteins, rather than the entire virus, could facilitate their large-scale production.
Using bioengineering techniques, scientists have succeeded in modifying bacteriophages to attack bacteria against which natural viruses have not been isolated.
And the list keeps growing.
The future of phage therapy
The more we discover about bacteriophages, the more questions we must answer regarding phage therapy.
Successful individual clinical cases are encouraging, but we need to establish large-scale controlled clinical trials. As of March 2021, at least 12 phage therapy clinical trials are active around the world. Your results are sure to provide us with important lessons.
The safety profile of bacteriophages is positive. There is no evidence of allergic reactions, as can be the case with antibiotics. However, we must learn more about their interactions with human cells, and with the bacteria they infect.
From a practical point of view, it is necessary to establish the optimal doses and routes of administration. It is worth trying to find out the most favorable combinations with antibiotics. Finally, we must build the necessary legal framework to regulate its use.
This is a developing story. And as we continue to explore this exciting field, I hope we remember that not all viruses are bad. Bacteriophages can save lives.