The Good Virus

1. Phages: Nature's Invisible Bacterial Predators

However, the truth is that the viruses that cause us such suffering are vastly outnumbered by viruses that do extraordinary things for us: there are trillions of viruses out there that could actually save lives.

Invisible allies. Most people view viruses negatively, associating them with illness and death, a perception reinforced by events like the COVID-19 pandemic. However, this perspective overlooks a vast majority of viruses, particularly bacteriophages (phages), which are viruses that specifically infect and kill bacteria. These "good viruses" are harmless to humans and represent an immense, overlooked resource.

Ubiquitous and abundant. Phages are the most abundant biological entities on Earth, outnumbering bacteria by at least ten to one in every environment, from oceans and soil to our own bodies. They exist solely to inject their genes into bacterial cells, hijacking their metabolism to produce more phages before bursting the host cell. This constant microbial warfare is happening millions of times over every second of our lives.

A forgotten promise. Historically, phages were once used to save lives, notably during World War II in the Soviet Union, where they combated diseases like cholera and gangrene. Their unique ability to target and destroy specific bacteria without harming human cells makes them a promising solution to the escalating crisis of antibiotic-resistant infections, a silent pandemic threatening global health.

2. A Century of Discovery and Dispute

On opening the incubator, I experienced one of those rare moments of intense emotion . . . I saw that the broth culture, which the night before had been very turbid, was perfectly clear: all the bacteria had vanished, they had dissolved away like sugar in water.

Early observations. The antibacterial effect of phages was first observed in 1896 by Ernest Hanbury Hankin, who noted the self-purifying properties of India's Ganges River against cholera. This phenomenon, where invisible agents destroyed bacterial cultures, was later independently observed by Frederick Twort in England (1915) and Félix d'Herelle in France (1917). D'Herelle, recognizing their parasitic nature, coined the term "bacteriophage," meaning "bacteria-eater."

Pioneering therapy. D'Herelle quickly moved to apply his discovery, successfully treating an 11-year-old boy with severe dysentery in 1919, marking the first human use of phage therapy. He theorized that phages were a natural part of the immune system, an idea initially met with skepticism. His work led to widespread adoption of phage therapy in the early 20th century, with pharmaceutical companies producing phage mixtures for various bacterial diseases.

Scientific feuds. Despite early successes, d'Herelle's abrasive personality and lack of formal qualifications fueled a decades-long feud with the scientific establishment, particularly the Pasteur Institute. Critics argued phages were merely enzymes or self-destructive bacterial stages, not distinct life forms. Large-scale trials in India, though seemingly positive, lacked rigorous controls, further undermining phage therapy's credibility in the West.

3. The Cold War's Divergent Paths

In contrast, the Soviets were experimenting with a new, staunchly anti-capitalist version of society.

Soviet embrace. While phage therapy's reputation waned in the West, it flourished in the Soviet Union. George Eliava, a Georgian scientist, collaborated with d'Herelle to establish a world-leading phage research institute in Tbilisi. The Soviet government, facing rampant infectious diseases and lacking effective antibiotics, invested heavily in phage production, seeing it as a cheap and effective solution for both military and civilian populations.

Stalin's shadow. The political climate under Joseph Stalin, however, cast a dark shadow. Eliava was arrested and executed during the Great Purge, his name erased from history. D'Herelle, disillusioned by the West's profit-driven medicine, had dedicated his book to Stalin, believing the Soviet system offered the ideal infrastructure for phage therapy. He narrowly escaped the purges himself, never returning to the USSR.

Parallel evolution. As penicillin and other chemical antibiotics revolutionized Western medicine, phage therapy was largely abandoned, deemed unreliable and unscientific. Meanwhile, behind the Iron Curtain, Soviet scientists continued to refine phage production and application, developing pure intravenous phage treatments and using them extensively in kindergartens and during wartime. This ideological and physical separation led to two parallel universes of medical science.

4. Antibiotic Resistance: A Silent Pandemic

The crisis threatens to return us to the pre-antibiotic age, where common illnesses, food poisoning, basic surgical procedures and even an infected cut could develop into life-changing infections, chronic disease, disfigurement, and death.

The miracle fades. Antibiotics, once hailed as miracle drugs, began to face a growing threat: bacterial resistance. Sir Alexander Fleming, penicillin's discoverer, warned as early as 1945 that overuse could lead to resistance. Hospitals became breeding grounds for resistant strains, and new antibiotics quickly lost efficacy, with resistance emerging, on average, just six years after market introduction.

Widespread misuse. The problem was exacerbated by the widespread and often indiscriminate use of antibiotics:

• Over-prescription in human medicine for viral infections.
• Extensive use in agriculture to promote animal growth and prevent disease.
• Antibiotic runoff into waterways, creating environments where resistance genes thrive.
  This created a selective pressure, favoring bacteria with resistance mechanisms.

A looming crisis. Today, multidrug-resistant (MDR), extensively drug-resistant (XDR), and pan-drug-resistant (PDR) bacteria, or "superbugs," are a global health crisis. In 2019 alone, nearly two million people died from untreatable bacterial infections. This silent pandemic threatens to undo decades of medical progress, making routine surgeries and common infections deadly once again, driving a desperate search for alternatives.

5. Phage Therapy's Western "Rediscovery"

I am not bragging when I say that I played a major role in people in the West learning about phage therapy in Georgia.

Coming in from the cold. With the collapse of the Soviet Union in 1991, the Eliava Institute in Tbilisi, Georgia, faced severe hardship but continued its phage work. American scientists, assessing former Soviet scientific capabilities, "rediscovered" Georgian phage therapy. Professor Betty Kutter, a phage expert, became a key advocate, channeling funds and organizing exchanges to support the struggling institute.

Early attempts and skepticism. Peter Radetsky's 1996 "The Good Virus" article introduced phage therapy to the American public, sparking interest from desperate patients and venture capitalists. Early commercial attempts to bring Georgian phages to the West failed due to regulatory hurdles, patent issues, and skepticism about the "Stalinist alternative." Carl Merril, a US scientist, also faced career setbacks for his early work on phages in vaccines and their therapeutic potential.

Compassionate use. The turning point came with Tom Patterson's life-threatening superbug infection in 2015. His wife, Steffanie Strathdee, spearheaded a desperate, global search for phages. Under Clause 37 of the Helsinki Declaration (emergency compassionate use), a team of US Navy and academic scientists found and purified phages that saved Patterson's life. This high-profile case brought phage therapy back into the Western medical spotlight.

6. Overcoming Regulatory and Logistical Hurdles

They hold phages to the same standards as normal medicine, but it’s not normal medicine.

Incompatible systems. Despite dramatic successes like Patterson's, mainstreaming phage therapy faces significant challenges. Western regulatory bodies like the FDA and EMA require rigorous, standardized clinical trials based on consistent chemical formulas. Phage products, often complex mixtures of evolving viruses, sometimes custom-made for each patient, do not fit this model.

Manufacturing and access. The Georgian and Polish institutes, while experienced, lack the GMP (Good Manufacturing Practice) standards required for Western markets. This creates a paradox:

• Regulators demand pharmaceutical-grade phages for trials.
• Companies are hesitant to invest billions in unpatentable natural phages or bespoke treatments.
• Patients resort to expensive, unregulated trips to Tbilisi or even self-sourcing phages online.

Failed trials. Early clinical trials in the West have struggled to show definitive efficacy, often due to:

• Difficulty recruiting enough patients with specific infections.
• Phage cocktails losing potency or not matching local bacterial strains.
• Inadequate dosing or administration protocols.
  These setbacks highlight the need for new regulatory frameworks, like Belgium's "magistral preparations" model, which allows for personalized, less-regulated phage treatments.

7. Phages as Molecular Biology's Foundation

I was absolutely overwhelmed that there were such very simple procedures with which you could visualise individual virus particles.

Atoms of biology. In the late 1930s, physicist Max Delbrück, frustrated by the complexity of traditional biology, saw phages as "atoms of biology"—simple systems to unravel the fundamental processes of life. Collaborating with Salvador Luria and Alfred Hershey, he formed the "Phage Group," which revolutionized biology by using phages to study genetics.

Unlocking DNA's secrets. The Phage Group's work led to groundbreaking discoveries:

• Luria-Delbrück experiment (1943): Proved bacterial mutations for resistance arise randomly, not in response to selection.
• Electron microscopy: Revealed phages' distinct structures (heads, tails) and their non-entry into host cells, suggesting genetic injection.
• Hershey-Chase experiment (1952): Using a kitchen blender, definitively proved DNA, not protein, was the genetic material injected by phages.
  These findings paved the way for Watson and Crick's discovery of the DNA double helix, the "secret of life."

Legacy of innovation. Phages became indispensable tools in molecular biology, contributing to at least six Nobel Prizes. They helped scientists understand:

• Gene expression and regulation.
• Horizontal gene transfer, refining evolutionary theory.
• The first sequenced gene (phage MS2) and genome (phage ΦX174).
• The discovery of restriction enzymes and ligases, foundational to genetic engineering and DNA fingerprinting.
  The Phage Group's rigorous, quantitative approach transformed biology into an exact science, laying the groundwork for modern biotechnology.

8. Planet Phage: Earth's Most Abundant Life

Viruses, in my field at the time, were just not relevant.

Oceanic revelations. Until the late 1980s, viruses were considered insignificant in marine environments. However, studies by Øivind Bergh and others revealed billions of viruses per milliliter of seawater, making them the most abundant biological entities on Earth. This discovery forced a complete reappraisal of ocean biogeochemistry.

Ecological puppet masters. Phages play a critical role in global ecosystems:

• Viral shunt: They kill 20-40% of bacteria daily, releasing vast amounts of carbon and nutrients back into the environment, driving nutrient recycling.
• Evolutionary drivers: Their relentless pressure forces bacteria to constantly evolve, promoting microbial diversity.
• Genetic exchange: Phages act as versatile carriers, swapping genes between bacteria, accelerating adaptation and innovation across species.
  This "dark matter of biology" significantly influences global carbon cycles and oxygen production, with cyanobacteria phages boosting photosynthesis, contributing up to an eighth of the oxygen we breathe.

Beyond the lab. Phage ecology, the study of viruses in their natural environments, is a crucial frontier in understanding our planet. Researchers like Jennifer Brum and Mya Breitbart explore phages in extreme environments, from deep-sea vents to hypersaline lakes, revealing insights into early life forms and the complex interplay between phages and host organisms, including the "third immune system" in animal mucus layers.

9. CRISPR: An Ancient Anti-Phage Technology

To his amazement, in 2003, there was an exact match. The DNA sequence in one of the spacers he found in the genome of E.coli was identical to a sequence found by another researcher in a phage.

A baffling discovery. In 1989, Francisco Mojica, studying archaea in Spanish salt lakes, discovered strange, regularly interspaced, short palindromic repeats in their DNA, which he later named CRISPR. For years, the function of these sequences remained a mystery, and his research was dismissed as obscure.

Microbial memory. Mojica's breakthrough came in 2003 when he found that the "spacer" DNA between the repeats matched fragments of phage DNA. This suggested CRISPR was a bacterial immune system, a molecular memory that allowed microbes to "remember" past viral attackers and defend against future infections. Rodolphe Barrangou's work with yogurt starter cultures provided conclusive experimental proof, showing that phage-resistant bacteria had incorporated phage DNA into their CRISPR regions.

Gene-editing revolution. In 2012, Jennifer Doudna and Emmanuelle Charpentier revealed how the CRISPR-Cas9 system could be repurposed as a programmable gene-editing tool. Cas-9, a protein that uses guide RNA to find and cut specific DNA sequences, could now be directed to any gene, enabling precise editing. This technology has revolutionized genetic engineering, offering unprecedented control over genomes in plants, animals, and humans, with profound implications for medicine and ethics.

10. Phage Therapy 2.0: Innovation for the Future

I want to invest in the approach where any phage you want or need is just on a USB stick.

Beyond traditional methods. The "third age of phage" is marked by a surge in interest and investment, but the challenges of cost, scalability, and regulation persist. A new generation of innovators is developing "phage therapy 2.0," leveraging cutting-edge technology to overcome these hurdles.

Synthetic phages. Researchers like Jean-Paul Pirnay envision a future where phages are synthesized on-demand from digital DNA sequences, eliminating contamination concerns and allowing for precise design. Companies like Felix Biotech are using AI and robotics to design broad-spectrum synthetic phages that can target multiple bacterial strains or enhance specific functions like biofilm degradation.

Automated biobanks. Adaptive Phage Therapeutics (APT), led by Carl Merril and his son, is building a vast biobank of naturally occurring phages, screened and purified to pharmaceutical standards. Their goal is to automate phage matching and delivery, with "vending machines" in hospitals providing FDA-approved phages within 24 hours of diagnosis, offering a scalable solution to antibiotic resistance.

Global health focus. Initiatives like "Phages for Global Health" are training scientists in Africa and Asia to discover and utilize local phages, offering low-cost, public health-focused solutions for regions disproportionately affected by AMR. Additionally, research into lysins (phage enzymes) and phage tails as standalone antibacterial agents offers drug-like alternatives without the complexities of live viruses.

11. Phages as Programmable Nanomachines

In other words, the army of invisible, endlessly proliferating nanobots are already here. The ‘grey goo’ already took over this planet aeons ago.

Nature's nanobots. Prince Charles's concern about "grey goo"—invisible, self-replicating nanobots—is ironically a reality with phages. These natural nanomachines, perfected over billions of years, are self-assembling, self-replicating, and largely non-toxic, making them ideal components for nanotechnology.

Nanomedicine applications. Phages are being repurposed as nanoscopic drug delivery vehicles:

• Blood-brain barrier: Modified phages can smuggle medicines across this barrier into the brain, offering new therapies for neurological disorders.
• Targeted drug delivery: Phages can be engineered to carry anti-cancer drugs directly to tumor cells, minimizing systemic toxicity.
• Tissue engineering: Filamentous phages can form scaffolds for regrowing damaged human tissues like bone, cartilage, or neural tissue.
  Their ease of genetic modification and high production yield make them superior to many synthetic nanoparticles.

Beyond medicine. Phage-based nanotechnology extends to diverse applications:

• Antibacterial surfaces: Phages can be "fixed" onto materials like medical devices, prosthetics, and food packaging to continuously kill bacteria.
• Environmental remediation: Projects like PhageLand explore deploying modified phages into wetlands to remove antibiotic-resistance genes.
• Biosensors and energy: Phages are used to create nanoscopic sensors for detecting pathogens or disease markers, and even for developing microbatteries and hydrogen generators.
  These innovations highlight phages' potential to address global challenges from pollution and climate change to food safety and human health, transforming our interaction with the microbial world.