The Viral Side of Life: How Bacteriophages Rule The Microbial World

Introduction:

We usually imagine the flu, COVID-19, or serious illnesses when we hear about viruses. But there is a fascinating class of viruses that does not infect us at all. Instead, they hunt bacteria. These are bacteriophages, or phages - viruses that specifically infect and destroy bacteria. Furthermore, they have been quietly affecting the world on Earth for many billions of years. 

Currently, phages are increasingly appreciated not only for their long history as predators of bacteria, but also for their possible role in modern medicine. 

What Are Bacteriophages?

• Bacteriophages invade bacteria and replicate themselves inside them
• Their name literally means "bacteria eaters."
• Soil, oceans, and even our bodies are abundant with these phages since they are the most abundant living things on Earth, estimated at 10³¹ particles worldwide. 

How Do They Work?

1. Attachment: The phage locks onto a specific bacterial cell.
2. Injection: It injects its RNA or DNA into the bacterium.
3. Hijack: The phage takes control of the bacterial machinery.
4. Explosion (Lysis): New phages are built inside the bacterium, which eventually burst open, releasing dozens of new viral particles. 

#Fun fact: A single phage can destroy a bacterial cell in under 30 minutes.

Figure A: Mechanism of action of bacteriophage therapy: After bacteriophage infection (A), phage DNA (purple) is either conventionally replicated and processed as new virions at the cost of the host cell (virulent phage in the lytic cycle; left, A, E and F) or reproduces with host DNA (temperate phage in the lysogenic cycle; right, B, C and D) (Fabijan et al. 2020)

Phages Are More Important Than Many Realize

1. Guardians of the Gut: Phages help maintain balance in our gut microbiome, by selectively eliminating harmful bacteria only.
   
2. Nature's Antibiotic: With antibiotic resistance on the rise, phage therapy is making a comeback, especially for drug-resistant infections where antibiotics fail
3. Genetic Engineers: Phages played a major role in the discovery of CRISPR, the revolutionary gene-editing tool. Yes, bacteria developed CRISPR as a defense system against phage attacks. 

How They Are Used In Real Life

• Phage Therapy: Custom phages are being used to treat infections in patients with no other options.
• Agriculture: Plants and livestock are protected from diseases by using phages instead of dangerous chemicals.
• Biotechnology: Phages are tools in genetic engineering, diagnostics, and nanotechnology. 

Common Misconceptions About Phages

Myth	Fact
Phages are dangerous to humans	Phages only infect bacteria, not human cells
They are too unpredictable for medicine	Modern tools allow precision phage engineering
Phage therapy is new	It was used over 100 years ago, before antibiotics became popular

Why This Matters Now

We are entering a post-antibiotic era, where once-curable infections are becoming deadly again. Phages could be the heroes we forgot about: they are found everywhere, aim at bacteria, and adapt as their enemies too. 

## The smallest predators on Earth may hold the biggest promise for the future of medicine. 

Sneak Peek at What's Next: "Rise of the Superbugs: Understanding and Combating Antibiotic Resistance"

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