The Hidden Heroes in Your DNA: Retrocopies and Their Role in Fighting Viruses 

In the world of genetics, there’s a fierce battle that’s been raging for millions of years– the struggle between viruses and our immune system. Retroviruses are a special kind of virus with a unique lifecycle that poses distinct challenges to our body’s defenses. Human immunodeficiency virus (HIV), the virus that causes AIDS, is probably the most commonly known retrovirus. Surprisingly, these viruses, in their quest for survival, may have inadvertently given us an unexpected advantage: retrocopies. 

Retroviruses are sneaky. They complete their lifecycle by exploiting our own cellular mechanisms and sidestepping our immune system’s roadblocks, which helps them integrate their genetic material into our DNA. They also have a habit of ‘accidentally’ copying our own messenger RNA (mRNA) into DNA to create new genes, called ‘retrocopies.’ These retrocopies, while born from retroviruses replicating in our cells, become a part of our genetic landscape.  

Here’s the surprising twist: thousands of these retrocopies can be found within each human genome. Even more intriguing, the number and sequences of retrocopies can differ from person to person. For a long time, these retrocopies were largely overlooked and dismissed as pseudogenes with no apparent purpose. 

“Within our DNA, new hidden copies of our genes, called retrocopies, may offer an unexpected advantage in the battle against viruses. They aren’t just remnants; they’re potentially powerful genetic defenders, shaping our evolution and influencing our resilience against viral diseases.”

Rick McLaughlin, PhD
PNRI Assistant Investigator

However, research from PNRI’s McLaughlin Lab has unveiled a remarkable discovery. They found that our genomes harbor retrocopies of a specific family of genes called APOBEC3, which play a crucial role in restricting viral infections. What’s more, these retrocopies are capable of fighting off viruses when tested in the lab. 

Further investigations by the McLaughlin Lab suggest the existence of retrocopies from multiple immune system-related gene families. These retrocopies may represent a powerful mechanism of genome evolution, allowing us to keep pace with ever-evolving viruses, like say…SARS-CoV-2, the virus that causes COVID. 

What’s even more exciting is the notion that some of these retrocopies could be relatively new additions to our genetic code, possibly present in only specific individuals. This suggests that retrocopies may hold a key to understanding why some people are more susceptible to viral infections while others seem almost immune.  

The work of PNRI’s McLaughlin Lab is shedding light on the complex dance between retroviruses and their human hosts and how our genetic makeup has evolved to cope with the persistent threat of viruses. This research not only expands our understanding of our genetic heritage, but it also has profound implications for our resistance and susceptibility to viral diseases.