My throat is itchy, my nose is clogged, and my body is achey. Schedules were changed, work was missed, chores were left undone. Most likely, my family can blame a virus for our less-than-stellar week.
We all know viruses, but our shared knowledge comes with a largely negative attitude. From little colds like mine to Ebola, viruses wreak havoc on human health across the globe. Zika virus and HIV have lifelong impacts, assuming they haven’t killed you. When viruses go especially wild, they can affect whole societies as the entire globe recently experienced with the COVID-19 pandemic. If all this chaos and pain comes from viruses, why would we ever be thankful for them?
While my heart does not exactly burst with gratitude for my current illness, here are four reasons you and I can be thankful for viruses:
Viruses Contributed Genetic Diversity to Humans
When a virus infects a cell, viral DNA can integrate into the host cell’s DNA. A lot of the time, this additional viral DNA gets weeded out of the host cell, but not always. If viral DNA persists in sperm or egg cells, like all other parental DNA, it is inherited by the child. These snippets of viral DNA that end up staying in the host DNA are called “endogenous retroviral elements” or EVEs, and they make up abut 8% of the human genome.*
Many of the EVEs found in humans aren’t junk either. For example, known EVEs play critical roles in brain* and placenta** development. In their 2017 paper, Katzourakis and Gifford identified hundreds of EVEs in mammals of all kinds. Viruses gave mammals, including humans, functional and helpful genes!
Viruses Allow Us to Trace Our Early History
In addition to contributing genetic diversity over time, viruses contribute knowledge. EVEs act as “molecular fossils.” By studying certain EVEs, scientists and anthropologists get a peek at virus-host interactions thorugh history. Comparing strains of HSV-1 (a virus responsible for cold sores) with human genetic data has even showed that humans likely originated in Africa before migrating across the world, affirming the Out-of-Africa hypothesis of human origins posed by anthropologists.***
Viruses in the Past Protect Us From Viruses in the Present
EVEs contribute to the human immune system in multiple different ways, all of which defend against disease-causing invaders.
If it’s been a while since you took a biology class, remember that a gene hosts instructions, the instructions are copied down in the form of RNA, and then protein-making machinery reads RNA to build proteins. EVEs are genes and many of them can be transcribed into EVE RNA and translated into EVE proteins. EVE RNA can detect and capture invading viral RNA, and EVE proteins can do the same to invading viral proteins. Both can trigger further immune responses, and some EVE proteins can even block invading viruses from binding to host cells.**** There are no EVEs without viruses! So in a funny twist, viruses protect us from viruses.
Viruses Make Gene Editing Technologies Possible
Ever heard of CRISPR-Cas9? The 2020 Nobel Prize in Chemistry was awarded to a pair of female scientists who discovered this system of molecules because it has had such a huge impact on scientific research, and now, medicine. Bacteria use the CRISPR-Cas9 system to defend themselves against viruses by recognizing invading viral genes and cutting them up. The Nobel Prize winners figured out how to manipulate this system for intentional gene editing. Without viruses, CRISPR-Cas9 wouldn’t exist, and gene editing technology probably wouldn’t either.
Gene editing technologies facilitate quite a lot of genetic research, letting scientists remove, add, or change genes to observe their effects. The information gleaned from gene editing alone would be revolutionary, but medicine is also benefitting from it. Multiple areas of medical research are developing gene editing tools as treatment for genetic conditions like cystic fibrosis, hemophilia, sickle cell disease, HIV Type 1, and blood cancer.
Viruses may or may not be “good.” I will not try to convince anyone that something set on exploiting another for its own purposes is inherently good or positive. Yet, for whatever reason, viruses abound in God’s creation.
In its concluding chapters, Genesis recounts the story of Joseph, who was sold into slavery by his own brothers and ended up in governmental authority. Even in the midst of famine, Joseph’s wisdom in leadership put his country in a position to thrive. This is when Joseph tells his brothers:
As for you, you meant evil against me, but God meant it for good…
Genesis 50:20a (ESV)
The entire story of scripture demonstrates how God has redeemed evil things for good results, with the pinnacle being his redemption of his own Son’s murder for the forgiveness of you and me. If God can bring good out of that, God can certainly bring good out of viruses, too. Thank you, God, for bringing good from viruses!
*Brattås, P. L., Jönsson, M. E., Fasching, L., Nelander Wahlestedt, J., Shahsavani, M., Falk, R., Falk, A., Jern, P., Parmar, M., & Jakobsson, J. (2017). TRIM28 Controls a Gene Regulatory Network Based on Endogenous Retroviruses in Human Neural Progenitor Cells. Cell Reports, 18(1), 1–11. https://doi.org/10.1016/j.celrep.2016.12.010
Dupré, J., & Guttinger, S. (2016). Viruses as living processes. Studies in History and Philosophy of Science Part C: Studies in History and Philosophy of Biological and Biomedical Sciences, 59, 109–116. https://doi.org/https://doi.org/10.1016/j.shpsc.2016.02.010
Gómez-Márquez, J. (2021). What is life? Molecular Biology Reports, 48(8), 6223–6230. https://doi.org/10.1007/s11033-021-06594-5
Katzourakis, A., & Gifford, R. J. (2010). Endogenous Viral Elements in Animal Genomes. PLOS Genetics, 6(11), e1001191. https://doi.org/10.1371/journal.pgen.1001191
***Kolb, A. W., Ané, C., & Brandt, C. R. (2013). Using HSV-1 Genome Phylogenetics to Track Past Human Migrations. PLOS ONE, 8(10), e76267. https://doi.org/10.1371/journal.pone.0076267
****Srinivasachar Badarinarayan, S., & Sauter, D. (2021). Switching Sides: How Endogenous Retroviruses Protect Us from Viral Infections. Journal of Virology, 95(12). https://doi.org/10.1128/JVI.02299-20
**Vargas, A., Moreau, J., Landry, S., LeBellego, F., Toufaily, C., Rassart, É., Lafond, J., & Barbeau, B. (2009). Syncytin-2 Plays an Important Role in the Fusion of Human Trophoblast Cells. Journal of Molecular Biology, 392(2), 301–318. https://doi.org/https://doi.org/10.1016/j.jmb.2009.07.025
Science Magnifies 