A Tale of Two Protein

A Tale of Two Proteins

Written by Samuel Salamun
Illustrated by Fiona Tung
Epstein-Barr virus (EBV) is a member of the herpesvirus family that infects around 90% of the adult population worldwide. EBV transmission happens through saliva and, in most people, primary infection of EBV usually happens during childhood, perhaps because kids put everything in their mouths! Thankfully, most kids with EBV infections don’t show any symptoms. However, infection in early adulthood can cause infectious mononucleosis, better known as mono or the “kissing disease”. Persistent EBV infection can even be associated with the development of some cancers! So, what’s the deal with EBV? Do our cells have any defences against this virus?

Well, there’s good news and bad news. The good news is that our bodies have an antiviral response to stop the viruses from multiplying. This defence mechanism is a protein called APOBEC3B. This protein can mutate the virus to prevent it from replicating. The bad news is, since viruses are good at their jobs, EBV has a defence mechanism against our defence mechanism! This finding came from a research project involving University of Toronto researchers, where they tried to figure out if virus proteins interact with our human proteins. Interestingly, they found that a viral protein called BORF2 can interact with APOBEC3B. It doesn’t stop there! Aside from interacting, BORF2 can relocalize APOBEC3B away from EBV DNA to protect it from mutations. This allows the virus to keep replicating despite the cell’s antiviral mechanism. So, is all hope lost? Does the virus win? Not so fast! Thankfully, humans are as smart, if not smarter, than viruses. The researchers showed that by deleting BORF2 using a revolutionary technique called the CRISPR/Cas9 genome-editing method, APOBEC3B can once again defeat the virus. While it doesn’t mean that we can start treating everyone using this method, this finding provides a novel therapeutic opportunity to stop EBV infection.


  1. D1. Cheng, A.Z., Yockteng-Melgar, J., Jarvis, M.C. et al. Epstein–Barr virus BORF2 inhibits cellular APOBEC3B to preserve viral genome integrity. Nat Microbiol 4, 78–88 (2019). https://doi.org/10.1038/s41564-018-0284-6
  2. University of Minnesota. “New strategy discovered toward possible prevention of cancers tied to mono.” ScienceDaily. ScienceDaily, 12 November 2018. <www.sciencedaily.com/releases/2018/11/181112131512.htm>.