Beauty becomes the Beast: Epstein-Barr virus
Published on 28 April 2023
The COVID-19 pandemic in the last three years has without doubt kept us on our toes about the threat of viruses. But viruses, like humans, have their own characteristics that are worth getting to know.
Some viruses, such as influenza viruses and coronaviruses, launch attack to the host's organs soon after infection. After the body's immune system recognises and eliminates the infected cells, the viruses will then disappear. On the other hand, Epstein-Barr virus (EBV) takes a "hit-and-stay" approach and remains dormant within our body cells like a sleepyhead. But don't take this lazybones lightly, it may catch you off guard with unexpected consequences!
EBV is a member of the human herpesvirus family, which is notorious for causing chickenpox, shingles or roseola. It has a multilayered structure similar to a surprise chocolate egg: an outer envelope, tegument layer, and a capsule enclosing the double-stranded DNA genome.
Unlike its siblings, EBV does not cause many symptoms to its hosts on their first infection. Nevertheless, this virus is so contagious that over 90 percent of the world's population has already been infected with EBV through body fluid transmission, such as saliva. EBV infects certain cell types, such as B-cells and epithelial cells that express specific cell surface receptor proteins for EBV entry. EBV passes through the nasopharyngeal epithelial cells, then goes into a long slumber in B-cells like a "sleeping beauty", waiting to be awakened.
It may look harmless enough, but once triggered, EBV becomes a self-multiplying "deadly monster", infecting more epithelial cells and disrupting their normal functions. This can lead to serious diseases, such as Nasopharyngeal Carcinoma (NPC). In most NPC patients, their tissues and blood samples show high levels of EBV DNA, revealing the link between EBV and the disease.
The nasopharynx is located deep within the head, and early symptoms of NPC are very similar to those of upper respiratory diseases, so patients are hardly aware of this disease. As the tumour grows, patients may experience recurring symptoms such as nosebleeds, stuffiness or headaches. Early diagnosis and treatment can help prevent the tumour from getting worse and increase the chance of cure. But if I were to choose, I would hope that this "sleeping beauty" never wakes up.
