Back to: MICROBIOLOGY 300 LEVEL
Welcome to class!
Hi brilliant mind! It’s such a joy to learn with you again today. I hope you’re feeling confident, focused, and ready to grow. What we’re learning today is something you’ve probably heard about before—names like Hepatitis B, or even Herpes may have come up in conversation, the news, or your biology classes. These viruses may be common, but they each have unique traits that every microbiology student like you must master. Let’s take this lesson step by step, together.
Herpesviruses, Adenoviruses, Hepatitis B
Viruses are like tricky guests—some come and go quietly, others overstay their welcome. Some even hide inside your body, waiting for the right moment to cause trouble. That’s what makes viruses like Herpesviruses, Adenoviruses and the Hepatitis B virus so fascinating and important to understand.
These three types of viruses are known to cause serious health issues in humans, but they’re also good examples for studying how viruses behave, how they affect our cells, and how the body responds. Let’s get to know them closely.
Herpesviruses
Herpesviruses are a large family of DNA viruses known for their ability to establish lifelong infections. One interesting fact? Once you get infected, the virus never truly leaves your body—it just hides and can reactivate later.
Genetic Material: Double-stranded DNA
Structure: Enveloped virus with an icosahedral capsid
Examples:
Herpes Simplex Virus (HSV-1 & HSV-2): Causes cold sores and genital herpes.
Varicella Zoster Virus (VZV): Causes chickenpox and shingles.
Epstein-Barr Virus (EBV): Causes infectious mononucleosis and is linked to some cancers.
These viruses enter through mucous membranes (like the mouth or genitals), infect nerve cells, and can lie dormant for years.
Adenoviruses
Unlike Herpesviruses, adenoviruses are more straightforward. They’re common, often harmless, and are frequently responsible for respiratory illnesses, eye infections, and diarrhoea, especially in children.
Genetic Material: Double-stranded DNA
Structure: Non-enveloped, icosahedral shape
Transmission: Through droplets, contact, or contaminated surfaces
Common Infections: Conjunctivitis (pink eye), sore throat, bronchitis, pneumonia, and gastroenteritis
Adenoviruses are also being used in medicine as vectors for gene therapy and vaccines, like some COVID-19 vaccines (e.g. Oxford-AstraZeneca).
Hepatitis B Virus (HBV)
This one is especially important in Nigeria and across Africa due to its serious impact on liver health.
Genetic Material: Partially double-stranded DNA (a unique feature)
Structure: Enveloped, spherical shape
Transmission: Blood, sexual contact, or from mother to child during birth
Target Organ: Liver
Diseases Caused: Acute and chronic hepatitis, liver cirrhosis, liver cancer
What makes HBV dangerous is that it can become chronic, silently damaging the liver over time. Thankfully, it can be prevented with vaccines—something that has saved millions of lives.
Imagine Herpesviruses as a neighbour who sneaks into your house, hides in the attic (nerve cells), and waits for the right time to come out—maybe when you’re stressed or sick. That’s why cold sores sometimes appear during exams or illness.
Adenoviruses are like seasonal visitors—they show up suddenly, cause a sore throat or runny nose, and leave after a while.
Hepatitis B is more like a dangerous guest who enters quietly, settles in your living room (the liver), and begins to damage your home bit by bit—often without you knowing until much later.
Summary
- Herpesviruses are enveloped DNA viruses that establish lifelong infections and can reactivate.
- Adenoviruses are non-enveloped DNA viruses that mainly cause respiratory and eye infections.
- Hepatitis B virus affects the liver, is spread through blood and body fluids, and can lead to chronic liver disease.
- Understanding their structure and behaviour helps us diagnose, treat and prevent serious diseases.
Evaluation
- What makes Herpesviruses capable of lifelong infections?
- List two infections caused by adenoviruses.
- Describe how Hepatitis B is transmitted and what organ it targets.
- Why is Hepatitis B considered more dangerous than a typical cold virus?
- Compare the structure of Herpesvirus and Adenovirus.
You’ve just tackled some of the most important human viruses—well done! These are not just facts; they’re the foundation for protecting lives and shaping better healthcare. Keep showing up with this energy and curiosity. Afrilearn is here with you all the way. You are becoming a microbiologist the world can count on. See you in the next lesson, champ!