Md Toy Blog

Virology Crash Course


Wouldn't it be nice to get a quick and dirty sum up of COVID-19 and understand everything ? Indeed, but not happening.

With all the hype, many unknowledgeable people will talk about coronavirus. And you'll spend lots of energy trying to figure out what is right or wrong. Instead, I suggest you to follow my steps on the path of building a solid foundation about the broader subject of viruses. We'll then be able how to tell the truth from the lie.

This content is based on my personal notes of Vincent Racaniello's lectures at Columbia University. Disclaimer: what is written below are my own interpretations of the lectures, not endorsed in any way by the lecturer.

Where do viruses live

Everywhere. Viruses infect all living things. We eat and breath billions virus particles. We carry viral genomes as part of our own genetic material.

Numbers about viruses

What is the weight of a virus

10^-15 grams

How many virus particles are there in the planet


Interesting facts (*)

  • If the total weight of humans on earth is 7.8 Billion x 50000g = 3.9*10^14g, then viruses total mass in the planet is 2.56 times greater (1*10^14g).
  • Whales excrete 10^13 caliciviruses daily.
  • There are more viruses in a liter of coastal seawater than the number of humans on earth
  • Prokaryotes total weight compared to viruses' is similar to viruses abundance (total amount) compared to prokaryotes'
  • Viruses are not always bad news, they are for example responsible for most of the recycling process going on in the seas.
  • There are ~ 10^16 HIV genomes in the planet today. This is computed using the number of infected people today 37 Million and the average genomes that they have (around 270 Million genomes per person).
  • There are around 40 very effective drugs to treat HIV infected patients (drugs allow them to live a proper life without getting diseases). But within these 10^16 genomes there exists resistance to each of these drugs. Because mutations arise randomly.
  • No matter how many drugs we make against this particular virus, there will always be resistance out there.
  • We all currently have about a dozen Herpes viruses in us. HSV-1, HSV-2, VZV, HCMV, EBV, HHV-6, HHV-7, HHV-8.
  • Once we are infected with one of these Herpes viruses it is for life ("unlike love, herpes is forever").
  • You cannot cure Herpes. When someone tells you they got cured from herpes, it is wrong.

Note: this is an approximation based on the assumption that the average weight of a human being is 50 Kg


  • bacteriophage particle :
  • caliciviruses : a virus commonly infecting whales. Also responsible for rashes, blisters, diarrhea etc.
  • prokaryotes :
  • genomes :
  • microbiome :
  • virome :
  • RNA virus :
  • DNA virus :