Fighting an enemy, it helps to know it. What is Corona Virus anyway?  Though I am not a microbiologist, I would like to share what I found about this subject. 

Ever since we are little, we know to say, “animal, plants, and mineral” for everything on earth. At one time, people discovered some living things that are neither animal nor plants.  Some scientists call them prokaryotes because they do not have membrane-bound nucleus, as opposed to the others that do have well defined nucleus and organelles, named eukaryotes (from Greek: well, kernel) including most of the animals and plants as we know them. Later, biologists found out that among the prokaryotes, there are two distinct kinds of structures (mainly differentiated by their cell membranes).  They now are classified as Bacteria and Archaea, two of the three domains of life while the third is eukaryote.  

At the time, they even invented filters as fine as micrometer size that can filter out anything alive. Well, guess what, some of the filtered liquid in addition to damage tobacco leaves the damages actually grew, indicating something alive in there. So they named this bugger virus, Greek for poison.  Now, all I can say is that virus does not belong to any of three domains of life but can get into a live cell, using its mechanism to replicate (not reproduce) itself, in a realm of its own called Riboviria, leaving the life and lifeless in their own realms.

How many kind of them are there? Many. The virologists (branch of microbiology) classify them in several ways: by their biological coding, by their structure, by the disease they cause … The formal classification, their taxonomical classification is done by ICTV (International Committee on Taxonomy of Viruses). This system is parallel to us human being in kingdom: animal, phylum: cordata, class: mammalis, order primate, family: Hominidae, genus: Homo, species: sapiens. (I may not have the correct use of upper case and italic here.)

In the mean while, David Baltimore proposed a classification based on their structure, such as whether their nucleic acid is DNA or RNA, whether they are single or double strand … into 7 groups.  Let me name a few examples for illustration:

Small pox virus is in Poxviridae family in ICTV but is in Baltimore group I because it is of double stranded DNA virus with enveloped Capsid …

Flu (A, B, C) virus is in Orthomyxoviridae family, in Baltimore Group V being single stranded RNA with enveloped Capsid …

SARS-CoV-2 (I guess CoVID-19 also) is in Coronaviridae family but group IV being ss RNA with enveloped Capsid …

The virologists not only classified them but also had tremendous success in the study of trying to cure and to avoid the diseases caused by virus. (Search online for related keywords is how I study. The wikipedia articles are very informative.) Virus cause various kind of our problems from cancer to things like hepatitis, HIV, flu … Generally speaking, our defense is from our own immune system.  Vaccine can trigger immune system and make them stronger.  Some drugs can actively interfere with the replicating of virus themselves.  From time to time, there is a new virus coming to us, by its own mutation (very rarely) or by introducing from outside environment (mostly virus jumped species from attacking animals to attacking human).  

Against COVID-19, we can only hope our researchers and health providers find vaccine and drugs soon. In the mean while, we need to do our part: stay self-quarantined, i. e., stay at “social distance”, stay home as much as possible, and wear masks, wear masks, wear masks.  (See the articles COVID, and Face Masks.)