[fChk]

I read the previous posts (or tried to..); each one focuses on some aspect of the Coronavirus drama .. So, I'll stick to the title's explicit questions, thus adding my own perspective.

Coronaviruses (CoVs) ?
They are ancient, ubiquitous and classified under 4 major categories: alpha, beta, delta and gamma. Only alpha and beta coronaviruses are known to be human pathogens as they are the second leading cause of the common cold -accounting for about 20% of the cases- ( the rhinoviruses are the first with 50% of the cases) and until fairly recently, rarely caused any disease more serious than a common cold in humans.

There are (as of this date) 3 highly pathogenic Human CoronaViruses (HCoVs) are:

• SARS-CoV (Severe Acute Respiratory Syndrome CoronaVirus) -a beta-HCoV that was responsible of the 2002 atypical pneumonia first described in Guangdong Province (China.) Genomic sequencing of the SARS-CoV helped in shaping a consensus postulating that bats were the natural hosts.
  SARS-CoV infected 8098 individuals; 774 died.
  
• MERS-CoV (Middle East Respiratory Syndrome CoronaVirus) -a 2012 HCoV that has caused a total of 2494 cases and 858 deaths, the majority in Saudi Arabia.
  
• 2019-nCoV (2019 novel CoronaVirus) - linked to the outbreak to a Huanan seafood market in Wuhan, China; the first case of pneumonia from 2019-nCoV was reported on Dec. 8th. The most important event uptil now is that chinese Scientists have sequenced the virus’s genome and made it available on Jan. 10 (here.)
  

The Commonalities:

• They all seem to emerge from animal reservoirs; so first there is an animal to human infection case, which then evolves into a global epidemics following flue-type human-2-human infections BUT an with alarming morbidity and mortality.
  
• The RNA genomes of these highly pathogenic HCoVs are very similar. It has been reported that the 2019-nCoV is 86.9% identical to the bat SARS-like coronavirus [See https://www.nejm.org/doi/full/10.1056/NE...tured_home]
  
• It's likely that they all enter human cells using the same receptor(/doorway) that SARS did. The receptor is called ACE2 (for Angiotensin Converting Enzyme 2), which is a glycoprotein exposed on the cell surface to which a “spike protein” on the virus’s surface first attaches and then enables the virus to fuse with the host cell and let it injects its "payload" (its genome that will hijack the host cell machimary). It's the classic key-lock analogy taught in Molecular Biology courses. Which means in layman's term that both HCoVs have the same KEY that they use to unlock the door/lock that exist in the cells of the bottom repiratory tract of Human-beings thus causing Pneumonia when they start their lytic cycle (multiplication.)
  

For the rest, much of it is just speculation and fearmongering, which is good for the 24/7 News cycle.

In essence, much of this is fueled by Globalization; China being the Epicentre of the World trade. Just contrast the impact of MERS-CoV (Saudi Arabia) versus SARS-CoV and 2019-nCoV (both from China.)

Welcome to the 21st century!