A
Anonymous
Guest
Got bored thought you might like this, for anyone weened on those books when you were puppies..enjoy..
Ladybird Book of Viruses
I thought a little light reading specifically orientated to the current COVID-19 might be interesting. It’s a simplification for many reasons, and focussed on COVID-19.
What is a virus? A virus is a submicroscopic infectious agent that replicates only inside the living cells of an organism. When not inside an infected cell or in the process of infecting a cell, viruses exist in the form of independent particles, or virions. So a virus needs a host to survive and create more of its own kind. Outside of a host, unlike the spores of a bacteria, a virus has a very limited life expectancy.
How big, how complex? Viruses are about 1/100 of the size of a bacterium and carry around 2kb-2mb of genetic code, the COVID-19 virus about 38kb of genetic code using RNA not DNA to encode it. There are over 1m different types of viruses in existence. Human DNA is around 3 billion bytes in size!
RNA/DNA? RNA is a simpler form of wrapper than DNA..as a result viruses like COVID-19 are more likely to have evolved or mutated from other similar viruses and is very likely to mutate again, although the mutations may not be more ‘successful’. In most cell structures non faithful replication is seen as a liability and cells do everything they can to stop this, viruses make it a virtue and hence the number and diversity. Natural selection leads to ‘better’ viruses.
What makes a virus lethal? Viruses once they enter a cell can cause malfunctions or usually death of the cell, often it’s the body’s response to the cell damage that causes more damage than the originating virus. The physical structure of the virus gives virologists insights into the possible lethality based on observations of similar structures in other viruses.
How do you stop viruses spreading? Once a virus has infected a host then the host can die, and if the virus doesn’t find a new host before the host dies those viruses on the host will die. A host can develop immunity from the virus and either tolerate it (dormant infection) or it can use antibodies to eradicate the virus in which case the viruses die. So if you stop the virus moving to fresh hosts then in most cases the viruses in the current hosts will die with the host or be overcome by the host’s defences.
How does COVID-19 spread? This virus is expunged through the fluids from nose, mouth, eyes like a common cold. By ingesting virions of COVID-19 carried in droplets from the noses/mouths of infected people or rubbing the eyes with hands contaminated with virions the virus enters a fresh host. Droplets can be carried over 6m when people sneeze or cough so the 2m distance is a minimum for people not coughing/sneezing.
So what’s with soap and water? The COVID-19 virus has a ‘lipid’ layer, a fatty overcoat that affords its quite some protection outside the host, however like Fairy Liquid soap (and alcohol and bleach) breaks down the fatty overcoat and the poor little virus dies. Water assists the process and dilutes the amount of virus present.
Viral load? This is a bit like filling a bucket from a tap with a hole in the bottom. So, when the virus enters the host, the host then after a period of time recognises the virus/its side effects and starts to manufacture antibodies to muster the host’s defences. Ideally you want the rate of antibody development to exceed the rate the virus replicates inside the host so that the host is not overwhelmed by the scale of the conflict. The more virus enters the host at one time the more the host is on the initial back foot and the longer it will take till the host regains control. Hence why health workers being coughed on at short range are at greater fatal risk compared to a small amount picked up from say a contaminated surface.
Why are all viruses not lethal? If a virus is too lethal, then it will tend to become extinct as it runs out of hosts to infect. Smallpox was relatively easily eliminated due to its long term stability so that vaccines continued to work and because it was so lethal (30%) it killed too many hosts off. Ebola suffered a similar fate (50% fatal). Influenza type viruses are successful as they only kill a small percentage of the population, usually less than 5%, so there are plenty of hosts to carry the virus to new hosts.
How do you stop the virus? You deprive it of fresh hosts and rely on those infected to either die or become immune and kill the virus off. You develop a vaccine which kills the virus on first entering the host as the antibodies are already there and waiting for thee little buggars. You can ruin a virus’s sex life by anti-viral drugs that puts if off replicating or plain just poisons it. Ideally you use all of the above to break the back of an epidemic then rely on immunization going forward.
The future? COVID-19 will be overcome by mankind’s incredible technological capabilities. However it will take time, nobody knows how long that will be..vaccines into mass production must be 6-9 months away at a minimum, anti-virals could be weeks to years..so…and of course the virus formerly known as COVID-19 may come back as COVID-2X etc which will require a new vaccine..
Ladybird Book of Viruses
I thought a little light reading specifically orientated to the current COVID-19 might be interesting. It’s a simplification for many reasons, and focussed on COVID-19.
What is a virus? A virus is a submicroscopic infectious agent that replicates only inside the living cells of an organism. When not inside an infected cell or in the process of infecting a cell, viruses exist in the form of independent particles, or virions. So a virus needs a host to survive and create more of its own kind. Outside of a host, unlike the spores of a bacteria, a virus has a very limited life expectancy.
How big, how complex? Viruses are about 1/100 of the size of a bacterium and carry around 2kb-2mb of genetic code, the COVID-19 virus about 38kb of genetic code using RNA not DNA to encode it. There are over 1m different types of viruses in existence. Human DNA is around 3 billion bytes in size!
RNA/DNA? RNA is a simpler form of wrapper than DNA..as a result viruses like COVID-19 are more likely to have evolved or mutated from other similar viruses and is very likely to mutate again, although the mutations may not be more ‘successful’. In most cell structures non faithful replication is seen as a liability and cells do everything they can to stop this, viruses make it a virtue and hence the number and diversity. Natural selection leads to ‘better’ viruses.
What makes a virus lethal? Viruses once they enter a cell can cause malfunctions or usually death of the cell, often it’s the body’s response to the cell damage that causes more damage than the originating virus. The physical structure of the virus gives virologists insights into the possible lethality based on observations of similar structures in other viruses.
How do you stop viruses spreading? Once a virus has infected a host then the host can die, and if the virus doesn’t find a new host before the host dies those viruses on the host will die. A host can develop immunity from the virus and either tolerate it (dormant infection) or it can use antibodies to eradicate the virus in which case the viruses die. So if you stop the virus moving to fresh hosts then in most cases the viruses in the current hosts will die with the host or be overcome by the host’s defences.
How does COVID-19 spread? This virus is expunged through the fluids from nose, mouth, eyes like a common cold. By ingesting virions of COVID-19 carried in droplets from the noses/mouths of infected people or rubbing the eyes with hands contaminated with virions the virus enters a fresh host. Droplets can be carried over 6m when people sneeze or cough so the 2m distance is a minimum for people not coughing/sneezing.
So what’s with soap and water? The COVID-19 virus has a ‘lipid’ layer, a fatty overcoat that affords its quite some protection outside the host, however like Fairy Liquid soap (and alcohol and bleach) breaks down the fatty overcoat and the poor little virus dies. Water assists the process and dilutes the amount of virus present.
Viral load? This is a bit like filling a bucket from a tap with a hole in the bottom. So, when the virus enters the host, the host then after a period of time recognises the virus/its side effects and starts to manufacture antibodies to muster the host’s defences. Ideally you want the rate of antibody development to exceed the rate the virus replicates inside the host so that the host is not overwhelmed by the scale of the conflict. The more virus enters the host at one time the more the host is on the initial back foot and the longer it will take till the host regains control. Hence why health workers being coughed on at short range are at greater fatal risk compared to a small amount picked up from say a contaminated surface.
Why are all viruses not lethal? If a virus is too lethal, then it will tend to become extinct as it runs out of hosts to infect. Smallpox was relatively easily eliminated due to its long term stability so that vaccines continued to work and because it was so lethal (30%) it killed too many hosts off. Ebola suffered a similar fate (50% fatal). Influenza type viruses are successful as they only kill a small percentage of the population, usually less than 5%, so there are plenty of hosts to carry the virus to new hosts.
How do you stop the virus? You deprive it of fresh hosts and rely on those infected to either die or become immune and kill the virus off. You develop a vaccine which kills the virus on first entering the host as the antibodies are already there and waiting for thee little buggars. You can ruin a virus’s sex life by anti-viral drugs that puts if off replicating or plain just poisons it. Ideally you use all of the above to break the back of an epidemic then rely on immunization going forward.
The future? COVID-19 will be overcome by mankind’s incredible technological capabilities. However it will take time, nobody knows how long that will be..vaccines into mass production must be 6-9 months away at a minimum, anti-virals could be weeks to years..so…and of course the virus formerly known as COVID-19 may come back as COVID-2X etc which will require a new vaccine..
Attleborough, Norfolk
