COVID-19, evolution and looking forward
The tale of virus evolution (whatever works
Life on earth, itself 4-5 billion years old, is thought to be 2,000 million years old. That is when cells developed as closed systems of production/organisation that allows some permeability of its boundaries to exchange materials with the environment. Cells are responsible for their own self maintenance and self perpetuating.
For a long time the only living things were bacteria with the simplest smaller cell, they were/are very successful, pervaded all habitats in the world. Viruses and bacteria both descended from an ancient cellular life form, but took different evolutionary paths, bacteria became more complex. Viruses became so small and simple that they can’t replicate on their own,
they need a host cell. Being so basic, many biologists argue whether they can be classified as a life form.
It isn’t just humans who bear the brunt. There are RNA and DNA viruses, the latter with much larger genomes that infect amoebae, bacteria, algae and more complex life forms. The influenza virus has a mere 14 protein- coding genes. Vaginalis, a single-celled parasitic organism (responsible for an estimated 180 million urogenital tract infections in humans every year) has approximately 60,000 protein-coding genes. Covid-19 is one of the largest RNA viruses in existence, though a hundred million coronavirus particles could still fit on the head of a pin. Typically, thousands of particles are necessary to infect someone.
The coronavirus family was discovered in the nineteen-fifties using electron microscopes on samples of chickens suffering from bronchitis. Though the family evolved in animals, the four members cause the common cold in humans no longer infect animals. COVID-19 likely to have evolved in bats.
This beautiful image is arbitrary regarding the colours. Viruses exist in dark silent worlds.
COVID-19 is bad news for a number of reasons:
1. The club-like “spikes” that it uses to establish infections latch on to human cells about four times more strongly than those on the related Sars coronavirus, which killed hundreds of people in a 2002 epidemic. The finding suggests that coronavirus particles relatively few are needed for an infection to gain a foothold.
2. It has the lower-respiratory severity of sars and mers coronaviruses which attack the lungs, together with the transmissibility of cold coronaviruses which attack the nose and throat.
3. Most RNA viruses replicate themselves quickly often creating random mutations, the majority killing the virus. Unlike other RNA viruses, coronaviruses is large and relatively complex and contains an enzyme that corrects mistakes in replication.
4. Covid-19 also sheds large quantities of virus before symptoms appear. And the virus can stay alive in the outside world for a week or more on hard surfaces. And patients can shed the virus from their respiratory tracts for as long as thirty-seven days.
5. It is not just old people dying or those with medical history. It seems that when the immune system finally does recognise the virus as a problem. Bing a new threat it throws all available resources into the fight. The lung tissue swells and fills with fluid, hampering breathing, the response increases until the lungs can’t get enough oxygen or body can go into shock.
We need a more microbial view of the world, since Pasteur coined the term germ, microbes have been associated with disease, but it is microbial life vital to eco-processes that keeps the plant thriving. Of the million or more microbes known to science, only about 1,500 cause human disease. We humans are wreaking unknown damage to the subtle interconnected systems of life. Nature can be source of solace in crisis, says David Attenborough, Guardian 30.3.That’s not right – it’s there all the time to energise, excite, sorry about, engage with. To be fair he actually says: In times of crisis, the natural world is a source of both joy and solace.
The natural world produces the comfort that can come from nothing else. And we are part of the natural world. If we damage the natural world, we damage ourselves.” The Big Issue, March,
‘Human health depends on healthy ecosystems. But this is rarely considered in policy decisions on projects that affect natural ecosystems – such as land clearing, major energy or transport infrastructure projects and industrial-scale farming.’ ‘Coronavirus is a wake-up call: our war with the environment is leading to pandemics.’ (Fiona Armstrong et al. The Conversation, March 30, 2020)