Good morning all,
I'm passing along here (at page bottom) a link to a recent news article about genetic sleuthing of the source for the 'Wuahn coronavirus', the virus that appears to have made its first appearance in humans and now is causing tens of thousands of infections, and perhaps >1,000 deaths, worldwide. As you now, this has been the top genetics and health news story for several weeks now.
Viruses are a bit of an evolutionary quandary. They are tiny objects, composed of protein and nucleic acid. They are not considered to be cells, and they are not considered to be 'alive'. They are parasitic 'replicating devices' - they can only replicate when they have successfully infected the cell of a host species. And, they are designed to take-over the protein machinery of their host's cell, causing it to make many more virus particles, and to spread them.
Mammals have evolved with viruses throughout our history, and our immune systems contain some viral defenses, just as our genomes contain bits and pieces of DNA that may have been viral in origin. In recent years and decades, we have increasingly been aware of 'new' viruses, not previously seen in humans, that are suddenly causing human disease. Swine flu, avian flu, MERS, SARS, and others - and now, the Wuhan coronavirus.
Why are viruses so common in mammals? Because we are really good hosts for them - lots of cellular protein machinery, warm-blooded cells which promote high rates of viral replication, dense social structure which promotes transmission. From rats to cats, bats, camels and more, each mammalian group bears its own viral load.
Why do viruses move between mammal species? Two words: mutation and opportunity. As viruses mutate, they can gain or lose features that make them better, or worse, suited for particular host species (e.g., cats versus dogs). As species co-mingle, the odds improve that a virus can successfully 'make the leap' to a host of a different species, one to which it is newly well-suited.
Why are so many of these novel viruses originating in Asia? Population density and food production practices. On the global scale, the U.S. is relatively sparsely populated (save our largest cities). Across the globe, it is very common for population densities to be much higher than those found here. And, high human densities require ramped-up food production. Much of food production here is commercialized and removed from the public, but again, this is a global exception. Across most of the world, food production tends to be on a smaller scale, and it tends to be much more personal - individuals tending their own animals, working with their tissues and bringing their own products to open market. Together, this density and close contact ups the risk of transmission of animal viruses to human hosts.
This article describes genetic efforts to identify the original animal source of the human virus, as well as to characterize the virus more fully. The more we know about the virus, the more likely we can stop the spread of infections and develop effective preventatives (such as a vaccine) and treatments.
I will occasionally pass along articles of this type during the semester. My purpose in doing so is to help you to become more aware of topics at the interface of biology and society, and also to help you assess how you obtain your science and health news.
Those of us working in science obtain our scientific news, quite often, directly from the original sources: the people conducting the studies and reporting the results. They publish their findings in science journals, or present them at conferences.
Most people do not obtain their news directly, but hear news via secondary sources, such as news releases from scientific organizations, or news stories from the major news outlets. These secondary reports often are then carried by tertiary outlets (smaller/other reporting sources).
Along the way from source to audience, science news is normally distilled (a lot) - much of the detail is excluded or simplified, and the reports often are boiled-down to singular take-home messages, which may (or may not) be good representations of the original work.
When you browse the links that I will forward, or when you access science and health news on your own, I'd encourage you to delve a little bit deeper into them, to read more than just the summaries, and to follow links back to original sources when possible. I'd also encourage you to think a little about the translation of news from source to consumer, and the reputability of the news outlets that you use.
You will not be formally tested on any of the material in the news stories that I will send you, but I do hope that the material in them makes its way into our classroom conversations.
Have a great weekend -