I grew up on a farm. It was common knowledge that when a calf, or a lamb was born they needed to get that first milk from their mom. The first milk looked different and was called colostrum. Colostrum contained a large assortment of antibodies from the mother that were transmitted to the newborn. If there was some health issue, the mother died or the newborn couldn't drink, we had colostrum in the freezer. If we didn't give it, the odds dropped dramatically of the newborn making it more than a few months.<p>So, yes, mammals, including people, get immunities to germs they have not been exposed to.
"...memory CD4s proliferated and otherwise became activated in response to exposure to certain components of the influenza virus, but also to epitopes of several different bacterial and protozoan microbes. This cross-reactivity could explain why exposure to common bugs in the dirt and in our homes renders us less susceptible to dangerous infectious agents."<p>So the CD4 is a key activated to fit a particular lock, but given the imperfections of locks it fits a random assortment of others too. As we build up a keychain of these we have a better chance to fit any random lock.<p>But why doesn't the larger keychain also increase the chances of auto-immune diseases when they happen to fit our own locks? Or increase inflammation from other benign microbes it fits? Seems like the metaphor needs work.
Could someone add 2013 to the title? I just spent 15 minutes thinking I must be a genius because I had already figured this out. Now I realise I read about it already.
So I do not understand much about biology but could this effect explain why we seem to have so many people test positive for anti-bodies on COVID-19 tests, compared to other forms of testing?
“It may even provide an evolutionary clue about why kids eat dirt,” said Davis. “The pre-existing immune memory of dangerous pathogens our immune systems have never seen before might stem from our constant exposure to ubiquitous, mostly harmless micro-organisms in soil and food and on our skin, our doorknobs, our telephones and our iPod earbuds.”<p>Have there been studies on the effects of being too clean? Will short term fear (e.g., Covid-19) hurt us in the long term?
Would epigenetics from past ancestors explain this? [0]<p>[0] = <a href="https://www.scientificamerican.com/article/fearful-memories-passed-down/" rel="nofollow">https://www.scientificamerican.com/article/fearful-memories-...</a>
Antibody production in vertebrates is an amazing example of an extremely efficient directed evolution system within our own tissues.<p>There is some interesting work being done to mine antibodies from people who have recovered from diseases and use those as a therapeutic medicine. Worked great for Ebola, would also work for COVID-19, but scaling production is really really hard (maybe some schlep blindness there)!<p>If I recall correctly, they pretty much put the gene for the anti-ebola antibody into a plasmid in bacteria, then vacuumed those bacteria into tobacco, which mated with the tobacco, which caused over-expression of the antibody. Then, you grind up the plant, and purify the protein.<p>I'm interested in trying that out with my own blood - effectively making open source antibodies for different diseases. I also know a few folks working on DNA vaccination, which could have an interesting intersection.
Could partly explain why it seems like covid-19 isn't hitting developing nations as hard. They have more antibodies to other viruses. There's also the theory that the tuberculosis vaccine (mandatory in many developing nations but not in developed ones) helps too, and there are clinical trials going on to confirm that.