Recent comments in /f/askscience

Shiningc t1_j9d9cf2 wrote

Reply to Are some people immune to HIV? by Lass_OM

The HIV bypasses the human immune system by hiding inside and attacking the T-helper cells. The T-helper cells are responsible for activating the other cells such as the Natural Killer cells to fight and attack against an infection.

It seems like the CCR5 delta 32 mutation disables the CCR5 receptor on the surface of white blood cells/T-helper cells. The HIV uses this CCR5 receptor to latch onto the T-helper cells and get into it.

People with these genes are immune to HIV because the HIV can't latch onto the white blood cells/T-helper cells.

The current traditional vaccines don't work against HIV because vaccines are about making the T-helper cells activate the other cells to fight against the infection. The HIV goes straight to the T-helper cells. Without the T-helper cells, the immune system is compromised and the body is completely helpless against infections.

Things like the bone marrow transplants work because the bone marrow creates the blood cells like the T-helper cells (without the CCR5 receptor).

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MrCyra t1_j9d8top wrote

Reply to comment by Ituzzip in Is COVID unique in the way it affects different individuals in such different ways? by stupidrobots

Yeah, for instance salmonella has over 2500 strains and can cause anything from light stomach bug that goes away on its own to death. Less severe cases can be easily mistaken with food poisoning and such. So in theory it's way less scary than it seems on other hand it's so easy to prevent it that there is no point in playing lottery with this.

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masken21 t1_j9d8hy7 wrote

Reply to Are some people immune to HIV? by Lass_OM

In Sweden it is not that uncommon that people are immune to HIV. I know that i have seen articles talking about 15%, but i don't think any large population wide studies has been made so they are estimates.

The core theory is that the resistance mutation was developed in Sweden and that the Vikings brought the resistance with them to the rest of Europe on their adventures during the Vendel and Viking age. This might explain the high amount of resistant people in Finland, Russia and the Baltic countries today along with Sweden.

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NW_thoughtful t1_j9d63en wrote

Reply to comment by princessParking in Is COVID unique in the way it affects different individuals in such different ways? by stupidrobots

The key is reactivation of the virus vs carrying the virus.

Think of the analogy of people who get cold sores. The virus lays dormant in the system and sometimes gets stirred up producing a cold sore. So the percentage of people who carry herpes virus in this example is much higher than the percentage of people who have it active at any given time.

With ebv, 95% of people have it and somewhere around 3 to 5% of people have it reactivate. When it reactivates, it can activate autoimmune processes such as MS as well as being directly inflammatory.

In the study on MS noted, most who had MS had EBV. The likelihood is that most of those actually had reactivated EBV.

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babar90 t1_j9d2tj5 wrote

Reply to Does evolution slow down over time? by AmTheHobo

In the simplest model there are 3 kind of mutations: neutral, positive, negative.

The rate at which neutral mutations accumulate (which really means the number of neutral mutations you'll observe between you and your parent) is roughly constant.

But the rate at which positive and negative mutations accumulate depend a lot on: how positive and negative they are (obviously mutations killing the organism won't accumulate) and how many they are among the total number of possible mutations.

When taking a bacteria adapted to a temperature of 20°C and putting it at 30°C the positive mutations (positive for this new environment) will accumulate very fast, at the beginning, and once the bacteria will be adapted to the new temperature there will be much less possible positive mutations, so their accumulation rate will slow down a lot.

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Civ6Ever t1_j9d2ivg wrote

Reply to comment by Final_Maintenance319 in Is COVID unique in the way it affects different individuals in such different ways? by stupidrobots

I always think about this. I was a pretty lazy teen, but after I got mono I reached a whole new level. Nearly failed my first semester of university, slept until 10-11 and had to start building class schedules around that (despite waking up at 630 to get ready every morning and arriving to high school an hour early), went from working out three days a week to feeling too tired to cook lunch (which didn't help the spiral). There are lots of possibilities - new environment, more difficult class level, less supervision, but I never felt so "out of it" in my life as that first two years.

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