viruses vs the immune system

[gusl]

I'd love to see a plot showing "number of viruses exposed" vs "probability of infection", where subjects are injected with viruses in varying quantities.

Presumably a single virus (what do you call an individual virus?) isn't enough to make you sick most of the time. I imagine we'd be sick all the time if that were the case...

If you inject a single virus into bloodstream, is it most likely to get lost, get blocked or reproduce?

Can we develop immunity by low-grade exposure to a virus?

My question also applies to other microbial parasites.

Comments

[flamingnerd.livejournal.com]

you're on the right track with your thinking except that many viruses aren't designed to invade blood, but act at mucosal surfaces like the nose.

and some bugs are easier to develop immunity to than others, depending on their ability to immunoevade.

[gustavolacerda.livejournal.com]

so... by default, the immune system has some resistance to all foreign cells thingies. Once infected, it builds up even more resistance to the particular invader.

Is this correct?

[flamingnerd.livejournal.com]

"by default, the immune system has some resistance to all foreign cells."
a pretty simplistic way to put it... but about right.

when your immune cells see foreign antigen (that's any bit of recognizable molecule) in the context of inflammation, it will remember it by making memory cells that recognize that particular antigen if it comes around again. if your cells see stuff outside of the context of badness, you can develop tolerance. (that's how allergy shots work)

If you care about this stuff, look up the innate and adaptive immune systems and how they work. briefly, innate is quick responding, less sensitive, less effective. adaptive comes after innate response and is highly specific because of the magic of permutation. I could blather about this, but I ought to get back to work.

[gustavolacerda.livejournal.com]

Thanks! Very cool.


<< if your cells see stuff outside of the context of badness, you can develop tolerance. >>

So I guess vaccines create some badness by design, so that you don't develop tolerance to the real parasite.

[flamingnerd.livejournal.com]

yes! http://en.wikipedia.org/wiki/Immunologic_adjuvant

[flamingnerd.livejournal.com]

although, it's used to increase effectiveness of a vax rather than prevent tolerance. it's not that easy to induce tolerance.