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Space_faces t1_j9bpgmi wrote

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

There was a great episode of radiolab about rabies on which they referenced a study where rabies antibodies were found in folks in South America who were not dead or sick. Obviously antibodies aren't a guarantee of immunity, but like, how did they get them without a vaccine? Super interesting

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Balthasar-Hohenheim t1_j9c3dxv wrote

Rabies is effectively a two-step infection. It can infect and propagate in your "normal" cells like any other viral infection. In this stage the infection isn't necessary lethal and the virus can remain undetected in the body for long timespans (sometimes months). The immune system can also fight the illness off during this time period, which would lead to one having antibodies without being noticably sick.

The actual rabies infection that we usually think of happens when the virus enters nerve cells. From this point the virus just jumps from one neuron to the next straight to the brain without our immune system being able to interfere. One this happens one is as good as dead.

The tricky part is that the virus can enter nerve cells at any time during the initial infection (or straight from the initial wound) and at least in theory just one viral particle doing so is enough to kill. Our immune system is simply no built to deal with this situation as it functions on the principle of "use antibodies to catch most (but not all!) viral particles and let macrophages deal with all cells that still get infected". And that last part either doesn't happen at all or too late once the virus is in the nervous system. So we have to neutralize every virus particle before that can happen, hence why one should get treatment ASAP if there is any chance of one having been infected with rabies.

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Ituzzip t1_j9fydz4 wrote

Do we actually know for sure the virus infects and propagates in non-nerve cells in these individuals? Viral particles can stimulate an immune response without ever infecting a cell (as in the way vaccines with dead virus work) so it doesn’t require propagation to stimulate antibodies in theory.

As to whether the immune system can stop rabies once it enters a nerve: animal bites take varying lengths of time to progress to symptomatic disease based on where they occur, with bites around the neck and face progressing to symptomatic rabies infections in days or weeks, but bites on the feet taking up to a year to reach the brain.

However, vaccination for rabies is effective at any time before symptoms appear. So it would seem that the body has ways of clearing the infection from nerve tissue. It is less effective at detecting the virus there and mounting a response, but when a response is stimulated by a vaccine, it seems to work.

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