The story I’ve been told about the action of viruses is confusing me. They get into our bodies, take over the nucleus of a cell, and use our genetic apparatus to manufacture more viruses, which go out and do the same. What we feel during the course of a cold or flu is largely the result of our immune system, and that it’s possible that without an immune system, the first symptoms of a viral infection might be the faltering of some major body system–heart failure or delirium, for example, if the heart or brain became compromised. Why do we have such a narrow range of symptoms? Fever, headache, congestion, sore throat, vomiting, tiredness, cough, maybe losing our voice–that’s about it, right? But why is there any variation, if what the virus does is the same? Why do we get a cough with one flu and not another?
October 18, 2009
Another Question I Would Like Answered
Posted by Nathen under immune system, questions, sickness, Uncategorized, viruses[6] Comments
Nathen's Miraculous Escape 
October 19, 2009 at 10:30 am
It’s probably more complicated than I am aware… However, I believe that the narrow range of symptoms are a direct result of the extent in which certain areas of the body are infected. Nose, throat and lungs are where most infections enter the body, so it would stand to reason that the infection has a larger population in those areas, thus a more fervent immune response.
That’s how I thought it worked at least.
October 19, 2009 at 10:02 pm
Hmm. I think you’re right about the areas infected… But I’m not sure about why, still. Most viral infection get in through our eyes, nose, & mouth (in descending order) but if you got a cold by rubbing your nose and I got the same cold by rubbing my eye, why do we both get the same symptoms?
That’s not to mention other viruses, like warts… It seems like viruses have affinities for particular tissues.
October 20, 2009 at 1:58 pm
Maybe there are weaknesses anatomically that allow infections to proliferate easily in certain areas of the body?
I’m particularly looking forward to taking my class in virology!
October 20, 2009 at 3:09 pm
I’m looking forward to you taking that class, too!
October 21, 2009 at 3:42 pm
Different types of viruses attack different types of cells. The specificity is based on some cell surface protein or carbohydrate (glycoproteins)structures. So if a virus doesn’t attack a mucous membrane then you shouldn’t have symptoms involving coughing or sneezing. Most hemorrhagic viruses don’t
attack mucous membranes directly so they start by feeling feverish rather then runny nose.
Most of the symptoms are similar because the body fights (or tries in the case of HIV) viruses in the same manner. Part of the response to viruses is the release of interleukins and interferons, which if I remember correctly, give you chills and fever and make you feel tired and crummy.
The interferons and interlukins cause more immune cells to be produced which in most viral situations leads to an immune response that destroys the virus infected cells.
I think that the coughing, sore throat, sneezing and runny nose are results of the mucous membrane’s response to irritants. These surfaces produce mucous to trap the irritating substance and get it off the membrane. Pure conjecture on my part but viruses could also enhance mucous production to enhance transmission.
October 21, 2009 at 5:11 pm
Yay! Thanks, Ceri!
So it sounds like, in general, symptoms that are site-specific are from specific tissues reacting to the virus and symptoms that are whole-body are from the actions of the immune system. Yes?
That reminds me of the next question I was going to ask… Maybe I’ll do it in a post, though, so it happens out in the open, so to speak.
Thanks again,
Nathen