Writer looking for help : Thankyou for kind responses - more detailed description

[Susan Harrison]

 I posted earlier to this newsgroup mainly because I was wondering if my post would get a 
response. I received overwhelming amounts of e-mail offering their services. This is certainly one 
of the most friendly groups I  have visited on the Net, and thank you to everyone who replied.
 In my original message I was completely vague because I was not expecting a response. It would be 
more useful to you if I posted what I needed and what I was doing and then any correspondance 
stemmed from there.
 What I have is a kind of virus which breaks down the immune system or something and alters the 
body so that it accepts bizarre diseases. In the book I have one person dying from acute scabiees 
(the itch mites mutate in the body and eat the entire thing -  charming...) I have another person 
who catches avian leukosis (which apparently is a set of diseases only poultry can catch) and i 
have another bloke dying from Legionnaire's Disease, a mutated version of Legionnaire's...  Later 
on I have a guy who dies because his lungs constrict and shrink in size and he dies of 
asphyxiation... What is actually  happening is that these   guys are part of a government 
experiment and have been fed with a drug which is affecting their bodies. The drug is supposed to 
make people live forever, and it works by de-aging the body at the same rate as it ages. This has 
different  effects for all the people - it is most noticeable in the last case, when his lungs 
constrict (ie. shrinking faster than growth rate)... All my victims are over 55 (does this helpp?)
 What I am asking isn't for a complete lesson in the basics of  virology - I understand that  this 
is impossible.  Obviously this is  science fantasy, this book, and there probably isn't a virus on 
earth that can do all of those things. It may not sound like a virus, either - after all, other 
people don't catch it and it originates because of this drug. I just thought that it had virus 
like properties in its effects. If I'm wrong, I'm sorry to waste all of your time - I know nothing 
about this kind of thing.
 I would just like to know how this might be vaguely possible (it doesn't have to be a a 
scientifically perfect answer, the 'virus' in my story is far from scientifically correct, even). 
I would just like suggestions on how this might be possible, abnd if it's totally impossible, any 
changes that might ground it further in truth. The further I can ground this disease in truth and 
science the better it will be, but I understand I can't make it work completely scientifically.
 Thank you in advance (again),..

 -- Susan