Re: Insufficient science killed Asimov

From: CurtAdams@aol.com
Date: Fri Mar 08 2002 - 15:12:49 MST


In a message dated 3/8/02 10:40:49, talon57@well.com writes:

>Remember that HIV is a retrovirus, mutating quickly, and it would
>be in the virus's best interest to mutate to a nonlethal form. That
>and some people might actually be immune.

Yes and no. It mutates so quickly that effectively an HIV virus
competes with its relatives within the same person. That selects
for viruses with highest in-host replication, long-term host survival
be damned. Same as cancer. Non-lethal retroviruses have 2
routes I know of - loss of a section of DNA coding for lethality
(tough in HIV as it has frameshifts and opposite-strand reading
to get the most out of its genome) and host evolution - like the
CD4 null mutant becoming dominant, which would happen eventually.

"Nice to host" is much easier to evolve with something like
herpes, where replication is pretty accurate and escape back
to lethality mutants thus rare. There, it happens.



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