HIV-1 Adaptation to host/various musings
nna at le.ac.uk
Fri Oct 20 06:52:58 EST 1995
york at mbcrr.dfci.harvard.edu (Ian A. York) wrote:
>This has been discussed in great detail on bionet.virology. The bottom
>line is that the generalization that viruses and other pathogens adapt to
>their hosts and become less virulent over time is a myth. There are some
>apaprent examples of this happening, but there are many examples where it
>deosn't happen and some where the reverse may be happening. My favourite
>counterexample is the most lethal virus known*, with a mortality rate of
>well over 99.99999%, rabies virus: this has been around for thousands of
>years at the least without any signs of attenuating.
Have to comment on this. The key phrases here are "adapt to their hosts" &
"mortality rate of well over 99.99999%" (do you mean 100% - not true;
99.9% would be more accurate). Snag is that humans are not the natural
host of rabies virus - they are dead end hosts who do not play a
significant part in the transmission of the virus over "thousands of
years". Hence each human infection is essentially a new event & the virus
does not have chance to "adapt to it's host" in evolutionary terms.
Dr Alan J. Cann PhD, Department of Microbiology & Immunology,
University of Leicester, P.O. Box 138, Medical Sciences Building,
University Road, Leicester LE1 9HN, UK.
Email: nna at le.ac.uk http://www-micro.msb.le.ac.uk/AJC/nna.html
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