Virus variation

[Ian A. York]

In article <9411111848.AA02302 at ariel.med.pitt.edu> bap at MED.PITT.EDU (Bruce Phillips) writes:

[mutation rate in HIV, possible role in immune evasion . . . ]

>     I did not mean to imply that recombination does not play a
>significant role in generating diversity in influenza viruses- but
>it does not seem to play a role in any given virus's ability to
>escape immune response ONCE INFECTION OCCURS.  Without question,
>genetic shift accounts for the appearance of flu viruses for which
>pre-existing immunity (or cross-immunity) doesn't exist.
> 

This is a very interesting subject, I think.  To extend the discussion to
other lentiviruses, I recall that Maedi-Visna also shows variation in
infected hosts.  I also recall (though this is foggy) that the mutations
appeared to follow a semi-regular pattern - almost as if there was a
program for mutation use.  (I think that the much more complex protozoal 
parasites may do the same thing; completely off topic, I guess.)  One 
would expect this to be of use only in persistent viruses and especially 
in viruses which continue replication within the host (therefore ruling 
out, for example, herpes simplex virus).  I don't think this occurs with 
EBV or cytomegaloviruses, the only non-lentivirus examples that spring to 
mind right now.  Does anyone know more about this?

Ian

-- 
Ian York   (york at mbcrr.harvard.edu)
Dana-Farber Cancer Institute, 44 Binney St., Boston MA 02115
Phone (617)-632-4328     Fax  (617)-632-2627