more on diploid viruses

JARDINE P F3CM at UNB.CA
Tue Nov 1 12:21:23 EST 1994


There's been a lot of input on the question of diploidy in viruses in
the listings. The case of "pseudodiploidy" for retroviruses has been
worked to death by Temin (?) over the past couple of years and appears
to be sound. They used constructs of HIV with different antibiotic
resistance markers in them to show real recombination, most likely
during replication, when progeny virus are formed in a cell with two
parental RNA templates i.e. a heterozygous virion produces a
recombinant daughter virus upon infection and replication.
The part everyone kind of dances around is the function of such an
event. Any basic Biology text will tell you this is one of the most
important mechanisms of generating genetic variability. Recombination,
usually talked about in sexually reproducing organism, is perhaps the
major source of variability available to any species and viruses, being,
being the "efficient" little buggers that they are are not about to miss
out on the fun. By recombining genomes you can develop and adapt much,
much faster than by waiting for mutations, even if you are as sloppy at
replication as HIV is. Coincidental coinfection of two different strains
and the subsequent generation of psuedodiploid virions gives you an
incredible selective advantage over any other competitor.

Hey, but I'm just a phage guy. PJ




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