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J. Virol., Jun 1997, 4479-4484, Vol 71, No. 6
J Goudsmit, A de Ronde, E de Rooij and R de Boer
Viral populations in a human immunodeficiency virus type 1 (HIV-1)-
infected individual behave as a quasispecies with a rated distribution of
fitness variants. Fitness distributions in naturally occurring viral
populations have been difficult to study due to the lack of markers for
individual virus clones and complicating inter- and intrahost factors like
the presence of multiple cell types with distinct tropisms, differences in
route of transmission, and intervening immunity. Here, we quantitated the
relative fitness in vivo of three subpopulations of HIV-1 marked by
mutations at codons 41 and 215 of reverse transcriptase (RT) directly
related to zidovudine resistance in an untreated individual who was
infected by a zidovudine-resistant strain transmitted from a donor on
therapy. The transmission event did not have a substantial impact on the
distribution of mutants within the dominant virus population replicating to
high levels in the recipient. The evolution of the RT gene was monitored
for 20 months. All 102 clones obtained from the donor and the recipient at
the different time points contained the M41L mutation, which is associated
with a fourfold reduction in zidovudine sensitivity. The leucine at
position 41 was stable, although it was encoded by TTG and CTG triplets
that fluctuated in abundance partially due to founder effects of clones
with nonsilent mutations at codon 215. Of the three subpopulations in the
patient, distinguished by a tyrosine (TAC), aspartic acid (GAC), or serine
(TCC) at the 215 position of RT, the relative fitness of the GAC variant
was calculated to be 10 to 25% higher than the initial TAC variant, and the
relative fitness of the TCC variant was 1% higher than that of the GAC
variant. Similar to other RNA viruses, lentivirus populations like HIV- 1
in patients with a high virus load apparently consist of a broader spectrum
of fitness variants than the 1 to 2% fitness difference sufficient for
significant replicative advantage.
Copyright © 1997, American Society for Microbiology
Broad spectrum of in vivo fitness of human immunodeficiency virus type 1 subpopulations differing at reverse transcriptase codons 41 and 215
Department of Human Retrovirology, Academic Medical Center, University of Amsterdam, The Netherlands.
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