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J. Virol., Sep 1997, 6348-6358, Vol 71, No. 9
M Cornelissen, R van den Burg, F Zorgdrager, V Lukashov and J Goudsmit
Naturally occurring mutations in the polymerase gene of human
immunodeficiency virus type 1 (HIV-1) have important implications for
therapy and the outcome of clinical studies. Using 42 virus isolates
obtained from the UNAIDS sample collection, we analyzed the protease (99
amino acids [aa]) and the first 297 aa of reverse transcriptase (RT) coding
regions. Based on the V3 sequence analysis, the collection includes subtype
A (n = 5), subtype B (n = 12), subtype C (n = 1), subtype D (n = 11), and
subtype E (n = 13) viruses. Of the 42 protease genes, 37 contained
naturally occurring mutations at positions in the gene that contribute to
resistance to protease inhibitors (indinavir, saquinavir, ritonavir, and
nelfinavir) in clade B isolates. The phenotypic effect of these
substitutions in non-B isolates is unclear. The The 5'half RT coding region
of the 42 isolates was found to be less variable, although 19 of the 42 RT
sequences contained amino acid substitutions known to contribute to
nucleoside and/or nonnucleoside drug resistance. Since the virus isolates
were obtained in 1992, it is unlikely that the infected subjects received
protease inhibitors, but we found evidence that one subject acquired a
zidovudine (AZT)- resistant HIV-1 strain from a contact who had received
AZT. Phylogenetic analysis identified five subtype pol clusters: A, B, C,
D, and A'. Comparison of env and pol sequences of the same viruses showed
no more recombination events than were already identified on the basis of
gag/env comparison (M. Cornelissen, G. Kampinga, F. Zorgdrager, J.
Goudsmit, and the UNAIDS Network for HIV Isolation and Characterization, J.
Virol. 70:8209-8212, 1996). In one of the known recombinants, a crossover
site between subtypes A and C could be identified, and in another, a
crossover site could not be identified due to lack of a reference subtype F
pol sequence. We analyzed the ds/da ratio of gag, pol, and env sequences of
35 isolates, excluding the recombinants. Our analysis showed that gag and
pol are subjected to purifying selection with an average ds/da ratio above
1, independent of the subtype and in contrast with V3 (ds/da approximately
1). Based on the low ds/da ratio of the intergroup analysis of A/E and B/D
gag and pol sequences, we analyzed the evolutionary relation between
subtypes B and D in more detail by constructing separate phylogenetic trees
for synonymous and nonsynonymous substitutions. Our analysis suggests a
common ancestry for subtypes B and D that is distinct from that of subtypes
A and E.
Copyright © 1997, American Society for Microbiology
pol gene diversity of five human immunodeficiency virus type 1 subtypes: evidence for naturally occurring mutations that contribute to drug resistance, limited recombination patterns, and common ancestry for subtypes B and D
Department of Human Retrovirology, Academic Medical Centre, Amsterdam, The Netherlands. M.I.Cornelissen@amc.uva.nl
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