This Article Full Text Full Text (PDF) Other Versions of this Article: JVI.02100-07v1 82/5/2376    most recent Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Reprints and Permissions Copyright Information Books from ASM Press MicrobeWorld Citing Articles Citing Articles via Google Scholar Google Scholar Articles by King, S. R. Articles by Telesnitsky, A. Search for Related Content PubMed PubMed Citation Articles by King, S. R. Articles by Telesnitsky, A.

 Previous Article  |  Next Article 

Journal of Virology, March 2008, p. 2376-2384, Vol. 82, No. 5
0022-538X/08/$08.00+0     doi:10.1128/JVI.02100-07
Copyright © 2008, American Society for Microbiology. All Rights Reserved.

Pseudodiploid Genome Organization Aids Full-Length Human Immunodeficiency Virus Type 1 DNA Synthesis

Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, Michigan 48109-0620,¹ Global AIDS Program, CDC-Haiti, Port-au-Prince, Haiti²

Received 21 September 2007/ Accepted 12 December 2007

Template switching between copackaged human immunodeficiency virus type 1 (HIV-1) genomic RNAs is genetically silent when identical RNAs are copackaged but yields recombinants when virions contain two distinct RNAs. Sequencing has revealed that errors at retroviral recombination junctions are infrequent, suggesting that template switching is not intrinsically mutagenic. Here, we tested the hypothesis that template switching may instead contribute to replication fidelity. This hypothesis predicts that reverse transcription of a single-copy gene will be more error prone than replication in the presence of a second copy. To test this, HIV-1-based vectors containing both lacZ and the puromycin resistance marker were expressed either alone or with an excess of an "empty" vector lacking lacZ and puro. This resulted in virions with either RNA homodimers or haploid genomes with only a single lacZ-puro RNA. In untreated cells, lacZ inactivation rates suggested that haploid vector reverse transcription was slightly more error prone than that of homodimerized pseudodiploid vectors. Haploid reverse transcription was at least threefold more error prone than pseudodiploid-templated synthesis when slowed by hydroxyurea treatment or stopped prematurely with zidovudine. Individual products of one- and two-copy genes revealed both nucleotide substitutions and deletions, with deletions more frequent than point mutations among haploid genome products. Similar spectra of defective products were observed at early reverse transcription time points and among products of haploid virions. These results indicate that faithful, full-length reverse transcription products were underrepresented in the absence of a reserve of genetic information and suggest that template switching contributes to HIV-1 genomic integrity.

Published ahead of print on 19 December 2007.