title: Dynamics of HIV-1 recombination in its natural target cells.
abstract: Genetic recombination is believed to assist HIV-1 diversification and escape from host immunity and antiviral therapies, yet this process remains largely unexamined within the natural target-cell populations. We developed a method for measuring HIV-1 recombination directly that employs reporter viruses bearing functional enhanced yellow fluorescent protein (YFP) and enhanced cyan fluorescent protein (CFP) genes in which recombination produces a modified GFP gene and GFP fluorescence in the infected cells. These reporter viruses allow simultaneous quantification of the dynamics of HIV-1 infection, coinfection, and recombination in cell culture and in animal models by flow-cytometric analysis. Multiround infection assays revealed that productive cellular coinfection was subject to little functional inhibition. As a result, generation of recombinants proceeded according to the square of the infection rate during HIV-1 replication in T lymphocytes and within human thymic grafts in severe combined immunodeficient (SCID)-hu (Thy/Liv) mice. These results suggest that increases in viral load may confer a compounding risk of virus escape by means of recombinational diversification. A single round of replication in T lymphocytes in culture generated an average of nine recombination events per virus, and infection of macrophages led to approximately 30 crossover events, making HIV-1 up to an order of magnitude more recombinogenic than recognized previously and demonstrating that the infected cell exerts a profound influence on the frequency of recombination.
authors.affiliation: Department of Medicine, University of Alabama at Birmingham, 848 Kaul Building, 720 20th Street South, Birmingham, AL 35294-0024, USA. levy@uab.edu
authors.forename: David N
authors.initials: DN
authors.lastname: Levy
authors.forename: Grace M
authors.initials: GM
authors.lastname: Aldrovandi
authors.forename: Olaf
authors.initials: O
authors.lastname: Kutsch
authors.forename: George M
authors.initials: GM
authors.lastname: Shaw
mesh_terms: D000818:Animals; D017930:Genes, Reporter; D015497:HIV-1 / Q000235:genetics*; D006367:HeLa Cells; D006801:Humans; D019169:Jurkat Cells; D008264:Macrophages / Q000821:virology; D051379:Mice; D016513:Mice, SCID; D011995:Recombination, Genetic; D013601:T-Lymphocytes / Q000821:virology*