scholarly journals Genetic Recombination between Human Immunodeficiency Virus Type 1 (HIV-1) and HIV-2, Two Distinct Human Lentiviruses

2007 ◽  
Vol 82 (4) ◽  
pp. 1923-1933 ◽  
Author(s):  
Kazushi Motomura ◽  
Jianbo Chen ◽  
Wei-Shau Hu
Keyword(s):  
Human Immunodeficiency Virus ◽  
Human Immunodeficiency Virus Type ◽  
Virus Type ◽  
Fluorescent Protein ◽  
Genetic Recombination ◽  
Green Fluorescent Protein Gene ◽  
Low Frequencies ◽  
Immunodeficiency Virus ◽  
Hiv 1

ABSTRACT Human immunodeficiency virus type 1 (HIV-1) and HIV-2 are genetically distinct viruses that each can cause AIDS. Approximately 1 million people are infected with both HIV-1 and HIV-2. Additionally, these two viruses use the same receptor and coreceptors and can therefore infect the same target cell populations. To explore potential genetic interactions, we first examined whether RNAs from HIV-1 and HIV-2 can be copackaged into the same virion. We used modified near-full-length viruses that each contained a green fluorescent protein gene (gfp) with a different inactivating mutation. Thus, a functional gfp could be reconstituted via recombination, which was used to detect the copackaging of HIV-1 and HIV-2 RNAs. The GFP-positive (GFP+) phenotype was detected in approximately 0.2% of the infection events, which was 35-fold lower than the intrasubtype HIV-1 rates. We isolated and characterized 54 GFP+ single-cell clones and determined that all of them contained proviruses with reconstituted gfp. We then mapped the general structures of the recombinant viruses and characterized the recombination junctions by DNA sequencing. We observed several different recombination patterns, including those that had crossovers only in gfp. The most common hybrid genomes had heterologous long terminal repeats. Although infrequent, crossovers in the viral sequences were also identified. Taken together, our study demonstrates that HIV-1 and HIV-2 can recombine, albeit at low frequencies. These observations indicate that multiple factors are likely to restrict the generation of viable hybrid HIV-1 and HIV-2 viruses. However, considering the large coinfected human population and the high viral load in patients, these rare events could provide the basis for the generation of novel human immunodeficiency viruses.

scholarly journals Effects of Varying Sequence Similarity on the Frequency of Repeat Deletion during Reverse Transcription of a Human Immunodeficiency Virus Type 1 Vector

2002 ◽  
Vol 76 (15) ◽  
pp. 7897-7902 ◽  
Author(s):  
Wenfeng An ◽  
Alice Telesnitsky
Keyword(s):  
Human Immunodeficiency Virus ◽  
Human Immunodeficiency Virus Type ◽  
Virus Type ◽  
Reverse Transcription ◽  
Genetic Recombination ◽  
Gene Segment ◽  
Immunodeficiency Virus ◽  
Hiv 1 ◽  
Deletion Frequency

ABSTRACT Genetic recombination contributes to human immunodeficiency virus type 1 (HIV-1) diversity, with homologous recombination being more frequent than nonhomologous recombination. In this study, HIV-1-based vectors were used to assay the effects of various extents of sequence divergence on the frequency of the recombination-related property of repeat deletion. Sequence variation, similar in degree to that which differentiates natural HIV-1 isolates, was introduced by synonymous substitutions into a gene segment. Repeated copies of this segment were then introduced into assay vectors. With the use of a phenotypic screen, the deletion frequency of identical repeats was compared to the frequencies of repeats that differed in sequence by various extents. During HIV-1 reverse transcription, the deletion frequency observed with repeats that differed by 5% was 65% of that observed with identical repeats. The deletion frequency decreased to 26% for repeats that differed by 9%, and when repeats differed by 18%, the deletion frequency was about 5% of the identical repeat value. Deletion frequencies fell to less than 0.3% of identical repeat values when genetic distances of 27% or more were examined. These data argue that genetic variation is not as inhibitory to HIV-1 repeat deletion as it is to the corresponding cellular process and suggest that, for sequences that differ by about 25% or more, HIV-1 recombination directed by sequence homology may be no more frequent than that which is homology independent.

scholarly journals Macrophages in Vaginal but Not Intestinal Mucosa Are Monocyte-Like and Permissive to Human Immunodeficiency Virus Type 1 Infection

2009 ◽  
Vol 83 (7) ◽  
pp. 3258-3267 ◽  
Author(s):  
Ruizhong Shen ◽  
Holly E. Richter ◽  
Ronald H. Clements ◽  
Lea Novak ◽  
Kayci Huff ◽  
...  
Keyword(s):  
Human Immunodeficiency Virus ◽  
Human Immunodeficiency Virus Type ◽  
Virus Type ◽  
Fluorescent Protein ◽  
Female Genital Tract ◽  
Vaginal Mucosa ◽  
Innate Response ◽  
Immunodeficiency Virus ◽  
Hiv 1

ABSTRACT Mucosal surfaces play a major role in human immunodeficiency virus type 1 (HIV-1) transmission and pathogenesis, and yet the role of lamina propria macrophages in mucosal HIV-1 infection has received little investigative attention. We report here that vaginal and intestinal macrophages display distinct phenotype and HIV-1 permissiveness profiles. Vaginal macrophages expressed the innate response receptors CD14, CD89, CD16, CD32, and CD64 and the HIV-1 receptor/coreceptors CD4, CCR5, and CXCR4, similar to monocytes. Consistent with this phenotype, green fluorescent protein-tagged R5 HIV-1 entered macrophages in explanted vaginal mucosa as early as 30 min after inoculation of virus onto the epithelium, and purified vaginal macrophages supported substantial levels of HIV-1 replication by a panel of highly macrophage-tropic R5 viruses. In sharp contrast, intestinal macrophages expressed no detectable, or very low levels of, innate response receptors and HIV-1 receptor/coreceptors and did not support HIV-1 replication, although virus occasionally entered macrophages in intestinal tissue explants. Thus, vaginal, but not intestinal, macrophages are monocyte-like and permissive to R5 HIV-1 after the virus has translocated across the epithelium. These findings suggest that genital and gut macrophages have different roles in mucosal HIV-1 pathogenesis and that vaginal macrophages play a previously underappreciated but potentially important role in mucosal HIV-1 infection in the female genital tract.

scholarly journals Virological Consequences of Early Events following Cell-Cell Contact between Human Immunodeficiency Virus Type 1-Infected and Uninfected CD4+ Cells

2008 ◽  
Vol 82 (16) ◽  
pp. 7773-7789 ◽  
Author(s):  
Eliana Ruggiero ◽  
Roberta Bona ◽  
Claudia Muratori ◽  
Maurizio Federico
Keyword(s):  
Human Immunodeficiency Virus ◽  
Human Immunodeficiency Virus Type ◽  
Virus Type ◽  
Fluorescent Protein ◽  
Cell Contact ◽  
Target Cells ◽  
Immunodeficiency Virus ◽  
Virus Expression ◽  
Hiv 1

ABSTRACT Human immunodeficiency virus type 1 (HIV-1)-infected cells transmit viral products to uninfected CD4+ cells very rapidly. However, the natures of the transmitted viral products and the mechanism of transmission, as well as the relative virological consequences, have not yet been fully clarified. We studied the virological events occurring a few hours after contact between HIV-1-infected and uninfected CD4+ cells using a coculture cell system in which the virus expression in target cells could be monitored through the induction of a green fluorescent protein reporter gene driven by HIV-1 long terminal repeats. Within 16 h of coculture, we observed two phenomena not related to the cell-free virus infection, i.e., the formation of donor-target cell fusions and a fusion-independent internalization of viral particles likely occurring at least in part through intercellular connections. Both events depended on the expression of Env and CD4 in donor and target cells, respectively, whereas the HIV-1 internalization required clathrin activity in target cells. Importantly, both phenomena were also observed in cocultures of primary CD4+ lymphocytes, while primary macrophages supported only HIV-1 endocytosis. By investigating the virological consequences of these events, we noticed that while fused cells released infectious HIV-1 particles, albeit with reduced efficiency compared with donor cells, no virus expression was detectable upon HIV-1 endocytosis in target cells. In sum, the HIV-1 transmission following contact between an HIV-1-infected and an uninfected CD4+ cell can occur through different mechanisms, leading to distinguishable virological outcomes.

scholarly journals Electrostatic Interactions Drive Membrane Association of the Human Immunodeficiency Virus Type 1 Gag MA Domain

2007 ◽  
Vol 81 (12) ◽  
pp. 6434-6445 ◽  
Author(s):  
Amanda K. Dalton ◽  
Danso Ako-Adjei ◽  
Paul S. Murray ◽  
Diana Murray ◽  
Volker M. Vogt
Keyword(s):  
Human Immunodeficiency Virus ◽  
Human Immunodeficiency Virus Type ◽  
Virus Type ◽  
Electrostatic Interactions ◽  
Fluorescent Protein ◽  
Ionic Interactions ◽  
Membrane Association ◽  
Immunodeficiency Virus ◽  
Hiv 1

ABSTRACT The assembly of most retroviruses occurs at the plasma membrane. Membrane association is directed by MA, the N-terminal domain of the Gag structural protein. For human immunodeficiency virus type 1 (HIV-1), this association is mediated in part by a myristate fatty acid modification. Conflicting evidence has been presented on the relative importance of myristoylation, of ionic interactions between protein and membrane, and of Gag multimerization in membrane association in vivo. We addressed these questions biochemically by determining the affinity of purified myristoylated HIV-1 MA for liposomes of defined composition, both for monomeric and for dimeric forms of the protein. Myristoylation increases the barely detectable intrinsic affinity of the apo-protein for liposomes by only 10-fold, and the resulting affinity is still weak, similar to that of the naturally nonmyristoylated MA of Rous sarcoma virus. Membrane binding of HIV-1 MA is absolutely dependent on the presence of negatively charged lipid and is abrogated at high ionic strength. Forced dimerization of MA increases its membrane affinity by several orders of magnitude. When green fluorescent protein fusions of monomeric or dimeric MA are expressed in cells, the dimeric but not the monomeric protein becomes strongly membrane associated. Computational modeling supports these results and suggests a molecular mechanism for the modest effect of myristoylation on binding, wherein the membrane provides a hydrophobic environment for the myristate that is energetically similar to that provided by the protein. Overall, the results imply that the driving force for membrane association stems largely from ionic interactions between multimerized Gag and negatively charged phospholipids.

scholarly journals Comparison of the Genetic Recombination Rates of Human Immunodeficiency Virus Type 1 in Macrophages and T Cells

2005 ◽  
Vol 79 (14) ◽  
pp. 9337-9340 ◽  
Author(s):  
Jianbo Chen ◽  
Terence D. Rhodes ◽  
Wei-Shau Hu
Keyword(s):  
Human Immunodeficiency Virus ◽  
T Cells ◽  
Human Immunodeficiency Virus Type ◽  
Virus Type ◽  
Genetic Recombination ◽  
Recombination Rates ◽  
Monocytic Cell ◽  
Immunodeficiency Virus ◽  
Hiv 1

ABSTRACT Human immunodeficiency virus type 1 (HIV-1) exhibits a high level of genetic variation generated by frequent mutation and genetic recombination during reverse transcription. We have measured HIV-1 recombination rates in T cells in one round of virus replication. It was recently proposed that HIV-1 recombines far more frequently in macrophages than in T cells. In an attempt to delineate the mechanisms that elevate recombination, we measured HIV-1 recombination rates in macrophages at three different marker distances. Surprisingly, the recombination rates were comparable in macrophages and in T cells. In addition, we observed similar recombination rates in two monocytic cell lines regardless of the differentiation status. These results indicate that HIV-1 undergoes similar numbers of recombination events when infecting macrophages and T cells.

scholarly journals The Remarkable Frequency of Human Immunodeficiency Virus Type 1 Genetic Recombination

2009 ◽  
Vol 73 (3) ◽  
pp. 451-480 ◽  
Author(s):  
Adewunmi Onafuwa-Nuga ◽  
Alice Telesnitsky
Keyword(s):  
Human Immunodeficiency Virus ◽  
Human Immunodeficiency Virus Type ◽  
Virus Type ◽  
Vaccine Development ◽  
Genetic Recombination ◽  
Genetic Material ◽  
Genomic Rnas ◽  
Immunodeficiency Virus ◽  
Hiv 1

SUMMARY The genetic diversity of human immunodeficiency virus type 1 (HIV-1) results from a combination of point mutations and genetic recombination, and rates of both processes are unusually high. This review focuses on the mechanisms and outcomes of HIV-1 genetic recombination and on the parameters that make recombination so remarkably frequent. Experimental work has demonstrated that the process that leads to recombination—a copy choice mechanism involving the migration of reverse transcriptase between viral RNA templates—occurs several times on average during every round of HIV-1 DNA synthesis. Key biological factors that lead to high recombination rates for all retroviruses are the recombination-prone nature of their reverse transcription machinery and their pseudodiploid RNA genomes. However, HIV-1 genes recombine even more frequently than do those of many other retroviruses. This reflects the way in which HIV-1 selects genomic RNAs for coencapsidation as well as cell-to-cell transmission properties that lead to unusually frequent associations between distinct viral genotypes. HIV-1 faces strong and changeable selective conditions during replication within patients. The mode of HIV-1 persistence as integrated proviruses and strong selection for defective proviruses in vivo provide conditions for archiving alleles, which can be resuscitated years after initial provirus establishment. Recombination can facilitate drug resistance and may allow superinfecting HIV-1 strains to evade preexisting immune responses, thus adding to challenges in vaccine development. These properties converge to provide HIV-1 with the means, motive, and opportunity to recombine its genetic material at an unprecedented high rate and to allow genetic recombination to serve as one of the highest barriers to HIV-1 eradication.

scholarly journals Cell-Based Fluorescence Assay for Human Immunodeficiency Virus Type 1 Protease Activity

2001 ◽  
Vol 45 (9) ◽  
pp. 2616-2622 ◽  
Author(s):  
Kristina Lindsten ◽  
Tat'ána Uhlı́ková ◽  
Jan Konvalinka ◽  
Maria G. Masucci ◽  
Nico P. Dantuma
Keyword(s):  
Human Immunodeficiency Virus ◽  
Human Immunodeficiency Virus Type ◽  
Virus Type ◽  
Fluorescent Protein ◽  
Autocatalytic Cleavage ◽  
Immunodeficiency Virus ◽  
Green Fluorescent ◽  
Hiv 1

ABSTRACT The human immunodeficiency virus type 1 (HIV-1) protease is essential for production of infectious virus and is therefore a major target for the development of drugs against AIDS. Cellular proteins are also cleaved by the protease, which explains its cytotoxic activity and the consequent failure to establish convenient cell-based protease assays. We have exploited this toxicity to develop a new protease assay that relies on transient expression of an artificial protease precursor harboring the green fluorescent protein (GFP-PR). The precursor is activated in vivo by autocatalytic cleavage, resulting in rapid elimination of protease-expressing cells. Treatment with therapeutic doses of HIV-1 protease inhibitors results in a dose-dependent accumulation of the fluorescent precursor that can be easily detected and quantified by flow cytometric and fluorimetric assays. The precursor provides a convenient and noninfectious model for high-throughput screenings of substances that can interfere with the activity of the protease in living cells.

Sign in / Sign up

Export Citation Format

Share Document