scholarly journals Detailed Characterization of Early HIV-1 Replication Dynamics in Primary Human Macrophages

Viruses ◽  
2018 ◽  
Vol 10 (11) ◽  
pp. 620 ◽  
Author(s):  
David Bejarano ◽  
Maria Puertas ◽  
Kathleen Börner ◽  
Javier Martinez-Picado ◽  
Barbara Müller ◽  
...  
Keyword(s):  
Viral Replication ◽  
Reverse Transcription ◽  
Human Monocyte ◽  
Digital Pcr ◽  
Productive Infection ◽  
Target Cells ◽  
Post Entry ◽  
Early Replication ◽  
Kinetics Of ◽  
Hiv 1

Macrophages are natural target cells of human immunodeficiency virus type 1 (HIV-1). Viral replication appears to be delayed in these cells compared to lymphocytes; however, little is known about the kinetics of early post-entry events. Time-of-addition experiments using several HIV-1 inhibitors and the detection of reverse transcriptase (RT) products with droplet digital PCR (ddPCR) revealed that early replication was delayed in primary human monocyte-derived macrophages of several donors and peaked late after infection. Direct imaging of reverse-transcription and pre-integration complexes (RTC/PIC) by click-labeling of newly synthesized DNA further confirmed our findings and showed a concomitant shift to the nuclear stage over time. Altering the entry pathway enhanced infectivity but did not affect kinetics of viral replication. The addition of viral protein X (Vpx) enhanced productive infection and accelerated completion of reverse transcription and nuclear entry. We propose that sterile alpha motif (SAM) and histidine/aspartate (HD) domain-containing protein 1 (SAMHD1) activity lowering deoxyribonucleotide triphosphate (dNTP) pools is the principal factor delaying early HIV-1 replication in macrophages.

scholarly journals HIV-1 Exploits a Dynamic Multi-aminoacyl-tRNA Synthetase Complex To Enhance Viral Replication

2017 ◽  
Vol 91 (21) ◽  
Author(s):  
Alice A. Duchon ◽  
Corine St. Gelais ◽  
Nathan Titkemeier ◽  
Joshua Hatterschide ◽  
Li Wu ◽  
...  
Keyword(s):  
Viral Replication ◽  
Nuclear Localization ◽  
Reverse Transcription ◽  
Transcriptase Inhibitor ◽  
Trna Synthetase ◽  
Mitogen Activated Protein Kinase ◽  
Heat Inactivation ◽  
Target Cells ◽  
Aminoacyl Trna Synthetase ◽  
Hiv 1

ABSTRACT A hallmark of retroviruses such as human immunodeficiency virus type 1 (HIV-1) is reverse transcription of genomic RNA to DNA, a process that is primed by cellular tRNAs. HIV-1 recruits human tRNALys3 to serve as the reverse transcription primer via an interaction between lysyl-tRNA synthetase (LysRS) and the HIV-1 Gag polyprotein. LysRS is normally sequestered in a multi-aminoacyl-tRNA synthetase complex (MSC). Previous studies demonstrated that components of the MSC can be mobilized in response to certain cellular stimuli, but how LysRS is redirected from the MSC to viral particles for packaging is unknown. Here, we show that upon HIV-1 infection, a free pool of non-MSC-associated LysRS is observed and partially relocalized to the nucleus. Heat inactivation of HIV-1 blocks nuclear localization of LysRS, but treatment with a reverse transcriptase inhibitor does not, suggesting that the trigger for relocalization occurs prior to reverse transcription. A reduction in HIV-1 infection is observed upon treatment with an inhibitor to mitogen-activated protein kinase that prevents phosphorylation of LysRS on Ser207, release of LysRS from the MSC, and nuclear localization. A phosphomimetic mutant of LysRS (S207D) that lacked the capability to aminoacylate tRNALys3 localized to the nucleus, rescued HIV-1 infectivity, and was packaged into virions. In contrast, a phosphoablative mutant (S207A) remained cytosolic and maintained full aminoacylation activity but failed to rescue infectivity and was not packaged. These findings suggest that HIV-1 takes advantage of the dynamic nature of the MSC to redirect and coopt cellular translation factors to enhance viral replication. IMPORTANCE Human tRNALys3, the primer for reverse transcription, and LysRS are essential host factors packaged into HIV-1 virions. Previous studies found that tRNALys3 packaging depends on interactions between LysRS and HIV-1 Gag; however, many details regarding the mechanism of tRNALys3 and LysRS packaging remain unknown. LysRS is normally sequestered in a high-molecular-weight multi-aminoacyl-tRNA synthetase complex (MSC), restricting the pool of free LysRS-tRNALys. Mounting evidence suggests that LysRS is released under a variety of stimuli to perform alternative functions within the cell. Here, we show that HIV-1 infection results in a free pool of LysRS that is relocalized to the nucleus of target cells. Blocking this pathway in HIV-1-producing cells resulted in less infectious progeny virions. Understanding the mechanism by which LysRS is recruited into the viral assembly pathway can be exploited for the development of specific and effective therapeutics targeting this nontranslational function.

scholarly journals Allosteric HIV-1 Integrase Inhibitors Lead to Premature Degradation of the Viral RNA Genome and Integrase in Target Cells

2017 ◽  
Vol 91 (17) ◽  
Author(s):  
Michaela K. Madison ◽  
Dana Q. Lawson ◽  
Jennifer Elliott ◽  
Ayşe Naz Ozantürk ◽  
Pratibha C. Koneru ◽  
...  
Keyword(s):  
Reverse Transcriptase ◽  
Reverse Transcription ◽  
Hexagonal Lattice ◽  
Viral Rna ◽  
Productive Infection ◽  
Target Cells ◽  
Integrase Inhibitors ◽  
Ribonucleoprotein Complexes ◽  
Rna Genome ◽  
Hiv 1

ABSTRACT Recent evidence indicates that inhibition of HIV-1 integrase (IN) binding to the viral RNA genome by allosteric integrase inhibitors (ALLINIs) or through mutations within IN yields aberrant particles in which the viral ribonucleoprotein complexes (vRNPs) are eccentrically localized outside the capsid lattice. These particles are noninfectious and are blocked at an early reverse transcription stage in target cells. However, the basis of this reverse transcription defect is unknown. Here, we show that the viral RNA genome and IN from ALLINI-treated virions are prematurely degraded in target cells, whereas reverse transcriptase remains active and stably associated with the capsid lattice. The aberrantly shaped cores in ALLINI-treated particles can efficiently saturate and be degraded by a restricting TRIM5 protein, indicating that they are still composed of capsid proteins arranged in a hexagonal lattice. Notably, the fates of viral core components follow a similar pattern in cells infected with eccentric particles generated by mutations within IN that inhibit its binding to the viral RNA genome. We propose that IN-RNA interactions allow packaging of both the viral RNA genome and IN within the protective capsid lattice to ensure subsequent reverse transcription and productive infection in target cells. Conversely, disruption of these interactions by ALLINIs or mutations in IN leads to premature degradation of both the viral RNA genome and IN, as well as the spatial separation of reverse transcriptase from the viral genome during early steps of infection. IMPORTANCE Recent evidence indicates that HIV-1 integrase (IN) plays a key role during particle maturation by binding to the viral RNA genome. Inhibition of IN-RNA interactions yields aberrant particles with the viral ribonucleoprotein complexes (vRNPs) eccentrically localized outside the conical capsid lattice. Although these particles contain all of the components necessary for reverse transcription, they are blocked at an early reverse transcription stage in target cells. To explain the basis of this defect, we tracked the fates of multiple viral components in infected cells. Here, we show that the viral RNA genome and IN in eccentric particles are prematurely degraded, whereas reverse transcriptase remains active and stably associated within the capsid lattice. We propose that IN-RNA interactions ensure the packaging of both vRNPs and IN within the protective capsid cores to facilitate subsequent reverse transcription and productive infection in target cells.

scholarly journals HIV Fusion in Dendritic Cells Occurs Mainly at the Surface and Is Limited by Low CD4 Levels

2017 ◽  
Vol 91 (21) ◽  
Author(s):  
Lise Chauveau ◽  
Daniel Aaron Donahue ◽  
Blandine Monel ◽  
Francoise Porrot ◽  
Timothée Bruel ◽  
...  
Keyword(s):  
Dendritic Cells ◽  
Plasma Membrane ◽  
Cell Surface ◽  
Viral Replication ◽  
Intracellular Localization ◽  
Temperature Shift ◽  
Productive Infection ◽  
Target Cells ◽  
Viral Fusion ◽  
Hiv 1

ABSTRACT HIV-1 poorly infects monocyte-derived dendritic cells (MDDCs). This is in large part due to SAMHD1, which restricts viral reverse transcription. Pseudotyping HIV-1 with vesicular stomatitis virus G protein (VSV-G) strongly enhances infection, suggesting that earlier steps of viral replication, including fusion, are also inefficient in MDDCs. The site of HIV-1 fusion remains controversial and may depend on the cell type, with reports indicating that it occurs at the plasma membrane or, conversely, in an endocytic compartment. Here, we examined the pathways of HIV-1 entry in MDDCs. Using a combination of temperature shift and fusion inhibitors, we show that HIV-1 fusion mainly occurs at the cell surface. We then asked whether surface levels or intracellular localization of CD4 modulates HIV-1 entry. Increasing CD4 levels strongly enhanced fusion and infection with various HIV-1 isolates, including reference and transmitted/founder strains, but not with BaL, which uses low CD4 levels for entry. Overexpressing coreceptors did not facilitate viral infection. To further study the localization of fusion events, we generated CD4 mutants carrying heterologous cytoplasmic tails (LAMP1 or Toll-like receptor 7 [TLR7]) to redirect the molecule to intracellular compartments. The intracellular CD4 mutants did not facilitate HIV-1 fusion and replication in MDDCs. Fusion of an HIV-2 isolate with MDDCs was also enhanced by increasing surface CD4 levels. Our results demonstrate that MDDCs are inefficiently infected by various HIV-1 and HIV-2 strains, in part because of low CD4 levels. In these cells, viral fusion occurs mainly at the surface, and probably not after internalization. IMPORTANCE Dendritic cells (DCs) are professional antigen-presenting cells inducing innate and adaptive immune responses. DCs express the HIV receptor CD4 and are potential target cells for HIV. There is debate about the sensitivity of DCs to productive HIV-1 and HIV-2 infection. The fusion step of the viral replication cycle is inefficient in DCs, and the underlying mechanisms are poorly characterized. We show that increasing the levels of CD4 at the plasma membrane allows more HIV fusion and productive infection in DCs. We further demonstrate that HIV fusion occurs mainly at the cell surface and not in an intracellular compartment. Our results help us understand why DCs are poorly sensitive to HIV infection.

scholarly journals HIV-1 Accessory Protein Vpr Interacts with REAF/RPRD2 To Mitigate Its Antiviral Activity

2019 ◽  
Vol 94 (4) ◽  
Author(s):  
Joseph M. Gibbons ◽  
Kelly M. Marno ◽  
Rebecca Pike ◽  
Wing-yiu Jason Lee ◽  
Christopher E. Jones ◽  
...  
Keyword(s):  
T Cells ◽  
Viral Replication ◽  
Nuclear Localization ◽  
Reverse Transcription ◽  
Early Phase ◽  
Early Stage ◽  
Target Cells ◽  
Accessory Protein ◽  
Hiv 1

ABSTRACT The human immunodeficiency virus type 1 (HIV-1) accessory protein Vpr enhances viral replication in both macrophages and, to a lesser extent, cycling T cells. Virion-packaged Vpr is released in target cells shortly after entry, suggesting it is required in the early phase of infection. Previously, we described REAF (RNA-associated early-stage antiviral factor; RPRD2), a constitutively expressed protein that potently restricts HIV replication at or during reverse transcription. Here, we show that a virus without an intact vpr gene is more highly restricted by REAF and, using delivery by virus-like particles (VLPs), that Vpr alone is sufficient for REAF degradation in primary macrophages. REAF is more highly expressed in macrophages than in cycling T cells, and we detected, by coimmunoprecipitation assay, an interaction between Vpr protein and endogenous REAF. Vpr acts quickly during the early phase of replication and induces the degradation of REAF within 30 min of viral entry. Using Vpr F34I and Q65R viral mutants, we show that nuclear localization and interaction with cullin 4A-DBB1 (DCAF1) E3 ubiquitin ligase are required for REAF degradation by Vpr. In response to infection, cells upregulate REAF levels. This response is curtailed in the presence of Vpr. These findings support the hypothesis that Vpr induces the degradation of a factor, REAF, that impedes HIV infection in macrophages. IMPORTANCE For at least 30 years, it has been known that HIV-1 Vpr, a protein carried in the virion, is important for efficient infection of primary macrophages. Vpr is also a determinant of the pathogenic effects of HIV-1 in vivo. A number of cellular proteins that interact with Vpr have been identified. So far, it has not been possible to associate these proteins with altered viral replication in macrophages or to explain why Vpr is carried in the virus particle. Here, we show that Vpr mitigates the antiviral effects of REAF, a protein highly expressed in primary macrophages and one that inhibits virus replication during reverse transcription. REAF is degraded by Vpr within 30 min of virus entry in a manner dependent on the nuclear localization of Vpr and its interaction with the cell’s protein degradation machinery.

scholarly journals Functional Analysis of Vif Protein Shows Less Restriction of Human Immunodeficiency Virus Type 2 by APOBEC3G

2005 ◽  
Vol 79 (2) ◽  
pp. 823-833 ◽  
Author(s):  
Ana Clara Ribeiro ◽  
Alexandra Maia e Silva ◽  
Mariana Santa-Marta ◽  
Ana Pombo ◽  
José Moniz-Pereira ◽  
...  
Keyword(s):  
Human Immunodeficiency Virus ◽  
Viral Replication ◽  
Productive Infection ◽  
Target Cells ◽  
Viral Infectivity ◽  
Single Cycle ◽  
Conserved Motifs ◽  
Immunodeficiency Virus ◽  
Vif Protein ◽  
Hiv 1

ABSTRACT Viral infectivity factor (Vif) is one of the human immunodeficiency virus (HIV) accessory proteins and is conserved in the primate lentivirus group. This protein is essential for viral replication in vivo and for productive infection of nonpermissive cells, such as peripheral blood mononuclear cells (PBMC). Vif counteracts an antiretroviral cellular factor in nonpermissive cells named CEM15/APOBEC3G. Although HIV type 1 (HIV-1) Vif protein (Vif1) can be functionally replaced by HIV-2 Vif protein (Vif2), its identity is very small. Most of the functional studies have been carried out with Vif1. Characterization of functional domains of Vif2 may elucidate its function, as well as differences between HIV-1 and HIV-2 infectivity. Our aim was to identify the permissivity of different cell lines for HIV-2 vif-minus viruses. By mutagenesis specific conserved motifs of HIV-2 Vif protein were analyzed, as well as in conserved motifs between Vif1 and Vif2 proteins. Vif2 mutants were examined for their stability, expression, and cellular localization in order to characterize essential domains of Vif2 proteins. Viral replication in various target cells (PBMC and H9, A3.01, U38, and Jurkat cells) and infectivity in single cycle assays in the presence of APOBEC3G were also analyzed. Our results of viral replication show that only PBMC have a nonpermissive phenotype in the absence of Vif2. Moreover, the HIV-1 vif-minus nonpermissive cell line H9 does not show a similar phenotype for vif-negative HIV-2. We also report a limited effect of APOBEC3G in a single-cycle infectivity assay, where only conserved domains between HIV-1 and HIV-2 Vif proteins influence viral infectivity. Taken together, these results allow us to speculate that viral inhibition by APOBEC3G is not the sole and most important determinant of antiviral activity against HIV-2.

scholarly journals HIV-1 accessory protein Vpr interacts with REAF/RPRD2 to mitigate its antiviral activity

2018 ◽  
Author(s):  
Joseph M Gibbons ◽  
Kelly M Marno ◽  
Rebecca Pike ◽  
Wing-yiu Jason Lee ◽  
Christopher E Jones ◽  
...  
Keyword(s):  
T Cells ◽  
Viral Replication ◽  
Viral Entry ◽  
Reverse Transcription ◽  
Early Phase ◽  
Early Stage ◽  
Target Cells ◽  
Accessory Protein ◽  
Hiv 1

AbstractThe Human Immunodeficiency Virus type 1 (HIV-1) accessory protein Vpr enhances viral replication in both macrophages and in cycling T cells to a lesser extent. Virion packaged Vpr is released in target cells shortly after entry, suggesting its requirement in the early phase of infection. Previously, we described REAF (RNA-associated Early-stage Antiviral Factor, RPRD2), a constitutively expressed protein that potently restricts HIV replication at or during reverse transcription. Here, we show that a virus without intactvpris more highly restricted by REAF and, using delivery by VLPs, that Vpr alone is sufficient for REAF degradation in primary macrophages. REAF is more highly expressed in macrophages than in cycling T cells and we detect, by co-immunoprecipitation assay, an interaction between Vpr protein and endogenous REAF. Vpr acts very quickly during the early phase of replication and induces the degradation of REAF within 30 minutes of viral entry. Using Vpr F34I and Q65R viral mutants, we show that nuclear localisation and interaction with cullin4A-DBB1 (DCAF1) E3 ubiquitin ligase is required for REAF degradation by Vpr. In response to infection, cells upregulate REAF levels. This response is curtailed in the presence of Vpr. These findings support the hypothesis that Vpr induces the degradation of a factor, REAF, which impedes HIV infection in macrophages.ImportanceFor at least 30 years, it has been known that HIV-1 Vpr, a protein carried in the virion, is important for efficient infection of primary macrophages. Vpr is also a determinant of the pathogenic effects of HIV-1in vivo. A number of cellular proteins that interact with Vpr have been identified. So far, it has not been possible to associate these proteins with altered viral replication in macrophages, or to explain why Vpr is carried in the virus particle. Here we show that Vpr mitigates the antiviral effects of REAF, a protein highly expressed in primary macrophages and one which inhibits virus replication early during reverse transcription. REAF is degraded by Vpr within 30 minutes of virus entry, in a manner dependent on the nuclear localization of Vpr and its interaction with the cell’s protein degradation machinery.

scholarly journals Clustering and reverse transcription of HIV-1 genomes in nuclear niches of macrophages

2020 ◽  
Author(s):  
Elena Rensen ◽  
Florian Mueller ◽  
Viviana Scoca ◽  
Jyotsana J. Parmar ◽  
Philippe Souque ◽  
...  
Keyword(s):  
Reverse Transcription ◽  
Replication Cycle ◽  
Viral Rna ◽  
Target Cells ◽  
Nuclear Speckles ◽  
Viral Dna ◽  
Immunodeficiency Virus ◽  
Early Replication ◽  
Key Events ◽  
Hiv 1

SummaryIn order to replicate, the Human Immunodeficiency Virus (HIV-1) reverse transcribes its RNA genome into DNA, which subsequently integrates into host cell chromosomes. These two key events of the viral life cycle are commonly viewed as separate not only in time but also in cellular space, since reverse transcription (RT) is thought to be completed in the cytoplasm before nuclear import and integration. However, the spatiotemporal organization of the early replication cycle in macrophages, natural non-dividing target cells that constitute reservoirs of HIV-1 and an obstacle to curing AIDS, remains unclear. Here, we demonstrate that infected macrophages display large nuclear foci of viral DNA and viral RNA, in which multiple genomes cluster together. These clusters form in the absence of chromosomal integration, sequester the paraspeckle protein CPSF6 and localize to nuclear speckles. Strikingly, we show that viral RNA clusters consist mostly of genomic, incoming RNA, both in cells where RT is pharmacologically suppressed and in untreated cells. We demonstrate that, after temporary inhibition, RT can resume in the nucleus and lead to vDNA accumulation in these clusters. We further show that nuclear RT can result in transcription competent viral DNA. These findings change our understanding of the early HIV-1 replication cycle, and may have implications for understanding HIV-1 persistence.

scholarly journals HIV-1 Uncoating and Nuclear Import Precede the Completion of Reverse Transcription in Cell Lines and in Primary Macrophages

Viruses ◽  
2020 ◽  
Vol 12 (11) ◽  
pp. 1234
Author(s):  
Ashwanth C. Francis ◽  
Mariana Marin ◽  
Mathew J. Prellberg ◽  
Kristina Palermino-Rowland ◽  
Gregory B. Melikyan
Keyword(s):  
Cell Lines ◽  
Reverse Transcription ◽  
Nuclear Import ◽  
Cyclophilin A ◽  
Target Cells ◽  
Nuclear Pore ◽  
Virus Escape ◽  
Infected Cells ◽  
Kinetics Of ◽  
Hiv 1

An assembly of capsid proteins (CA) form the mature viral core enclosing the HIV-1 ribonucleoprotein complex. Discrepant findings have been reported regarding the cellular sites and the extent of core disassembly (uncoating) in infected cells. Here, we combined single-virus imaging and time-of-drug-addition assays to elucidate the kinetic relationship between uncoating, reverse transcription, and nuclear import of HIV-1 complexes in cell lines and monocyte-derived macrophages (MDMs). By using cyclophilin A-DsRed (CDR) as a marker for CA, we show that, in contrast to TZM-bl cells, early cytoplasmic uncoating (loss of CDR) is limited in MDMs and is correlated with the efficiency of reverse transcription. However, we find that reverse transcription is dispensable for HIV-1 nuclear import, which progressed through an uncoating step at the nuclear pore. Comparison of the kinetics of nuclear import and the virus escape from inhibitors targeting distinct steps of infection, as well as direct quantification of viral DNA synthesis, revealed that reverse transcription is completed after nuclear import of HIV-1 complexes. Collectively, these results suggest that reverse transcription is dispensable for the uncoating step at the nuclear pore and that vDNA synthesis is completed in the nucleus of unrelated target cells.

scholarly journals HIV-1 Gag recruits oligomeric Vpr via two binding sites in p6, but both mature p6 and Vpr are rapidly lost upon target cell entry

2021 ◽  
Author(s):  
Madushi Wanaguru ◽  
Kate N. Bishop
Keyword(s):  
Viral Replication ◽  
Target Cell ◽  
Binding Sites ◽  
Cell Entry ◽  
Target Cells ◽  
Accessory Protein ◽  
Virus Budding ◽  
Early Replication ◽  
Hiv 1

The p12 region of MLV Gag and the p6 region of HIV-1 Gag contain late-domains required for virus budding. Additionally, the accessory protein Vpr is recruited into HIV particles via p6. Mature p12 is essential for early viral replication events, but the role of mature p6 in early replication is unknown. Using a proviral vector in which the gag and pol reading frames are uncoupled, we have performed the first alanine-scanning mutagenesis screens across p6, to probe its importance for early HIV-1 replication and to further understand its interaction with Vpr. The infectivity of our mutants suggests that, unlike p12, p6 is not important for early viral replication. Consistent with this, we observed that p6 is rapidly lost upon target cell entry in time-course immunoblotting experiments. By analysing Vpr incorporation in p6 mutant virions, we identified that the 15-FRFG-18 and 41-LXXLF-45 motifs previously identified as putative Vpr-binding sites are important for Vpr recruitment, but that the 34-ELY-36 motif also suggested to be a Vpr-binding site is dispensable. Additionally, disrupting Vpr oligomerization together with removing either binding motif in p6 reduced Vpr incorporation ∼25-50-fold more than inhibiting Vpr oligomerization alone and ∼10-25-fold more than deletion of each p6 motif alone, implying that multivalency/avidity is important for the interaction. Interestingly, using immunoblotting and immunofluorescence, we observed that most of Vpr is lost concomitantly with p6 during infection, but that a small fraction remains associated with the viral capsid for several hours. This has implications for the function of Vpr in early replication. Importance The p12 protein of MLV and the p6 protein of HIV-1 are both supplementary Gag cleavage products that carry proline-rich motifs which facilitate virus budding. Importantly, p12 has also been found to be essential for early viral replication events. However, whilst Vpr, the only accessory protein packaged into HIV-1 virions, is recruited via the p6 region of Gag, the function of both mature p6 and Vpr in early replication is unclear. Here, we have systematically mutated the p6 region of gag and have studied the effects on HIV infectivity and Vpr packaging. We have also investigated what happens to p6 and Vpr during early infection. We show that, unlike p12, mature p6 is not required for early replication and that most of the mature p6, and the Vpr that it recruits, are lost rapidly upon target cell entry. This has implications for the role of Vpr in target cells.

scholarly journals Continuous HIV-1 Escape from Autologous Neutralization and Development of Cross-Reactive Antibody Responses Characterizes Slow Disease Progression of Children

Vaccines ◽  
2021 ◽  
Vol 9 (3) ◽  
pp. 260
Author(s):  
Stefania Dispinseri ◽  
Mariangela Cavarelli ◽  
Monica Tolazzi ◽  
Anna Maria Plebani ◽  
Marianne Jansson ◽  
...  
Keyword(s):  
Disease Progression ◽  
Antibody Responses ◽  
Viral Escape ◽  
Target Cells ◽  
Transmitted Virus ◽  
Slow Progressors ◽  
Vaccine Antigens ◽  
Kinetics Of ◽  
Hiv 1

The antibodies with different effector functions evoked by Human Immunodeficiency Virus type 1 (HIV-1) transmitted from mother to child, and their role in the pathogenesis of infected children remain unresolved. So, too, the kinetics and breadth of these responses remain to be clearly defined, compared to those developing in adults. Here, we studied the kinetics of the autologous and heterologous neutralizing antibody (Nab) responses, in addition to antibody-dependent cellular cytotoxicity (ADCC), in HIV-1 infected children with different disease progression rates followed from close after birth and five years on. Autologous and heterologous neutralization were determined by Peripheral blood mononuclear cells (PBMC)- and TZMbl-based assays, and ADCC was assessed with the GranToxiLux assay. The reactivity to an immunodominant HIV-1 gp41 epitope, and childhood vaccine antigens, was assessed by ELISA. Newborns displayed antibodies directed towards the HIV-1 gp41 epitope. However, antibodies neutralizing the transmitted virus were undetectable. Nabs directed against the transmitted virus developed usually within 12 months of age in children with slow progression, but rarely in rapid progressors. Thereafter, autologous Nabs persisted throughout the follow-up of the slow progressors and induced a continuous emergence of escape variants. Heterologous cross-Nabs were detected within two years, but their subsequent increase in potency and breadth was mainly a trait of slow progressors. Analogously, titers of antibodies mediating ADCC to gp120 BaL pulsed target cells increased in slow progressors during follow-up. The kinetics of antibody responses to the immunodominant viral antigen and the vaccine antigens were sustained and independent of disease progression. Persistent autologous Nabs triggering viral escape and an increase in the breadth and potency of cross-Nabs are exclusive to HIV-1 infected slowly progressing children.

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