scholarly journals The Role of L-Selectin in HIV Infection

2021 ◽  
Vol 12 ◽  
Author(s):  
Jason Segura ◽  
Biao He ◽  
Joanna Ireland ◽  
Zhongcheng Zou ◽  
Thomas Shen ◽  
...  
Keyword(s):  
T Lymphocytes ◽  
Viral Entry ◽  
Chemokine Receptors ◽  
Neutralizing Antibodies ◽  
Immune Recognition ◽  
Lectin Receptor ◽  
Viral Release ◽  
Hiv Entry ◽  
Hiv Envelope

HIV envelope glycoprotein is the most heavily glycosylated viral protein complex identified with over 20 glycans on its surface. This glycan canopy is thought to primarily shield the virus from host immune recognition as glycans are poor immunogens in general, however rare HIV neutralizing antibodies nevertheless potently recognize the glycan epitopes. While CD4 and chemokine receptors have been known as viral entry receptor and coreceptor, for many years the role of viral glycans in HIV entry was controversial. Recently, we showed that HIV envelope glycan binds to L-selectin in solution and on CD4 T lymphocytes. The viral glycan and L-selectin interaction functions to facilitate the viral adhesion and entry. Upon entry, infected CD4 T lymphocytes are stimulated to progressively shed L-selectin and suppressing this lectin receptor shedding greatly reduced HIV viral release and caused aggregation of diminutive virus-like particles within experimental infections and from infected primary T lymphocytes derived from both viremic and aviremic individuals. As shedding of L-selectin is mediated by ADAM metalloproteinases downstream of host-cell stimulation, these findings showed a novel mechanism for HIV viral release and offer a potential new class of anti-HIV compounds.

scholarly journals Maternal Broadly Neutralizing Antibodies Can Select for Neutralization-Resistant, Infant-Transmitted/Founder HIV Variants

mBio ◽  
2020 ◽  
Vol 11 (2) ◽  
Author(s):  
David R. Martinez ◽  
Joshua J. Tu ◽  
Amit Kumar ◽  
Jesse F. Mangold ◽  
Riley J. Mangan ◽  
...  
Keyword(s):  
Neutralizing Antibodies ◽  
Neutralizing Antibody ◽  
Maternal Plasma ◽  
Small Subset ◽  
Maternal Hiv ◽  
Broadly Neutralizing Antibody ◽  
Specific Igg ◽  
Hiv Envelope ◽  
Mother To Child

ABSTRACT Each year, >180,000 infants become infected via mother-to-child transmission (MTCT) of HIV despite the availability of effective maternal antiretroviral treatments, underlining the need for a maternal HIV vaccine. We characterized 224 maternal HIV envelope (Env)-specific IgG monoclonal antibodies (MAbs) from seven nontransmitting and transmitting HIV-infected U.S. and Malawian mothers and examined their neutralization activities against nontransmitted autologous circulating viruses and infant-transmitted founder (infant-T/F) viruses. Only a small subset of maternal viruses, 3 of 72 (4%), were weakly neutralized by maternal linear V3 epitope-specific IgG MAbs, whereas 6 out of 6 (100%) infant-T/F viruses were neutralization resistant to these V3-specific IgG MAbs. We also show that maternal-plasma broadly neutralizing antibody (bNAb) responses targeting the V3 glycan supersite in a transmitting woman may have selected for an N332 V3 glycan neutralization-resistant infant-T/F virus. These data have important implications for bNAb-eliciting vaccines and passively administered bNAbs in the setting of MTCT. IMPORTANCE Efforts to eliminate MTCT of HIV with antiretroviral therapy (ART) have met little success, with >180,000 infant infections each year worldwide. It is therefore likely that additional immunologic strategies that can synergize with ART will be required to eliminate MTCT of HIV. To this end, understanding the role of maternal HIV Env-specific IgG antibodies in the setting of MTCT is crucial. In this study, we found that maternal-plasma broadly neutralizing antibody (bNAb) responses can select for T/F viruses that initiate infection in infants. We propose that clinical trials testing the efficacy of single bNAb specificities should not include HIV-infected pregnant women, as a single bNAb might select for neutralization-resistant infant-T/F viruses.

Antiretroviral agents: Focus on Maraviroc for the Treatment of HIV-1-Infected Adults

2010 ◽  
Vol 2 ◽  
pp. CMT.S5420
Author(s):  
SL. Pett ◽  
S. Emery ◽  
AD. Kelleher ◽  
DA. Cooper
Keyword(s):  
Hiv Infection ◽  
Chemokine Receptors ◽  
Hiv Transmission ◽  
Hiv Therapy ◽  
Ccr5 Receptor ◽  
Tick Borne Encephalitis ◽  
Hiv Entry ◽  
Orally Bioavailable ◽  
Hiv Envelope ◽  
Hiv 1

Over a decade has passed since several groups identified the chemokine receptors CXCR4 and CCR5 as key co-receptors for HIV entry. CCR5 is more important in HIV transmission and during the early course of HIV infection. It is also apparent that protection from HIV infection is afforded to those lacking CCR5–-the so called delta-32 homozygotes; in those heterozygous for this mutation, an attenuated course of HIV-infection is observed. Provocatively, those with modified expression of CCR5 are physiologically normal with the exception of poorer outcomes with some of the viral encephalitides specifically West Nile virus and Tick Borne encephalitis. The small molecule, orally-bioavailable CCR5 receptor antagonists, including, maraviroc (MVC), are allosteric inhibitors that lock the CCR5 receptor into a conformation such that the receptor is not able to bind HIV envelope protein; the molecules also variably block intracellular signalling induced by different receptor-binding chemokines. The aims of this review on the CCR5 receptor inhibitors are to summarise information relevant to treatment in individuals with HIV-1 infection. Data from the licensing studies, the side-effect profile and putative long-term risks of CCR5 receptor inhibitor exposure, tropism testing and mechanisms of resistance will be reviewed. The potential for using this class of agent as an immunomodulating agent will be detailed. Given that MVC is the only licensed drug in this class at present and reflecting the greater body of work describing this agent, the majority of information in this review relates to MVC. Last, the authors propose the place of MVC in the hierarchy of HIV therapy and future opportunities for research.

Human Immunodeficiency Virus (HIV)-Resistant CD4+ UT-7 Megakaryocytic Human Cell Line Becomes Highly HIV-1 and HIV-2 Susceptible Upon CXCR4 Transfection: Induction of Cell Differentiation by HIV-1 Infection

Blood ◽  
1997 ◽  
Vol 89 (8) ◽  
pp. 2670-2678 ◽  
Author(s):  
Marta Baiocchi ◽  
Eleonora Olivetta ◽  
Cristiana Chelucci ◽  
Anna Claudia Santarcangelo ◽  
Roberta Bona ◽  
...  
Keyword(s):  
Human Immunodeficiency Virus ◽  
Hiv Infection ◽  
Cell Line ◽  
Viral Entry ◽  
Human Cell Line ◽  
Immunodeficiency Virus ◽  
Hiv Entry ◽  
Stromal Cell Derived Factor ◽  
Hiv 1

Abstract Recent findings have shown that the expression of the seven trans-membrane G-protein–coupled CXCR4 (the receptor for the stromal cell-derived factor [SDF]-1 chemokine) is necessary for the entry of T-lymphotropic human immunodeficiency virus (HIV) strains, acting as a coreceptor of the CD4 molecule. In the human system, the role of CXCR4 in HIV infection has been determined through env-mediated cell fusion assays and confirmed by blocking viral entry in CD4+/CXCR4+ cells by SDF-1 pretreatment. We observed that the human megakaryoblastic CD4+ UT-7 cell line fails to express CXCR4 RNA and is fully resistant to HIV entry. Transfection of an expression vector containing the CXCR4 c-DNA rendered UT-7 cells readily infectable by different T-lymphotropic syncytium-inducing HIV-1 and HIV-2 isolates. Interestingly, HIV-1 infection of CXCR4 expressing UT-7 cells (named UT-7/fus) induces the formation of polynucleated cells through a process highly reminiscent of megakaryocytic differentiation and maturation. On the contrary, no morphologic changes were observed in HIV-2–infected UT-7/fus cells. These findings further strengthen the role of CXCR4 as a molecule necessary for the replication of T-lymphotropic HIV-1 and HIV-2 isolates and provide a useful model to study the functional role of CD4 coreceptors in HIV infection.

scholarly journals Chemokines: understanding their role in T-lymphocyte biology

1998 ◽  
Vol 333 (3) ◽  
pp. 457-470 ◽  
Author(s):  
Stephen G. WARD ◽  
John WESTWICK
Keyword(s):  
T Lymphocytes ◽  
Chemokine Receptors ◽  
Protein Tyrosine Kinase ◽  
Cell Function ◽  
Signalling Pathways ◽  
Cc Chemokine ◽  
Intracellular Signalling Pathways ◽  
And Function ◽  
Hiv 1

The chemokines are a complex superfamily of small, secreted proteins that were initially characterized through their chemotactic effects on a variety of leucocytes. The superfamily is divided into families based on structural and genetic considerations and have been termed the CXC, CC, C and CX3C families. Chemokines from these families have a key role in the recruitment and function of T lymphocytes. Moreover, T lymphocytes have also been identified as a source of a number of chemokines. T lymphocytes also express most of the known CXC and CC chemokine receptors to an extent that depends on their state of activation/differentiation and/or the activating stimuli. The expression of two chemokine receptors, namely CXCR4 and CCR5, together with the regulated production of their respective ligands, appears to be extremely important in determining sensitivity of T cells to HIV-1 infection. The intracellular events which mediate the effects of chemokines, particularly those elicited by the CC chemokine RANTES, include activation of both G-protein- and protein tyrosine kinase-coupled signalling pathways. The present review describes our current understanding of the structure and expression of chemokines and their receptors, the effects of chemokines on T-cell function(s), the intracellular signalling pathways activated by chemokines and the role of certain chemokines and chemokine receptors in determining sensitivity to HIV-1 infection.

scholarly journals Role of N-Linked Glycans in a Human Immunodeficiency Virus Envelope Glycoprotein: Effects on Protein Function and the Neutralizing Antibody Response

2002 ◽  
Vol 76 (9) ◽  
pp. 4199-4211 ◽  
Author(s):  
Miriam I. Quiñones-Kochs ◽  
Linda Buonocore ◽  
John K. Rose
Keyword(s):  
Human Immunodeficiency Virus ◽  
Envelope Glycoprotein ◽  
Protein Function ◽  
Neutralizing Antibodies ◽  
Immune Recognition ◽  
Wild Type ◽  
Virus Envelope ◽  
Mutant Proteins ◽  
Immunodeficiency Virus

ABSTRACT The envelope (Env) glycoprotein of human immunodeficiency virus (HIV) contains 24 N-glycosylation sites covering much of the protein surface. It has been proposed that one role of these carbohydrates is to form a shield that protects the virus from immune recognition. Strong evidence for such a role for glycosylation has been reported for simian immunodeficiency virus (SIV) mutants lacking glycans in the V1 region of Env (J. N. Reitter, R. E. Means, and R. C. Desrosiers, Nat. Med. 4:679-684, 1998). Here we used recombinant vesicular stomatitis viruses (VSVs) expressing HIV Env glycosylation mutants to determine if removal of carbohydrates in the V1 and V2 domains affected protein function and the generation of neutralizing antibodies in mice. Mutations that eliminated one to six of the sites for N-linked glycosylation in the V1 and V2 loops were introduced into a gene encoding the HIV type 1 primary isolate 89.6 envelope glycoprotein with its cytoplasmic domain replaced by that of the VSV G glycoprotein. The membrane fusion activities of the mutant proteins were studied in a syncytium induction assay. The transport and processing of the mutant proteins were studied with recombinant VSVs expressing mutant Env G proteins. We found that HIV Env V1 and V2 glycosylation mutants were no better than wild-type envelope at inducing antibodies neutralizing wild-type Env, although an Env mutant lacking glycans appeared somewhat more sensitive to neutralization by antibodies raised to mutant or wild-type Env. These results indicate significant differences between SIV and HIV with regard to the roles of glycans in the V1 and V2 domains.

scholarly journals Insight into vaccine development for Alpha-coronaviruses based on structural and immunological analyses of spike proteins

2020 ◽  
Author(s):  
Yuejun Shi ◽  
Jiale Shi ◽  
Limeng Sun ◽  
Yubei Tan ◽  
Gang Wang ◽  
...  
Keyword(s):  
Public Health ◽  
Viral Entry ◽  
Neutralizing Antibodies ◽  
Vaccine Development ◽  
Neutralizing Antibody ◽  
Immune Recognition ◽  
Global Public Health ◽  
S Protein ◽  
Specific Antibodies ◽  
Major Target

AbstractCoronaviruses that infect humans belong to the Alpha-coronavirus (including HCoV-229E) and Beta-coronavirus (including SARS-CoV and SARS-CoV-2) genera. In particular, SARS-CoV-2 is currently a major threat to public health worldwide. However, no commercial vaccines against the coronaviruses that can infect humans are available. The spike (S) homotrimers bind to their receptors through the receptor-binding domain (RBD), which is believed to be a major target to block viral entry. In this study, we selected Alpha-coronavirus (HCoV-229E) and Beta-coronavirus (SARS-CoV and SARS-CoV-2) as models. Their RBDs were observed to adopt two different conformational states (lying or standing). Then, structural and immunological analyses were used to explore differences in the immune response with RBDs among these coronaviruses. Our results showed that more RBD-specific antibodies were induced by the S trimer with the RBD in the “standing” state (SARS-CoV and SARS-CoV-2) than the S trimer with the RBD in the “lying” state (HCoV-229E), and the affinity between the RBD-specific antibodies and S trimer was also higher in the SARS-CoV and SARS-CoV-2. In addition, we found that the ability of the HCoV-229E RBD to induce neutralizing antibodies was much lower and the intact and stable S1 subunit was essential for producing efficient neutralizing antibodies against HCoV-229E. Importantly, our results reveal different vaccine strategies for coronaviruses, and S-trimer is better than RBD as a target for vaccine development in Alpha-coronavirus. Our findings will provide important implications for future development of coronavirus vaccines.ImportanceOutbreak of coronaviruses, especially SARS-CoV-2, poses a serious threat to global public health. Development of vaccines to prevent the coronaviruses that can infect humans has always been a top priority. Coronavirus spike (S) protein is considered as a major target for vaccine development. Currently, structural studies have shown that Alpha-coronavirus (HCoV-229E) and Beta-coronavirus (SARS-CoV and SARS-CoV-2) RBDs are in lying and standing state, respectively. Here, we tested the ability of S-trimer and RBD to induce neutralizing antibodies among these coronaviruses. Our results showed that Beta-CoVs RBDs are in a standing state, and their S proteins can induce more neutralizing antibodies targeting RBD. However, HCoV-229E RBD is in a lying state, and its S protein induces a low level of neutralizing antibody targeting RBD. Our results indicate that Alpha-coronavirus is more conducive to escape host immune recognition, and also provide novel ideas for the development of vaccines targeting S protein.

scholarly journals Interleukin-2 regulates CC chemokine receptor expression and chemotactic responsiveness in T lymphocytes.

1996 ◽  
Vol 184 (2) ◽  
pp. 569-577 ◽  
Author(s):  
P Loetscher ◽  
M Seitz ◽  
M Baggiolini ◽  
B Moser
Keyword(s):  
T Lymphocytes ◽  
Chemokine Receptor ◽  
Chemokine Receptors ◽  
Interleukin 2 ◽  
Receptor Expression ◽  
Activated T Cells ◽  
Chemokine Receptor Expression ◽  
Cc Chemokine ◽  
Cc Chemokines

Several studies have shown that CC chemokines attract T lymphocytes, and that CD45RO+, memory phenotype cells are considered to be the main responders. The results, however, have often been contradictory and the role of lymphocyte activation and proliferation has remained unclear. Using CD45RO+ blood lymphocytes cultured under different stimulatory conditions, we have now studied chemotaxis as well as chemokine receptor expression. Expression of the RANTES/MIP-1 alpha receptor (CC-CKR1) and the MCP-1 receptor (CC-CKR2) was highly correlated with migration toward RANTES, MCP-1, and other CC chemokines, and was strictly dependent on the presence of IL-2 in the culture medium. Migration and receptor expression were rapidly downregulated when IL-2 was withdrawn, but were fully restored when IL-2 was added again. The effect of IL-2 could be partially mimicked by IL-4, IL-10, or IL-12, but not by IL-13, IFN gamma, IL-1 beta, TNF-alpha, or by exposure to anti-CD3, anti-CD28 or phytohemagglutinin. Activation of fully responsive lymphocytes through the TCR/CD3 complex and CD28 antigen actually had the opposite effect. It rapidly downregulated receptor expression and consequent migration even in the presence of IL-2. In contrast to the effects on CC chemokine receptors, stimulation of CD45RO+ T lymphocytes with IL-2 neither induced the expression of the CXC chemokine receptors, IL8-R1 and IL8-R2, nor chemotaxis to IL-8. The prominent role of IL-2 in CC chemokine responsiveness of lymphocytes suggests that IL-2-mediated expansion is a prerequisite for the recruitment of antigen-activated T cells into sites of immune and inflammatory reactions.

scholarly journals Shed EBA-175 mediates red blood cell clustering that enhances malaria parasite growth and enables immune evasion

eLife ◽  
2018 ◽  
Vol 7 ◽  
Author(s):  
May M Paing ◽  
Nichole D Salinas ◽  
Yvonne Adams ◽  
Anna Oksman ◽  
Anja TR Jensen ◽  
...  
Keyword(s):  
Immune Evasion ◽  
Neutralizing Antibodies ◽  
Parasite Growth ◽  
Immune Recognition ◽  
Dependent Manner ◽  
Cell Clustering ◽  
Erythrocyte Binding ◽  
Region Ii ◽  
General Method

Erythrocyte Binding Antigen of 175 kDa (EBA-175) has a well-defined role in binding to glycophorin A (GpA) during Plasmodium falciparum invasion of erythrocytes. However, EBA-175 is shed post invasion and a role for this shed protein has not been defined. We show that EBA-175 shed from parasites promotes clustering of RBCs, and EBA-175-dependent clusters occur in parasite culture. Region II of EBA-175 is sufficient for clustering RBCs in a GpA-dependent manner. These clusters are capable of forming under physiological flow conditions and across a range of concentrations. EBA-175-dependent RBC clustering provides daughter merozoites ready access to uninfected RBCs enhancing parasite growth. Clustering provides a general method to protect the invasion machinery from immune recognition and disruption as exemplified by protection from neutralizing antibodies that target AMA-1 and RH5. These findings provide a mechanistic framework for the role of shed proteins in RBC clustering, immune evasion, and malaria.

scholarly journals Role of HIV-1 subtype C envelope V3 to V5 regions in viral entry, coreceptor utilization and replication efficiency in primary T-lymphocytes and monocyte-derived macrophages

2007 ◽  
Vol 4 (1) ◽  
pp. 126 ◽  
Author(s):  
Vasudha Sundaravaradan ◽  
Suman R Das ◽  
Rajesh Ramakrishnan ◽  
Shobha Sehgal ◽  
Sarla Gopalan ◽  
...  
Keyword(s):  
T Lymphocytes ◽  
Viral Entry ◽  
Subtype C ◽  
Replication Efficiency ◽  
Hiv 1

scholarly journals Lineage-Specific Differences between the gp120 Inner Domain Layer 3 of Human Immunodeficiency Virus and That of Simian Immunodeficiency Virus

2016 ◽  
Vol 90 (22) ◽  
pp. 10065-10073 ◽  
Author(s):  
Shilei Ding ◽  
Halima Medjahed ◽  
Jérémie Prévost ◽  
Mathieu Coutu ◽  
Shi-Hua Xiang ◽  
...  
Keyword(s):  
Human Immunodeficiency Virus ◽  
Simian Immunodeficiency Virus ◽  
Conformational Changes ◽  
Viral Entry ◽  
Chemokine Receptors ◽  
Immunodeficiency Virus ◽  
Layer 2 ◽  
Hiv 1

ABSTRACT Binding of human immunodeficiency virus type 1 (HIV-1) and simian immunodeficiency virus (SIV) gp120 exterior envelope glycoprotein to CD4 triggers conformational changes in gp120 that promote its interaction with one of the chemokine receptors, usually CCR5, ultimately leading to gp41-mediated virus-cell membrane fusion and entry. We previously described that topological layers (layer 1, layer 2, and layer 3) in the gp120 inner domain contribute to gp120-trimer association in the unliganded state but also help secure CD4 binding. Relative to layer 1 of HIV-1 gp120, the SIVmac239 gp120 layer 1 plays a more prominent role in maintaining gp120-trimer association but is minimally involved in promoting CD4 binding, which could be explained by the existence of a well-conserved tryptophan at position 375 (Trp 375) in HIV-2/SIVsmm. In this study, we investigated the role of SIV layer 3 in viral entry, cell-to-cell fusion, and CD4 binding. We observed that a network of interactions involving some residues of the β8-α5 region in SIVmac239 layer 3 may contribute to CD4 binding by helping shape the nearby Phe 43 cavity, which directly contacts CD4. In summary, our results suggest that layer 3 in SIV has a greater impact on CD4 binding than in HIV-1. This work defines lineage-specific differences in layer 3 from HIV-1 and that from SIV. IMPORTANCE CD4-induced conformational changes in the gp120 inner domain involve rearrangements between three topological layers. While the role of layers 1 to 3 for HIV-1 and layers 1 and 2 for SIV on gp120 transition to the CD4-bound conformation has been reported, the role of SIV layer 3 remains unknown. Here we report that SIV layer 3 has a greater impact on CD4 binding than does layer 3 in HIV-1 gp120. This work defines lineage-specific differences in layer 3 from HIV-1 and SIV.

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