A human immunodeficiency virus type-1 (HIV-1) vaccine which is able to effectively prevent infection would be the most powerful method of extinguishing pandemic of the acquired immunodeficiency syndrome (AIDS). Yet, achieving such vaccine remains great challenges. The membrane-proximal external region (MPER) is a highly conserved region of the envelope glycoprotein (Env) gp41 subunit near the viral envelope surface, and it plays a key role in membrane fusion. It is also the target of some reported broadly neutralizing antibodies (bNAbs). Thus, MPER is deemed to be one of the most attractive vaccine targets. However, no one can induce these bNAbs by immunization with immunogens containing the MPER sequence(s). The few attempts at developing a vaccine have only resulted in the induction of neutralizing antibodies with quite low potency and limited breadth. Thus far, vaccine failure can be attributed to various characteristics of MPER, such as those involving structure and immunology; therefore, we will focus on these and review the recent progress in the field from the following perspectives: (1) MPER structure and its role in membrane fusion, (2) the epitopes and neutralization mechanisms of MPER-specific bNAbs, as well as the limitations in eliciting neutralizing antibodies, and (3) different strategies for MPER vaccine design and current harvests.
AIDS Vaccines ; chemistry ; immunology ; Antibodies, Neutralizing ; immunology ; HIV Antibodies ; immunology ; HIV Envelope Protein gp41 ; immunology ; HIV-1 ; chemistry ; immunology ; Humans

HIV-1 gp41 is an envelope protein that plays an essential role in virus entry. The mutation of gp41 affects HIV-1 entry and susceptibility to the fusion inhibitor T-20. Therefore, we analyzed the natural polymorphism of gp41 of 163 HIV-1 isolates from T-20-naive Koreans infected with HIV-1. This study of gp41 polymorphisms showed that insertions in the fourth threonine (74.8%) and L7M substitutions (85.3%) were more frequent in the fusion peptide motif in Korean HIV-1 isolates compared with those from other countries. Minor T-20 resistance mutations such as L45M (1.2%), N126K (1.2%), and E137K (6.7%) were detected, but the critical T-20 resistance mutations were not detected in the gp41 HR1 and HR2 regions. In addition, the N42S mutation (12.9%) associated with T-20 hypersusceptibility was detected at a high frequency. These results may serve as useful data for studies considering T-20 for use in the development of a more effective anti-retroviral treatment in Korea.
Anti-HIV Agents/pharmacology ; Drug Resistance, Viral/*genetics ; HIV Envelope Protein gp41/*genetics/metabolism/pharmacology ; HIV Infections/virology ; HIV-1/*genetics/isolation & purification/*metabolism ; Humans ; Peptide Fragments/pharmacology ; *Polymorphism, Genetic ; Protein Structure, Tertiary/genetics ; Republic of Korea ; Virus Internalization

To enhance the immunogenicity of DNA and adenoviral vector vaccines expressing HIV-1 subtype B gp160, human interleukin 15 (hIL15) DNA adjuvant (pVR-hIL15) was constructed. BALB/c mice received DNA prime/protein boost immunization with pVR-HIVgp160/Ad5-HIVgp160 alone or combined with pVR-hIL15. Cellular and humoral immune responses were evaluated by IFN-gamma enzyme-linked immunosorbent spot assay and enzyme-linked immunosorbent assay, respectively. Compared with those immunized with vaccines alone, the mice immunized with vaccines combined with pVR-hIL15 had significantly increased specific cellular response and antibody titer (P < 0.05). It suggests that the IL15 DNA adjuvant can enhance the immune responses induced by prime-boost regimen using DNA and adenoviral vector encoding HIV-1 subtype B gp160.
Adenoviridae ; genetics ; Adjuvants, Immunologic ; Animals ; Antibodies, Viral ; immunology ; Antibody Specificity ; Female ; Genetic Vectors ; genetics ; HIV Envelope Protein gp120 ; immunology ; HIV Envelope Protein gp160 ; genetics ; immunology ; HIV Envelope Protein gp41 ; immunology ; Humans ; Immunity, Cellular ; Immunity, Humoral ; Interleukin-15 ; genetics ; Mice ; Mice, Inbred BALB C ; Vaccines, DNA ; genetics ; immunology

OBJECTIVEThis study aimed to investigate the subtype distribution of gp41 gene of human immunodeficiency virus-1 (HIV-1) among men who have sex with men (MSM) in Zhengzhou.

METHODSThirty blood samples were collected from men who have sex with men infected by HIV. The complete gp41 gene was amplified by RT-PCR and nested-PCR and sequenced. All sequences were edited by Bioedit and subtyped with HIV sequence library US Los Alamos National Laboratory and online genotyping software provided by American National Center of Biotechnology Information. Phylogenetic analysis of gp41 gene was performed using the MEGA 3.1 software, and the genic dispersion rates among subtype of gp41 gene were analyzed.

RESULTSA total of eighteen gene sequences of HIV-1 gp41 gene were obtained from thirty men who have sex with men infected by HIV, which belonged to subtype CRF15-01B (50% (9/18)), CRF01-AE (22% (4/18)), CRF07-B (22% (4/18)) and B (6% (1/18)), respectively. The intersubtype HIV-1 strains aggregate with according reference strains. The genetic distance inter-subtype of subtype CRF15-01B, CRF01-AE and CRF07-B were 0.050 ± 0.007, 0.052 ± 0.009 and 0.082 ± 0.012, respectively.

CONCLUSIONThe prevalent subtypes of HIV-1 among among MSM in Zhengzhou was complicated and recombinant HIV-1 strains were the most prevalent strains.

Genotype ; HIV Envelope Protein gp41 ; genetics ; HIV Infections ; epidemiology ; virology ; HIV-1 ; genetics ; Homosexuality, Male ; Humans ; Male ; Molecular Epidemiology ; Phylogeny ; Sequence Analysis, DNA

OBJECTIVETo express N51 derived from the N-terminal heptad repeat (NHR) domain in gp41 of the HIV-1 CRF07_BC strain and analyze its molecular structure and antigenicity.

METHODSOverlapping PCR was used to amplify the DNA fragment encoding N51Fd gene, which was then subcloned into the vector pFUSE-hIgG1-Fc2. The construct was confirmed by DNA sequencing. The structure and antigenicity of the recombinant protein N51FdFc-BC were analyzed using bioinformatic software, circular dichroism, and Western blotting.

RESULTSA recombinant expression vector pFUSE/N51Fd-BC was successfully constructed. N51FdFc-BC recombinant protein with a relative molecular mass of about 35 000 was effectively expressed in mammalian 293T cells and could be recognized by rabbit antibodies against HIV-1 gp41 N/C peptides as shown by Western blotting. Bioinformatic analysis showed that the recombinant protein N51FdFc-BC, with a relative molecular mass of 34 315.1 and a PI of 7.59, formed a secondary structure of random coil to allow its interactions as an antigen with antibodies. Circular dichroism measurement confirmed the random coil structure of N51FdFc-BC protein.

CONCLUSIONThe recombinant protein N51FdFc-BC has a random coil structure and can be used as an immunogen for development of HIV-1 subunit vaccine.

Amino Acid Sequence ; HEK293 Cells ; HIV Envelope Protein gp41 ; genetics ; immunology ; HIV-1 ; chemistry ; genetics ; Humans ; Protein Structure, Secondary ; Recombinant Proteins ; genetics ; immunology ; Sequence Analysis, DNA

OBJECTIVETo study the effect of HIV-1 gp41 ectodomain (gp41-I90) on the cytoskeletal changes in human brain microvascular endothelial cells (HBMECs) induced by Cryptococcus neoformans.

METHODSHBMECs were cultured on collagen-coated chamber slide or transwell to allow the formation of cell monolayers. After pre-treatment with gp41-I90 and infection with Cryptococcus neoformans, the HBMECs were examined for the expression of actin or filamin by immunofluorescence assay. HRP permeability of the HBMECs treated with gp41-I90 was detected by ELISA. Transcytosis of Cryptococcus neoformans through the gp41-I90-treated HBMECs was detected by direct counting from a hemocytometer.

RESULTSgp41-I90 obviously enhanced the cytoskeletal changes of the HBMECs infected by Cryptococcus neoformans, causing curved and sparse filamentous arrangement of actin and filamin. gp41-I90 treatment also resulted in obviously increased HRP permeability of the cells and transcytosis of Cryptococcus neoformans.

CONCLUSIONgp41- I90 enhances Cryptococcus neoformans binding to HBMECs, which is related to its effect in enhancing Cryptococcus neoformans-induced cytoskeletal changes of the cells.

Brain ; blood supply ; Cells, Cultured ; Cryptococcosis ; pathology ; Cryptococcus neoformans ; pathogenicity ; Cytoskeleton ; drug effects ; metabolism ; Endothelial Cells ; cytology ; drug effects ; microbiology ; Endothelium, Vascular ; cytology ; drug effects ; metabolism ; HIV Envelope Protein gp41 ; pharmacology ; Humans ; Microcirculation

Despite the high mutation rate of HIV-1, the amino acid sequences of the membrane-spanning domain (MSD) of HIV-1 gp41 are well conserved. Arginine residues are rarely found in single membrane-spanning domains, yet an arginine residue, R(696) (the numbering is based on that of HXB2), is highly conserved in HIV-1 gp41. To examine the role of R(696), it was mutated to K, A, I, L, D, E, N, and Q. Most of these substitutions did not affect the expression, processing or surface distribution of the envelope protein (Env). However, a syncytia formation assay showed that the substitution of R(696) with amino acid residues other than K, a naturally observed mutation in the gp41 MSD, decreased fusion activity. Substitution with hydrophobic amino acid residues (A, I, and L) resulted in a modest decrease, while substitution with D or E, potentially negatively-charged residues, almost abolished the syncytia formation. All the fusion-defective mutants showed slower kinetics with the cell-based dual split protein (DSP) assay that scores the degree of membrane fusion based on pore formation between fusing cells. Interestingly, the D and E substitutions did show some fusion activity in the DSP assays, suggesting that proteins containing D or E substitutions retained some fusion pore-forming capability. However, nascent pores failed to develop, due probably to impaired activity in the pore enlargement process. Our data show the importance of this conserved arginine residue for efficient membrane fusion.
Amino Acid Substitution ; Animals ; Arginine ; chemistry ; metabolism ; Cell Line ; Cercopithecus aethiops ; HIV Envelope Protein gp41 ; chemistry ; metabolism ; HIV-1 ; metabolism ; Humans ; Kinetics ; Membrane Fusion ; physiology ; Mutation ; Protein Structure, Tertiary

BACKGROUNDStudies on human immunodeficiency virus type 1 (HIV-1) vaccines have recently focused on targeting the conserved neutralizing epitopes 2F5 and 4E10, and hence it is important to understand the extent of mutations in these two viral epitopes. Here, we investigated the amino acid mutations in epitopes of 2F5 (ELDKWA, HIV-1 HXB2 env 662 - 667 aa) and 4E10 (NWFDIT, HIV-1 HXB2 env 671 - 676 aa) in the membrane proximal-external region of gp41 from clade B' HIV-1-infected individuals living in Henan province, China. We also examined the frequency of a mutation and its relation to disease progression.

METHODSA cohort of 54 treatment-naïve HIV-1-infected individuals was recruited in this study, and 16 individuals were selected for a short-term longitudinal study on sequence evolution. The HIV-1 env gp41 gene was amplified, cloned, and sequenced, and predicted amino acid sequences were aligned for analysis.

RESULTSThe mutations E662A and K665E on the 2F5 epitope and N671S and T676S on the 4E10 epitope were seen. Simultaneous RNA sequencing showed some discrepancies with proviral DNA sequences. In our longitudinal study, mutation levels of these two neutralizing epitopes were low but diverse and persistent. The frequencies of mutations within the 4E10 peptide NWFDIT in slow progressors were noticeably lower than those in AIDS patients (P < 0.05).

CONCLUSIONSAntigenic variation of the neutralizing epitopes 2F5 and 4E10 is limited in subtype B' infection, and that 4E10 peptide mutation is correlated with disease progression. Monitoring epitope mutations will offer useful data for development of the candidate 2F5-like and 4E10-like antibodies to prevent and treat AIDS.

Acquired Immunodeficiency Syndrome ; drug therapy ; Adult ; Antibodies, Neutralizing ; genetics ; Asian Continental Ancestry Group ; genetics ; Disease Progression ; Epitopes ; genetics ; Evolution, Molecular ; HIV Antibodies ; genetics ; HIV Envelope Protein gp41 ; immunology ; HIV-1 ; immunology ; Humans ; Longitudinal Studies ; Middle Aged ; Mutation ; RNA, Viral ; blood ; chemistry

In the two decades since AZT was first approved for clinical use in 1987, 24 additional antiretroviral agents have been approved. They include 7 nucleoside analogs, a nucleotide analog and 4 non-nucleoside reverse transcriptase inhibitors, 10 protease inhibitors, 2 entry inhibitors and an integrase inhibitor. More than 20 investigational agents are currently being studied in clinical trials. Highly active antiretroviral therapy (HAART), which involves a combination of anti-HIV-1 drugs, is extremely effective in suppressing HIV-1 replication and increasing CD4+ number and results in substantial reductions in HIV-1-related morbidity and mortality. In last 20 years, much has been learned about resistance to antiretroviral drugs, drug interactions and metabolic complications of antiviral drug use. Drugs are now selected on the basis of resistance tests and on the risk of specific drug complications in individual patients. As a result, decisions about the therapy of HIV/AIDS have become personalized and are made on a patient-by-patient basis. With appropriate medical management, a person with HIV-1 now has the possibility of a nearly normal life expectancy.
Anti-HIV Agents ; adverse effects ; pharmacology ; therapeutic use ; Antiretroviral Therapy, Highly Active ; Cyclohexanes ; chemistry ; pharmacology ; therapeutic use ; Drug Resistance, Viral ; HIV Envelope Protein gp41 ; chemistry ; therapeutic use ; HIV Fusion Inhibitors ; chemistry ; pharmacology ; therapeutic use ; HIV Infections ; drug therapy ; HIV Integrase Inhibitors ; chemistry ; pharmacology ; therapeutic use ; HIV Protease Inhibitors ; chemistry ; pharmacology ; therapeutic use ; HIV Reverse Transcriptase ; chemistry ; pharmacology ; therapeutic use ; HIV-1 ; drug effects ; physiology ; Humans ; Molecular Structure ; Peptide Fragments ; chemistry ; therapeutic use ; Pyrrolidinones ; chemistry ; pharmacology ; therapeutic use ; Raltegravir Potassium ; Saquinavir ; chemistry ; pharmacology ; therapeutic use ; Triazoles ; chemistry ; pharmacology ; therapeutic use ; Virus Replication ; drug effects ; Zidovudine ; chemistry ; pharmacology ; therapeutic use

HIV-1 fusion inhibitors are a new class of anti-HIV compounds, which block the entry of HIV into target cells through preventing the fusion between viral and cell plasma membrane and thus interrupt the initial steps of viral replication. T-20 (enfuvirtide), which has been clinically approved as the first fusion inhibitor of HIV-1 by U.S. FDA in 2003, can suppress replication of HIV variants with multi-drug resistance to reverse transcriptase and protease inhibitors. Peptides and small molecules display potent anti-HIV fusion activities by targeting gp41 thus inhibit its fusogenic function. In recent years, with the development of studies on the molecular mechanism of HIV membrane fusion process and the function of gp41, many new fusion inhibitors are found and some have been in advanced clinical trials. This review discusses recent progress in the development of HIV-1 fusion inhibitors targeting the gp41.
Anti-HIV Agents ; chemical synthesis ; chemistry ; pharmacology ; Drug Resistance, Multiple ; HIV Envelope Protein gp41 ; chemical synthesis ; chemistry ; pharmacology ; HIV Fusion Inhibitors ; chemical synthesis ; chemistry ; pharmacology ; HIV Infections ; drug therapy ; HIV-1 ; drug effects ; physiology ; Humans ; Peptide Fragments ; chemical synthesis ; chemistry ; pharmacology ; Peptides ; chemical synthesis ; chemistry ; pharmacology ; Recombinant Fusion Proteins ; chemical synthesis ; chemistry ; pharmacology ; Virus Replication ; drug effects ; alpha 1-Antitrypsin ; chemical synthesis ; chemistry ; pharmacology