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

OBJECTIVETo compare the in vitro inhibitory effect of expolysaccharides from Streptomyces, polysaccharides of Ganoderma lucidum and rice bran on six-alpha-helix bundle formation of HIV gp41 protein.

METHODSThe amount of six-alpha-helix bundle formed in the presence of N36 and C34 was tested by ELISA in response to treatments with different doses of polysaccharides.

RESULTSExpolysaccharides from Streptomyces potentially inhibited six-alpha-helix bundle formation with the effective concentration (IC(50)) of 145.48-/+7.25 mg /L. Polysaccharides of Ganoderma lucidum and rice bran showed no effect on the six-alpha-helix bundle formation.

CONCLUSIONExpolysaccharides from Streptomyces can inhibit the six-alpha-helix bundle formation of HIV gp41, whereas polysaccharides of Ganoderma lucidum and rice bran do not exhibit such activity.

HIV Envelope Protein gp41 ; chemistry ; Kinetics ; Oryza ; chemistry ; Polysaccharides ; pharmacology ; Protein Structure, Secondary ; drug effects ; Reishi ; chemistry ; Streptomyces ; chemistry

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 develop an objective bioassay for quantitative detection of HIV-induced cell-cell fusion for screening HIV entry inhibitors.

METHODSHL2/3 cells expressing HIV envelope proteins gp120/gp41, Tat, and other HIV proteins were co-cultured with HeLa-CD4-LTR-beta-gal cells expressing CD4 receptor and HIV LTR triggered reporter gene beta-galactosidase. The enzyme activities of beta-galactosidase were detected by a chromogenic substrate, chlorophenol red-beta-galactopyranoside (CPRG). Specific HIV entry inhibitors were used to validate the established detecting method.

RESULTSNo syncytium was formed by mixing HL2/3 and HeLa-CD4-LTR-beta-gal cells. However, the membrane could be fused and the Tat expressed by HL2/3 cells could bind to HIV LTR on HeLa-CD4-LTR-beta-gal cells and trigger the expression of beta-galactosidase. CPRG allowed quantitative and sensitive detection of the activity of beta-galactosidase. Further studies showed that HIV entry inhibitors could inhibit the activity of beta-galactosidase in a dose-dependent manner.

CONCLUSIONWe have developed a simple, cheap, objective and quantitative non-infectious cell-cell fusion bioassay that can be used to screen for anti-HIV agents targeting the virus entry from natural and synthetic compound libraries.

Biological Assay ; Cell Fusion ; Cell Line ; Coculture Techniques ; Drug Evaluation, Preclinical ; methods ; HIV Envelope Protein gp120 ; metabolism ; HIV Envelope Protein gp41 ; metabolism ; HIV Fusion Inhibitors ; chemistry ; pharmacology ; Humans ; beta-Galactosidase ; metabolism

OBJECTIVETo develop a rapid test kit for antibody to HIV by nano immunomagnetic lateral flow method.

METHODSA rapid test kit was developed by conjugation of the HIV antigen gp41 and gp36 to 200nm super paramagnetic particles by carbodiimide (EDC) and coating of the HIV antigen gp41 and gp36 to nitrocellulose membrane. Then the kit was evaluated with serials of experiments.

RESULTSThe kit was qualified with examination of national reference panel of anti-HIV antibody for colloidal gold diagnostic kit. The sensitivity was 100% by tested with 20 HIV antibody positive sera, the specificity was 98.5% by tested with 600 HIV antibody negative sera, respectively. The stability of the kit was over 12 month by storage at room temperature.

CONCLUSIONA diagnostic kit for antibody to HIV was developed with the advantages of convenience, rapid test, good stability and point of care.

Antibodies, Anti-Idiotypic ; immunology ; Gold Colloid ; chemistry ; HIV ; immunology ; isolation & purification ; HIV Antibodies ; HIV Envelope Protein gp41 ; HIV Infections ; diagnosis ; HIV Seropositivity ; blood ; HIV-1 ; immunology ; isolation & purification ; Immunomagnetic Separation ; methods ; Molecular Biology ; methods ; Nanotechnology ; Reagent Kits, Diagnostic

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

OBJECTIVETo observe the inhibitory effect of 1,2,6-Tri-O-galloyl-beta-D-glucopyranose (TGGP) from Balanophora japonica Makino on human immunodeficiency virus (HIV) entry into the host cells and explore the mechanisms.

METHODSTGGP was purified from Balanophora japonica Makino by n-hexane and ethyl acetate extraction and column chromatography. The inhibitory activity of TGGP on HIV gp41 six-helix bundle formation was measured with ELISA, N-PAGE and SE-HPLC, and the inhibitory effect of TGGP on HIV envelope grlycoprotein-induced cell-cell fusion was detected using a non-infectious cell-based assay.

RESULTSTGGP inhibited HIV gp41 six-helix bundle formation, with an IC50 of 1.37-/+0.19 microg/ml as determined by ELISA, and this activity was further confirmed by N-PAGE and SE-HPLC. TGGP at 25 microg/ml significantly inhibited syncytium formation between the effector (CHO-WT) and the target (MT-2) cells.

CONCLUSIONThe HIV transmembrane subunit gp41 mediates the entry of HIV into the target cells. TGGP can inhibit HIV fusion and entry into the target cells by inhibiting the formation of gp41 six-helix bundles, suggesting the potential of TGGP as a microbicide to prevent sexual transmission of HIV.

Anti-HIV Agents ; pharmacology ; Cell Membrane ; drug effects ; metabolism ; HIV Envelope Protein gp41 ; metabolism ; HIV Fusion Inhibitors ; pharmacology ; HIV-1 ; drug effects ; growth & development ; metabolism ; Humans ; Hydrolyzable Tannins ; pharmacology ; Membrane Fusion ; drug effects

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

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