The human immunodeficiency virus type 1 (HIV - 1 ) envelope glycoprotein gp41 plays a critical role in the fusion of viral and target cell membranes. The gp41 extracellular domain,which contains fusion peptide (FP), N - and C - terminal hydrophobic heptad repeats (NHR and CHR, respectively).Peptides derived from NHR and CHR regions,designated N- and C- peptides, respectively, can interact with each other to form a six - stranded coiled - coil domain, representing the fusion-active gp41 core. Our previous studies demonstrated that the C- peptides have potent inhibitory activity against HIV- 1 infection.These peptides inhibit HIV- 1 -mediated membrane fusion by binding to NHR regions for preventing the formation of fusion- active gp41 core.One of the C - peptides, T - 20, which is in the phase Ⅲ clinical trails, is expected to become the first peptide HIV fusion inhibitory drug in the near future.However, this peptide HIV fusion inhibitor lacks oral availability and is sensitive to the proteolytic digestion.Therefore, it is essential to develop small molecular non -peptide HIV fusion inhibitors having similar mechanism of action as the C- peptides.We have established an ELISA- based screening assay using a unique monoclonal antibody, NC- 1, which can specifically bind to a conformational epitope on the gp41 core domain.Using this screening assay, we have identified a small molecular anti- HIV- 1 compound,named ADS-Jl, which inhibits HIV- 1- mediated membrane fusion by blocking the interaction between the NHR and CHR regions to form the fusion - active gp41 core.This compound will be used as a lead to design and develop novel HIV fusion inhibitors as new drugs for the treatment of HIV infection and/or AIDS.

HIV-1 envelope glycoprotein gp120 and gp41 are considered as two important parts in viral entry.In the process of virus entry,CD4 first binds to gp120 and causes the conformation of gp120 to change.Furthermore the conformation of gp41 has also been changed.Many peptides,macromolecular compounds and small molecule compounds which bind to gp120 or gp41 can deter the progress of virus entry.These compounds can play an important role in halting the spread of HIV-1 in this way.The structure and interaction of gp120 and gp41 are reviewed here,as well as the anti-HIV agents blocking the HIV entry by targeting the HIV-1 envelope glycoprotein.

Objective:To find small molecular leads for inhibition on early stage of HIV infection by identification and characterization of the HIV-1 gp41 C-helix mimotopes.Methods:For identification of the gp41 C-helix mimotopes,C7C phage display peptide library was biopanning by using a synthetic peptide N36 which was derived from the gp41 N-helix as target.After three rounds of screening,positive phage clones were identified by ELISA and sequenced.Results:16 of 26 phage clones were identified to bind with peptide N36,and 10 of them were sequenced.Every clone of ten clones contains at least two hydrophobic residues,which may dock into the hydrophobic pocket in the gp41 N-helix domain.9 of the 10 clones have a conservative sequence WW,which may mimic the W628 and W631 in C-helix to interact with the hydrophobic residues in the gp41 pocket.One clone expressing the conservative sequence named clone No.8(CYWWHRLHC) was selected for characterization.The binding between the clone No.8 and N36 was blocked by free peptide N36.And the binding between clone No.8 and peptide N36 was inhibited by peptide C34(IC 50=12.5 ?g/ml).Conclusion:The short circular peptides displayed on phages containing WW residues may mimic the conformational epitope of the HIV-1 gp41 C-helix to interact with the N-helix.This information may be useful for design of HIV-1 fusion inhibitors.

A xylanase producing strain was screened with xylan as the only carbon source. The strain was identified as Streptomyces cirratus. The effects of different factore on the enzyme production were studied. Corncobs xylan (water insoluble) and tryptone were the best C and N sources, respectively. The enzyme activity was increased to about 2.5 times by addition of 0.5% Tween 80 in the medium. The highest xylanase activity was up to 623u/mL.

In 2012, a new SARS-like coronavirus emerged in the Middle East, namely the Middle East respiratory syndrome coronavirus (MERS-CoV). It has caused outbreaks with high mortality. During infection of target cell, MERS-CoV S protein S1 subunit binds to the cellular receptor (DPP4), and its S2 subunit HR1 and HR2 regions intact with each other to form a stable six-helix bundle to mediate the fusion between virus and target cell membranes. Hence, blocking the process of six-helix bundle formation can effectively inhibit MERS-CoV entry into the target cells. This review focuses on the recent advance in the development of peptidic entry inhibitors targeting the MERS-CoV S2 subunit.

Middle East respiratory syndrome coronavirus (MERS-CoV) has caused outbreaks of SARS-like disease with 35% case-fatality rate, mainly in the Middle East. A more severe outbreak of MERS occurred recently in the Republic of Korea, where 186 people contracted the infections, causing great concern worldwide. So far, there has been no clinically available drug for the treatment of MERS-CoV infection. The potential drugs against MERS-CoV mainly consist of monoclonal antibodies, peptides and small molecular agents. Small molecular agents have an advantage of easier synthesis, lower cost in production and relatively higher stability. There is better chance for those candidates to gain a quick development. This article reviews the progress of developing small molecular MERS-CoV agents.

Aim To investigate the HIV-1 entry inhibitory activities of myriceric acid B and C isolated from Rhoiptelea chiliantha Diels et Hand-Mazz and their mechanism of action.Method The plasmids encoding envelope proteins of HIV-1 (pHXB2) and VSV (pVSV-G) were cotransfected 293T cells with pNL4-3.Luc.R-E- to produce HIV-1 Env pseudovirus and VSV-G pseudovirus,respectively,which were used for testing the antiviral activities of these compounds.ELISA and molecular docking were used to study the mechanism of action of the active compounds.Results Myriceric acid B could significantly inhibit the infection of HIV-1 Env pseudovirus with an IC_(50) of(8.3±0.2)mg·L~(-1).The carbonoxyl group at C-28 position and the hydroxyl group at the C-3 position of myriceric acid B are important for its anti-HIV-1 activity.Like other HIV-1 entry inhibitors targeting gp41 (eg,ADS-J1 and NB-64), myriceric acid B could also block the gp41 six-helix bundle formation.Molecular docking analysis suggests that myriceric acid B may bind to the hydrophobic cavity of the gp41 N-trimeric coiled coil.Conclusion Myriceric acid B is a potent HIV-1 entry inhibitor targeting gp41 and can serve as a lead compound for developing novel anti-HIV-1 drug.

Aim ADS-J1 is a low molecular HIV entry inhibitor targeting HIV transmembrane subunit gp41 through virtual screening from a compound library containing 20 000 molecules.This study is to investigate the binding sites of ADS-J1 on gp41.Methods Acid native polyacrylamide gel electrophoresis (AN-PAGE) assay was applied to test the binding ability of ADS-J1 with the peptides derived from gp41 N-terminal heptad repeat (NHR) region.Results It was reported previously that ADS-J1 could block the gp41 six-helix bundle (6-HB) formation using native polyacrylamide gel electrophoresis (N-PAGE).However,the binding sites could not be found because positive charged N-peptides derived from gp41 NHR could not show bands on the gel.In the present study,the AN-PAGE assay which could show N-peptides in the gel was established,and it was found that ADS-J1 could inhibit the gp41 6-HB formation.Moreover,ADS-J1 bound directly to the gp41 cavity region of NHR.The positively charged residue (K574) located in this region was critical for the binding of ADS-J1.Conclusions ADS-J1 inhibits HIV entry by targeting the cavity region of gp41 NHR,whereas K574 in the cavity plays a critical role for the binding.Furthermore,the AN-PAGE assay provides a simple method for studying the mechanism of action of virus entry inhibitors targeting the transmembrane protein of type I enveloped virus.

AIM To modify and improve a screening assay so that it becomes more convenient, economic and adaptable in China for high throughput screening of HIV fusion inhibitors targeting gp41. METHODS The original screening method reported by Jiang et al (J Virol. Methods 1999;80:85 96) was modified by: ① using a conformation specific monoclonal antibody to replace a polyclonal antibody for coating plates; ②simplifying the procedures; ③using parts of the reagents produced in China. RESULTS The modified screening assay is simpler, more convenient, and more economic than the original assay, but its sensitivity is comparable to and specificity is a little better than the original method. CONCLUSIONS The modified screening assay is more convenient and economic and can be used in China for high throughput screening of HIV fusion inhibitors from complex sample, such as phage display peptide libraries, microorganism fermentation liquids, herbs and other natural products.

Objective To design and synthesize a series of new type four hydrogen quinoline-benzyl/benzimidazole amine derivatives as a potential new inhibitor targeting auxiliary receptor CXCR 4, and determine their inhibitory activities to HIV-1.Methods Based on HIV-1 receptor CXCR4 inhibitors containing three nitrogen structure-activity motif and CCR5 partial hydrophobic pharmacophore , a series of new compounds were designed , synthesized and characterized by 1 HNMR and MS.The inhibitory activities of these compounds were determined using HIV-1 IIIB virus.Results and Conclusion Ten target compounds are synthesized .Four hydrogen quinoline-benzimidazole amine derivatives exhibit good anti-HIV activity(IC50 <1 μmol/L), but four hydrogen quinoline-benzyl amine compounds are less active ((IC50 >8 μmol/L).