Maleic anhydride-modified chicken ovalbumin as an effective and inexpensive anti-HIV microbicide candidate for prevention of HIV sexual transmission

Bcl-2 Antagonist Obatoclax Reactivates Latent HIV-1 via the NF-κB Pathway and Induces Latent Reservoir Cell Apoptosis in Latently Infected Cells

The implementation of combined antiretroviral therapy (cART) has rendered HIV-1 infection clinically manageable and efficiently improves the quality of life for patients with AIDS. However, the persistence of a latent HIV-1 reservoir is a major obstacle to achieving a cure for AIDS. A "shock and kill" strategy aims to reactivate latent HIV and then kill it by the immune system or cART drugs. To date, none of the LRA candidates has yet demonstrated effectiveness in achieving a promising functional cure. Interestingly, the phosphorylation and activation of antiapoptotic Bcl-2 protein induce resistance to apoptosis during HIV-1 infection and the reactivation of HIV-1 latency in central memory CD4+ T cells from HIV-1-positive patients. Therefore, a Bcl-2 antagonist might be an effective LRA candidate for HIV-1 cure. In this study, we reported that a pan-Bcl-2 antagonist obatoclax induces HIV-1 reactivation in latently infected cell lines in vitro and in PBMCs/CD4+ T cells of HIV-infected individuals ex vivo. Obatoclax promotes HIV-1 transcriptional initiation and elongation by regulating the NF-κB pathway. Obatoclax activates caspase 8 and does not induce the phosphorylation of the antiapoptotic protein Bcl-2 in latent HIV-1 infected cell lines. More importantly, it preferentially induces apoptosis in latently infected cells. In addition, obatoclax exhibited potent anti-HIV-1 activity on target cells. The abilities to reactivate latent HIV-1 reservoirs, inhibit HIV-1 infection, and induce HIV-1 latent cell apoptosis make obatoclax worth investigating for development as an ideal LRA for use in the "shock and kill" approach.

Chemically Modified Bovine β-Lactoglobulin as a Broad-Spectrum Influenza Virus Entry Inhibitor with the Potential to Combat Influenza Outbreaks

Frequent outbreaks of the highly pathogenic influenza A virus (AIV) infection, together with the lack of broad-spectrum influenza vaccines, call for the development of broad-spectrum prophylactic agents. Previously, 3-hydroxyphthalic anhydride-modified bovine β-lactoglobulin (3HP-β-LG) was proven to be effective against human immunodeficiency virus (HIV) and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and it has also been used in the clinical control of cervical human papillomavirus (HPV) infections. Here, we show its efficacy in potently inhibiting infection by divergent influenza A and B viruses. Mechanistic studies suggest that 3HP-β-LG binds, possibly through its negatively charged residues, to the receptor-binding domain in the hemagglutinin 1 (HA1) subunit in the HA of the influenza virus, thus inhibiting the attachment of the HA to sialic acid on host cells. The intranasal administration of 3HP-β-LG led to the protection of mice against challenges by influenza A(H1N1)/PR8, A(H3N2), and A(H7N9) viruses. Furthermore, 3HP-β-LG is highly stable when stored at 50 °C for 30 days and it shows excellent safety in vitro and in vivo. Collectively, our findings suggest that 3HP-β-LG could be successfully repurposed as an intranasal prophylactic agent to prevent influenza virus infections during influenza outbreaks.

Carboxyl Group-Modified Myoglobin Induces TNF-α-Mediated Apoptosis in Leukemia Cells

Previous studies have shown that chemical modification may increase the activity of proteins or confer novel activity to proteins. Some studies have indicated that myoglobin (Mb) is cytotoxic; however, the underlying mechanisms remain unclear. In this study, we investigated whether chemical modification of the carboxyl group by semicarbazide could promote the Mb cytotoxicity in human leukemia U937 cells and the underlying mechanism of semicarbazide-modified myoglobin (SEM-Mb)-induced U937 cell death. The semicarbazide-modified Mb (SEM-Mb) induced U937 cell apoptosis via the production of cleaved caspase-8 and t-Bid, while silencing of FADD abolished this effect. These findings suggest that SEM-Mb can induce U937 cell death by activating the death receptor-mediated pathway. The SEM-Mb inhibited miR-99a expression, leading to increased NOX4 mRNA and protein expression, which promoted SIRT3 degradation, and, in turn, induced ROS-mediated p38 MAPK phosphorylation. Activated p38 MAPK stimulated miR-29a-dependent tristetraprolin (TTP) mRNA decay. Downregulation of TTP slowed TNF-α mRNA turnover, thereby increasing TNF-α protein expression. The SEM-Mb-induced decrease in cell viability and TNF-α upregulation were alleviated by abrogating the NOX4/SIRT3/ROS/p38 MAPK axis or ectopic expression of TTP. Taken together, our results demonstrated that the NOX4/SIRT3/p38 MAPK/TTP axis induces TNF-α-mediated apoptosis in U937 cells following SEM-Mb treatment. A pathway regulating p38 MAPK-mediated TNF-α expression also explains the cytotoxicity of SEM-Mb in the human leukemia cell lines HL-60, THP-1, K562, Jurkat, and ABT-199-resistant U937. Furthermore, these findings suggest that the carboxyl group-modified Mb is a potential structural template for the generation of tumoricidal proteins.

3-Hydroxyphthalic Anhydride-Modified Chicken Ovalbumin as a Potential Candidate Inhibits SARS-CoV-2 Infection by Disrupting the Interaction of Spike Protein With Host ACE2 Receptor

The global spread of the novel coronavirus SARS-CoV-2 urgently requires discovery of effective therapeutics for the treatment of COVID-19. The spike (S) protein of SARS-CoV-2 plays a key role in receptor recognition, virus-cell membrane fusion and virus entry. Our previous studies have reported that 3-hydroxyphthalic anhydride-modified chicken ovalbumin (HP-OVA) serves as a viral entry inhibitor to prevent several kinds of virus infection. Here, our results reveal that HP-OVA can effectively inhibit SARS-CoV-2 replication and S protein-mediated cell-cell fusion in a dose-dependent manner without obvious cytopathic effects. Further analysis suggests that HP-OVA can bind to both the S protein of SARS-CoV-2 and host angiotensin-converting enzyme 2 (ACE2), the functional receptor of SARS-CoV-2, and disrupt the S protein-ACE2 interaction, thereby exhibiting inhibitory activity against SARS-CoV-2 infection. In summary, our findings suggest that HP-OVA can serve as a potential therapeutic agent for the treatment of deadly COVID-19.

Tolcapone Potently Inhibits Seminal Amyloid Fibrils Formation and Blocks Entry of Ebola Pseudoviruses

Ebola virus (EBOV), the causative pathogen of the deadly EBOV disease (EVD), can be transmitted via sexual transmission. Seminal amyloid fibrils have been found enhancers of EBOV infection. Currently, limited preventive vaccine or therapeutic is available to block EBOV infection through sexual intercourse. In this study, we repurpose tolcapone, a US Food and Drug Administration (FDA)-approved agent for Parkinson’s disease, as a potent inhibitor of seminal amyloid fibrils, among which semen-derived enhancer of viral infection (SEVI) is the best-characterized. Tolcapone binds to the amyloidogenic region of the SEVI precursor peptide (PAP248–286) and inhibits PAP248–286 aggregation by disrupting PAP248–286 oligomerization. In addition, tolcapone interacts with preformed SEVI fibrils and influences the activity of SEVI in promoting infection of pseudovirus (PsV) carrying the envelope glycoprotein (GP) of the EBOV Zaire or Sudan species (Zaire PsV and Sudan PsV, respectively). Tolcapone significantly antagonizes SEVI-mediated enhancement of both Zaire PsV and Sudan PsV binding to and subsequent internalization in HeLa cells. Of note, tolcapone is also effective in inhibiting the entry of both Zaire PsV and Sudan PsV. Tolcapone inhibits viral entry possibly through binding with critical residues in EBOV GP. Moreover, the combination of tolcapone with two small-molecule entry inhibitors, including bepridil and sertraline, exhibited synergistic anti-EBOV effects in semen. Collectively, as a bifunctional agent targeting the viral infection-enhancing amyloid and the virus itself during sexual intercourse, tolcapone can act as either a prophylactic topical agent to prevent the sexual transmission of EBOV or a therapeutic to treat EBOV infection.

Resveratrol Reactivates Latent HIV through Increasing Histone Acetylation and Activating Heat Shock Factor 1

The persistence of latent HIV reservoirs presents a significant challenge to viral eradication. Effective latency reversing agents (LRAs) based on "shock and kill" strategy are urgently needed. The natural phytoalexin resveratrol has been demonstrated to enhance HIV gene expression, although its mechanism remains unclear. In this study, we demonstrated that resveratrol was able to reactivate latent HIV without global T cell activation in vitro. Mode of action studies showed resveratrol-mediated reactivation from latency did not involve the activation of silent mating type information regulation 2 homologue 1 (SIRT1), which belonged to class-3 histone deacetylase (HDAC). However, latent HIV was reactivated by resveratrol mediated through increasing histone acetylation and activation of heat shock factor 1 (HSF1). Additionally, synergistic activation of the latent HIV reservoirs was observed under cotreatment with resveratrol and conventional LRAs. Collectively, this research reveals that resveratrol is a natural LRA and shows promise for HIV therapy.

Chemically Modified Human Serum Albumin Potently Blocks Entry of Ebola Pseudoviruses and Viruslike Particles

Ebola virus (EBOV), the causative pathogen of the deadly Ebola virus disease (EVD), can be transmitted via contact with EVD patients, including sexual contact with EVD survivors. At present, no licensed vaccine or therapeutic is available. In this study, we compared eight anhydride-modified proteins for their entry-inhibitory activity against the pseudovirus (PsV) carrying the envelope glycoprotein (GP) of the EBOV Zaire or Sudan species (Zaire PsV and Sudan PsV, respectively). We found that 3-hydroxyphthalic anhydride-modified human serum albumin (HP-HSA) was the most effective in inhibiting the entry of both Zaire PsV and Sudan PsV, with the 50% effective concentration being at the nanomolar level and with HP-HSA being more potent than EBOV-neutralizing antibody MIL77-2 (4G7, a component antibody of the ZMapp drug cocktail). The combination of HP-HSA and MIL77-2 exhibited a synergistic effect. HP-HSA had no obvious in vitro or in vivo toxicity. The EBOV PsV entry-inhibitory activity of HP-HSA remained intact after storage at 45°C for 8 weeks, suggesting that HP-HSA has the potential for worldwide use, including tropical regions in African countries, as either a therapeutic to treat EBOV infection or a prophylactic microbicide to prevent the sexual transmission of EBOV.

Ovalbumin with Glycated Carboxyl Groups Shows Membrane-Damaging Activity

The aim of the present study was to investigate whether glycated ovalbumin (OVA) showed novel activity at the lipid-water interface. Mannosylated OVA (Man-OVA) was prepared by modification of the carboxyl groups with p-aminophenyl α-dextro (d)-mannopyranoside. An increase in the number of modified carboxyl groups increased the membrane-damaging activity of Man-OVA on cell membrane-mimicking vesicles, whereas OVA did not induce membrane permeability in the tested phospholipid vesicles. The glycation of carboxyl groups caused a notable change in the gross conformation of OVA. Moreover, owing to their spatial positions, the Trp residues in Man-OVA were more exposed, unlike those in OVA. Fluorescence quenching studies suggested that the Trp residues in Man-OVA were located on the interface binds with the lipid vesicles, and their microenvironment was abundant in positively charged residues. Although OVA and Man-OVA showed a similar binding affinity for lipid vesicles, the lipid-interacting feature of Man-OVA was distinct from that of OVA. Chemical modification studies revealed that Lys and Arg residues, but not Trp residues, played a crucial role in the membrane-damaging activity of Man-OVA. Taken together, our data suggest that glycation of carboxyl groups causes changes in the structural properties and membrane-interacting features of OVA, generating OVA with membrane-perturbing activities at the lipid-water interface.

Safety evaluation of chemically modified beta-lactoglobulin administered intravaginally

Currently, there is no specific antiviral therapy for treatment of HPV infection. Jiang and colleagues previously reported that anhydride-modified proteins have inhibitory activities against multiple viruses including HPV. Here, we evaluated the safety of 3-hydroxyphthalic anhydride-modified bovine beta-lactoglobulin, designated JB01, vaginally applied in women infected by high-risk HPV. After the vaginal application of JB01 in 38 women for 3 months, no serious adverse events were reported, and normalization of the vaginal micro-environment has been observed. It can be concluded that JB01-BD is safe for vaginal use in HPV-infected women, suggesting its potential application for the treatment of HPV infection.

A Peptide Derived from the HIV-1 gp120 Coreceptor-Binding Region Promotes Formation of PAP248-286 Amyloid Fibrils to Enhance HIV-1 Infection

Background

Semen is a major vehicle for HIV transmission. Prostatic acid phosphatase (PAP) fragments, such as PAP248-286, in human semen can form amyloid fibrils to enhance HIV infection. Other endogenous or exogenous factors present during sexual intercourse have also been reported to promote the formation of seminal amyloid fibrils.

Methodology and Principal Findings

Here, we demonstrated that a synthetic 15-residue peptide derived from the HIV-1 gp120 coreceptor-binding region, designated enhancing peptide 2 (EP2), can rapidly self-assemble into nanofibers. These EP2-derivated nanofibers promptly accelerated the formation of semen amyloid fibrils by PAP248-286, as shown by Thioflavin T (ThT) and Congo red assays. The amyloid fibrils presented similar morphology, assessed via transmission electron microscopy (TEM), in the presence or absence of EP2. Circular dichroism (CD) spectroscopy revealed that EP2 accelerates PAP248-286 amyloid fibril formation by promoting the structural transition of PAP248-286 from a random coil into a cross-β-sheet. Newly formed semen amyloid fibrils effectively enhanced HIV-1 infection in TZM-bl cells and U87 cells by promoting the binding of HIV-1 virions to target cells.

Conclusions and Significance

Nanofibers composed of EP2 promote the formation of PAP248-286 amyloid fibrils and enhance HIV-1 infection.

Intranasal administration of maleic anhydride-modified human serum albumin for pre-exposure prophylaxis of respiratory syncytial virus infection

Respiratory syncytial virus (RSV) is the leading cause of pediatric viral respiratory tract infections. Neither vaccine nor effective antiviral therapy is available to prevent and treat RSV infection. Palivizumab, a humanized monoclonal antibody, is the only product approved to prevent serious RSV infection, but its high cost is prohibitive in low-income countries. Here, we aimed to identify an effective, safe, and affordable antiviral agent for pre-exposure prophylaxis (PrEP) of RSV infection in children at high risk. We found that maleic anhydride (ML)-modified human serum albumin (HSA), designated ML-HSA, exhibited potent antiviral activity against RSV and that the percentages of the modified lysines and arginies in ML- are correlated with such anti-RSV activity. ML-HSA inhibited RSV entry and replication by interacting with viral G protein and blocking RSV attachment to the target cells, while ML-HAS neither bound to F protein, nor inhibited F protein-mediated membrane fusion. Intranasal administration of ML-HSA before RSV infection resulted in significant decrease of the viral titers in the lungs of mice. ML-HSA shows promise for further development into an effective, safe, affordable, and easy-to-use intranasal regimen for pre-exposure prophylaxis of RSV infection in children at high risk in both low- and high-income countries.

Prophylactic treatment with a novel bioadhesive gel formulation containing aciclovir and tenofovir protects from HSV-2 infection

OBJECTIVES

Over-the-counter access to an inexpensive, effective topical microbicide could reduce the transmission of HIV and would increase women's control over their health and eliminate the need to obtain their partners' consent for prophylaxis. Chronic infection with herpes simplex virus 2 (HSV-2), also known as human herpes virus 2, has been shown to facilitate HIV infection and speed the progression to immunodeficiency disease. Our objective is to develop a drug formulation that protects against both HSV-2 and HIV infection and adheres to the vaginal surface with extended residence time.

METHODS

We developed a formulation using two approved antiviral active pharmaceutical ingredients, aciclovir and tenofovir, in a novel bioadhesive vaginal delivery platform (designated SR-2P) composed of two polymers, poloxamer 407 NF (Pluronic(®) F-127) and polycarbophil USP (Noveon(®) AA-1). The efficacy of the formulation to protect from HSV-2 infection was tested in vitro and in vivo. In addition to its efficacy, it is essential for a successful microbicide to be non-irritating to the vaginal mucosa. We therefore tested our SR-2P platform gel in the FDA gold-standard microbicide safety model in rabbits and also in a rat vaginal irritation model.

RESULTS

Our studies indicated that SR-2P containing 1% aciclovir and 5% tenofovir protects (i) Vero cells from HSV-2 infection in vitro and (ii) mice from HSV-2 infection in vivo. Our results further demonstrated that SR-2P was not irritating in either vaginal irritation model.

CONCLUSIONS

We conclude that SR-2P containing aciclovir and tenofovir may be a suitable candidate microbicide to protect humans from vaginal HSV-2 infection.

3-hydroxyphthalic anhydride-modified human serum albumin as a microbicide candidate against HIV type 1 entry by targeting both viral envelope glycoprotein gp120 and cellular receptor CD4

We previously reported that 3-hydroxyphthalic anhydride-modified human serum albumin (HP-HSA) as an anti-HIV microbicide could potently inhibit infection by a broad spectrum of HIV-1 strains; however, its mechanism of action is still elusive. Here, we aimed to identify the target(s) of HP-HSA. HIV-1 envelope glycoprotein (Env)-mediated cell-cell fusion assays were conducted using noninfectious CHO-WT cells or infectious HIV-1IIIB-infected H9 cells as effector cells and MT-2 as target cells. The cell-to-cell transmission and single-round HIV-1 infection assays were performed by measuring luciferase activity. Binding of HP-HSA to CD4 or gp120 was determined by enzyme-linked immunosorbent assay (ELISA) and flow cytometry, while binding of HP-HSA to the coreceptor CXCR4 or CCR5 was detected by cell-based ELISA. HP-HSA strongly inhibited HIV-1 Env-mediated cell-cell fusion and blocked infection by HIV-1 pseudoviruses bearing Env of HIV-1HXB2 (X4 strain) or HIV-1SF162 (R5 strain). HP-HSA was also effective in blocking HIV-1BaL transmission from infected to uninfected cells. HP-HSA could strongly bind to HIV-1 Env gp120 and cellular receptor CD4. These results suggest that HP-HSA inhibits HIV-1 entry into the target cell by interacting with viral Env gp120 and/or the cellular CD4 receptor, making it a promising microbicide candidate for preventing HIV-1 sexual transmission.

A safe and convenient pseudovirus-based inhibition assay to detect neutralizing antibodies and screen for viral entry inhibitors against the novel human coronavirus MERS-CoV

Background

Evidence points to the emergence of a novel human coronavirus, Middle East respiratory syndrome coronavirus (MERS-CoV), which causes a severe acute respiratory syndrome (SARS)-like disease. In response, the development of effective vaccines and therapeutics remains a clinical priority. To accomplish this, it is necessary to evaluate neutralizing antibodies and screen for MERS-CoV entry inhibitors.

Methods

In this study, we produced a pseudovirus bearing the full-length spike (S) protein of MERS-CoV in the Env-defective, luciferase-expressing HIV-1 backbone. We then established a pseudovirus-based inhibition assay to detect neutralizing antibodies and anti-MERS-CoV entry inhibitors.

Results

Our results demonstrated that the generated MERS-CoV pseudovirus allows for single-cycle infection of a variety of cells expressing dipeptidyl peptidase-4 (DPP4), the confirmed receptor for MERS-CoV. Consistent with the results from a live MERS-CoV-based inhibition assay, the antisera of mice vaccinated with a recombinant protein containing receptor-binding domain (RBD, residues 377–662) of MERS-CoV S fused with Fc of human IgG exhibited neutralizing antibody response against infection of MERS-CoV pseudovirus. Furthermore, one small molecule HIV entry inhibitor targeting gp41 (ADS-J1) and the 3-hydroxyphthalic anhydride-modified human serum albumin (HP-HSA) could significantly inhibit MERS-CoV pseudovirus infection.

Conclusion

Taken together, the established MERS-CoV inhibition assay is a safe and convenient pseudovirus-based alternative to BSL-3 live-virus restrictions and can be used to rapidly screen MERS-CoV entry inhibitors, as well as evaluate vaccine-induced neutralizing antibodies against the highly pathogenic MERS-CoV.

Polyanionic candidate microbicides accelerate the formation of semen-derived amyloid fibrils to enhance HIV-1 infection

Polyanionic candidate microbicides, including cellulose sulfate, carrageenan, PRO 2000, were proven ineffective in preventing HIV-1 transmission and even cellulose sulfate showed increased risk of HIV acquisition in the Phase III efficacy trials. Semen plays critical roles in HIV-1 sexual transmission. Specifically, amyloid fibrils formed by fragments of prostatic acidic phosphatase (PAP) in semen termed semen-derived enhancer of virus infection (SEVI) could drastically enhance HIV-1 infection. Here we investigated the interaction between polyanions and PAP248-286, a prototype peptide of SEVI, to understand the possible cause of polyanionic candidate microbicides to fail in clinical trials. We found anionic polymers could efficiently promote SEVI fibril formation, most likely mediated by the natural electrostatic interaction between polyanions and PAP248-286, as revealed by acid native PAGE and Western blot. The overall anti-HIV-1 activity of polyanions in the presence or absence of PAP248-286 or semen was evaluated. In the viral infection assay, the supernatants of polyanions/PAP248-286 or polyanions/semen mixtures containing the free, unbound polyanionic molecules showed a general reduction in antiviral efficacy, while the pellets containing amyloid fibrils formed by the polyanion-bound PAP248-286 showed aggravated enhancement of viral infection. Collectively, from the point of drug-host protein interaction, our study revealed that polyanions facilitate SEVI fibril formation to promote HIV-1 infection, thus highlighting a molecular mechanism underlying the failure of polyanions in clinical trials and the importance of drug-semen interaction in evaluating the anti-HIV-1 efficacy of candidate microbicides.

3-Hydroxyphthalic anhydride-modified human serum albumin as a microbicide candidate inhibits HIV infection by blocking viral entry

OBJECTIVES

We recently demonstrated that both 3-hydroxyphthalic anhydride (HP)- and maleic anhydride-modified chicken ovalbumin (OVA) could effectively inhibit HIV-1 infection. But because OVA may cause allergy in some human subjects, here we replaced OVA with human serum albumin (HSA) in designing a new anti-HIV-1 agent, HP-HSA, and then tested its anti-HIV-1 activity and cytotoxicity.

METHODS

The in vitro anti-HIV-1 activities of HP-HSA were detected by measuring p24 production and luciferase activity. The cytotoxicities of HP-HSA on target cells and human vaginal and cervical epithelial cells and the effect of HP-HSA on human peripheral blood mononuclear cell (PBMC) proliferation were evaluated by XTT assay. The effect of HP-HSA on interferon-γ secretion by PBMCs was detected by enzyme-linked immunospot (ELISPOT) assay.

RESULTS

We found that HP-HSA exhibited broad and potent antiviral activity against infection by the HIV-1 strains tested, including drug-resistant strains. HP-HSA displayed no or low cytotoxicity on human vaginal and cervical epithelial cells and the cells used for testing HIV-1 infectivity. In addition, HP-HSA had no significant effect on proliferation or interferon-γ secretion by normal or phytohaemagglutinin-stimulated human PBMCs. A time-of-addition assay indicated that HP-HSA was an HIV-1 entry inhibitor.

CONCLUSIONS

Because of its broad and potent anti-HIV-1 activity, low cytotoxicity and low immunogenicity to humans, HP-HSA has great potential for further development as a microbicide to prevent the sexual transmission of HIV.

A bivalent recombinant protein inactivates HIV-1 by targeting the gp41 prehairpin fusion intermediate induced by CD4 D1D2 domains

Background

Most currently approved anti-HIV drugs (e.g., reverse transcriptase inhibitors, protease inhibitors and fusion/entry inhibitors) must act inside or on surface of the target cell to inhibit HIV infection, but none can directly inactivate virions away from cells. Although soluble CD4 (sCD4) can inactivate laboratory-adapted HIV-1 strains, it fails to reduce the viral loads in clinical trials because of its low potency against primary isolates and tendency to enhance HIV-1 infection at low concentration. Thus, it is essential to design a better HIV inactivator with improved potency for developing new anti-HIV therapeutics that can actively attack the virus in the circulation before it attaches to and enter into the target cell.

Results

We engineered a bivalent HIV-1 inactivator, designated 2DLT, by linking the D1D2 domain of CD4 to T1144, the next generation HIV fusion inhibitor, with a 35-mer linker. The D1D2 domain in this soluble 2DLT protein could bind to the CD4-binding site and induce the formation of the gp41 prehairpin fusion-intermediate (PFI), but showed no sCD4-mediated enhancement of HIV-1 infection. The T1144 domain in 2DLT then bound to the exposed PFI, resulting in rapid inactivation of HIV-1 virions in the absence of the target cell. Beside, 2DLT could also inhibit fusion of the virus with the target cell if the virion escapes the first attack of 2DLT.

Conclusion

This bivalent molecule can serve as a dual barrier against HIV infection by first inactivating HIV-1 virions away from cells and then blocking HIV-1 entry on the target cell surface, indicating its potential for development as a new class of anti-HIV drug.

Poly (4-styrenesulfonic acid-co-maleic acid) is an entry inhibitor against both HIV-1 and HSV infections - potential as a dual functional microbicide

Genital herpes is one of the most prevalent sexually transmitted diseases (STD) caused by herpes simplex viruses type 1 and 2 (HSV-1 and -2). HSV is considered as a major risk factor in human immunodeficiency virus type-1 (HIV-1) infection and rapid progression to acquired immunodeficiency syndrome (AIDS). Here, we reported the finding of a polymer of styrenesulfonic acid and maleic acid (PSM) which exhibited antiviral activity with low cytotoxicity. PSM exhibited in vitro inhibitory activity against HIV-1 pseudovirus and HSV-1 and -2. In vivo efficacy of PSM against HSV-2 (G) was also investigated. We found that both 1% and 5% PSM gels protected mice from HSV-2 vaginal infection and disease progression significantly. Mechanistic analysis demonstrated that PSM was likely an entry inhibitor that disrupted viral attachment to the target cells. In particular, PSM disrupted gp120 binding to CD4 by interacting with the gp120 V3-loop and the CD4-binding site. The in vitro cytotoxicity studies showed that PSM did not stimulate NF-κB activation and up-regulation of proinflammatory cytokine IL-1β and IL-8 in vaginal epithelial cells. In addition, PSM also showed low adverse effect on the growth of vaginal Lactobacillus strains. PSM is, therefore, a novel viral entry inhibitor and a potential microbicide candidate against both HIV-1 and HSV.

Combinations of 3-hydroxyphthalic anhydride-modified ovalbumin with antiretroviral drug-based microbicide candidates display synergistic and complementary effects against HIV-1 infection

BACKGROUND

The development of a safe, effective, and affordable microbicide to prevent the sexual transmission of HIV combination is urgently needed. Our previous studies demonstrated that 3-hydroxyphthalic anhydride-modified chicken ovalbumin (HP-OVA) exhibited potent antiviral activity against a broad spectrum of HIV, simian immunodeficiency virus, and herpes simplex virus, making it a promising candidate as a component of combination microbicide. We intended to evaluate potential the synergistic anti-HIV-1 effect of HP-OVA in combination with antiretroviral drug (ARV)-based microbicide candidates.

METHODS

The antiviral activity of HP-OVA and the ARVs, including HIV-1 entry inhibitors (T20, C52L, NB64, NBD556, AMD3100, and Maraviroc) and reverse transcriptase inhibitors (Tenofovir, UC781, and TMC120), tested alone or in combination, against HIV-1 X4 and R5 viruses, including some drug-resistant strains, was determined in MT-2 and peripheral blood mononuclear cells using p24 assay. The immune responses induced by HP-OVA that was applied in the vaginas of rats were detected by enzyme-linked immunosorbent assay.

RESULTS

When each of these ARV-based microbicide candidates was combined with HP-OVA, synergistic activity was observed against infection by both X4 and R5 strains, and the degree of synergy differed in each case. HP-OVA was highly effective against several ARV-resistant HIV-1 strains, suggesting that combining HP-OVA with these ARV-based microbicide candidates might work cooperatively against both drug-sensitive and -resistant HIV-1 strains. Human body fluids and human proteins had little or no effects on HP-OVA-mediated inhibitory activity against HIV-1 infection. HP-OVA formulated in the universal gel maintained its antiviral activity for at least 1 month and only induced weak immune responses after its multiple applications in the vaginas of rats.

CONCLUSIONS

Synergistic and complementary effects against infection by a broad spectrum of HIV-1 strains were observed by combining HP-OVA with the ARV-based microbicide candidates. These findings provide a sound scientific platform for the development of a safe, effective, and affordable combination microbicide to prevent the sexual transmission of HIV and other sexually transmissible viruses.

HIV-1 gp41 core with exposed membrane-proximal external region inducing broad HIV-1 neutralizing antibodies

The membrane-proximal external region (MPER) of the HIV-1 gp41 consists of epitopes for the broadly cross-neutralizing monoclonal antibodies 2F5 and 4E10. However, antigens containing the linear sequence of these epitopes are unable to elicit potent and broad neutralizing antibody responses in vaccinated hosts, possibly because of inappropriate conformation of these epitopes. Here we designed a recombinant antigen, designated NCM, which comprises the N- and C-terminal heptad repeats that can form a six-helix bundle (6HB) core and the MPER domain of gp41. Two mutations (T569A and I675V) previously reported to expose the neutralization epitopes were introduced into NCM to generate mutants named NCM(TA), NCM(IV), and NCM(TAIV). Our results showed that NCM and its mutants could react with antibodies specific for 6HB and MPER of gp41, suggesting that these antigens are in the form of a trimer of heterodimer (i.e., 6HB) with three exposed MPER tails. Antigen with double mutations, NCM(TAIV), elicited much stronger antibody response in rabbits than immunogens with single mutation, NCM(TA) and NCM(IV), or no mutation, NCM. The purified MPER-specific antibodies induced by NCM(TAIV) exhibited broad neutralizing activity, while the purified 6HB-specific antibodies showed no detectable neutralizing activity. Our recombinant antigen design supported by an investigation of its underlying molecular mechanisms provides a strong scientific platform for the discovery of a gp41 MPER-based AIDS vaccine.

The rise of bioscience in the East

The rapid growth of bioscience in China is considered.