A peptide-based viral inactivator inhibits Zika virus infection in pregnant mice and fetuses

Peptides P4 and P7 derived from E protein inhibit entry of dengue virus serotype 2 via interacting with β3 integrin

Dengue virus (DENV) infection has become a severe public health problem worldwide. However, there is no specific antiviral drug available yet. In this study, we found that DENV serotype 2 (DENV2) infection enhanced the expression of β3 integrin on human umbilical vein endothelial cells (HUVECs) and that DENV2 antigens co-localized with β3 integrin. DENV2 envelope protein (E) directly interacted with β3 integrin, and their interacting sites were located at domain III of E protein (EDIII). Several synthetic peptides were designed based on the amino acid sequence of EDIII, and peptides P4 and P7 could inhibit DENV2 entry into HUVECs in a dose-dependent manner. The inhibitory concentration (IC₅₀) of the two peptides was 19.08 ± 2.52 μM for P4 and 12.86 ± 5.96 μM for P7. Moreover, P7 containing an FG-loop, but not P4, could also inhibit DENV1 entry into HUVECs. Our results suggest a novel mechanism in which interaction between β3 integrin and EDIII is involved in DENV entry. The findings on the inhibitory effect of the peptides on viral entry have significance for anti-DENV drug design.

What we know and what we don't know about perinatal Zika virus infection: a systematic review

INTRODUCTION

Zika virus (ZIKV) infection has caused the most challenging worldwide infectious epidemic outbreak in recent months. ZIKV causes microcephaly and other congenital malformations. There is a need to perform updated systematic reviews on ZIKV infection periodically because this epidemic is bringing up new evidence with extraordinary speed. Areas covered: Evidence related to ZIKV infection in the gestational, perinatal, and early infant periods covering epidemiology, virology, pathogenesis, risk factors, time of infection during pregnancy, newborn symptoms, treatment, and vaccines. To this end, a search was performed using terms ['Zika'] AND ['Perinatal Infection'] OR ['Congenital Infection'] in the PubMed® international electronic database. Out of a total of 1,538 articles published until 30 November 2017, we finally assessed 106 articles articles that were relevant to the research areas included in this study. Expert commentary: ZIKV is a new teratogenic/neurotropic virus affecting fetuses. Many challenges are still far from being solved regarding the epidemiology, case definition, clinical and laboratory diagnosis, and preventive measures. An approach using 'omics' and new biomarkers for diagnosis, and a ZIKV-vaccine for treatment, might finally give us the tools to solve these challenges.

Peptide-Based Membrane Fusion Inhibitors Targeting HCoV-229E Spike Protein HR1 and HR2 Domains

Human coronavirus 229E (HCoV-229E) infection in infants, elderly people, and immunocompromised patients can cause severe disease, thus calling for the development of effective and safe therapeutics to treat it. Here we reported the design, synthesis and characterization of two peptide-based membrane fusion inhibitors targeting HCoV-229E spike protein heptad repeat 1 (HR1) and heptad repeat 2 (HR2) domains, 229E-HR1P and 229E-HR2P, respectively. We found that 229E-HR1P and 229E-HR2P could interact to form a stable six-helix bundle and inhibit HCoV-229E spike protein-mediated cell-cell fusion with IC₅₀ of 5.7 and 0.3 µM, respectively. 229E-HR2P effectively inhibited pseudotyped and live HCoV-229E infection with IC₅₀ of 0.5 and 1.7 µM, respectively. In a mouse model, 229E-HR2P administered intranasally could widely distribute in the upper and lower respiratory tracts and maintain its fusion-inhibitory activity. Therefore, 229E-HR2P is a promising candidate for further development as an antiviral agent for the treatment and prevention of HCoV-229E infection.

Critical neutralizing fragment of Zika virus EDIII elicits cross-neutralization and protection against divergent Zika viruses

Zika virus (ZIKV) infection remains a serious health threat due to its close association with congenital Zika syndrome (CZS), which includes microcephaly and other severe birth defects. As no vaccines are available for human use, continuous effort is needed to develop effective and safe vaccines to prevent ZIKV infection. In this study, we constructed three recombinant proteins comprising, respectively, residues 296-406 (E296-406), 298-409 (E298-409), and 301-404 (E301-404) of ZIKV envelope (E) protein domain III (EDIII) fused with a C-terminal Fc of human IgG. Our results demonstrated that E298-409 induced the highest titer of neutralizing antibodies against infection with nine ZIKV strains isolated from different hosts, countries, and time periods, and it maintained long-term anti-ZIKV immunogenicity to induce neutralizing antibodies. Pups born to mice immunized with E298-409 were fully protected against lethal challenge with two epidemic human ZIKV strains, 2015/Honduras (R103451) and 2015/Colombia (FLR). Passive transfer of anti-E298-409 mouse sera protected pups born to naive mice, as well as type I interferon receptor-deficient adult A129 mice, from lethal challenge with human ZIKV strains R103451 and FLR, and this protection was positively correlated with neutralizing antibodies. These data suggest that the critical neutralizing fragment (i.e., a fragment that can induce highly potent neutralizing antibodies against divergent ZIKV strains) of ZIKV EDIII is a good candidate for development as an effective and safe ZIKV subunit vaccine to protect pregnant mothers and their fetuses against ZIKV infection. The E298-409-specific antibodies can be used for passive immunization to prevent ZIKV infection in newborns or immunocompromised adults.

Identification of novel small-molecule inhibitors of Zika virus infection

The recent re-emergence of Zika virus (ZIKV), a member of the Flaviviridae family, has become a global emergency and a serious public health threat worldwide. ZIKV infection causes severe neuroimmunopathology and is particularly harmful to the developing fetuses of infected pregnant women causing various developmental abnormalities. Currently, there are no effective methods of preventing or treating ZIKV infection, and new treatment options are urgently needed. Therefore, we have used an in vitro plaque assay to screen a limited proprietary library of small organic compounds and identified highly bioactive leads, with the most active analogs showing activity in low picomolar range. Identified "hits" possess certain common structural features that can be used in the design of the next generation(s) of ZIKV inhibitors. Collectively, our findings suggest that identified compounds represent excellent template(s) for the development of inexpensive and orally available anti-Zika drugs.

Development of small-molecule viral inhibitors targeting various stages of the life cycle of emerging and re-emerging viruses

In recent years, unexpected outbreaks of infectious diseases caused by emerging and re-emerging viruses have become more frequent, which is possibly due to environmental changes. These outbreaks result in the loss of life and economic hardship. Vaccines and therapeutics should be developed for the prevention and treatment of infectious diseases. In this review, we summarize and discuss the latest progress in the development of small-molecule viral inhibitors against highly pathogenic coronaviruses, including severe acute respiratory syndrome coronavirus and Middle East respiratory syndrome coronavirus, Ebola virus, and Zika virus. These viruses can interfere with the specific steps of viral life cycle by blocking the binding between virus and host cells, disrupting viral endocytosis, disturbing membrane fusion, and interrupting viral RNA replication and translation, thereby demonstrating potent therapeutic effect against various emerging and re-emerging viruses. We also discuss some general strategies for developing small-molecule viral inhibitors.

Chidamide, a histone deacetylase inhibitor-based anticancer drug, effectively reactivates latent HIV-1 provirus

Although combination antiretroviral therapy (cART) is highly effective in suppressing human immunodeficiency virus type 1 (HIV-1) replication, it fails to eradicate the virus from HIV-1-infected individuals because HIV-1 integrates into the resting CD4⁺ T cells, establishing latently infected reservoirs. Histone deacetylation is a key element in regulating HIV-1 latent infection. Chidamide, a new anticancer drug, is a novel type of selective histone deacetylase inhibitor. Here we showed that chidamide effectively reactivated HIV-1 latent provirus in different latently infected cell lines in a dose- and time-dependent manner. Chidamide had relatively low cytotoxicity to peripheral blood mononuclear cells (PBMCs) and other latent cell lines. We have demonstrated that chidamide reactivated HIV-1 latent provirus through the NF-κB signaling pathway. The replication of the newly reactivated HIV-1 could then be effectively inhibited by the anti-HIV-1 drugs Zidovudine, Nevirapine, and Indinavir. Therefore, chidamide might be used in combination with cART for functional HIV-1 cure.

Interfering peptides targeting protein-protein interactions: the next generation of drugs?

Protein-protein interactions (PPIs) are well recognized as promising therapeutic targets. Consequently, interfering peptides (IPs) - natural or synthetic peptides capable of interfering with PPIs - are receiving increasing attention. Given their physicochemical characteristics, IPs seem better suited than small molecules to interfere with the large surfaces implicated in PPIs. Progress on peptide administration, stability, biodelivery and safety are also encouraging the interest in peptide drug development. The concept of IPs has been validated for several PPIs, generating great expectations for their therapeutic potential. Here, we describe approaches and methods useful for IPs identification and in silico, physicochemical and biological-based strategies for their design and optimization. Selected promising in-vivo-validated examples are described and advantages, limitations and potential of IPs as therapeutic tools are discussed.

Neutralization of Zika virus by germline-like human monoclonal antibodies targeting cryptic epitopes on envelope domain III

The Zika virus (ZIKV), a flavivirus transmitted by Aedes mosquitoes, has emerged as a global public health concern. Pre-existing cross-reactive antibodies against other flaviviruses could modulate immune responses to ZIKV infection by antibody-dependent enhancement, highlighting the importance of understanding the immunogenicity of the ZIKV envelope protein. In this study, we identified a panel of human monoclonal antibodies (mAbs) that target domain III (DIII) of the ZIKV envelope protein from a very large phage-display naive antibody library. These germline-like antibodies, sharing 98%-100% hoLogy with their corresponding germline IGHV genes, bound ZIKV DIII specifically with high affinities. One mAb, m301, broadly neutralized the currently circulating ZIKV strains and showed a synergistic effect with another mAb, m302, in neutralizing ZIKV in vitro and in a mouse model of ZIKV infection. Interestingly, epitope mapping and competitive binding studies suggest that m301 and m302 bind adjacent regions of the DIII C-C' loop, which represents a recently identified cryptic epitope that is intermittently exposed in an uncharacterized virus conformation. This study extended our understanding of antigenic epitopes of ZIKV antibodies and has direct implications for the design of ZIKV vaccines.

Therapeutic Approaches for Zika Virus Infection of the Nervous System

Zika virus has spread rapidly in the Americas and has caused devastation of human populations affected in these regions. The virus causes teratogenic effects involving the nervous system, and in adults and children can cause a neuropathy similar to Guillain-Barré syndrome, an anterior myelitis, or, rarely, an encephalitis. While major efforts have been undertaken to control mosquito populations that spread the virus and to develop a vaccine, drug development that directly targets the virus in an infected individual to prevent or treat the neurological manifestations is necessary. Rational and targeted drug development is possible since the viral life cycle and the structure of the key viral proteins are now well understood. While several groups have identified therapeutic candidates, their approaches differ in the types of screening processes and viral assays used. Animal studies are available for only a few compounds. Here we provide an exhaustive review and compare each of the classes of drugs discovered, the methods used for drug discovery, and their potential use in humans for the prevention or treatment of neurological complications of Zika virus infection.