ABSTRACT
SARS-CoV-2 infection has emerged as a serious global pandemic. Because of the high transmissibility of the virus and the high rate of morbidity and mortality associated with COVID-19, developing effective and safe vaccines is a top research priority. Here, we provide a detailed evaluation of the immunogenicity of lipid nanoparticle-encapsulated, nucleoside-modified mRNA (mRNA-LNP) vaccines encoding the full-length SARS-CoV-2 spike protein or the spike receptor binding domain in mice. We demonstrate that a single dose of these vaccines induces strong type 1 CD4+ and CD8+ T cell responses, as well as long-lived plasma and memory B cell responses. Additionally, we detect robust and sustained neutralizing antibody responses and the antibodies elicited by nucleoside-modified mRNA vaccines do not show antibody-dependent enhancement of infection in vitro. Our findings suggest that the nucleoside-modified mRNA-LNP vaccine platform can induce robust immune responses and is a promising candidate to combat COVID-19.
Subject(s)
Antibodies, Neutralizing/biosynthesis , Antibodies, Viral/biosynthesis , Betacoronavirus/drug effects , Coronavirus Infections/prevention & control , Pandemics/prevention & control , Pneumonia, Viral/prevention & control , RNA, Messenger/immunology , RNA, Viral/immunology , Viral Vaccines/administration & dosage , Animals , B-Lymphocytes/drug effects , B-Lymphocytes/immunology , B-Lymphocytes/virology , Betacoronavirus/immunology , Betacoronavirus/pathogenicity , CD4-Positive T-Lymphocytes/drug effects , CD4-Positive T-Lymphocytes/immunology , CD4-Positive T-Lymphocytes/virology , CD8-Positive T-Lymphocytes/drug effects , CD8-Positive T-Lymphocytes/immunology , CD8-Positive T-Lymphocytes/virology , COVID-19 , COVID-19 Vaccines , Coronavirus Infections/genetics , Coronavirus Infections/immunology , Coronavirus Infections/pathology , Disease Models, Animal , Furin/genetics , Furin/immunology , Humans , Immunity, Humoral/drug effects , Immunization/methods , Immunogenicity, Vaccine , Immunologic Memory/drug effects , Lymphocyte Activation/drug effects , Mice , Mice, Inbred BALB C , Nanoparticles/administration & dosage , Nanoparticles/chemistry , Pneumonia, Viral/immunology , Pneumonia, Viral/pathology , RNA, Messenger/genetics , RNA, Viral/genetics , SARS-CoV-2 , Spike Glycoprotein, Coronavirus/genetics , Spike Glycoprotein, Coronavirus/immunology , Vaccines, Synthetic , Viral Vaccines/biosynthesis , Viral Vaccines/geneticsABSTRACT
Nucleoside-modified mRNA technology has revolutionized vaccine development with the success of mRNA COVID-19 vaccines. We used modified mRNA technology for the design of envelopes (Env) to induce HIV-1 broadly neutralizing antibodies (bnAbs). However, unlike SARS-CoV-2 neutralizing antibodies that are readily made, HIV-1 bnAb induction is disfavored by the immune system because of the rarity of bnAb B cell precursors and the cross-reactivity of bnAbs targeting certain Env epitopes with host molecules, thus requiring optimized immunogen design. The use of protein nanoparticles (NPs) has been reported to enhance B cell germinal center responses to HIV-1 Env. Here, we report our experience with the expression of Env-ferritin NPs compared with membrane-bound Env gp160 when encoded by modified mRNA. We found that well-folded Env-ferritin NPs were a minority of the protein expressed by an mRNA design and were immunogenic at 20 µg but minimally immunogenic in mice at 1 µg dose in vivo and were not expressed well in draining lymph nodes (LNs) following intramuscular immunization. In contrast, mRNA encoding gp160 was more immunogenic than mRNA encoding Env-NP at 1 µg dose and was expressed well in draining LN following intramuscular immunization. Thus, analysis of mRNA expression in vitro and immunogenicity at low doses in vivo are critical for the evaluation of mRNA designs for optimal immunogenicity of HIV-1 immunogens.IMPORTANCEAn effective HIV-1 vaccine that induces protective antibody responses remains elusive. We have used mRNA technology for designs of HIV-1 immunogens in the forms of membrane-bound full-length envelope gp160 and envelope ferritin nanoparticle. Here, we demonstrated in a mouse model that the membrane-bound form induced a better response than envelope ferritin nanoparticle because of higher in vivo protein expression. The significance of our research is in highlighting the importance of analysis of mRNA design expression and low-dose immunogenicity studies for HIV-1 immunogens before moving to vaccine clinical trials.
ABSTRACT
The envelope glycoprotein (Env) is the main focus of human immunodeficiency virus type 1 (HIV-1) vaccine development due to its critical role in viral entry. Despite advances in protein engineering, many Env proteins remain recalcitrant to recombinant expression due to their inherent metastability, making biochemical and immunological experiments impractical or impossible. Here, we report a novel proline stabilization strategy to facilitate the production of prefusion Env trimers. This approach, termed "2P," works synergistically with previously described SOSIP mutations and dramatically increases the yield of recombinantly expressed Env ectodomains without altering the antigenic or conformational properties of near-native Env. We determined that the 2P mutations function by enhancing the durability of the prefusion conformation and that this stabilization strategy is broadly applicable to evolutionarily and antigenically diverse Env constructs. These findings provide a new Env stabilization platform to facilitate biochemical research and expand the number of Env variants that can be developed as future HIV-1 vaccine candidates. IMPORTANCE Recent estimates have placed the number of new human immunodeficiency virus type 1 (HIV-1) infections at approximately 1.5 million per year, emphasizing the ongoing and urgent need for an effective vaccine. The envelope (Env) glycoprotein is the main focus of HIV-1 vaccine development, but, due to its inherent metastability, many Env variants are difficult to recombinantly express in the relatively large quantities that are required for biochemical studies and animal trials. Here, we describe a novel structure-based stabilization strategy that works synergistically with previously described SOSIP mutations to increase the yield of prefusion HIV-1 Env.
Subject(s)
Glycoproteins , env Gene Products, Human Immunodeficiency Virus , Humans , env Gene Products, Human Immunodeficiency Virus/genetics , Glycoproteins/genetics , HIV Infections , Molecular Conformation , Protein Engineering , Protein Multimerization , Recombinant Proteins/genetics , HIV-1/geneticsABSTRACT
The non-classical class Ib molecule human leukocyte antigen E (HLA-E) has limited polymorphism and can bind HLA class Ia leader peptides (VL9). HLA-E-VL9 complexes interact with the natural killer (NK) cell receptors NKG2A-C/CD94 and regulate NK cell-mediated cytotoxicity. Here we report the isolation of 3H4, a murine HLA-E-VL9-specific IgM antibody that enhances killing of HLA-E-VL9-expressing cells by an NKG2A+ NK cell line. Structural analysis reveal that 3H4 acts by preventing CD94/NKG2A docking on HLA-E-VL9. Upon in vitro maturation, an affinity-optimized IgG form of 3H4 showes enhanced NK killing of HLA-E-VL9-expressing cells. HLA-E-VL9-specific IgM antibodies similar in function to 3H4 are also isolated from naïve B cells of cytomegalovirus (CMV)-negative, healthy humans. Thus, HLA-E-VL9-targeting mouse and human antibodies isolated from the naïve B cell antibody pool have the capacity to enhance NK cell cytotoxicity.
Subject(s)
Cytotoxicity, Immunologic , Histocompatibility Antigens Class I , Animals , HLA Antigens , Histocompatibility Antigens Class I/genetics , Humans , Immunoglobulins/metabolism , Killer Cells, Natural , Mice , Peptides/metabolism , Protein Sorting Signals , HLA-E AntigensABSTRACT
The success of nucleoside-modified mRNAs in lipid nanoparticles (mRNA-LNP) as COVID-19 vaccines heralded a new era of vaccine development. For HIV-1, multivalent envelope (Env) trimer protein nanoparticles are superior immunogens compared with trimers alone for priming of broadly neutralizing antibody (bnAb) B cell lineages. The successful expression of complex multivalent nanoparticle immunogens with mRNAs has not been demonstrated. Here, we show that mRNAs can encode antigenic Env trimers on ferritin nanoparticles that initiate bnAb precursor B cell expansion and induce serum autologous tier 2 neutralizing activity in bnAb precursor VH + VL knock-in mice. Next-generation sequencing demonstrates acquisition of critical mutations, and monoclonal antibodies that neutralize heterologous HIV-1 isolates are isolated. Thus, mRNA-LNP can encode complex immunogens and may be of use in design of germline-targeting and sequential boosting immunogens for HIV-1 vaccine development.
Subject(s)
AIDS Vaccines , COVID-19 , HIV-1 , Nanoparticles , Animals , Antibodies, Monoclonal , Antibodies, Neutralizing , COVID-19 Vaccines , Epitopes , Ferritins/genetics , HIV Antibodies , Humans , Liposomes , Mice , RNA, Messenger , env Gene Products, Human Immunodeficiency Virus/geneticsABSTRACT
A prophylactic vaccine would be a powerful tool in the fight against HIV. Passive immunization of animals with broadly neutralizing antibodies (bnAbs) affords protection against viral challenge, and recent data from the Antibody Mediated Prevention clinical trials support the concept of bnAbs providing protection against HIV in humans, albeit only at broad and potent neutralizing antibody titers. Moreover, it is now clear that a successful vaccine will also need to induce bnAbs against multiple neutralizing epitopes on the HIV envelope (Env) glycoprotein. Here, we review recent clinical trials evaluating bnAb-based vaccines, and discuss key issues in the development of an HIV vaccine capable of targeting multiple Env neutralizing epitopes.
Subject(s)
AIDS Vaccines/immunology , Broadly Neutralizing Antibodies/immunology , HIV Antibodies/immunology , HIV/chemistry , HIV/immunology , Vaccination , Animals , Epitopes/chemistry , Epitopes/immunology , HIV Infections/immunology , HIV Infections/prevention & control , HumansABSTRACT
The SARS-CoV-2 pandemic introduced the world to a new type of vaccine based on mRNA encapsulated in lipid nanoparticles (LNPs). Instead of delivering antigenic proteins directly, an mRNA-based vaccine relies on the host's cells to manufacture protein immunogens which, in turn, are targets for antibody and cytotoxic T cell responses. mRNA-based vaccines have been the subject of research for over three decades as a platform to protect against or treat a variety of cancers, amyloidosis and infectious diseases. In this review, we discuss mRNA-based approaches for the generation of prophylactic and therapeutic vaccines to HIV. We examine the special immunological hurdles for a vaccine to elicit broadly neutralizing antibodies and effective T cell responses to HIV. Lastly, we outline an mRNA-based HIV vaccination strategy based on the immunobiology of broadly neutralizing antibody development.
ABSTRACT
The success of nucleoside-modified mRNAs in lipid nanoparticles (mRNA-LNP) as COVID-19 vaccines heralded a new era of vaccine development. For HIV-1, multivalent envelope (Env) trimer protein nanoparticles are superior immunogens compared to trimers alone for priming of broadly neutralizing antibody (bnAb) B cell lineages. The successful expression of complex multivalent nanoparticle immunogens with mRNAs has not been demonstrated. Here we show that mRNAs can encode antigenic Env trimers on ferritin nanoparticles that initiate bnAb precursor B cell expansion and induce serum autologous tier 2 neutralizing activity in bnAb precursor VH + VL knock-in mice. Next generation sequencing demonstrated acquisition of critical mutations, and monoclonal antibodies that neutralized heterologous HIV-1 isolates were isolated. Thus, mRNA-LNP can encode complex immunogens and are of use in design of germline-targeting and sequential boosting immunogens for HIV-1 vaccine development.
ABSTRACT
The SARS-CoV-2 spike (S) protein, a primary target for COVID-19 vaccine development, presents its receptor binding domain in two conformations, the receptor-accessible 'up' or receptor-inaccessible 'down' states. Here we report that the commonly used stabilized S ectodomain construct '2P' is sensitive to cold temperatures, and this cold sensitivity is abrogated in a 'down' state-stabilized ectodomain. Our findings will impact structural, functional and vaccine studies that use the SARS-CoV-2 S ectodomain.
Subject(s)
Spike Glycoprotein, Coronavirus/chemistry , Antibodies, Viral/chemistry , COVID-19 Vaccines/chemistry , Cold Temperature , Cryoelectron Microscopy , Enzyme-Linked Immunosorbent Assay , Humans , Protein Denaturation , Protein Domains , Protein Stability , Spike Glycoprotein, Coronavirus/ultrastructure , Surface Plasmon ResonanceABSTRACT
The development of an effective AIDS vaccine remains a challenge. Nucleoside-modified mRNAs formulated in lipid nanoparticles (mRNA-LNP) have proved to be a potent mode of immunization against infectious diseases in preclinical studies, and are being tested for SARS-CoV-2 in humans. A critical question is how mRNA-LNP vaccine immunogenicity compares to that of traditional adjuvanted protein vaccines in primates. Here, we show that mRNA-LNP immunization compared to protein immunization elicits either the same or superior magnitude and breadth of HIV-1 Env-specific polyfunctional antibodies. Immunization with mRNA-LNP encoding Zika premembrane and envelope or HIV-1 Env gp160 induces durable neutralizing antibodies for at least 41 weeks. Doses of mRNA-LNP as low as 5 µg are immunogenic in macaques. Thus, mRNA-LNP can be used to rapidly generate single or multi-component vaccines, such as sequential vaccines needed to protect against HIV-1 infection. Such vaccines would be as or more immunogenic than adjuvanted recombinant protein vaccines in primates.
ABSTRACT
Malignant glioma constitutes one of the fatal primary brain tumors in adults. Such poor prognosis calls for a better understanding of cancer-related signaling pathways of this disease. Here we elucidate a MYC-miRNA-MXI1 feedback loop that regulates proliferation and tumorigenesis in glioma. MYC suppressed MXI1 expression via microRNA-155 (miR-155) and the microRNA-23aâ¼27aâ¼24-2 cluster (miR-23a cluster), whereas MXI1, in turn, inhibited MYC expression by binding to its promoter. Overexpression of miR-155 and the miR-23a cluster promoted tumorigenesis in U87 glioma cells. Furthermore, fat mass and obesity-associated protein (FTO), an N6-methyladenosine (m6A) RNA demethylase, regulated the loop by targeting MYC. The ethyl ester form of meclofenamic acid (MA2) inhibited FTO and enhanced the effect of the chemotherapy drug temozolomide on suppressing proliferation of glioma cells and negatively regulated the loop. These data collectively highlight a key regulatory circuit in glioma and provide potential targets for clinical treatment. SIGNIFICANCE: These findings elucidate a novel feedback loop that regulates proliferation in glioma and can be targeted via inhibition of FTO to enhance the efficacy of temozolomide.
Subject(s)
Alpha-Ketoglutarate-Dependent Dioxygenase FTO/antagonists & inhibitors , Basic Helix-Loop-Helix Transcription Factors/metabolism , Brain Neoplasms/metabolism , Glioma/metabolism , MicroRNAs/metabolism , Proto-Oncogene Proteins c-myc/metabolism , Tumor Suppressor Proteins/metabolism , Alpha-Ketoglutarate-Dependent Dioxygenase FTO/metabolism , Animals , Antineoplastic Agents, Alkylating/pharmacology , Brain Neoplasms/drug therapy , Brain Neoplasms/pathology , Cell Line, Tumor , Cell Proliferation/drug effects , Cyclooxygenase Inhibitors/pharmacology , Drug Synergism , Feedback, Physiological/drug effects , Feedback, Physiological/physiology , Female , Glioma/drug therapy , Glioma/pathology , Humans , Meclofenamic Acid/pharmacology , Mice , Mice, Nude , Neoplasm Transplantation , Temozolomide/pharmacologyABSTRACT
The trimeric HIV-1 Envelope protein (Env) mediates viral-host cell fusion via a network of conformational transitions, with allosteric elements in each protomer orchestrating host receptor-induced exposure of the co-receptor binding site and fusion elements. To understand the molecular details of this allostery, here, we introduce Env mutations aimed to prevent CD4-induced rearrangements in the HIV-1 BG505 Env trimer. Binding analysis and single-molecule Förster Resonance Energy Transfer confirm that these mutations prevent CD4-induced transitions of the HIV-1 Env. Structural analysis by single-particle cryo-electron microscopy performed on the BG505 SOSIP mutant Env proteins shows rearrangements in the gp120 topological layer contacts with gp41. Displacement of a conserved tryptophan (W571) from its typical pocket in these Env mutants renders the Env insensitive to CD4 binding. These results reveal the critical function of W571 as a conformational switch in Env allostery and receptor-mediated viral entry and provide insights on Env conformation that are relevant for vaccine design.
Subject(s)
CD4 Antigens/metabolism , HIV-1/metabolism , env Gene Products, Human Immunodeficiency Virus/metabolism , Allosteric Regulation , Amino Acid Sequence , Humans , Models, Molecular , Mutant Proteins/chemistry , Mutant Proteins/metabolism , Mutation/genetics , Protein Binding , Protein Domains , Protein Multimerization , Protein Stability , Solubility , Temperature , env Gene Products, Human Immunodeficiency Virus/chemistry , env Gene Products, Human Immunodeficiency Virus/ultrastructureABSTRACT
The SARS-CoV-2 spike (S) protein, a primary target for COVID-19 vaccine development, presents its Receptor Binding Domain in two conformations: receptor-accessible "up" or receptor-inaccessible "down" conformations. Here, we report that the commonly used stabilized S ectodomain construct "2P" is sensitive to cold temperature, and that this cold sensitivity is resolved in a "down" state stabilized spike. Our results will impact structural, functional and vaccine studies that use the SARS-CoV-2 S ectodomain.
ABSTRACT
Development of an effective AIDS vaccine remains a challenge. Nucleoside-modified mRNAs formulated in lipid nanoparticles (mRNA-LNP) have proved to be a potent mode of immunization against infectious diseases in preclinical studies, and are being tested for SARS-CoV-2 in humans. A critical question is how mRNA-LNP vaccine immunogenicity compares to that of traditional adjuvanted protein vaccines in primates. Here, we found that mRNA-LNP immunization compared to protein immunization elicited either the same or superior magnitude and breadth of HIV-1 Env-specific polyfunctional antibodies. Immunization with mRNA-LNP encoding Zika premembrane and envelope (prM-E) or HIV-1 Env gp160 induced durable neutralizing antibodies for at least 41 weeks. Doses of mRNA-LNP as low as 5 µg were immunogenic in macaques. Thus, mRNA-LNP can be used to rapidly generate single or multi-component vaccines, such as sequential vaccines needed to protect against HIV-1 infection. Such vaccines would be as or more immunogenic than adjuvanted recombinant protein vaccines in primates.
ABSTRACT
Chemotherapy is the preferred treatment for advanced ovarian cancer, but the 5-year survival rate remains low partly because of the development of drug resistance. Although it has been reported that X-linked inhibitor of apoptosis (XIAP) causes more severe chemoresistance in ovarian cancer cells and is highly expressed in chemoresistant ovarian cancer, the molecular mechanism underlying this dysregulation is unknown. The purpose of this study was to identify microRNAs (miRNAs) that bind to the 3' untranslated region (3'UTR) of XIAP and have a role in chemoresistance in ovarian cancer. Using in silico analysis and literature review, a panel of miRNAs dysregulated in chemoresistant ovarian cancer was generated from hundreds of miRNAs that were predicted to target the XIAP 3'UTR. Using a dual luciferase reporter assay and cellular co-transfection of a miRNA expression vector and a luciferase reporter fused to the XIAP 3'UTR cognate miRNA binding site, we identified three miRNAs of which miR-142-5p had the greatest inhibitory effect. We found that overexpression of miR-142-5p suppressed XIAP expression by binding to its 3'UTR in OVCAR3 and SKOV3 cells. Using a chemosensitivity assay, we found that in OVCAR3, SKOV3, and primary epithelial ovarian cancer (EOC) cells, overexpression or inhibition of miR-142-5p increased or suppressed their sensitivities to cisplatin respectively. In contrast, introducing XIAP without a 3'UTR counteracted the effect of overexpressed miR-142-5p on cisplatin-induced apoptosis in OVCAR3 ovarian cancer cells. Furthermore, we found a negative correlation between miR-142-5p expression and XIAP protein levels in clinical samples from patients with EOC. Using clinical and miRNA expression data of more than 200 ovarian cancer patients treated with platinum-based chemotherapy from The Cancer Genome Atlas (TCGA) database, we found ovarian cancer patients with higher expression levels of miR-142-5p had longer median progression-free survival as compared to patients with lower miR-142-5p levels. We demonstrated that miR-142-5p also targeted four other anti-apoptotic genes, baculoviral IAP repeat-containing 3 (BIRC3), B-cell lymphoma-2 (BCL2), BCL2 like 2 (BCL2L2), and myeloid cell leukemia sequence 1 (MCL1) specifically. Transcriptome sequencing shed light on the essential apoptosis-related pathway in which miR-142-5p may be involved. To conclude, our findings illustrate that miR-142-5p sensitizes ovarian cancer cells to cisplatin-induced apoptosis by targeting multiple anti-apoptotic genes including XIAP, and may also suggest the therapeutic potential of miR-142-5p in ovarian cancer treatment.
Subject(s)
Antineoplastic Agents/metabolism , Apoptosis/physiology , Cisplatin/metabolism , Gene Targeting/methods , MicroRNAs/metabolism , Ovarian Neoplasms/metabolism , Antineoplastic Agents/pharmacology , Antineoplastic Agents/therapeutic use , Apoptosis/drug effects , Cell Line, Tumor , Cisplatin/pharmacology , Cisplatin/therapeutic use , Dose-Response Relationship, Drug , Female , HEK293 Cells , Humans , MicroRNAs/genetics , Ovarian Neoplasms/drug therapy , Ovarian Neoplasms/geneticsABSTRACT
MicroRNAs play a crucial role in gene expression regulation in various types of cancers. Previous studies show the expression level of miR146a5p is downregulated in epithelial ovarian cancer. Further investigations suggest this downregulation is responsible for apoptosis resistance in ovarian cancer cells. However, the mechanism of how miR146a5p promotes apoptosis remains unclear. In this study, the role of miR146a5p in cisplatininduced apoptosis of ovarian cancer cells was assessed by DAPI staining, MTT assays, and monitoring expression of XIAP, BCL2L2, BIRC2 and BIRC5 through a dualluciferase assay. Our results show that miR146a5p can regulate three important antiapoptotic genes including XIAP, BCL2L2 and BIRC5 via their 3'UTRs. Not only can overexpression of miR146a5p downregulate the expression of XIAP in SKOV3 cells, but it also lowers the IC50 values of cisplatin in OVCAR3 and SKOV3 cells and enhances the susceptibility of OVCAR3, SKOV3 and primary ovarian cancer cells to cisplatininduced apoptosis. The effect of XIAP rescuing cisplatininduced apoptosis accelerated by miR146a5p further supports our conclusion. Our results suggest that the regulation of three antiapoptotic genes by miR1465p enhances the therapeutic effects of cisplatin.