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1.
PLoS Pathog ; 18(2): e1010282, 2022 02.
Article in English | MEDLINE | ID: covidwho-1753213

ABSTRACT

Immunization with radiation-attenuated sporozoites (RAS) can confer sterilizing protection against malaria, although the mechanisms behind this protection are incompletely understood. We performed a systems biology analysis of samples from the Immunization by Mosquito with Radiation Attenuated Sporozoites (IMRAS) trial, which comprised P. falciparum RAS-immunized (PfRAS), malaria-naive participants whose protection from malaria infection was subsequently assessed by controlled human malaria infection (CHMI). Blood samples collected after initial PfRAS immunization were analyzed to compare immune responses between protected and non-protected volunteers leveraging integrative analysis of whole blood RNA-seq, high parameter flow cytometry, and single cell CITEseq of PBMCs. This analysis revealed differences in early innate immune responses indicating divergent paths associated with protection. In particular, elevated levels of inflammatory responses early after the initial immunization were detrimental for the development of protective adaptive immunity. Specifically, non-classical monocytes and early type I interferon responses induced within 1 day of PfRAS vaccination correlated with impaired immunity. Non-protected individuals also showed an increase in Th2 polarized T cell responses whereas we observed a trend towards increased Th1 and T-bet+ CD8 T cell responses in protected individuals. Temporal differences in genes associated with natural killer cells suggest an important role in immune regulation by these cells. These findings give insight into the immune responses that confer protection against malaria and may guide further malaria vaccine development. Trial registration: ClinicalTrials.gov NCT01994525.


Subject(s)
Immunity , Inflammation , Malaria Vaccines/immunology , Malaria, Falciparum/immunology , Plasmodium falciparum/immunology , Sporozoites/immunology , Adult , Animals , Anopheles/parasitology , Female , Humans , Immunization/methods , Insect Bites and Stings/immunology , Malaria, Falciparum/parasitology , Male , Mosquito Vectors/parasitology , T-Lymphocytes/immunology , Vaccination/methods , Vaccines, Attenuated/immunology
2.
EBioMedicine ; 75: 103762, 2022 Jan.
Article in English | MEDLINE | ID: covidwho-1587929

ABSTRACT

BACKGROUND: Vaccines in emergency use are efficacious against COVID-19, yet vaccine-induced prevention against nasal SARS-CoV-2 infection remains suboptimal. METHODS: Since mucosal immunity is critical for nasal prevention, we investigated the efficacy of an intramuscular PD1-based receptor-binding domain (RBD) DNA vaccine (PD1-RBD-DNA) and intranasal live attenuated influenza-based vaccines (LAIV-CA4-RBD and LAIV-HK68-RBD) against SARS-CoV-2. FINDINGS: Substantially higher systemic and mucosal immune responses, including bronchoalveolar lavage IgA/IgG and lung polyfunctional memory CD8 T cells, were induced by the heterologous PD1-RBD-DNA/LAIV-HK68-RBD as compared with other regimens. When vaccinated animals were challenged at the memory phase, prevention of robust SARS-CoV-2 infection in nasal turbinate was achieved primarily by the heterologous regimen besides consistent protection in lungs. The regimen-induced antibodies cross-neutralized variants of concerns. Furthermore, LAIV-CA4-RBD could boost the BioNTech vaccine for improved mucosal immunity. INTERPRETATION: Our results demonstrated that intranasal influenza-based boost vaccination induces mucosal and systemic immunity for effective SARS-CoV-2 prevention in both upper and lower respiratory systems. FUNDING: This study was supported by the Research Grants Council Collaborative Research Fund, General Research Fund and Health and Medical Research Fund in Hong Kong; Outbreak Response to Novel Coronavirus (COVID-19) by the Coalition for Epidemic Preparedness Innovations; Shenzhen Science and Technology Program and matching fund from Shenzhen Immuno Cure BioTech Limited; the Health@InnoHK, Innovation and Technology Commission of Hong Kong; National Program on Key Research Project of China; donations from the Friends of Hope Education Fund; the Theme-Based Research Scheme.


Subject(s)
COVID-19 Vaccines , COVID-19/prevention & control , Immunization, Secondary , Influenza Vaccines , SARS-CoV-2 , Vaccines, DNA , Administration, Intranasal , Animals , COVID-19/genetics , COVID-19/immunology , COVID-19 Vaccines/genetics , COVID-19 Vaccines/immunology , Chlorocebus aethiops , Disease Models, Animal , Dogs , Female , HEK293 Cells , Humans , Immunity, Mucosal , Influenza Vaccines/genetics , Influenza Vaccines/immunology , Madin Darby Canine Kidney Cells , Male , Mice , Mice, Inbred BALB C , Mice, Transgenic , SARS-CoV-2/genetics , SARS-CoV-2/immunology , Vaccines, Attenuated/genetics , Vaccines, Attenuated/immunology , Vaccines, DNA/genetics , Vaccines, DNA/immunology , Vero Cells
3.
Methods Mol Biol ; 2410: 229-263, 2022.
Article in English | MEDLINE | ID: covidwho-1575944

ABSTRACT

Vaccines are one of mankind's greatest medical advances, and their use has drastically reduced and in some cases eliminated (e.g., smallpox) disease and death caused by infectious agents. Traditional vaccine modalities including live-attenuated pathogen vaccines, wholly inactivated pathogen vaccines, and protein-based pathogen subunit vaccines have successfully been used to create efficacious vaccines against measles, mumps, rubella, polio, and yellow fever. These traditional vaccine modalities, however, take many months to years to develop and have thus proven less effective for use in creating vaccines to emerging or reemerging infectious diseases (EIDs) including influenza, Human immunodeficiency virus (HIV), dengue virus (DENV), chikungunya virus (CHIKV), West Nile virus (WNV), Middle East respiratory syndrome (MERS), and the severe acute respiratory syndrome coronaviruses 1 and 2 (SARS-CoV and SARS-CoV-2). As factors such as climate change and increased globalization continue to increase the pace of EID development, newer vaccine modalities are required to develop vaccines that can prevent or attenuate EID outbreaks throughout the world. One such modality, DNA vaccines, has been studied for over 30 years and has numerous qualities that make them ideal for meeting the challenge of EIDs including; (1) DNA vaccine candidates can be designed within hours of publishing of a pathogens genetic sequence; (2) they can be manufactured cheaply and rapidly in large quantities; (3) they are thermostable and have reduced requirement for a cold-chain during distribution, and (4) they have a remarkable safety record in the clinic. Optimizations made in plasmid design as well as in DNA vaccine delivery have greatly improved the immunogenicity of these vaccines. Here we describe the process of making a DNA vaccine to an EID pathogen and describe methods used for assessing the immunogenicity and protective efficacy of DNA vaccines in small animal models.


Subject(s)
Communicable Diseases, Emerging , Vaccines, DNA , Viral Vaccines , Animals , COVID-19 , Communicable Diseases, Emerging/prevention & control , Humans , Immunity , SARS Virus , SARS-CoV-2 , Vaccines, Attenuated/immunology , Vaccines, DNA/immunology , Vaccines, Inactivated/immunology , Vaccines, Synthetic/immunology , Viral Vaccines/genetics , Viral Vaccines/immunology
4.
Proc Natl Acad Sci U S A ; 118(50)2021 12 14.
Article in English | MEDLINE | ID: covidwho-1560743

ABSTRACT

Single-dose vaccines with the ability to restrict SARS-CoV-2 replication in the respiratory tract are needed for all age groups, aiding efforts toward control of COVID-19. We developed a live intranasal vector vaccine for infants and children against COVID-19 based on replication-competent chimeric bovine/human parainfluenza virus type 3 (B/HPIV3) that express the native (S) or prefusion-stabilized (S-2P) SARS-CoV-2 S spike protein, the major protective and neutralization antigen of SARS-CoV-2. B/HPIV3/S and B/HPIV3/S-2P replicated as efficiently as B/HPIV3 in vitro and stably expressed SARS-CoV-2 S. Prefusion stabilization increased S expression by B/HPIV3 in vitro. In hamsters, a single intranasal dose of B/HPIV3/S-2P induced significantly higher titers compared to B/HPIV3/S of serum SARS-CoV-2-neutralizing antibodies (12-fold higher), serum IgA and IgG to SARS-CoV-2 S protein (5-fold and 13-fold), and IgG to the receptor binding domain (10-fold). Antibodies exhibited broad neutralizing activity against SARS-CoV-2 of lineages A, B.1.1.7, and B.1.351. Four weeks after immunization, hamsters were challenged intranasally with 104.5 50% tissue-culture infectious-dose (TCID50) of SARS-CoV-2. In B/HPIV3 empty vector-immunized hamsters, SARS-CoV-2 replicated to mean titers of 106.6 TCID50/g in lungs and 107 TCID50/g in nasal tissues and induced moderate weight loss. In B/HPIV3/S-immunized hamsters, SARS-CoV-2 challenge virus was reduced 20-fold in nasal tissues and undetectable in lungs. In B/HPIV3/S-2P-immunized hamsters, infectious challenge virus was undetectable in nasal tissues and lungs; B/HPIV3/S and B/HPIV3/S-2P completely protected against weight loss after SARS-CoV-2 challenge. B/HPIV3/S-2P is a promising vaccine candidate to protect infants and young children against HPIV3 and SARS-CoV-2.


Subject(s)
COVID-19 Vaccines/administration & dosage , COVID-19/prevention & control , SARS-CoV-2/immunology , Administration, Intranasal , Animals , Antibodies, Viral/blood , COVID-19 Vaccines/genetics , COVID-19 Vaccines/immunology , Cricetinae , Genetic Vectors , Immunization , Parainfluenza Virus 3, Bovine/genetics , Parainfluenza Virus 3, Human/genetics , Spike Glycoprotein, Coronavirus/genetics , Spike Glycoprotein, Coronavirus/immunology , Vaccines, Attenuated/administration & dosage , Vaccines, Attenuated/genetics , Vaccines, Attenuated/immunology , Vaccines, Synthetic/administration & dosage , Vaccines, Synthetic/genetics , Vaccines, Synthetic/immunology
5.
J Med Virol ; 94(1): 82-87, 2022 01.
Article in English | MEDLINE | ID: covidwho-1544347

ABSTRACT

The rapid spread of the Delta variant suggests that SARS-CoV-2 will likely be rampant for months or years and could claim millions of more lives. All the known vaccines cannot well defeat SARS-CoV-2 due to their limited efficacy and production efficiency, except for the neglected live-attenuated vaccines (LAVs), which could have a much higher efficacy and much higher production efficiency than other vaccines. LAVs, like messiahs, have defeated far more pathogenic viruses than other vaccines in history, and most current human vaccines for viral diseases are safe LAVs. LAVs can block completely infection and transmission of relevant viruses and their variants. They can hence inhibit the emergence of vaccine-escape and virulence-enhancing variants and protect immunologically abnormal individuals better in general. The safety of COVID-19 LAVs, which could save millions of more lives, can be solidly guaranteed through animal experiments and clinical trials. The safety of COVID-19 LAVs could be greatly enhanced with intramuscular or oral administration, or administration along with humanized neutralizing monoclonal antibodies. Together, extensive global collaboration, which can greatly accelerate the development of safe COVID-19 LAVs, is imminently needed.


Subject(s)
COVID-19 Vaccines/immunology , COVID-19/prevention & control , SARS-CoV-2/immunology , Vaccines, Attenuated/immunology , Drug Development , Humans , Mass Vaccination
6.
Sci Rep ; 11(1): 22164, 2021 11 12.
Article in English | MEDLINE | ID: covidwho-1514425

ABSTRACT

The influenza A non-structural protein 1 (NS1) is known for its ability to hinder the synthesis of type I interferon (IFN) during viral infection. Influenza viruses lacking NS1 (ΔNS1) are under clinical development as live attenuated human influenza virus vaccines and induce potent influenza virus-specific humoral and cellular adaptive immune responses. Attenuation of ΔNS1 influenza viruses is due to their high IFN inducing properties, that limit their replication in vivo. This study demonstrates that pre-treatment with a ΔNS1 virus results in an antiviral state which prevents subsequent replication of homologous and heterologous viruses, preventing disease from virus respiratory pathogens, including SARS-CoV-2. Our studies suggest that ΔNS1 influenza viruses could be used for the prophylaxis of influenza, SARS-CoV-2 and other human respiratory viral infections, and that an influenza virus vaccine based on ΔNS1 live attenuated viruses would confer broad protection against influenza virus infection from the moment of administration, first by non-specific innate immune induction, followed by specific adaptive immunity.


Subject(s)
Influenza A virus/immunology , Influenza Vaccines/therapeutic use , Interferon Type I/immunology , Orthomyxoviridae Infections/prevention & control , Vaccines, Attenuated/therapeutic use , Viral Nonstructural Proteins/immunology , Adaptive Immunity , Animals , COVID-19/immunology , COVID-19/prevention & control , Chickens , Gene Deletion , Humans , Influenza A virus/genetics , Influenza Vaccines/genetics , Influenza Vaccines/immunology , Influenza, Human/immunology , Influenza, Human/prevention & control , Mice , Mice, Inbred C57BL , Orthomyxoviridae Infections/immunology , Vaccines, Attenuated/genetics , Vaccines, Attenuated/immunology , Viral Nonstructural Proteins/genetics
7.
mBio ; 12(4): e0141521, 2021 08 31.
Article in English | MEDLINE | ID: covidwho-1370889

ABSTRACT

Severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2) possesses a discriminative polybasic cleavage motif in its spike protein that is recognized by the host furin protease. Proteolytic cleavage activates the spike protein, thereby affecting both the cellular entry pathway and cell tropism of SARS-CoV-2. Here, we investigated the impact of the furin cleavage site on viral growth and pathogenesis using a hamster animal model infected with SARS-CoV-2 variants bearing mutations at the furin cleavage site (S gene mutants). In the airway tissues of hamsters, the S gene mutants exhibited low growth properties. In contrast to parental pathogenic SARS-CoV-2, hamsters infected with the S gene mutants showed no body weight loss and only a mild inflammatory response, thereby indicating the attenuated variant nature of S gene mutants. This transient infection was sufficient for inducing protective neutralizing antibodies that cross-react with different SARS-CoV-2 lineages. Consequently, hamsters inoculated with S gene mutants showed resistance to subsequent infection with both the parental strain and the currently emerging SARS-CoV-2 variants belonging to lineages B.1.1.7 and P.1. Taken together, our findings revealed that the loss of the furin cleavage site causes attenuation in the airway tissues of hamsters and highlighted the potential benefits of S gene mutants as potential immunogens. IMPORTANCE SARS-CoV-2 uses its spike protein to enter target cells. The spike protein is cleaved by a host protease, and this event facilitates viral entry and broadens cell tropism. In this study, we employed SARS-CoV-2 mutants lacking the S protein cleavage site and characterized their growth and pathogenicity using hamsters, a laboratory animal model for SARS-CoV-2 infection. These mutants exerted low pathogenicity but induced sufficient levels of neutralizing antibodies in hamsters, which protected hamsters from rechallenge with pathogenic clinical SARS-CoV-2 strains. These virus mutants may be used as protective immunogens against SARS-CoV-2 infection.


Subject(s)
Antibodies, Neutralizing/immunology , Antibodies, Viral/immunology , COVID-19/pathology , SARS-CoV-2 , Spike Glycoprotein, Coronavirus/genetics , Animals , Cell Line , Chlorocebus aethiops , Cross Reactions/immunology , Furin/metabolism , Humans , SARS-CoV-2/genetics , SARS-CoV-2/immunology , SARS-CoV-2/pathogenicity , Vaccines, Attenuated/immunology , Vero Cells , Virulence/genetics
8.
J Virol ; 95(17): e0040221, 2021 08 10.
Article in English | MEDLINE | ID: covidwho-1350001

ABSTRACT

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the viral pathogen responsible for the current coronavirus disease 2019 (COVID-19) pandemic. As of 19 May 2021, John Hopkins University's COVID-19 tracking platform reported 3.3 million deaths associated with SARS-CoV-2 infection. Currently, the World Health Organization has granted emergency use listing (EUL) to six COVID-19 vaccine candidates. However, much of the pathogenesis observed during SARS-CoV-2 infection remains elusive. To gain insight into the contribution of individual accessory open reading frame (ORF) proteins in SARS-CoV-2 pathogenesis, we used our recently described reverse-genetics system approach to successfully engineer recombinant SARS-CoV-2 (rSARS-CoV-2) constructs; we removed individual viral ORF3a, -6, -7a, -7b, and -8 proteins from them, and we characterized the resulting recombinant viruses in vitro and in vivo. Our results indicate differences in plaque morphology, with ORF-deficient (ΔORF) viruses producing smaller plaques than those of the wild type (rSARS-CoV-2/WT). However, growth kinetics of ΔORF viruses were like those of rSARS-CoV-2/WT. Interestingly, infection of K18 human angiotensin-converting enzyme 2 (hACE2) transgenic mice with the ΔORF rSARS-CoV-2s identified ORF3a and ORF6 as the major contributors of viral pathogenesis, while ΔORF7a, ΔORF7b, and ΔORF8 rSARS-CoV-2s induced pathology comparable to that of rSARS-CoV-2/WT. This study demonstrates the robustness of our reverse-genetics system to generate rSARS-CoV-2 constructs and the major role for ORF3a and ORF6 in viral pathogenesis, providing important information for the generation of attenuated forms of SARS-CoV-2 for their implementation as live attenuated vaccines for the treatment of SARS-CoV-2 infection and associated COVID-19. IMPORTANCE Despite great efforts put forward worldwide to combat the current coronavirus disease 2019 (COVID-19) pandemic, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) continues to be a human health and socioeconomic threat. Insights into the pathogenesis of SARS-CoV-2 and the contribution of viral proteins to disease outcome remain elusive. Our study aims (i) to determine the contribution of SARS-CoV-2 accessory open reading frame (ORF) proteins to viral pathogenesis and disease outcome and (ii) to develop a synergistic platform combining our robust reverse-genetics system to generate recombinant SARS-CoV-2 constructs with a validated rodent model of infection and disease. We demonstrate that SARS-CoV-2 ORF3a and ORF6 contribute to lung pathology and ultimately disease outcome in K18 hACE2 transgenic mice, while ORF7a, ORF7b, and ORF8 have little impact on disease outcome. Moreover, our combinatory platform serves as a foundation for generating attenuated forms of the virus to develop live attenuated vaccines for the treatment of SARS-CoV-2.


Subject(s)
Angiotensin-Converting Enzyme 2/immunology , Open Reading Frames/immunology , SARS-CoV-2 , Viral Proteins , A549 Cells , Angiotensin-Converting Enzyme 2/genetics , Animals , COVID-19 Vaccines/genetics , COVID-19 Vaccines/immunology , Chlorocebus aethiops , HEK293 Cells , Humans , Mice , Mice, Transgenic , SARS-CoV-2/genetics , SARS-CoV-2/immunology , Vaccines, Attenuated/genetics , Vaccines, Attenuated/immunology , Vero Cells , Viral Proteins/genetics , Viral Proteins/immunology
9.
Emerg Microbes Infect ; 10(1): 1626-1637, 2021 Dec.
Article in English | MEDLINE | ID: covidwho-1348038

ABSTRACT

Coronaviruses (CoVs) can infect a variety of hosts, including humans, livestock and companion animals, and pose a serious threat to human health and the economy. The current COVID-19 pandemic, which is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has killed millions of people. Unfortunately, effective treatments for CoVs infection are still lacking, suggesting the importance of coronavirus vaccines. Our previous work showed that CoV nonstuctural protein 14 (nsp14) functions as (guanine-N7)-methyltransferase (N7-MTase), which is involved in RNA cap formation. Moreover, we found that N7-MTase is well conserved among different CoVs and is a universal target for developing antivirals against CoVs. Here, we show that N7-MTase of CoVs can be an ideal target for designing live attenuated vaccines. Using murine hepatitis virus strain A59 (MHV-A59), a representative and well-studied model of coronaviruses, we constructed N7-MTase-deficient recombinant MHV D330A and Y414A. These two mutants are highly attenuated in mice and exhibit similar replication efficiency to the wild-type (WT) virus in the cell culture. Furthermore, a single dose immunization of D330A or Y414A can induce long-term humoral immune responses and robust CD4+ and CD8+ T cell responses, which can provide full protection against the challenge of a lethal-dose of MHV-A59. Collectively, this study provides an ideal strategy to design live attenuated vaccines for coronavirus by abolishing viral RNA N7-MTase activity. This approach may apply to other RNA viruses that encode their own conservative viral N7-methyltransferase.


Subject(s)
COVID-19 Vaccines/immunology , COVID-19/prevention & control , SARS-CoV-2/immunology , Vaccines, Attenuated/immunology , Animals , COVID-19 Vaccines/administration & dosage , Cytokines/biosynthesis , Humans , Immunity, Cellular , Immunity, Humoral , Immunogenicity, Vaccine , Interferon Type I/biosynthesis , Male , Mice , Mutation , Vaccines, Attenuated/administration & dosage , Viral Nonstructural Proteins/genetics , Viral Nonstructural Proteins/immunology
10.
Expert Rev Vaccines ; 20(9): 1059-1063, 2021 09.
Article in English | MEDLINE | ID: covidwho-1348017

ABSTRACT

INTRODUCTION: The Development of the SARS-CoV-2 virus vaccine and its update on an ongoing pandemic is the first subject of the world health agenda. AREAS COVERED: First, we will scrutinize the biological features of the measles virus (MV), variola virus (smallpox virus), influenza virus, and their vaccines to compare them with the SARS-CoV-2 virus and vaccine. Next, we will discuss the statistical details of measuring the effectiveness of an improved vaccine. EXPERT OPINION: Amidst the pandemic, we ought to acknowledge our prior experiences with respiratory viruses and vaccines. In the planning stage of observational Phase-III vaccine effectiveness studies, the sample size, sampling method, statistical model, and selection of variables are crucial in obtaining high-quality and valid results.


Subject(s)
COVID-19 Vaccines/immunology , COVID-19/prevention & control , Immunity, Cellular/immunology , SARS-CoV-2/immunology , COVID-19/pathology , Humans , Influenza Vaccines/immunology , Mass Vaccination/methods , Measles virus/immunology , Measles-Mumps-Rubella Vaccine/immunology , Orthomyxoviridae/immunology , Smallpox Vaccine/immunology , Vaccination , Vaccines, Attenuated/immunology , Variola virus/immunology
11.
Expert Rev Vaccines ; 20(9): 1051-1057, 2021 09.
Article in English | MEDLINE | ID: covidwho-1327291

ABSTRACT

INTRODUCTION: The COVID-19 pandemic is a globalized health concern caused by a beta-coronavirus named Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2). Since December 2019, when this outbreak flared in Wuhan, China, COVID-19 cases have been continuously rising all over the world. Due to the emergence of SARS-CoV-2 mutants, subsequent waves are flowing in a faster manner as compared to the primary wave, which is more contagious and causing higher mortality. Recently, India has emerged as the new epicenter of the second wave by mutants of SARS-CoV-2. After almost eighteen months of this outbreak, some COVID-19 dedicated therapeutics and vaccines are available, and a few are under trial, but the situation is still uncontrolled. AREA COVERED: This perspective article covers the repurposing of childhood vaccines like Bacille Calmette-Guerin (BCG), Measles, Mumps, Rubella (MMR), and Oral Polio Vaccine (OPV), which are live attenuated vaccines and have been shown the protective effect through 'trained immunity and 'crossreactivity.' EXPERT OPINION: This perspective article has suggested that combinatorial use of these childhood vaccines might exert a better protective effect along with the available COVID-19 therapeutic and vaccines which could be considered as a preventive option against SARS-CoV-2 infection as well as its subsequent waves.


Subject(s)
BCG Vaccine/immunology , COVID-19 Vaccines/immunology , COVID-19/prevention & control , Drug Repositioning/methods , SARS-CoV-2/immunology , Vaccines, Attenuated/immunology , Cross Reactions/immunology , Diphtheria-Tetanus-Pertussis Vaccine/immunology , Humans , Immunity, Innate/drug effects , Immunity, Innate/immunology , Measles-Mumps-Rubella Vaccine/immunology , Poliovirus Vaccine, Oral/immunology , Spike Glycoprotein, Coronavirus/immunology , Vaccination , Yellow Fever Vaccine/immunology
12.
Proc Natl Acad Sci U S A ; 118(29)2021 07 20.
Article in English | MEDLINE | ID: covidwho-1292059

ABSTRACT

Successfully combating the COVID-19 pandemic depends on mass vaccination with suitable vaccines to achieve herd immunity. Here, we describe COVI-VAC, the only live attenuated severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccine currently in clinical development. COVI-VAC was developed by recoding a segment of the viral spike protein with synonymous suboptimal codon pairs (codon-pair deoptimization), thereby introducing 283 silent (point) mutations. In addition, the furin cleavage site within the spike protein was deleted from the viral genome for added safety of the vaccine strain. Except for the furin cleavage site deletion, the COVI-VAC and parental SARS-CoV-2 amino acid sequences are identical, ensuring that all viral proteins can engage with the host immune system of vaccine recipients. COVI-VAC was temperature sensitive in vitro yet grew robustly (>107 plaque forming units/mL) at the permissive temperature. Tissue viral loads were consistently lower, lung pathology milder, and weight loss reduced in Syrian golden hamsters (Mesocricetus auratus) vaccinated intranasally with COVI-VAC compared to those inoculated with wild-type (WT) virus. COVI-VAC inoculation generated spike IgG antibody levels and plaque reduction neutralization titers similar to those in hamsters inoculated with WT virus. Upon challenge with WT virus, COVI-VAC vaccination reduced lung challenge viral titers, resulted in undetectable virus in the brain, and protected hamsters from almost all SARS-CoV-2-associated weight loss. Highly attenuated COVI-VAC is protective at a single intranasal dose in a relevant in vivo model. This, coupled with its large-scale manufacturing potential, supports its potential use in mass vaccination programs.


Subject(s)
COVID-19 Vaccines/immunology , COVID-19 Vaccines/pharmacology , COVID-19/immunology , COVID-19/prevention & control , SARS-CoV-2/immunology , Animals , Antibodies, Viral/immunology , COVID-19/epidemiology , Chlorocebus aethiops , Female , Humans , Male , Mesocricetus , Pandemics , Spike Glycoprotein, Coronavirus/genetics , Spike Glycoprotein, Coronavirus/immunology , Vaccination , Vaccines, Attenuated/immunology , Vero Cells
13.
Vet Microbiol ; 254: 109014, 2021 Mar.
Article in English | MEDLINE | ID: covidwho-1107294

ABSTRACT

TW-like infectious bronchitis virus (IBV) with high pathogenicity is becoming the predominant IBV type circulating in China. To develop vaccines against TW-like IBV strains and investigate the critical genes associated with their virulence, GD strain was attenuated by 140 serial passages in specific-pathogen-free embryonated eggs and the safety and efficacy of the attenuated GD strain (aGD) were examined. The genome sequences of GD and aGD were also compared and the effects of mutations in the S gene were observed. The results revealed that aGD strain showed no obvious pathogenicity with superior protective efficacy against TW-like and QX-like virulent IBV strains. The genomes of strains aGD and GD shared high similarity (99.87 %) and most of the mutations occurred in S gene. Recombinant IBV strain rGDaGD-S, in which the S gene was replaced with the corresponding regions from aGD, showed decreased pathogenicity compared with its parental strain. In conclusion, attenuated TW-like IBV strain aGD is a potential vaccine candidate and the S gene is responsible for its attenuation. Our research has laid the foundation for future exploration of the attenuating molecular mechanism of IBV.


Subject(s)
Chickens/virology , Infectious bronchitis virus/genetics , Infectious bronchitis virus/pathogenicity , Spike Glycoprotein, Coronavirus/genetics , Viral Vaccines/genetics , Virulence Factors/genetics , Animals , Chick Embryo , Coronavirus Infections/prevention & control , Infectious bronchitis virus/immunology , Poultry Diseases/prevention & control , Poultry Diseases/virology , Reverse Genetics/methods , Serial Passage , Specific Pathogen-Free Organisms , Spike Glycoprotein, Coronavirus/immunology , Vaccines, Attenuated/immunology , Viral Vaccines/immunology
14.
Proc Natl Acad Sci U S A ; 118(21)2021 05 25.
Article in English | MEDLINE | ID: covidwho-1233774

ABSTRACT

The COVID-19 pandemic triggered an unparalleled pursuit of vaccines to induce specific adaptive immunity, based on virus-neutralizing antibodies and T cell responses. Although several vaccines have been developed just a year after SARS-CoV-2 emerged in late 2019, global deployment will take months or even years. Meanwhile, the virus continues to take a severe toll on human life and exact substantial economic costs. Innate immunity is fundamental to mammalian host defense capacity to combat infections. Innate immune responses, triggered by a family of pattern recognition receptors, induce interferons and other cytokines and activate both myeloid and lymphoid immune cells to provide protection against a wide range of pathogens. Epidemiological and biological evidence suggests that the live-attenuated vaccines (LAV) targeting tuberculosis, measles, and polio induce protective innate immunity by a newly described form of immunological memory termed "trained immunity." An LAV designed to induce adaptive immunity targeting a particular pathogen may also induce innate immunity that mitigates other infectious diseases, including COVID-19, as well as future pandemic threats. Deployment of existing LAVs early in pandemics could complement the development of specific vaccines, bridging the protection gap until specific vaccines arrive. The broad protection induced by LAVs would not be compromised by potential antigenic drift (immune escape) that can render viruses resistant to specific vaccines. LAVs might offer an essential tool to "bend the pandemic curve," averting the exhaustion of public health resources and preventing needless deaths and may also have therapeutic benefits if used for postexposure prophylaxis of disease.


Subject(s)
COVID-19/prevention & control , Immunity, Innate , Pandemics/prevention & control , Vaccines/immunology , Adaptive Immunity , COVID-19/immunology , COVID-19 Vaccines/immunology , Immunity, Heterologous , Immunologic Memory , SARS-CoV-2/immunology , Vaccines, Attenuated/immunology
15.
J Exp Med ; 218(4)2021 04 05.
Article in English | MEDLINE | ID: covidwho-1066211

ABSTRACT

Yellow fever virus (YFV) live attenuated vaccine can, in rare cases, cause life-threatening disease, typically in patients with no previous history of severe viral illness. Autosomal recessive (AR) complete IFNAR1 deficiency was reported in one 12-yr-old patient. Here, we studied seven other previously healthy patients aged 13 to 80 yr with unexplained life-threatening YFV vaccine-associated disease. One 13-yr-old patient had AR complete IFNAR2 deficiency. Three other patients vaccinated at the ages of 47, 57, and 64 yr had high titers of circulating auto-Abs against at least 14 of the 17 individual type I IFNs. These antibodies were recently shown to underlie at least 10% of cases of life-threatening COVID-19 pneumonia. The auto-Abs were neutralizing in vitro, blocking the protective effect of IFN-α2 against YFV vaccine strains. AR IFNAR1 or IFNAR2 deficiency and neutralizing auto-Abs against type I IFNs thus accounted for more than half the cases of life-threatening YFV vaccine-associated disease studied here. Previously healthy subjects could be tested for both predispositions before anti-YFV vaccination.


Subject(s)
Antibodies, Neutralizing/immunology , Autoantibodies/immunology , Autoimmune Diseases , COVID-19 , Genetic Diseases, Inborn , Interferon-alpha , Receptor, Interferon alpha-beta , SARS-CoV-2 , Yellow Fever Vaccine , Yellow fever virus , Adolescent , Adult , Aged , Autoimmune Diseases/genetics , Autoimmune Diseases/immunology , COVID-19/genetics , COVID-19/immunology , Female , Genetic Diseases, Inborn/genetics , Genetic Diseases, Inborn/immunology , HEK293 Cells , Humans , Interferon-alpha/genetics , Interferon-alpha/immunology , Male , Middle Aged , Receptor, Interferon alpha-beta/deficiency , Receptor, Interferon alpha-beta/immunology , SARS-CoV-2/genetics , SARS-CoV-2/immunology , Vaccines, Attenuated/genetics , Vaccines, Attenuated/immunology , Yellow Fever Vaccine/adverse effects , Yellow Fever Vaccine/genetics , Yellow Fever Vaccine/immunology , Yellow fever virus/genetics , Yellow fever virus/immunology
16.
J Pharm Sci ; 110(2): 627-634, 2021 02.
Article in English | MEDLINE | ID: covidwho-1060168

ABSTRACT

Once Covid-19 vaccines become available, 5-10 billion vaccine doses should be globally distributed, stored and administered. In this commentary, we discuss how this enormous challenge could be addressed for viral vector-based Covid-19 vaccines by learning from the wealth of formulation development experience gained over the years on stability issues related to live attenuated virus vaccines and viral vector vaccines for other diseases. This experience has led -over time- to major improvements on storage temperature, shelf-life and in-use stability requirements. First, we will cover work on 'classical' live attenuated virus vaccines as well as replication competent viral vector vaccines. Subsequently, we address replication deficient viral vector vaccines. Freeze drying and storage at 2-8 °C with a shelf life of years has become the norm. In the case of pandemics with incredibly high and urgent product demands, however, the desire for rapid and convenient distribution chains combined with short end-user storage times require that liquid formulations with shelf lives of months stored at 2-8 °C be considered. In confronting this "perfect storm" of Covid-19 vaccine stability challenges, understanding the many lessons learned from decades of development and manufacturing of live virus-based vaccines is the shortest path for finding promising and rapid solutions.


Subject(s)
COVID-19 Vaccines/immunology , COVID-19/prevention & control , Drug Stability , Genetic Vectors , SARS-CoV-2/immunology , COVID-19/immunology , Drug Compounding , Drug Storage , Freeze Drying , Humans , SARS-CoV-2/genetics , Vaccines, Attenuated/immunology
17.
Nature ; 590(7845): 320-325, 2021 02.
Article in English | MEDLINE | ID: covidwho-953381

ABSTRACT

The expanding pandemic of coronavirus disease 2019 (COVID-19) requires the development of safe, efficacious and fast-acting vaccines. Several vaccine platforms are being leveraged for a rapid emergency response1. Here we describe the development of a candidate vaccine (YF-S0) for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) that uses live-attenuated yellow fever 17D (YF17D) vaccine as a vector to express a noncleavable prefusion form of the SARS-CoV-2 spike antigen. We assess vaccine safety, immunogenicity and efficacy in several animal models. YF-S0 has an excellent safety profile and induces high levels of SARS-CoV-2 neutralizing antibodies in hamsters (Mesocricetus auratus), mice (Mus musculus) and cynomolgus macaques (Macaca fascicularis), and-concomitantly-protective immunity against yellow fever virus. Humoral immunity is complemented by a cellular immune response with favourable T helper 1 polarization, as profiled in mice. In a hamster model2 and in macaques, YF-S0 prevents infection with SARS-CoV-2. Moreover, a single dose conferred protection from lung disease in most of the vaccinated hamsters within as little as 10 days. Taken together, the quality of the immune responses triggered and the rapid kinetics by which protective immunity can be attained after a single dose warrant further development of this potent SARS-CoV-2 vaccine candidate.


Subject(s)
COVID-19 Vaccines/immunology , COVID-19/immunology , COVID-19/prevention & control , Genetic Vectors/genetics , SARS-CoV-2/immunology , Vaccines, Attenuated/immunology , Yellow Fever Vaccine/genetics , Animals , COVID-19 Vaccines/administration & dosage , COVID-19 Vaccines/adverse effects , COVID-19 Vaccines/genetics , Cricetinae , Disease Models, Animal , Female , Glycosylation , Macaca fascicularis/genetics , Macaca fascicularis/immunology , Macaca fascicularis/virology , Male , Mesocricetus/genetics , Mesocricetus/immunology , Mesocricetus/virology , Mice , Safety , Spike Glycoprotein, Coronavirus/chemistry , Spike Glycoprotein, Coronavirus/genetics , Spike Glycoprotein, Coronavirus/immunology , Spike Glycoprotein, Coronavirus/metabolism , Vaccines, Attenuated/administration & dosage , Vaccines, Attenuated/adverse effects , Vaccines, Attenuated/genetics
18.
Nat Commun ; 11(1): 6121, 2020 11 30.
Article in English | MEDLINE | ID: covidwho-951617

ABSTRACT

Modified Vaccinia Ankara (MVA) is a highly attenuated poxvirus vector that is widely used to develop vaccines for infectious diseases and cancer. We demonstrate the construction of a vaccine platform based on a unique three-plasmid system to efficiently generate recombinant MVA vectors from chemically synthesized DNA. In response to the ongoing global pandemic caused by SARS coronavirus-2 (SARS-CoV-2), we use this vaccine platform to rapidly produce fully synthetic MVA (sMVA) vectors co-expressing SARS-CoV-2 spike and nucleocapsid antigens, two immunodominant antigens implicated in protective immunity. We show that mice immunized with these sMVA vectors develop robust SARS-CoV-2 antigen-specific humoral and cellular immune responses, including potent neutralizing antibodies. These results demonstrate the potential of a vaccine platform based on synthetic DNA to efficiently generate recombinant MVA vectors and to rapidly develop a multi-antigenic poxvirus-based SARS-CoV-2 vaccine candidate.


Subject(s)
COVID-19 Vaccines/immunology , Coronavirus Nucleocapsid Proteins/immunology , Spike Glycoprotein, Coronavirus/immunology , Vaccines, Synthetic/immunology , Adaptive Immunity , Animals , Antibodies, Neutralizing , Antibodies, Viral/immunology , Antigens, Viral/immunology , Genetic Vectors/immunology , Humans , Immunity, Cellular , Mice , Phosphoproteins/immunology , SARS-CoV-2/immunology , Vaccines, Attenuated/immunology , Vaccinia virus/immunology , Viral Vaccines/immunology
19.
Biomolecules ; 10(10)2020 10 14.
Article in English | MEDLINE | ID: covidwho-906422

ABSTRACT

Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) is the causative agent of the coronavirus disease 2019 (COVID-19) pandemic spreading around the world, causing massive distress to the world's economy and affecting healthcare systems worldwide. Although some exposed individuals have no symptoms and most symptomatic infections are not severe, COVID-19 cases span a wide spectrum, ranging from mild to critical and sometimes resulting in life-threatening complications, such as pneumonia, severe respiratory distress and cardiac problems. Currently, there is no curative drug for COVID-19 and vaccines are still under development. We are presenting here a strategy for the fast development of natural live-attenuated SARS-CoV-2 vaccines. Our proposed approach is based on screening for, identifying, analyzing and selecting naturally attenuated yet highly immunogenic SARS-CoV-2 strains, which may lead to a shorter cycle of vaccine development, as well as higher vaccine effectiveness.


Subject(s)
Coronavirus Infections/immunology , Pneumonia, Viral/immunology , Vaccines, Attenuated/immunology , Viral Vaccines/immunology , COVID-19 , COVID-19 Vaccines , Coronavirus Infections/prevention & control , Humans , Pandemics/prevention & control , Pneumonia, Viral/prevention & control , Vaccines, Attenuated/adverse effects , Viral Vaccines/adverse effects
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