Structural and Biophysical Characterization of the HCV E1E2 Heterodimer for Vaccine Development

An effective vaccine for the hepatitis C virus (HCV) is a major unmet medical and public health need, and it requires an antigen that elicits immune responses to multiple key conserved epitopes. Decades of research have generated a number of vaccine candidates; based on these data and research through clinical development, a vaccine antigen based on the E1E2 glycoprotein complex appears to be the best choice. One bottleneck in the development of an E1E2-based vaccine is that the antigen is challenging to produce in large quantities and at high levels of purity and antigenic/functional integrity. This review describes the production and characterization of E1E2-based vaccine antigens, both membrane-associated and a novel secreted form of E1E2, with a particular emphasis on the major challenges facing the field and how those challenges can be addressed.

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COVID-19 Vaccines Currently under Preclinical and Clinical Studies, and Associated Antiviral Immune Response

Vaccines ◽

10.3390/vaccines8040649 ◽

2020 ◽

Vol 8 (4) ◽

pp. 649 ◽

Cited By ~ 2

Author(s):

Swati Jain ◽

Himanshu Batra ◽

Poonam Yadav ◽

Subhash Chand

Keyword(s):

Immune Responses ◽

Vaccine Development ◽

Economic Status ◽

Vaccine Safety ◽

Effective Vaccine ◽

Vaccine Platform ◽

Antiviral Immune Response ◽

Vaccine Candidates ◽

Preclinical And Clinical Studies ◽

Everyday Living

With a death toll of over one million worldwide, the COVID-19 pandemic caused by SARS-CoV-2 has become the most devastating humanitarian catastrophe in recent decades. The fear of acquiring infection and spreading to vulnerable people has severely impacted society’s socio-economic status. To put an end to this growing number of infections and deaths as well as to switch from restricted to everyday living, an effective vaccine is desperately needed. As a result, enormous efforts have been made globally to develop numerous vaccine candidates in a matter of months. Currently, over 30 vaccine candidates are under assessment in clinical trials, with several undergoing preclinical studies. Here, we reviewed the major vaccine candidates based on the specific vaccine platform utilized to develop them. We also discussed the immune responses generated by these candidates in humans and preclinical models to determine vaccine safety, immunogenicity, and efficacy. Finally, immune responses induced in recovered COVID-19 patients and their possible vaccine development implications were also briefly reviewed.

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SARS-CoV-2 vaccines strategies: a comprehensive review of phase 3 candidates

npj Vaccines ◽

10.1038/s41541-021-00292-w ◽

2021 ◽

Vol 6 (1) ◽

Cited By ~ 3

Author(s):

Nikolaos C. Kyriakidis ◽

Andrés López-Cortés ◽

Eduardo Vásconez González ◽

Alejandra Barreto Grimaldos ◽

Esteban Ortiz Prado

Keyword(s):

Neutralizing Antibodies ◽

Large Scale ◽

Vaccine Development ◽

Rna Virus ◽

Protein S ◽

Effective Vaccine ◽

Phase 3 ◽

Vaccine Candidates ◽

Advantages And Disadvantages ◽

The World

AbstractThe new SARS-CoV-2 virus is an RNA virus that belongs to the Coronaviridae family and causes COVID-19 disease. The newly sequenced virus appears to originate in China and rapidly spread throughout the world, becoming a pandemic that, until January 5th, 2021, has caused more than 1,866,000 deaths. Hence, laboratories worldwide are developing an effective vaccine against this disease, which will be essential to reduce morbidity and mortality. Currently, there more than 64 vaccine candidates, most of them aiming to induce neutralizing antibodies against the spike protein (S). These antibodies will prevent uptake through the human ACE-2 receptor, thereby limiting viral entrance. Different vaccine platforms are being used for vaccine development, each one presenting several advantages and disadvantages. Thus far, thirteen vaccine candidates are being tested in Phase 3 clinical trials; therefore, it is closer to receiving approval or authorization for large-scale immunizations.

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Use of a Clostridioides difficile Murine Immunization and Challenge Model to Evaluate Single and Combination Vaccine Adjuvants Consisting of Alum and NKT Cell-Activating Ligands

Frontiers in Immunology ◽

10.3389/fimmu.2021.818734 ◽

2022 ◽

Vol 12 ◽

Author(s):

Gillian A. Lang ◽

Kaylee Norman ◽

Souwelimatou Amadou Amani ◽

Tyler M. Shadid ◽

Jimmy D. Ballard ◽

...

Keyword(s):

Immune Responses ◽

Additional Benefit ◽

Vaccine Antigen ◽

Vaccine Adjuvants ◽

Inkt Cells ◽

Nkt Cell ◽

Cell Compartment ◽

Clostridioides Difficile ◽

Vaccine Antigens ◽

The Impact

Adjuvant combinations may enhance or broaden the expression of immune responses to vaccine antigens. Information on whether established Alum type adjuvants can be combined with experimental CD1d ligand adjuvants is currently lacking. In this study, we used a murine Clostridioides difficile immunization and challenge model to evaluate Alum (Alhydrogel™), α-galactosylceramide (α-GC), and one of its analogs 7DW8-5 singly and in combination as vaccine adjuvants. We observed that the Alum/α-GC combination caused modest enhancement of vaccine antigen-specific IgG1 and IgG2b responses, and a broadening to include IgG2c that did not significantly impact overall protection. Similar observations were made using the Alum/7DW8-5 combination. Examination of the impact of adjuvants on NKT cells revealed expansion of invariant NKT (iNKT) cells with modest expansion of their iNKTfh subset and little effect on diverse NKT (dNKT) cells. Side effects of the adjuvants was determined and revealed transient hepatotoxicity when Alum/α-GC was used in combination but not singly. In summary these results showed that the Alum/α-GC or the Alum/7DW8-5 combination could exert distinct effects on the NKT cell compartment and on isotype switch to produce Th1-driven IgG subclasses in addition to Alum/Th2-driven subclasses. While Alum alone was efficacious in stimulating IgG-mediated protection, and α-GC offered no apparent additional benefit in the C. difficile challenge model, the work herein reveals immune response features that could be optimized and harnessed in other vaccine contexts.

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A Combined Adjuvant TF–Al Consisting of TFPR1 and Aluminum Hydroxide Augments Strong Humoral and Cellular Immune Responses in Both C57BL/6 and BALB/c Mice

Vaccines ◽

10.3390/vaccines9121408 ◽

2021 ◽

Vol 9 (12) ◽

pp. 1408

Author(s):

Qiao Li ◽

Zhihua Liu ◽

Yi Liu ◽

Chen Liang ◽

Jiayi Shu ◽

...

Keyword(s):

Immune Responses ◽

Vaccine Development ◽

Inbred Mouse ◽

Effective Vaccine ◽

Mouse Strains ◽

Cellular Immune Responses ◽

Recombinant Hbsag ◽

Cellular Immune

TFPR1 is a novel adjuvant for protein and peptide antigens, which has been demonstrated in BALB/c mice in our previous studies; however, its adjuvanticity in mice with different genetic backgrounds remains unknown, and its adjuvanticity needs to be improved to fit the requirements for various vaccines. In this study, we first compared the adjuvanticity of TFPR1 in two commonly used inbred mouse strains, BALB/c and C57BL/6 mice, in vitro and in vivo, and demonstrated that TFPR1 activated TLR2 to exert its immune activity in vivo. Next, to prove the feasibility of TFPR1 acting as a major component of combined adjuvants, we prepared a combined adjuvant, TF–Al, by formulating TFPR1 and alum at a certain ratio and compared its adjuvanticity with that of TFPR1 and alum alone using OVA and recombinant HBsAg as model antigens in both BALB/c and C57BL/6 mice. Results showed that TFPR1 acts as an effective vaccine adjuvant in both BALB/c mice and C57BL/6 mice, and further demonstrated the role of TLR2 in the adjuvanticity of TFPR1 in vivo. In addition, we obtained a novel combined adjuvant, TF–Al, based on TFPR1, which can augment antibody and cellular immune responses in mice with different genetic backgrounds, suggesting its promise for vaccine development in the future.

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Characterization of the Immune Response of MERS-CoV Vaccine Candidates Derived from Two Different Vectors in Mice

Viruses ◽

10.3390/v12010125 ◽

2020 ◽

Vol 12 (1) ◽

pp. 125 ◽

Cited By ~ 7

Author(s):

Entao Li ◽

Feihu Yan ◽

Pei Huang ◽

Hang Chi ◽

Shengnan Xu ◽

...

Keyword(s):

Immune Responses ◽

Antibody Response ◽

Rabies Virus ◽

Vaccine Development ◽

Vaccine Candidate ◽

Viral Vector ◽

Vaccine Vector ◽

Vaccine Candidates ◽

Cellular Immune Responses ◽

Cellular Immune

Middle East respiratory syndrome (MERS) is an acute, high-mortality-rate, severe infectious disease caused by an emerging MERS coronavirus (MERS-CoV) that causes severe respiratory diseases. The continuous spread and great pandemic potential of MERS-CoV make it necessarily important to develop effective vaccines. We previously demonstrated that the application of Gram-positive enhancer matrix (GEM) particles as a bacterial vector displaying the MERS-CoV receptor-binding domain (RBD) is a very promising MERS vaccine candidate that is capable of producing potential neutralization antibodies. We have also used the rabies virus (RV) as a viral vector to design a recombinant vaccine by expressing the MERS-CoV S1 (spike) protein on the surface of the RV. In this study, we compared the immunological efficacy of the vaccine candidates in BALB/c mice in terms of the levels of humoral and cellular immune responses. The results show that the rabies virus vector-based vaccine can induce remarkably earlier antibody response and higher levels of cellular immunity than the GEM particles vector. However, the GEM particles vector-based vaccine candidate can induce remarkably higher antibody response, even at a very low dose of 1 µg. These results indicate that vaccines constructed using different vaccine vector platforms for the same pathogen have different rates and trends in humoral and cellular immune responses in the same animal model. This discovery not only provides more alternative vaccine development platforms for MERS-CoV vaccine development, but also provides a theoretical basis for our future selection of vaccine vector platforms for other specific pathogens.

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Vaccination with Recombinant Cryptococcus Proteins in Glucan Particles Protects Mice against Cryptococcosis in a Manner Dependent upon Mouse Strain and Cryptococcal Species

mBio ◽

10.1128/mbio.01872-17 ◽

2017 ◽

Vol 8 (6) ◽

Cited By ~ 27

Author(s):

Charles A. Specht ◽

Chrono K. Lee ◽

Haibin Huang ◽

Maureen M. Hester ◽

Jianhua Liu ◽

...

Keyword(s):

Cryptococcus Neoformans ◽

Mouse Strain ◽

Subunit Vaccine ◽

Vaccine Development ◽

Inflammatory Responses ◽

Cryptococcus Gattii ◽

Candidate Vaccine ◽

Effective Vaccine ◽

Mouse Strains ◽

Vaccine Antigens

ABSTRACT Development of a vaccine to protect against cryptococcosis is a priority given the enormous global burden of disease in at-risk individuals. Using glucan particles (GPs) as a delivery system, we previously demonstrated that mice vaccinated with crude Cryptococcus -derived alkaline extracts were protected against lethal challenge with Cryptococcus neoformans and Cryptococcus gattii . The goal of the present study was to identify protective protein antigens that could be used in a subunit vaccine. Using biased and unbiased approaches, six candidate antigens (Cda1, Cda2, Cda3, Fpd1, MP88, and Sod1) were selected, recombinantly expressed in Escherichia coli , purified, and loaded into GPs. Three mouse strains (C57BL/6, BALB/c, and DR4) were then vaccinated with the antigen-laden GPs, following which they received a pulmonary challenge with virulent C. neoformans and C. gattii strains. Four candidate vaccines (GP-Cda1, GP-Cda2, GP-Cda3, and GP-Sod1) afforded a significant survival advantage in at least one mouse model; some vaccine combinations provided added protection over that seen with either antigen alone. Vaccine-mediated protection against C. neoformans did not necessarily predict protection against C. gattii . Vaccinated mice developed pulmonary inflammatory responses that effectively contained the infection; many surviving mice developed sterilizing immunity. Predicted T helper cell epitopes differed between mouse strains and in the degree to which they matched epitopes predicted in humans. Thus, we have discovered cryptococcal proteins that make promising candidate vaccine antigens. Protection varied depending on the mouse strain and cryptococcal species, suggesting that a successful human subunit vaccine will need to contain multiple antigens, including ones that are species specific. IMPORTANCE The encapsulated fungi Cryptococcus neoformans and Cryptococcus gattii are responsible for nearly 200,000 deaths annually, mostly in immunocompromised individuals. An effective vaccine could substantially reduce the burden of cryptococcosis. However, a major gap in cryptococcal vaccine development has been the discovery of protective antigens to use in vaccines. Here, six cryptococcal proteins with potential as vaccine antigens were expressed recombinantly and purified. Mice were then vaccinated with glucan particle preparations containing each antigen. Of the six candidate vaccines, four protected mice from a lethal cryptococcal challenge. However, the degree of protection varied as a function of mouse strain and cryptococcal species. These preclinical studies identify cryptococcal proteins that could serve as candidate vaccine antigens and provide a proof of principle regarding the feasibility of protein antigen-based vaccines to protect against cryptococcosis.

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Genetically identical primate modelling systems for HIV vaccines

Reproduction Fertility and Development ◽

10.1071/rd98057 ◽

1998 ◽

Vol 10 (8) ◽

pp. 651 ◽

Cited By ~ 2

Author(s):

Stephen J. Kent ◽

Ian M. Lewis

Keyword(s):

Immune Responses ◽

Hiv Infection ◽

Vaccine Development ◽

Careful Consideration ◽

Hiv Vaccine ◽

Effective Vaccine ◽

Hiv Vaccines ◽

Major Step ◽

Immunodeficiency Virus ◽

Hiv 1

There is an urgent need for a safe and effective vaccine to prevent human immunodeficiency virus (HIV) infection. Several HIV vaccine candidates have shown promise, but many concerns regarding the safety and efficacy of current vaccines remain. A major hindrance in HIV vaccine development is a poor understanding of precisely what functions HIV vaccines are required to perform in order to protect humans from HIV-1. Only higher primates (i.e. macaques, chimpanzees and humans) are susceptible to HIV-1 or the closely related virus ‘simian immunodeficiency virus’. These species are outbred and there are remarkable genetic differences in both the immune responses to vaccines and their susceptibility to infection. The development of genetically identical macaques would be a major step towards dissecting what immune responses are required to protect from HIV infection. For example, live attenuated HIV-1 vaccines are likely to be highly efficacious, but will induce disease in a substantial proportion of recipients. Defining why a live attenuated vaccine is effective should allow safer vaccines to be developed, retaining only the immunologic properties of an effective vaccine. The reduction in ‘background genetic noise’ obtained by studying genetically identical primates would provide concise answers to critical HIV vaccine issues, by studying a minimal number of animals. Such an approach could potentially be employed in other diseases where non-human primates are the only available model. Small studies can be performed where identical twins are generated by embryo bisection; however, larger studies where multiple immune parameters are simultaneously evaluated would be facilitated by cloning technology. Despite the technical difficulties to be overcome, the potential gains in human health from the development of genetically identical non-human primates are worthy of careful consideration.

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An Overview of the Progress Made on the Coronavirus Vaccine

E3S Web of Conferences ◽

10.1051/e3sconf/202018503042 ◽

2020 ◽

Vol 185 ◽

pp. 03042

Author(s):

Yu Fang

Keyword(s):

United States ◽

Infectious Diseases ◽

Incidence Rate ◽

Scientific Reasoning ◽

Vaccine Development ◽

The United States ◽

Ideal Solution ◽

Vaccine Candidates ◽

Number Of Individuals

The Coronavirus Disease-2019 (COVID-19) pandemic has led to a critical economic crash around the globe, affecting billions of people worldwide. Without a cure, the number of cases continues to increase exponentially. Countries, including the United States, Brazil, and India, currently lead in the number of cases with numbers soaring in the millions. Immunization is crucial to preventing the spread of infectious diseases and can help a large number of individuals quickly while keeping current cases under control. Following the publication of the genome sequence of SARS-CoV-2, vaccine development has been accelerated at an unprecedented rate. 115 vaccine candidates are currently under study with the hope of finding an ideal solution and mitigating the Coronavirus incidence rate. With some vaccine candidates having more potential than others, this review focuses on the characterization of different vaccine options. The analysis of probable vaccines, including mRNA vaccines and adenovirus vaccines, is conducted, and the scientific reasoning behind the vaccines is also discussed. In this review, the latest strategy vaccine is introduced and the effective vaccines are analysed.

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Characterization of Plasmodium falciparum Proteome at Asexual Blood Stages for Screening of Effective Vaccine Candidates: An Immunoinformatics Approach

Immunology and Immunogenetics Insights ◽

10.4137/iii.s24755 ◽

2015 ◽

Vol 7 ◽

pp. III.S24755 ◽

Cited By ~ 5

Author(s):

Satarudra Prakash Singh ◽

Vishal Verma ◽

Bhartendu Nath Mishra

Keyword(s):

Plasmodium Falciparum ◽

T Cell ◽

Cell Epitope ◽

Epitope Prediction ◽

Proteome Analysis ◽

Effective Vaccine ◽

Secretory Proteins ◽

Vaccine Candidates ◽

Proteome Level

Malaria is a complex parasitic disease that is currently causing great concerns globally owing to the resistance to antimalarial drugs and lack of an effective vaccine. The present study involves the characterization of extracellular secretory proteins as vaccine candidates derived from proteome analysis of Plasmodium falciparum at asexual blood stages of malaria. Among the screened 32 proteins, 31 were predicted as antigens by the VaxiJen program, and 26 proteins had less than two transmembrane spanning regions predicted using the THMMM program. Moreover, 10 and 5 proteins were predicted to contain secretory signals by SignalP and TargetP, respectively. T-cell epitope prediction using MULTIPRED2 and NetCTL programs revealed that most of the predicted antigens are immunogenic and contain more than 10% supertype and 5% promiscuous epitopes of HLA-A, -B, or -DR. We anticipate that T-cell immune responses against asexual blood stages of Plasmodium are dispersed on a relatively large number of parasite antigens. This is the first report, to the best of our knowledge, offering new insights, at the proteome level, for the putative screening of effective vaccine candidates against the malaria pathogen. The findings also suggest new ways forward for the modern omics-guided vaccine target discovery using reverse vaccinology.

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