Engineering and characterization of a novel Self Assembling Protein for Toxoplasma peptide vaccine in HLA-A*11:01, HLA-A*02:01 and HLA-B*07:02 transgenic mice

Improved ELISPOT protocol for monitoring Th1/Th17 T-cell response following T.gondii infection

In the monitoring of human Toxoplasma gondii infection, it is crucial to confirm the development of a specific Th1/Th17 immune response memory. The use of a simple, specific, and sensitive assay to follow the T-cell activation is thus required. Current protocols are not always specific as stimulation with peptides is Human Leukocyte Antigen (HLA)-dependent, while stimulation with total-lysis antigens tends to stimulate seronegative donors resulting to false positives. Here, an improved ELISPOT protocol is reported, using peripheral blood mononuclear cells (PBMC) of T.gondii-infected donors, incubated with the inactivated parasite. The results showed that, contrary to standard protocols, a pre-incubation step at high cell density in presence of the inactivated parasite allowed a specific Th1/Th17 response with the secretion of IFN-γ, IL-2, IL-12 and IL-17 cytokines. This protocol allows to evaluate precisely the immune response after a T.gondii infection.

Novel paradigm enables accurate monthly gestational screening to prevent congenital toxoplasmosis and more

BACKGROUND

Congenital toxoplasmosis is a treatable, preventable disease, but untreated causes death, prematurity, loss of sight, cognition and motor function, and substantial costs worldwide.

OBJECTIVES

We asked whether high performance of an Immunochromatographic-test (ICT) could enable accurate, rapid diagnosis/treatment, establishing new, improved care-paradigms at point-of-care and clinical laboratory.

METHODS

Data were obtained in 12 studies/analyses addressing: 1-feasibility/efficacy; 2-false-positives; 3-acceptability; 4-pink/black-line/all studies; 5-time/cost; 6-Quick-Information/Limit-of-detection; 7, 8-acute;-chronic; 9-epidemiology; 10-ADBio; 11,12-Commentary/Cases/Chronology.

FINDINGS

ICT was compared with gold-standard or predicate-tests. Overall, ICT performance for 1093 blood/4967 sera was 99.2%/97.5% sensitive and 99.0%/99.7% specific. However, in clinical trial, FDA-cleared-predicate tests initially caused practical, costly problems due to false-positive-IgM results. For 58 persons, 3/43 seronegative and 2/15 chronically infected persons had false positive IgM predicate tests. This caused substantial anxiety, concerns, and required costly, delayed confirmation in reference centers. Absence of false positive ICT results contributes to solutions: Lyon and Paris France and USA Reference laboratories frequently receive sera with erroneously positive local laboratory IgM results impeding patient care. Therefore, thirty-two such sera referred to Lyon's Reference laboratory were ICT-tested. We collated these with other earlier/ongoing results: 132 of 137 USA or French persons had false-positive local laboratory IgM results identified correctly as negative by ICT. Five false positive ICT results in Tunisia and Marseille, France, emphasize need to confirm positive ICT results with Sabin-Feldman-Dye-test or western blot. Separate studies demonstrated high performance in detecting acute infections, meeting FDA, CLIA, WHO REASSURED, CEMark criteria and patient and physician satisfaction with monthly-gestational-ICT-screening.

CONCLUSIONS/SIGNIFICANCE

This novel paradigm using ICT identifies likely false positives or raises suspicion that a result is truly positive, rapidly needing prompt follow up and treatment. Thus, ICT enables well-accepted gestational screening programs that facilitate rapid treatment saving lives, sight, cognition and motor function. This reduces anxiety, delays, work, and cost at point-of-care and clinical laboratories.

TRIAL REGISTRATION

NCT04474132, https://clinicaltrials.gov/study/NCT04474132 ClinicalTrials.gov.

Preorganized cyclic modules facilitate the self-assembly of protein nanostructures

The rational design of supramolecular assemblies aims to generate complex systems based on the simple information encoded in the chemical structure. Programmable molecules such as nucleic acids and polypeptides are particularly suitable for designing diverse assemblies and shapes not found in nature. Here, we describe a strategy for assembling modular architectures based on structurally and covalently preorganized subunits. Cyclization through spontaneous self-splicing of split intein and coiled-coil dimer-based interactions of polypeptide chains provide structural constraints, facilitating the desired assembly. We demonstrate the implementation of a strategy based on the preorganization of the subunits by designing a two-chain coiled-coil protein origami (CCPO) assembly that adopts a tetrahedral topology only when one or both subunit chains are covalently cyclized. Employing this strategy, we further design a 109 kDa trimeric CCPO assembly comprising 24 CC-forming segments. In this case, intein cyclization was crucial for the assembly of a concave octahedral scaffold, a newly designed protein fold. The study highlights the importance of preorganization of building modules to facilitate the self-assembly of higher-order supramolecular structures.

Immunization with the amino-terminus region of dense granule protein 6 (GRA6) of Toxoplasma gondii activates CD8+ cytotoxic T cells capable of removing tissue cysts of the parasite through antigen presentation by human HLA-A2.1

CD8+ T cells from HLA-A2.1-transgenic mice, but not wild-type mice, immunized with the amino-terminus region (aa 41-152) of dense granule protein 6 (GRA6Nt) of Toxoplasma gondii secreted large amounts of perforin and granzyme B in response to GRA6Nt through antigen presentation by HLA-A2.1 in vitro. When those CD8+ T cells were transferred into chronically infected HLA-A2.1-expressing NSG mice deficient in T cells, cerebral cyst burden of the recipients of HLA-A2.1-transgenic T cells, but not of WT T cells, became significantly less than that of control mice with no cell transfer. Furthermore, the significant reduction of the cyst burden by a transfer of the HLA-A2.1-transgenic CD8+ immune T cells required an expression of HLA-A2.1 in the recipient NSG mice. Thus, antigen presentation of GRA6Nt by human HLA-A2.1is able to activate anti-cyst CD8+ T cells that eliminate T. gondii cysts through antigen presentation by human HLA-A2.1.

Plant-Produced Nanoparticles Based on Artificial Self-Assembling Peptide Bearing the Influenza M2e Epitope

Despite advances in vaccine development, influenza remains a persistent global health threat and the search for a broad-spectrum recombinant vaccine against influenza continues. The extracellular domain of the transmembrane protein M2 (M2e) of the influenza A virus is highly conserved and can be used to develop a universal vaccine. M2e is a poor immunogen by itself, but it becomes highly immunogenic when linked to an appropriate carrier. Here, we report the transient expression of a recombinant protein comprising four tandem copies of M2e fused to an artificial self-assembling peptide (SAP) in plants. The hybrid protein was efficiently expressed in Nicotiana benthamiana using the self-replicating potato virus X-based vector pEff. The protein was purified using metal affinity chromatography under denaturing conditions. The hybrid protein was capable of self-assembly in vitro into spherical particles 15-30 nm in size. The subcutaneous immunization of mice with M2e-carrying nanoparticles induced high levels of M2e-specific IgG antibodies in serum and mucosal secretions. Immunization provided mice with protection against a lethal influenza A virus challenge. SAP-based nanoparticles displaying M2e peptides can be further used to develop a recombinant "universal" vaccine against influenza A produced in plants.

Nanoparticles as a Delivery System of Antigens for the Development of an Effective Vaccine against Toxoplasma gondii

Nanoparticles include particles ranging in size from nanometers to micrometers, whose physicochemical characteristics are optimized to make them appropriate delivery vehicles for drugs or immunogens important in the fight and/or prevention of infectious diseases. There has been a rise in the use of nanoparticles in preventive vaccine formulations as immunostimulatory adjuvants, and as vehicles for immunogen delivery to target immune cells. Toxoplasma is important worldwide, and may cause human toxoplasmosis. In immunocompetent hosts, infection is usually asymptomatic, but in immunocompromised patients it can cause serious neurological and ocular consequences, such as encephalitis and retinochoroiditis. Primary infection during pregnancy may cause abortion or congenital toxoplasmosis. Currently, there is no effective human vaccine against this disease. Evidence has emerged from several experimental studies testing nanovaccines showing them to be promising tools in the prevention of experimental toxoplasmosis. For the present study, a literature review was carried out on articles published over the last 10 years through the PubMed database, pertaining to in vivo experimental models of T. gondii infection where nanovaccines were tested and protection and immune responses evaluated. This review aims to highlight the way forward in the search for an effective vaccine for toxoplasmosis.

Toxoplasmosis vaccines: what we have and where to go?

Despite recent major advances in developing effective vaccines against toxoplasmosis, finding new protective vaccination strategies remains a challenging and elusive goal as it is critical to prevent the disease. Over the past few years, various experimental approaches have shown that developing an effective vaccine against T. gondii is achievable. However, more remains unknown due to its complicated life cycle, difficulties in clinical translation, and lack of a standardized platform. This minireview summarizes the recent advances in the development of T. gondii vaccines and the main obstacles to developing a safe, effective and durable T. gondii vaccine. The successes and failures in developing and testing vaccine candidates for the T. gondii vaccine are also discussed, which may facilitate the future development of T. gondii vaccines.

Human MHC class I molecule, HLA-A2.1, mediates activation of CD8+ T cell IFN-γ production and the T cell-dependent protection against reactivation of cerebral Toxoplasma infection

To examine whether the HLA-A2.1, one of the most common MHC class I molecules in humans, activates the protective immunity against reactivation of cerebral infection with Toxoplasma gondii, HLA-A2.1-transgenic and wild-type (WT) mice were infected and treated with sulfadiazine to establish chronic infection in their brains. One month after discontinuation of sulfadiazine, which initiates reactivation of the infection, mRNA levels for tachyzoite (the acute stage form)-specific SAG1 and numbers of the foci associated tachyzoites were significantly less in the brains of the HLA-A2.1-transgenic than WT mice. Greater numbers of IFN-γ-producing CD8+ T cells were detected in the spleens of infected transgenic than WT mice, and CD8+ T cells from the former produced markedly greater amounts of IFN-γ than the T cells from the latter in response to tachyzoite antigens in vitro. When their CD8+ T cells were systemically transferred to infected immunodeficient NSG mice expressing the HLA-A2.1, the CD8+ T cells from HLA-A2.1-transgenic mice inhibited reactivation of the cerebral infection in the recipients more efficiently than did the WT T cells. Furthermore, the inhibition of reactivation of the infection by CD8+ T cells from the transgenic mice was associated with increased cerebral expression of IFN-γ and effector molecules against tachyzoites in the recipients when compared to the WT CD8+ T cell recipients. Thus, the human HLA-A2.1 is able to effectively activate IFN-γ production of CD8+ T cells against T. gondii tachyzoites and confer a potent protection against reactivation of cerebral infection with this parasite through the CD8+ T cells activation.

Recent advances in coiled-coil peptide materials and their biomedical applications

Extensive research has gone into deciphering the sequence requirements for peptides to fold into coiled-coils of varying oligomeric states. More recently, additional signals have been introduced within coiled-coils to promote higher order assembly into biomaterials with a rich distribution of morphologies. Herein we describe these strategies for association of coiled-coil building blocks and biomedical applications. With many of the systems described herein having proven use in protein storage, cargo binding and delivery, three dimensional cell culturing and vaccine development, the future potential of coiled-coil materials to have significant biomedical impact is highly promising.

Building Programs to Eradicate Toxoplasmosis Part I: Introduction and Overview

Purpose of Review

Review building of programs to eliminate Toxoplasma infections.

Recent Findings

Morbidity and mortality from toxoplasmosis led to programs in USA, Panama, and Colombia to facilitate understanding, treatment, prevention, and regional resources, incorporating student work.

Summary

Studies foundational for building recent, regional approaches/programs are reviewed. Introduction provides an overview/review of programs in Panamá, the United States, and other countries. High prevalence/risk of exposure led to laws mandating testing in gestation, reporting, and development of broad-based teaching materials about Toxoplasma. These were tested for efficacy as learning tools for high-school students, pregnant women, medical students, physicians, scientists, public health officials and general public. Digitized, free, smart phone application effectively taught pregnant women about toxoplasmosis prevention. Perinatal infection care programs, identifying true regional risk factors, and point-of-care gestational screening facilitate prevention and care. When implemented fully across all demographics, such programs present opportunities to save lives, sight, and cognition with considerable spillover benefits for individuals and societies.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40124-022-00269-w.

Building Programs to Eradicate Toxoplasmosis Part IV: Understanding and Development of Public Health Strategies and Advances “Take a Village”

Purpose of Review

Review international efforts to build a global public health initiative focused on toxoplasmosis with spillover benefits to save lives, sight, cognition and motor function benefiting maternal and child health.

Recent Findings

Multiple countries’ efforts to eliminate toxoplasmosis demonstrate progress and context for this review and new work.

Summary

Problems with potential solutions proposed include accessibility of accurate, inexpensive diagnostic testing, pre-natal screening and facilitating tools, missed and delayed neonatal diagnosis, restricted access, high costs, delays in obtaining medicines emergently, delayed insurance pre-approvals and high medicare copays taking considerable physician time and effort, harmful shortcuts being taken in methods to prepare medicines in settings where access is restricted, reluctance to perform ventriculoperitoneal shunts promptly when needed without recognition of potential benefit, access to resources for care, especially for marginalized populations, and limited use of recent advances in management of neurologic and retinal disease which can lead to good outcomes.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40124-022-00268-x.

Vaccine Technologies and Platforms for Infectious Diseases: Current Progress, Challenges, and Opportunities

Vaccination is a key component of public health policy with demonstrated cost-effective benefits in protecting both human and animal populations. Vaccines can be manufactured under multiple forms including, inactivated (killed), toxoid, live attenuated, Virus-like Particles, synthetic peptide, polysaccharide, polysaccharide conjugate (glycoconjugate), viral vectored (vector-based), nucleic acids (DNA and mRNA) and bacterial vector/synthetic antigen presenting cells. Several processes are used in the manufacturing of vaccines and recent developments in medical/biomedical engineering, biology, immunology, and vaccinology have led to the emergence of innovative nucleic acid vaccines, a novel category added to conventional and subunit vaccines. In this review, we have summarized recent advances in vaccine technologies and platforms focusing on their mechanisms of action, advantages, and possible drawbacks.

Peptide-based supramolecular vaccine systems

Currently approved replication-competent and inactivated vaccines are limited by excessive reactogenicity and poor safety profiles, while subunit vaccines are often insufficiently immunogenic without co-administering exogenous adjuvants. Self-assembling peptide-, peptidomimetic-, and protein-based biomaterials offer a means to overcome these challenges through their inherent modularity, multivalency, and biocompatibility. As these scaffolds are biologically derived and present antigenic arrays reminiscent of natural viruses, they are prone to immune recognition and are uniquely capable of functioning as self-adjuvanting vaccine delivery vehicles that improve humoral and cellular responses. Beyond this intrinsic immunological advantage, the wide range of available amino acids allows for facile de novo design or straightforward modifications to existing sequences. This has permitted the development of vaccines and immunotherapies tailored to specific disease models, as well as generalizable platforms that have been successfully applied to prevent or treat numerous infectious and non-infectious diseases. In this review, we briefly introduce the immune system, discuss the structural determinants of coiled coils, β-sheets, peptide amphiphiles, and protein subunit nanoparticles, and highlight the utility of these materials using notable examples of their innate and adaptive immunomodulatory capacity.

Nanovaccines against Animal Pathogens: The Latest Findings

Nowadays, safe and efficacious vaccines represent powerful and cost-effective tools for global health and economic growth. In the veterinary field, these are undoubtedly key tools for improving productivity and fighting zoonoses. However, cases of persistent infections, rapidly evolving pathogens having high variability or emerging/re-emerging pathogens for which no effective vaccines have been developed point out the continuing need for new vaccine alternatives to control outbreaks. Most licensed vaccines have been successfully used for many years now; however, they have intrinsic limitations, such as variable efficacy, adverse effects, and some shortcomings. More effective adjuvants and novel delivery systems may foster real vaccine effectiveness and timely implementation. Emerging vaccine technologies involving nanoparticles such as self-assembling proteins, virus-like particles, liposomes, virosomes, and polymeric nanoparticles offer novel, safe, and high-potential approaches to address many vaccine development-related challenges. Nanotechnology is accelerating the evolution of vaccines because nanomaterials having encapsulation ability and very advantageous properties due to their size and surface area serve as effective vehicles for antigen delivery and immunostimulatory agents. This review discusses the requirements for an effective, broad-coverage-elicited immune response, the main nanoplatforms for producing it, and the latest nanovaccine applications for fighting animal pathogens.

[Toxoplasma gondii-Current drugs and future vaccines against an underestimated protozoan infection]

Toxoplasma gondii is a unicellular organism of the Apicomplexa that occurs worldwide and is therefore a close relative of the malaria pathogen Plasmodium. As T. gondii infests every warm-blooded vertebrate species as an intermediate host and has a very high prevalence worldwide, toxoplasmosis is one of the most important international foodborne diseases. Potential vaccines (human as well as veterinary) play a crucial role in controlling this disease.

The current and future role of nanovaccines in HIV-1 vaccine development

Introduction: An efficacious vaccine for HIV-1 has been sought for over 30 years to eliminate the virus from the human population. Many challenges have occurred in the attempt to produce a successful immunogen, mainly caused by the basic biology of the virus. Immunogens have been developed focusing on inducing one or more of the following types of immune responses; neutralizing antibodies, non-neutralizing antibodies, and T-cell mediated responses. One way to better present and develop an immunogen for HIV-1 is through the use of nanotechnology and nanoparticles.Areas covered: This article gives a basic overview of the HIV-1 vaccine field, as well as nanotechnology, specifically nanovaccines. It then covers the application of nanovaccines made from biological macromolecules to HIV-1 vaccine development for neutralizing antibodies, non-neutralizing antibodies, and T-cell-mediated responses.Expert opinion: Nanovaccines are an area that is ripe for further exploration in HIV-1 vaccine field. Not only are nanovaccines capable of carrying and presenting antigens in native-like conformations, but they have also repeatedly been shown to increase immunogenicity over recombinant antigens alone. Only through further research can the true role of nanovaccines in the development of an efficacious HIV-1 vaccine be established.

Advances in Toxoplasma gondii Vaccines: Current Strategies and Challenges for Vaccine Development

Toxoplasmosis, caused by the apicomplexan parasite Toxoplasma gondii, is one of the most damaging parasite-borne zoonotic diseases of global importance. While approximately one-third of the entire world’s population is estimated to be infected with T. gondii, an effective vaccine for human use remains unavailable. Global efforts in pursuit of developing a T. gondii vaccine have been ongoing for decades, and novel innovative approaches have been introduced to aid this process. A wide array of vaccination strategies have been conducted to date including, but not limited to, nucleic acids, protein subunits, attenuated vaccines, and nanoparticles, which have been assessed in rodents with promising results. Yet, translation of these in vivo results into clinical studies remains a major obstacle that needs to be overcome. In this review, we will aim to summarize the current advances in T. gondii vaccine strategies and address the challenges hindering vaccine development.

The diversity of HIV-1 fights against vaccine efficacy: how self-assembling protein nanoparticle technology may fight back

An efficacious HIV-1 vaccine has remained an elusive target for almost 40 years. The sheer diversity of the virus is one of the major roadblocks for vaccine development. HIV-1 frequently mutates and various strains predominate in different geographic regions, making the development of a globally applicable vaccine extremely difficult. Multiple approaches have been taken to overcome the issue of viral diversity, including sequence optimization, development of consensus and mosaic sequences and the use of different prime-boost approaches. To develop an efficacious vaccine, these approaches may need to be combined. One way to potentially synergize these approaches is to use a rationally designed protein nanoparticle that allows for the native-like presentation of antigens, such as the self-assembling protein nanoparticle.