Designs of Antigen Structure and Composition for Improved Protein-Based Vaccine Efficacy

Helminth-induced immune modulation in colorectal cancer: exploring therapeutic applications

Colorectal cancer is one of the most lethal tumors, posing a financial and healthcare burden. This study investigates how helminths and pre-existing diseases such as colitis, obesity, diabetes, and gut microbiota issues influence colon cancer development and prognosis. The immune system's protective immunosuppressive response to helminth invasion minimizes inflammation-induced cell damage and DNA mutations, lowering the risk of colorectal cancer precursor lesions. Helminth infection-mediated immunosuppression can hasten colorectal cancer growth and metastasis, which is detrimental to patient outcomes. Some helminth derivatives can activate immune cells to attack cancer cells, making them potentially useful as colorectal cancer vaccines or therapies. This review also covers gene editing approaches. We discovered that using CRISPR/Cas9 to inhibit live helminths modulates miRNA, which limits tumor growth. We propose more multicenter studies into helminth therapy's long-term effects and immune regulation pathways. We hope to treat colorectal cancer patients with helminth therapy and conventional cancer treatments in an integrative setting.

Lyophilization Strategy Enhances the Thermostability and Field-Based Stability of Conjugated and Comixed Subunit Liposomal Adjuvant-containing Tuberculosis Vaccine Formulation (ID93 + GLA-LSQ)

ID93 + GLA-LSQ is an adjuvanted recombinant protein vaccine candidate that has demonstrated robust T-cell immunity and reduced bacterial burden in preclinical studies. Here, we explored the strategy of lyophilization by introducing 10% Trehalose as a bulking agent and cryoprotectant to develop a thermostable single-vial formulation of ID93 + GLA-LSQ. We further examined the stability of lyophilized formulations stored at 4 and 37 °C in the research laboratory and field stability across five study sites. Co-mixed (CoVL) and conjugated (ConjVL) formulations were prepared and assessed for various stability parameters including cake quality, melting point, liposome reformation, particle size, GLA/QS-21 concentration, presence of ID93, and biological activity for three months in the research laboratory and nine months at ambient temperature in five health centers. Stability assessment for both formulations stored in the research laboratory for three months showed that they were physically stable and biologically active. The field-based ambient stability assessment showed that the formulations maintained physical integrity, liposomal structure, and antigen integrity, with limited chemical degradation of GLA and QS-21 adjuvants observed. ConjVL retains GLA slightly better than the CoVL formulation, and a moderate increase in particle size was observed after nine months. These findings showed that the formulations demonstrate a promising stability profile after extended storage at ambient temperature, suggesting the potential for real-world application without strict refrigeration requirements.

Pseudomonas aeruginosa Vaccine Development: Lessons, Challenges, and Future Innovations

Pseudomonas aeruginosa is an opportunistic pathogen with a multidrug-resistant profile that has become a critical threat to global public health. It is one of the main causes of severe nosocomial infections, including ventilator-associated pneumonia, chronic infections in patients with cystic fibrosis, and bloodstream infections in immunosuppressed individuals. Development of vaccines against P. aeruginosa is a major challenge owing to the high capacity of this bacterium to form biofilms, its wide arsenal of virulence factors (including secretion systems, lipopolysaccharides, and outer membrane proteins), and its ability to evade the host immune system. This review provides a comprehensive historical overview of vaccine development efforts targeting this pathogen, ranging from early attempts in the 1970s to recent advancements, including vaccines based on novel proteins and emerging technologies such as nanoparticles and synthetic conjugates. Despite numerous promising preclinical developments, very few candidates have progressed to clinical trials, and none have achieved final approval. This panorama highlights the significant scientific efforts undertaken and the inherent complexity of successfully developing an effective vaccine against P. aeruginosa.

Immunization with recombinant HPV16-E7d in fusion with Flagellin as a cancer vaccine: Effect of antigen-adjuvant orientation on the immune response pattern

Human papillomavirus (HPV) is the leading cause of cervical cancer worldwide. The pathogenesis of HPV is mainly dependent on its E7 and E6 proteins. Up to now, different adjuvants have been used to enhance the efficacy of the immune response against these two proteins. In this study, Flagellin (FLA) was used as adjuvant to test adjuvant activity and also see whether its orientation of attachment can affect the immune response pattern. The E7d-FLA and FLA-E7d in pET28a vector were constructed and then the recombinant proteins were expressed in E. coli BL21 (DE3) bacteria under IPTG induction. The expression of recombinant E7d-FLA and FLA-E7d proteins is confirmed by SDS-PAGE and western blot. Then, recombinant fusion proteins were purified using a nickel-nitrilotriacetic acid (Ni-NTA) column. The recombinant proteins were checked for endotoxin contamination and then quantified by Bradford. Eight-to-ten-week-old male Balb/C mice were immunized subcutaneously with 10 µg recombinant E7d-FLA, FLA-E7d and HPV16E7d vaccine on days 0, 14 and 28. In addition, PBS and FLA groups were considered as control group. Then, spleen cells were harvested to assess lymphocyte proliferation and IFN-γ, IL-4 and IL-17 cytokines. In addition, mice sera were used for specific total IgG and IgG1, IgG2a, IgG2b and IgM antibodies assessment by ELISA. The results show that E7d-FLA is more potent in the induction of lymphocyte proliferation, CTL response and specific total IgG, IgG2a and IgG2b response, while the FLA-E7d vaccine was associated with more IFN-γ, and IL-17 cytokine response. The results of this study proved the ability of FLA as an adjuvant in fusion with E7d in the induction of cellular and humoral immune responses. In addition, it also emphasizes that antigen-adjuvant orientation can affect the immune response strength and polarization against HPV E7d vaccine candidate. HIGHLIGHTS: Flagellin is attached to HPV-16 E7d at the C- or N-terminus to create E7d-FLA and FLA-E7d candidate vaccines. The E7d-FLA vaccine showed a significant increase in lymphocyte proliferation, CTL response and IgG response versus FLA-E7d vaccine. The FLA-E7d vaccine is associated with a significant increase in IFN-γ and IL-17 cytokines response versus E7d-FLA vaccine. It seems that that antigen-adjuvant orientation is an important parameter in the strength and polarization of immune response in HPV E7d vaccine candidate.

Lipid Antigens: Revealing the Hidden Players in Adaptive Immune Responses

Traditionally, research on the adaptive immune system has focused on protein antigens, but emerging evidence has underscored the essential role of lipid antigens in immune modulation. Lipid antigens are presented by CD1 molecules and activate invariant natural killer T (iNKT) cells and group 1 CD1-restricted T cells, whereby they impact immune responses to pathogens and tumors. Recent advances in mass spectrometry, imaging techniques, and lipidomics have revolutionized the identification and characterization of lipid antigens and enhanced our understanding of their structural diversity and functional significance. These advancements have paved the way for lipid-based vaccines and immunotherapies through the application of nanoparticles and synthetic lipid antigens designed to boost immune responses against cancers and infectious diseases. Lipid trafficking, CD1 molecule interactions, and the immune system's response to lipid antigens are yet to be completely understood, particularly in the context of autoimmunity and microbial infections. In the years to come, continued research efforts are needed to uncover its underlying biological mechanisms and to exploit the full potential of therapies directed against lipid antigens.

Conjugation of Multiple Proteins Onto the Surface of PLGA/Lipid Hybrid Nanoparticles

Nanoparticles are increasingly being used in the development of vaccines for disease prevention or treatment. Recent research has demonstrated that conjugating a protein onto the surface of nanoparticles can significantly increase its immunogenicity. Considering various pathogens that threaten human health, multivalent vaccines are often desirable. Up to now, nanoparticle-based vaccines are mostly limited to one protein per nanoparticle. No research has been conducted to explore the possibility of conjugating more than one protein onto the surface of a nanoparticle. Here we developed a specific conjugation strategy to conjugate multiple proteins to the PLGA/lipid hybrid nanoparticle surface. The maleimide-thiol Michael addition, Aizde-DBCO (Dibenzocyclooctyne), and TCO (trans-cycloctene)-Tetrazine click chemistry were employed to conjugate three different proteins, subunit keyhole limpet hemocyanin (sKLH), Ovalbumin (OVA), and cross-reactive material 197 (CRM197), to the surface of PLGA/lipid hybrid nanoparticles (hNPs). The successful results of this study pave the way for developing multivalent vaccines against different pathogens.

Robust genome and cell engineering via in vitro and in situ circularized RNAs

Circularization can improve RNA persistence, yet simple and scalable approaches to achieve this are lacking. Here we report two methods that facilitate the pursuit of circular RNAs (cRNAs): cRNAs developed via in vitro circularization using group II introns, and cRNAs developed via in-cell circularization by the ubiquitously expressed RtcB protein. We also report simple purification protocols that enable high cRNA yields (40-75%) while maintaining low immune responses. These methods and protocols facilitate a broad range of applications in stem cell engineering as well as robust genome and epigenome targeting via zinc finger proteins and CRISPR-Cas9. Notably, cRNAs bearing the encephalomyocarditis internal ribosome entry enabled robust expression and persistence compared with linear capped RNAs in cardiomyocytes and neurons, which highlights the utility of cRNAs in these non-dividing cells. We also describe genome targeting via deimmunized Cas9 delivered as cRNA and a long-range multiplexed protein engineering methodology for the combinatorial screening of deimmunized protein variants that enables compatibility between persistence of expression and immunogenicity in cRNA-delivered proteins. The cRNA toolset will aid research and the development of therapeutics.

Cryptococcus neoformans infections: aspartyl protease potential to improve outcome in susceptible hosts

Though a confined or a broad population is exposed respectively to endemic or pandemic infections, in the same environment, some individuals resist the development of infections. The attributed reason is the inheritance of a set of immune system genes that can efficiently deal with the pathogens. In this study, we show how outbred mice differentially respond to Cryptococcus neoformans, a fungal pathogen, and the mechanism through which the surviving mice mount a protective immune defense. We identified that those mice developing antibodies specifically against Pep1p, an aspartic protease secreted by C. neoformans, had significantly improved survival. Vaccination (either prophylactic or therapeutic) with a recombinant Pep1p significantly increased the survival of the mice by decreasing the fungal load and stimulating a protective immune response. Passive immunization of C. neoformans-infected mice with monoclonal antibodies developed against Pep1p also improves the survival of the mice by increasing phagocytosis of C. neoformans and decreasing the multiplication of this fungus. Together, these data demonstrate the prophylactic and therapeutic potentials of the C. neoformans antigenic protein Pep1p or Pep1p-specific antibodies against this fungal infection. Also, this study suggests that the immunological interaction and thereby the responses developed against a pathogen guide the hosts to behave differentially against microbial pathogenicity.

IMPORTANCE

Vaccination and immunotherapies against fungal pathogens still remain a challenge. Here, we show using an in vivo model based on outbred mice that development of antibodies against Pep1p, an antigenic protein of the fungal pathogen Cryptococcus neoformans, confers resistance to this fungal infection. In support of this observation, prophylactic or therapeutic immunization of the mice with recombinant Pep1p could improve their survival when infected with a lethal dose of C. neoformans. Moreover, passive therapy with monoclonal anti-Pep1p antibodies also enhanced survival of the mice from C. neoformans infection. The associated antifungal mechanisms were mounting of a protective immune response and the development of fungal specific antibodies that decrease the fungal burden due to an increase in their phagocytosis and/or inhibit the fungal multiplication. Together, our study demonstrates (a) the mode of host-fungal interaction and the immune response developed thereby play a crucial role in developing resistance against C. neoformans; (b) Pep1p, an aspartic protease as well as an antigenic protein secreted by C. neoformans, can be exploited for vaccination (both prophylactic and therapeutic) or immunotherapy to improve the host defense during this fungal infection.

Bioinformatics Analysis and Immunogenicity Assessment of the Novel Multi-Stage DNA Vaccine W541 Against Mycobacterium Tuberculosis

BACKGROUND

Vaccination is one of the effective measures to prevent latent tuberculosis infection (LTBI) from developing into active tuberculosis (TB). Applying bioinformatics methods to pre-evaluate the biological characteristics and immunogenicity of vaccines can improve the efficiency of vaccine development.

OBJECTIVES

To evaluate the immunogenicity of TB vaccine W541 and to explore the application of bioinformatics technology in TB vaccine research.

METHODS

This study concatenated the immunodominant sequences of Ag85A, Ag85B, Rv3407, and Rv1733c to construct the W541 DNA vaccine. Then, bioinformatics methods were used to analyze the physicochemical properties, antigenicity, allergenicity, toxicity, and population coverage of the vaccine, to identify its epitopes, and to perform molecular docking with MHC alleles and Toll-like receptor 4 (TLR4) of the host. Finally, the immunogenicity of the vaccine was evaluated in animal experiments.

RESULTS

The W541 vaccine protein is a soluble cytoplasmic protein with a half-life of 1.1 h in vivo and an instability index of 45.37. It has good antigenicity and wide population coverage without allergenicity and toxicity. It contains 138 HTL epitopes, 73 CTL epitopes, 8 linear and 14 discontinuous B cell epitopes, and has a strong affinity for TLR4. Immune simulations have shown that it can effectively stimulate innate and adaptive immune responses. Animal experiments confirmed that the W541 DNA vaccine could effectively activate Th1- and Th17-type immune responses, producing high levels of IFN-γ and IL-17A, but could not significantly increase antibody levels.

CONCLUSION

The W541 DNA vaccine can induce strong cellular immune responses. However, further optimization of the vaccine design is needed to make the expressed protein more stable in vivo. Bioinformatics analysis could reveal the physicochemical and immunological information of vaccines, which is critical for guiding vaccine design and development.

Leveraging artificial intelligence in vaccine development: A narrative review

Vaccine development stands as a cornerstone of public health efforts, pivotal in curbing infectious diseases and reducing global morbidity and mortality. However, traditional vaccine development methods are often time-consuming, costly, and inefficient. The advent of artificial intelligence (AI) has ushered in a new era in vaccine design, offering unprecedented opportunities to expedite the process. This narrative review explores the role of AI in vaccine development, focusing on antigen selection, epitope prediction, adjuvant identification, and optimization strategies. AI algorithms, including machine learning and deep learning, leverage genomic data, protein structures, and immune system interactions to predict antigenic epitopes, assess immunogenicity, and prioritize antigens for experimentation. Furthermore, AI-driven approaches facilitate the rational design of immunogens and the identification of novel adjuvant candidates with optimal safety and efficacy profiles. Challenges such as data heterogeneity, model interpretability, and regulatory considerations must be addressed to realize the full potential of AI in vaccine development. Integrating emerging technologies, such as single-cell omics and synthetic biology, promises to enhance vaccine design precision and scalability. This review underscores the transformative impact of AI on vaccine development and highlights the need for interdisciplinary collaborations and regulatory harmonization to accelerate the delivery of safe and effective vaccines against infectious diseases.

Enhanced Immune Responses in Mice by Combining the Mpox Virus B6R-Protein and Aluminum Hydroxide-CpG Vaccine Adjuvants

Novel adjuvants and innovative combinations of adjuvants (Adjuvant Systems) have facilitated the development of enhanced and new vaccines against re-emerging and challenging pathogenic microorganisms. Nonetheless, the efficacy of adjuvants is influenced by various factors, and the same adjuvant may generate entirely different immune responses when paired with different antigens. Herein, we combined the MPXV-B6R antigen with BC02, a novel adjuvant with proprietary technology, to assess its capability to induce both cellular and humoral immunity in mouse models. Mice received two intramuscular injections of B6R-BC02, which resulted in the production of MPXV-specific IgG, IgG1, and IgG2a antibodies. Additionally, it elicited strong MPXV-specific Th1-oriented cellular immunity and persistent effector memory B-cell responses. The advantages of BC02 were further validated, including rapid initiation of the immune response, robust recall memory, and sustained immune response induction. Although the potential of immunized mice to produce serum-neutralizing antibodies against the vaccinia virus requires further improvement, the exceptional performance of BC02 as an adjuvant for the MPXV-B6R antigen has been consistently demonstrated.

A Comprehensive Review of Our Understanding and Challenges of Viral Vaccines against Swine Pathogens

Pig farming has become a strategically significant and economically important industry across the globe. It is also a potentially vulnerable sector due to challenges posed by transboundary diseases in which viral infections are at the forefront. Among the porcine viral diseases, African swine fever, classical swine fever, foot and mouth disease, porcine reproductive and respiratory syndrome, pseudorabies, swine influenza, and transmissible gastroenteritis are some of the diseases that cause substantial economic losses in the pig industry. It is a well-established fact that vaccination is undoubtedly the most effective strategy to control viral infections in animals. From the period of Jenner and Pasteur to the recent new-generation technology era, the development of vaccines has contributed significantly to reducing the burden of viral infections on animals and humans. Inactivated and modified live viral vaccines provide partial protection against key pathogens. However, there is a need to improve these vaccines to address emerging infections more comprehensively and ensure their safety. The recent reports on new-generation vaccines against swine viruses like DNA, viral-vector-based replicon, chimeric, peptide, plant-made, virus-like particle, and nanoparticle-based vaccines are very encouraging. The current review gathers comprehensive information on the available vaccines and the future perspectives on porcine viral vaccines.

Poly(I:C) and R848 ligands show better adjuvanticity to induce B and T cell responses against the antigen(s)

Poly(I:C) and R848, synthetic ligands that activate Toll-like receptor 3 (TLR3) and TLR7/8 respectively, have been well-established for their ability to stimulate the immune system and induce antigen-specific immune responses. These ligands are capable of inducing the production of cytokines and chemokines, and hence support the activation and differentiation of B and T cells. We saw the long-lasting and perdurable immune responses by these adjuvants essentially required for an efficacious subunit vaccine. In this study, we investigated the potential of poly(I:C) and R848 to elicit B and T cell responses to the OVA antigen. We assessed the stimulatory effects of these ligands on the immune system, their impact on B and T cell activation, and their ability to enhanced generation of B and T cells. Collectively, our findings contribute to the understanding how poly(I:C) and R848 can be utilized as an adjuvant system to enhance immune responses to protein-based subunit vaccines. In the end, this work provides insights for the development of novel vaccination strategies and improving the vaccine efficacy. Present work shall help formulate newer strategies for subunit vaccines to address the infectious diseases.

BCG-booster vaccination with HSP90-ESAT-6-HspX-RipA multivalent subunit vaccine confers durable protection against hypervirulent Mtb in mice

The quest for effective and enhanced multiantigenic tuberculosis (TB) subunit vaccine necessitates the induction of a protective pathogen-specific immune response while circumventing detrimental inflammation within the lung milieu. In line with this goal, we engineered a modified iteration of the quadrivalent vaccine, namely HSP90-ESAT-6-HspX-RipA (HEHR), which was coupled with the TLR4 adjuvant, CIA09A. The ensuing formulation was subjected to comprehensive assessment to gauge its protective efficacy against the hypervirulent Mycobacterium tuberculosis (Mtb) Haarlem clinical strain M2, following a BCG-prime boost regimen. Regardless of vaccination route, both intramuscular and subcutaneous administration with the HEHR vaccine exhibited remarkable protective efficacy in significantly reducing the Mtb bacterial burden and pulmonary inflammation. This underscores its notably superior protective potential compared to the BCG vaccine alone or a former prototype, the HSP90-E6 subunit vaccine. In addition, this superior protective efficacy was confirmed when testing a tag-free version of the HEHR vaccine. Furthermore, the protective immune determinant, represented by durable antigen-specific CD4+IFN-γ+IL-17A+ T-cells expressing a CXCR3+KLRG1- cell surface phenotype in the lung, was robustly induced in HEHR-boosted mice at 12 weeks post-challenge. Collectively, our data suggest that the BCG-prime HEHR boost vaccine regimen conferred improved and long-term protection against hypervirulent Mtb strain with robust antigen-specific Th1/Th17 responses.

A Novel Recombinant Modified Vaccinia Ankara Virus expressing Interleukin-13 Receptor α2 Antigen for Potential Cancer Immunotherapy

BACKGROUND

Genetically altered recombinant poxviruses hold great therapeutic promise in animal models of cancer. Poxviruses can induce effective cellmediated immune responses against tumor-associated antigens. Preventive and therapeutic vaccination with a DNA vaccine expressing IL-13Rα2 can mediate partial regression of established tumors in vivo, indicating that host immune responses against IL-13Rα2 need further augmentation.

OBJECTIVE

The aim of the study is developing a recombinant modified vaccinia Ankara (MVA) expressing IL-13Rα2 (rMVA-IL13Rα2) virus and study in vitro infectivity and efficacy against IL-13Rα2 positive cell lines.

METHODS

We constructed a recombinant MVA expressing IL-13Rα2 and a green fluorescent protein (GFP) reporter gene. Purified virus titration by infection of target cells and immunostaining using anti-vaccinia and anti-IL-13Rα2 antibodies was used to confirm the identity and purity of the rMVA-IL13Rα2.

RESULTS

Western Blot analysis confirmed the presence of IL-13Rα2 protein (~52 kDa). Flow cytometric analysis of IL-13Rα2 negative T98G glioma cells when infected with rMVA-IL13Rα2 virus demonstrated cell-surface expression of IL-13Rα2, indicating the infectivity of the recombinant virus. Incubation of T98G-IL13Rα2 cells with varying concentrations (0.1-100 ng/ml) of interleukin-13 fused to truncated Pseudomonas exotoxin (IL13-PE) resulted in depletion of GFP+ fluorescence in T98G-IL13Rα2 cells. IL13-PE (10-1000 ng/ml) at higher concentrations also inhibited the protein synthesis in T98G-IL13Rα2 cells compared to cells infected with the control pLW44-MVA virus. IL13- PE treatment of rMVA-IL13Rα2 infected chicken embryonic fibroblast and DF-1 cell line reduced virus titer compared to untreated cells.

CONCLUSION

rMVA-IL13Rα2 virus can successfully infect mammalian cells to express IL-13Rα2 in a biologically active form on the surface of infected cells. To evaluate the efficacy of rMVA-IL13Rα2, immunization studies are planned in murine tumor models.

Immunogenicity and Neutralization Potential of Recombinant Chimeric Protein Comprising the Catalytic Region of Gp63 of Leishmania and LTB against Leishmania donovani

AIM

To study the inhibition potential of antibody against a recombinant chimera comprising of the catalytic epitope of gp63 of Leishmania donovani and B subunit of heat-labile enterotoxin (LTB) in the functional activity of L. donovani.

BACKGROUND

Visceral leishmaniasis, caused by the protozoan parasite Leishmania donovani, is a major health problem and causes mortality in tropical regions. Protozoan proteases play a crucial role in the pathogenesis of the disease and in establishing infection by countering the host's innate immune responses, namely complement-mediated lysis and phagocytosis. A surface-bound metalloprotease (gp63) has been reported to be a major virulence factor resulting in the evasion of complement- mediated lysis, cleaving host extracellular and intracellular substrates, resulting in intra- phagolysosomal survival.

METHODS

The epitope corresponding to the catalytic motif of gp63 of Leishmania donovani was fused with the B subunit of heat-labile enterotoxin, which is known to be immunogenic. The chimera was cloned to a prokaryotic expression vector and purified using Ni NTA affinity chromatography. Antibodies were generated against the purified fusion protein and analyzed for its ability to bind to the gp63 catalytic motif peptide by ELISA. The effect of fusion protein antibody on the functional activity of gp63 was evaluated by assessing the effect of purified IgGs on the protease activity and complement-mediated lysis of L. donovani promastigotes in vitro.

RESULTS

The present study reports that a recombinant chimera of the catalytic epitope of gp63 and B subunit of heat-labile enterotoxin (LTB) of E. coli, a potent adjuvant of humoral response can mount significant immune response towards the catalytic epitope. ELISA and Western blot analysis showed that the anti-fusion protein antiserum could recognize the native gp63. Also, it significantly inhibited the protease activity of promastigotes and subsequently increased complement-mediated lysis of the promastigotes in vitro.

CONCLUSION

It could be concluded that the hybrid protein containing catalytic motif L. donovani gp63 protein and carrier protein (LTB) could elicit antibodies that could neutralise the functional activity of gp63 and thus could be a potential candidate for subunit leishmaniasis vaccine.

Engineering Protein Nanoparticles Functionalized with an Immunodominant Coxiella burnetii Antigen to Generate a Q Fever Vaccine

Coxiella burnetii is the causative agent of Q fever, for which there is yet to be an FDA-approved vaccine. This bacterial pathogen has both extra- and intracellular stages in its life cycle, and therefore both a cell-mediated (i.e., T lymphocyte) and humoral (i.e., antibody) immune response are necessary for effective eradication of this pathogen. However, most proposed vaccines elicit strong responses to only one mechanism of adaptive immunity, and some can either cause reactogenicity or lack sufficient immunogenicity. In this work, we aim to apply a nanoparticle-based platform toward producing both antibody and T cell immune responses against C. burnetii. We investigated three approaches for conjugation of the immunodominant outer membrane protein antigen (CBU1910) to the E2 nanoparticle to obtain a consistent antigen orientation: direct genetic fusion, high affinity tris-NTA-Ni conjugation to polyhistidine-tagged CBU1910, and the SpyTag/SpyCatcher (ST/SC) system. Overall, we found that the ST/SC approach yielded nanoparticles loaded with the highest number of antigens while maintaining stability, enabling formulations that could simultaneously co-deliver the protein antigen (CBU1910) and adjuvant (CpG1826) on one nanoparticle (CBU1910-CpG-E2). Using protein microarray analyses, we found that after immunization, antigen-bound nanoparticle formulations elicited significantly higher antigen-specific IgG responses than soluble CBU1910 alone and produced more balanced IgG1/IgG2c ratios. Although T cell recall assays from these protein antigen formulations did not show significant increases in antigen-specific IFN-γ production compared to soluble CBU1910 alone, nanoparticles conjugated with a CD4 peptide epitope from CBU1910 generated elevated T cell responses in mice to both the CBU1910 peptide epitope and whole CBU1910 protein. These investigations highlight the feasibility of conjugating antigens to nanoparticles for tuning and improving both humoral- and cell-mediated adaptive immunity against C. burnetii.

Polyfunctional CD4 T-cells correlating with neutralising antibody is a hallmark of COVISHIELDTM and COVAXIN® induced immunity in COVID-19 exposed Indians

Detailed characterisation of immune responses induced by COVID-19 vaccines rolled out in India: COVISHIELDTM (CS) and COVAXIN® (CO) in a pre-exposed population is only recently being discovered. We addressed this issue in subjects who received their primary series of vaccination between November 2021 and January 2022. Both vaccines are capable of strongly boosting Wuhan Spike-specific neutralising antibody, polyfunctional Th1 cytokine producing CD4+ T-cells and single IFN-γ + CD8+ T-cells. Consistent with inherent differences in vaccine platform, the vector-based CS vaccine-induced immunity was of greater magnitude, breadth, targeting Delta and Omicron variants compared to the whole-virion inactivated vaccine CO, with CS vaccinees showing persistent CD8+ T-cells responses until 3 months post primary vaccination. This study provides detailed evidence on the magnitude and quality of CS and CO vaccine induced responses in subjects with pre-existing SARS-CoV-2 immunity in India, thereby mitigating vaccine hesitancy arguments in such a population, which remains a global health challenge.

Production of recombinant proteins including the B-cell epitopes of autolysin A of Staphylococcus aureus isolated from clinical sheep mastitis and their potential for vaccine development

Staphylococcus aureus is the most common clinical mastitis-associated pathogen in sheep which contributes to reduced welfare of affected animals and, therefore, compromises the quality and quantity of milk production. To prevent mastitis and its spread, it is essential to guarantee adequate breeding conditions and animal health, through the adoption of good farm management practices and the application of suitable biosecurity measures. Vaccination can play a strategic role in prevention, control, and eradication of diseases. The identification of secreted and cellular antigens of the predominant sheep-CC130/ST700/t1773 lineage would assist in the design of effective vaccine against mammary infections caused by S. aureus. In the current study, we carried out a 3D structural prediction analysis with the identification of the best B cell epitopes of the whole and secreted portion of S. aureus AtlA. Fragments of atlA, containing the main predicted epitopes, were amplified, cloned, and expressed in Escherichia coli for recombinant protein production. Two selected clones produced recombinant proteins (rAtl4 and rAtl8) showing strong reactivity with a hyperimmune serum against the native AtlA and with blood sera collected from sheep with clinical S. aureus mastitis. These may represent potential candidate protein-based vaccines able to elicit a protective immune response to be evaluated by vaccination and subsequent challenge of the vaccinated sheep.

A two-protein cocktail elicits a protective immune response against Acinetobacter baumannii in a murine infection model

PURPOSE

Due to its high drug resistance, Acinetobacter baumannii is a priority for new therapeutic measures like vaccines. In this study, the protectivity of a combination cocktail of Omp34 and BauA as a vaccine against A. baumannii was studied in a murine sepsis model.

METHODS

The antibody titers were raised to Omp34 and BauA in BALB/c mice and assessed by indirect ELISA. The immunized mice were challenged with A. baumannii ATCC 19606. The bacterial loads in the liver, spleen, and lungs were also determined.

RESULTS

A significant increase in survival of the immunized mice was noted. In active immunity, the survival rates in mice receiving Omp34 and BauA alone or in combination were 100%. A significant decrease in the bacterial load was observed in the spleens, livers, and lungs of vaccinated mice. Anti-BauA and anti-Omp34 sera crossly detected Omp34 and BauA respectively. The decrease in bacterial load in body organs of mice vaccinated with a combination of the two proteins was significantly higher than those of the single proteins in both actively and passively immunized mice. In passive immunity, the survival rate of mice receiving specific sera raised to the combination of these proteins was 85.7%.

CONCLUSION

Higher protection by a combination of Omp34 and BauA than Omp34 or BauA could be attributed to targeting simultaneously both surface antigens indicating the synergistic effect of Omp34 and BauA as suitable vaccine candidates in the prevention or treatment of A. baumannii infections.

More than Three Decades of Bm86: What We Know and Where to Go

Tick and tick-borne disease control have been a serious research focus for many decades. In a global climate of increasing acaricide resistance, host immunity against tick infestation has become a much-needed complementary strategy to common chemical control. From the earliest acquired resistance studies in small animal models to proof of concept in large production animals, it was the isolation, characterization, and final recombinant protein production of the midgut antigen Bm86 from the Australian cattle tick strain of Rhipicephalus (Boophilus) microplus (later reinstated as R. (B.) australis) that established tick subunit vaccines as a viable alternative in tick and tick-borne disease control. In the past 37 years, this antigen has spawned numerous tick subunit vaccines (either Bm86-based or novel), and though we are still describing its molecular structure and function, this antigen remains the gold standard for all tick vaccines. In this paper, advances in tick vaccine development over the past three decades are discussed alongside the development of biotechnology, where existing gaps and future directives in the field are highlighted.

Optimization, characterization, comparison of self-assembly VLP of capsid protein L1 in yeast and reverse vaccinology design against human papillomavirus type 52

BACKGROUND

Vaccination is the one of the agendas of many countries to reduce cervical cancer caused by the Human papillomavirus. Currently, VLP-based vaccine is the most potent vaccine against HPV, which could be produced by a variety of expression systems. Our study focuses on a comparison of recombinant protein expression L1 HPV52 using two common yeasts, Pichia pastoris and Hansenula polymorpha that have been used for vaccine production on an industrial scale. We also applied bioinformatics approach using reverse vaccinology to design alternative multi-epitope vaccines in recombinant protein and mRNA types.

RESULTS

Our study found that P. pastoris relatively provided higher level of L1 protein expression and production efficiency compared to H. polymorpha in a batch system. However, both hosts showed self-assembly VLP formation and stable integration during protein induction. The vaccine we have designed exhibited high immune activation and safe in computational prediction. It is also potentially suitable for production in a variety of expression systems.

CONCLUSION

By monitoring the overall optimization parameter assessment, this study can be used as the basis reference for large-scale production of the HPV52 vaccine.

Molecular Bases of Protein Antigenicity and Determinants of Immunogenicity, Anergy, and Mitogenicity

BACKGROUND

The immune system is able to recognize substances that originate from inside or outside the body and are potentially harmful. Foreign substances that bind to immune system components exhibit antigenicity and are defined as antigens. The antigens exhibiting immunogenicity can induce innate or adaptive immune responses and give rise to humoral or cell-mediated immunity. The antigens exhibiting mitogenicity can cross-link cell membrane receptors on B and T lymphocytes leading to cell proliferation. All antigens vary greatly in physicochemical features such as biochemical nature, structural complexity, molecular size, foreignness, solubility, and so on.

OBJECTIVE

Thus, this review aims to describe the molecular bases of protein-antigenicity and those molecular bases that lead to an immune response, lymphocyte proliferation, or unresponsiveness.

CONCLUSION

The epitopes of an antigen are located in surface areas; they are about 880-3,300 Da in size. They are protein, carbohydrate, or lipid in nature. Soluble antigens are smaller than 1 nm and are endocytosed less efficiently than particulate antigens. The more the structural complexity of an antigen increases, the more the antigenicity increases due to the number and variety of epitopes. The smallest immunogens are about 4,000-10,000 Da in size. The more phylogenetically distant immunogens are from the immunogen-recipient, the more immunogenicity increases. Antigens that are immunogens can trigger an innate or adaptive immune response. The innate response is induced by antigens that are pathogen-associated molecular patterns. Exogenous antigens, T Dependent or T Independent, induce humoral immunogenicity. TD protein-antigens require two epitopes, one sequential and one conformational to induce antibodies, whereas, TI non-protein-antigens require only one conformational epitope to induce low-affinity antibodies. Endogenous protein antigens require only one sequential epitope to induce cell-mediated immunogenicity.

A novel structurally identified epitope delivered by macrophage membrane-coated PLGA nanoparticles elicits protection against Pseudomonas aeruginosa

The increasing prevalence of antibiotic resistance by Pseudomonas aeruginosa (PA) raises an urgent need for an effective vaccine. The outer membrane proteins of PA, especially those that are upregulated during infection, are ideal vaccine targets. However, the strong hydrophobicity of these proteins hinders their application for this purpose. In this study, we selected eight outer membrane proteins from PA with the most significantly upregulated expression. Their extracellular loops were analyzed and screened by using sera from patients who had recovered from PA infection. As a result, a novel immunogenic epitope (Ep_167-193) from PilY1 (PA4554) was found. Moreover, we constructed a macrophage membrane-coated PLGA (poly lactic-co-glycolic acid) nanoparticle vaccine carrying PilY1 Ep_167-193 (PNPs@M-Ep_167-193) that elicits a Th2 immune response and confers adequate protection in mice. Our data furnished the promising vaccine candidate PNPs@M-Ep_167-193 while providing additional evidence for structure-based epitope identification and vaccine design.

Immunostimulant plant proteins: Potential candidates as vaccine adjuvants

The COVID-19 pandemic is shaking up global scientific structures toward addressing antibiotic resistance threats and indicates an urgent need to develop more cost-effective vaccines. Vaccine adjuvants play a crucial role in boosting immunogenicity and improving vaccine efficacy. The toxicity and adversity of most adjuvant formulations are the major human immunization problems, especially in routine pediatric and immunocompromised patients. The present review focused on preclinical studies of immunoadjuvant plant proteins in use with antiparasitic, antifungal, and antiviral vaccines. Moreover, this report outlines the current perspective of immunostimulant plant protein candidates that can be used by researchers in developing new generations of vaccine-adjuvants. Future clinical studies are required to substantiate the plant proteins' safety and applicability as a vaccine adjuvant in pharmaceutical manufacturing.

Haemonchosis in Sheep and Goats, Control Strategies and Development of Vaccines against Haemonchus contortus

Simple Summary

Haemonchus contortus is the most pathogenic blood-feeding parasitic nematode in sheep and goats, threatening animal welfare and causing tremendous economic losses to the small ruminant industry. This comprehensive review article sums up current control strategies, worm-derived antigens and recent advances in anti-Haemonchus vaccine development. New insights into antigen engineering and general considerations for clinical trials are discussed here.

Abstract

The evolutionary success of parasitic worms causes significant economic losses and animal health problems, including in the small ruminant industry. The hematophagous nematode Haemonchus contortus is a common endoparasite that infects wild and domestic ruminants worldwide, especially in tropical and subtropical regions. To date, the most commonly applied control strategy is the administration of anthelminthic drugs. The main disadvantages of these chemicals are their ecotoxic effects, the necessary withdrawal period (especially important in dairy animals) and the increasing development of resistance. Vaccines offer an attractive alternative control strategy against Haemonchus infections. In previous years, several potential vaccine antigens prepared from H. contortus using the latest technologies have been assessed in clinical trials using different methods and strategies. This review highlights the current state of knowledge on anti-H. contortus vaccines (covering native, recombinant and DNA-based vaccines), including an evaluation, as well a discussion of the challenges and achievements in developing protective, efficient, and long-lasting vaccines to control H. contortus infection and haemonchosis in small ruminants. This paper also addresses novel developments tackling the challenge of glycosylation of putative candidates in recombinant form.

The influence of component structural arrangement on peptide vaccine immunogenicity

Peptide-based subunit vaccines utilise minimal immunogenic components (i.e. peptides) to generate highly specific immune responses, without triggering adverse reactions. However, strong adjuvants and/or effective delivery systems must be incorporated into such vaccines, as peptide antigens cannot induce substantial immune responses on their own. Unfortunately, many adjuvants are too weak or too toxic to be used in combination with peptide antigens. These shortcomings have been addressed by the conjugation of peptide antigens with lipidic/ hydrophobic adjuvanting moieties. The conjugates have shown promising safety profiles and improved immunogenicity without the help of traditional adjuvants and have been efficient in inducing desired immune responses following various routes of administration, including subcutaneous, oral and intranasal. However, not only conjugation per se, but also component arrangement influences vaccine efficacy. This review highlights the importance of influence of the vaccine chemical structure modification on the immune responses generated. It discusses a variety of factors that affect the immunogenicity of peptide conjugates, including: i) self-adjuvanting moiety length and number; ii) the orientation of epitopes and self-adjuvanting moieties in the conjugate; iii) the presence of spacers between conjugated components; iv) multiepitopic arrangement; and v) the effect of chirality on vaccine efficacy.

Protein-Based Adjuvants for Vaccines as Immunomodulators of the Innate and Adaptive Immune Response: Current Knowledge, Challenges, and Future Opportunities

New-generation vaccines, formulated with subunits or nucleic acids, are less immunogenic than classical vaccines formulated with live-attenuated or inactivated pathogens. This difference has led to an intensified search for additional potent vaccine adjuvants that meet safety and efficacy criteria and confer long-term protection. This review provides an overview of protein-based adjuvants (PBAs) obtained from different organisms, including bacteria, mollusks, plants, and humans. Notably, despite structural differences, all PBAs show significant immunostimulatory properties, eliciting B-cell- and T-cell-mediated immune responses to administered antigens, providing advantages over many currently adopted adjuvant approaches. Furthermore, PBAs are natural biocompatible and biodegradable substances that induce minimal reactogenicity and toxicity and interact with innate immune receptors, enhancing their endocytosis and modulating subsequent adaptive immune responses. We propose that PBAs can contribute to the development of vaccines against complex pathogens, including intracellular pathogens such as Mycobacterium tuberculosis, those with complex life cycles such as Plasmodium falciparum, those that induce host immune dysfunction such as HIV, those that target immunocompromised individuals such as fungi, those with a latent disease phase such as Herpes, those that are antigenically variable such as SARS-CoV-2 and those that undergo continuous evolution, to reduce the likelihood of outbreaks.

Modern vaccine development via reverse vaccinology to combat antimicrobial resistance

With the continuous evolution of bacteria, the global antimicrobial resistance health threat is causing millions of deaths yearly. While depending on antibiotics as a primary treatment has its merits, there are no effective alternatives thus far in the pharmaceutical market against some drug-resistant bacteria. In recent years, vaccinology has become a key topic in scientific research. Combining with the growth of technology, vaccine research is seeing a new light where the process is made faster and more efficient. Although less discussed, bacterial vaccine is a feasible strategy to combat antimicrobial resistance. Some vaccines have shown promising results with good efficacy against numerous multidrug-resistant strains of bacteria. In this review, we aim to discuss the findings from studies utilizing reverse vaccinology for vaccine development against some multidrug-resistant bacteria, as well as provide a summary of multi-year bacterial vaccine studies in clinical trials. The advantages of reverse vaccinology in the generation of new bacterial vaccines are also highlighted. Meanwhile, the limitations and future prospects of bacterial vaccine concludes this review.

First-in-human study of WT1 recombinant protein vaccination in elderly patients with AML in remission: a single-center experience

Wilms’ tumor 1 (WT1) protein is highly immunogenic and overexpressed in acute myeloid leukemia (AML), consequently ranked as a promising target for novel immunotherapeutic strategies. Here we report our experience of a phase I/II clinical trial (NCT01051063) of a vaccination strategy based on WT1 recombinant protein (WT1-A10) together with vaccine adjuvant AS01_B in five elderly AML patients (median age 69 years, range 63–75) receiving a total of 62 vaccinations (median 18, range 3–20) after standard chemotherapy. Clinical benefit was observed in three patients: one patient achieved measurable residual disease clearance during WT1 vaccination therapy, another patient maintained long-term molecular remission over 59 months after the first vaccination cycle. Interestingly, in one case, we observed a complete clonal switch at AML relapse with loss of WT1 expression, proposing suppression of the original AML clone by WT1-based vaccination therapy. Detected humoral and cellular CD4⁺ T cell immune responses point to efficient immune stimulation post-vaccination, complementing hints for induced conventional T cell infiltration into the bone marrow and a shift from senescent/exhausted to a more activated T cell profile. Overall, the vaccinations with WT1 recombinant protein had an acceptable safety profile and were thus well tolerated.

To conclude, our data provide evidence of potential clinical efficacy of WT1 protein-based vaccination therapy in AML patients, warranting further investigations.

Structural characterization of a cross-protective natural chimera of factor H binding protein from meningococcal serogroup B strain NL096

Invasive meningococcal disease can cause fatal sepsis and meningitis and is a global health threat. Factor H binding protein (fHbp) is a protective antigen included in the two currently available vaccines against serogroup B meningococcus (MenB). FHbp is a remarkably variable surface-exposed meningococcal virulence factor with over 1300 different amino acid sequences identified so far. Based on this variability, fHbp has been classified into three variants, two subfamilies or nine modular groups, with low degrees of cross-protective activity. Here, we report the crystal structure of a natural fHbp cross-variant chimera, named variant1-2,3.x expressed by the MenB clinical isolate NL096, at 1.2 Å resolution, the highest resolution of any fHbp structure reported to date. We combined biochemical, site-directed mutagenesis and computational biophysics studies to deeply characterize this rare chimera. We determined the structure to be composed of two adjacent domains deriving from the three variants and determined the molecular basis of its stability, ability to bind Factor H and to adopt the canonical three-dimensional fHbp structure. These studies guided the design of loss-of-function mutations with potential for even greater immunogenicity. Moreover, this study represents a further step in the understanding of the fHbp biological and immunological evolution in nature. The chimeric variant1-2,3.x fHbp protein emerges as an intriguing cross-protective immunogen and suggests that identification of such naturally occurring hybrid proteins may result in stable and cross-protective immunogens when seeking to design and develop vaccines against highly variable pathogens.

Computational mining of MHC class II epitopes for the development of universal immunogenic proteins

The human leukocyte antigen (HLA) gene complex, one of the most diverse gene complexes found in the human genome, largely dictates how our immune systems recognize pathogens. Specifically, HLA genetic variability has been linked to vaccine effectiveness in humans and it has likely played some role in the shortcomings of the numerous human vaccines that have failed clinical trials. This variability is largely impossible to evaluate in animal models, however, as their immune systems generally 1) lack the diversity of the HLA complex and/or 2) express major histocompatibility complex (MHC) receptors that differ in specificity when compared to human MHC. In order to effectively engage the majority of human MHC receptors during vaccine design, here, we describe the use of HLA population frequency data from the USA and MHC epitope prediction software to facilitate the in silico mining of universal helper T cell epitopes and the subsequent design of a universal human immunogen using these predictions. This research highlights a novel approach to using in silico prediction software and data processing to direct vaccine development efforts.

Functional Reconstitution of the MERS CoV Receptor Binding Motif

In the early 1960’s the first human coronaviruses (designated 229E and OC43) were identified as etiologic agents of the common cold, to be followed by the subsequent isolation of three more human coronaviruses similarly associated with cold-like diseases. In contrast to these “mild” coronaviruses, over the last 20 years there have been three independent events of emergence of pandemic severe and acute life-threatening respiratory diseases caused by three novel beta-coronaviruses, SARS CoV, MERS CoV and most recently SARS CoV2. Whereas the first SARS CoV appeared in November 2002 and spontaneously disappeared by the summer of 2003, MERS CoV has continued persistently to spill over to humans via an intermediary camel vector, causing tens of cases annually. Although human-to-human transmission is rare, the fatality rate of MERS CoV disease is remarkably higher than 30%. COVID-19 however, is fortunately much less fatal, despite that its etiologic agent, SARS CoV2, is tremendously infectious, particularly with the recent evolution of the Omicron variants of concern (BA.1 and BA.2). Of note, MERS CoV prevalence in camel populations in Africa and the Middle East is extremely high. Moreover, MERS CoV and SARS CoV2 co-exist in the Middle East and especially in Saudi Arabia and the UAE, where sporadic incidences of co-infection have already been reported. Co-infection, either due to reverse spill-over of SARS CoV2 to camels or in double infected humans could lead to recombination between the two viruses, rendering either SARS CoV2 more lethal or MERS CoV more transmittable. In an attempt to prepare for what could develop into a catastrophic event, we have focused on developing a novel epitope-based immunogen for MERS CoV. Implementing combinatorial phage-display conformer libraries, the Receptor Binding Motif (RBM) of the MERS CoV Spike protein has been successfully reconstituted and shown to be recognized by a panel of seven neutralizing monoclonal antibodies.

Exploring the COVID-19 vaccine candidates against SARS-CoV-2 and its variants: where do we stand and where do we go?

As of September 2021, 117 COVID-19 vaccines are in clinical development, and 194 are in preclinical development as per the World Health Organization (WHO) published draft landscape. Among the 117 vaccines undergoing clinical trials, the major platforms include protein subunit; RNA; inactivated virus; viral vector, among others. So far, USFDA recognized to approve the Pfizer-BioNTech (Comirnaty) COVID-19 vaccine for its full use in individuals of 16 years of age and older. Though the approved vaccines are being manufactured at a tremendous pace, the wealthiest countries have about 28% of total vaccines despite possessing only 10.8% of the total world population, suggesting an inequity of vaccine distribution. The review comprehensively summarizes the history of vaccines, mainly focusing on vaccines for SARS-CoV-2. The review also connects relevant topics, including measurement of vaccines efficacy against SARS-CoV-2 and its variants, associated challenges, and limitations, as hurdles in global vaccination are also kept forth.

A Review of UK-Registered and Candidate Vaccines for Bovine Respiratory Disease

Vaccination is widely regarded as a cornerstone in animal or herd health and infectious disease management. Nineteen vaccines against the major pathogens implicated in bovine respiratory disease are registered for use in the UK by the Veterinary Medicines Directorate (VMD). However, despite annual prophylactic vaccination, bovine respiratory disease is still conservatively estimated to cost the UK economy approximately £80 million per annum. This review examines the vaccine types available, discusses the surrounding literature and scientific rationale of the limitations and assesses the potential of novel vaccine technologies.

Recent Development of Ruminant Vaccine Against Viral Diseases

Pathogens of viral origin produce a large variety of infectious diseases in livestock. It is essential to establish the best practices in animal care and an efficient way to stop and prevent infectious diseases that impact animal husbandry. So far, the greatest way to combat the disease is to adopt a vaccine policy. In the fight against infectious diseases, vaccines are very popular. Vaccination's fundamental concept is to utilize particular antigens, either endogenous or exogenous to induce immunity against the antigens or cells. In light of how past emerging and reemerging infectious diseases and pandemics were handled, examining the vaccination methods and technological platforms utilized for the animals may provide some useful insights. New vaccine manufacturing methods have evolved because of developments in technology and medicine and our broad knowledge of immunology, molecular biology, microbiology, and biochemistry, among other basic science disciplines. Genetic engineering, proteomics, and other advanced technologies have aided in implementing novel vaccine theories, resulting in the discovery of new ruminant vaccines and the improvement of existing ones. Subunit vaccines, recombinant vaccines, DNA vaccines, and vectored vaccines are increasingly gaining scientific and public attention as the next generation of vaccines and are being seen as viable replacements to conventional vaccines. The current review looks at the effects and implications of recent ruminant vaccine advances in terms of evolving microbiology, immunology, and molecular biology.

Putative novel B-cell vaccine candidates identified by reverse vaccinology and genomics approaches to control Acinetobacter baumannii serotypes

In the last decade, Multi-drug resistance (MDR)-associated infections of Acinetobacter baumannii have grown worldwide. A cost-effective preventative strategy against this bacterium is vaccination. This study has presented five novel vaccine candidates against A. baumannii produced using the reverse vaccinology method. BLASTn was done to identify the most conserved antigens. PSORTb 3.0.2 was run to predict the subcellular localization of the proteins. The initial screening and antigenicity evaluation were performed using Vaxign. The ccSOL omics was also employed to predict protein solubility. The cross-membrane localization of the protein was predicted using PRED-TMBB. B cell epitope prediction was made for immunogenicity using the IEDB and BepiPred-2.0 database. Eventually, BLASTp was done to verify the extent of similarity to the human proteome to exclude the possibility of autoimmunity. Proteins failing to comply with the set parameters were filtered at each step. In silico, potential vaccines against 21 A. baumannii strains were identified using reverse vaccinology and subtractive genomic techniques. Based on the above criteria, out of the initial 15 A. baumannii proteins selected for screening, nine exposed/secreted/membrane proteins, i.e., Pfsr, LptE, OmpH, CarO, CsuB, CdiB, MlaA, FhuE, and were the most promising candidates. Their solubility and antigenicity were also examined and found to be more than 0.45 and 0.6, respectively. Based on the results, LptE was selected with the highest average antigenic score of 1.043 as the best protein, followed by FimF and Pfsr with scores of 1.022 and 1.014, respectively. In the end, five proteins were verified as promising candidates. Overall, the targets identified herein may be utilized in future strategies to control A. baumannii worldwide.

Introduction of novel putative immunogenic targets against Proteus mirabilis using a reverse vaccinology approach

Multi-drug resistance of Proteus mirabilis, a frequent cause of catheter-associated urinary tract infections, renders ineffective treatment. Therefore, new advanced strategies are needed to overcome it. In the meantime, vaccination may be the most effective and promising method. In this study antigenicity, allergenicity, subcellular localization, human homology, B-cell epitopes and MHC-II binding sites, conserved domains and protein-protein interactions were predicted using different reverse vaccinology methods and bioinformatics databases to find new putative immunogenic targets against P. mirabilis. Finally, 5 putative immunogenic targets against P. mirabilis were identified. Considering all criteria, QKQ94350.1 (Cell envelope opacity-associated protein A), QKQ94681.1 (Porin), QKQ95001.1 (TonB-dependent hemoglobin/ transferrin/ lactoferrin family receptor), QKQ95221.1 (AsmA) and QKQ94335.1 (N-acetylmuramoyl-L-alanine amidase) are excellent putative immunogenic targets. Finally, a multi-epitope vaccine was designed using the conserved linear epitopes of two OMPs (QKQ94681.1 and QKQ95001.1) and N-acetylmuramoyl-L-alanine amidase (QKQ94335.1), which have promising properties for immunization. These findings can simplify the development of efficient vaccines against P. mirabilis.

Recent advances in microneedles-mediated transdermal delivery of protein and peptide drugs

Proteins and peptides have become a significant therapeutic modality for various diseases because of their high potency and specificity. However, the inherent properties of these drugs, such as large molecular weight, poor stability, and conformational flexibility, make them difficult to be formulated and delivered. Injection is the primary route for clinical administration of protein and peptide drugs, which usually leads to poor patient's compliance. As a portable, minimally invasive device, microneedles (MNs) can overcome the skin barrier and generate reversible microchannels for effective macromolecule permeation. In this review, we highlighted the recent advances in MNs-mediated transdermal delivery of protein and peptide drugs. Emphasis was given to the latest development in representative MNs design and fabrication. We also summarize the current application status of MNs-mediated transdermal protein and peptide delivery, especially in the field of infectious disease, diabetes, cancer, and other disease therapy. Finally, the current status of clinical translation and a perspective on future development are also provided.

Novel and emerging mutations of SARS-CoV-2: Biomedical implications

Coronavirus disease-19 (COVID-19) is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The SARS-CoV-2 virus strains has geographical diversity associated with diverse severity, mortality rate, and response to treatment that were characterized using phylogenetic network analysis of SARS-CoV-2 genomes. Although, there is no explicit and integrative explanation for these variations, the genetic arrangement, and stability of SARS-CoV-2 are basic contributing factors to its virulence and pathogenesis. Hence, understanding these features can be used to predict the future transmission dynamics of SARS-CoV-2 infection, drug development, and vaccine. In this review, we discuss the most recent findings on the mutations in the SARS-CoV-2, which provide valuable information on the genetic diversity of SARS-CoV-2, especially for DNA-based diagnosis, antivirals, and vaccine development for COVID-19.

Immunoprotective Activity Induced by Leptospiral Outer Membrane Proteins in Hamster Model of Acute Leptospirosis

Leptospirosis is a zoonotic disease of worldwide distribution, affecting both humans and animals. The development of an effective vaccine against leptospirosis has long been pursued but without success. Humans are contaminated after direct contact with the urine of infected animals or indirectly by contaminated water or soil. The vaccines available consist of inactivated whole-bacterial cells, and the active immunoprotective antigen is the lipopolysaccharide moiety, which is also the basis for serovar classification. However, these vaccines are short-lasting, and protection is only against serovars contained in the preparation. The search for prevalent antigens, present in pathogenic species of Leptospira, represents the most cost-effective strategy for prevention of leptospirosis. Thus, the identification of these antigens is a priority. In this study, we examined the immunoprotective effect of eight leptospiral recombinant proteins using hamster as the challenge model. Animals received subcutaneously two doses of vaccine containing 50 μg of each recombinant protein adsorbed on alum adjuvant. Two weeks after the booster, animals were challenged with virulent leptospires and monitored for 21 days. All proteins were able to induce a specific immune response, although significant protective effects on survival rate were observed only for the proteins Lsa14, rLIC13259, and rLIC11711. Of these, only rLIC13259 and rLIC11711 were found to be highly prospective in promoting renal clearance. The sterilizing potential of both proteins will be further investigated to elucidate the immunoprotective mechanisms involved in leptospirosis control. These are the first proteins involved with human complement components with the capacity to protect against virulent challenge and to eliminate the bacteria from the host.

Quantification of Receptor Occupancy by Ligand—An Understudied Class of Potential Biomarkers

Molecular complexes, such as ligand–receptor complexes, are vital for both health and disease and can be shed into the circulation in soluble form. Relatively little is known about the biology of soluble ligand–receptor complexes. The functional importance of such complexes and their potential use as clinical biomarkers in diagnosis and therapy remains underappreciated. Most traditional technologies used to study ligand–receptor complexes measure the individual levels of soluble ligands or receptors rather than the complexes themselves. The fraction of receptors occupied by ligand, and the potential clinical relevance of such information, has been largely overlooked. Here, we review the biological significance of soluble ligand–receptor complexes with a specific focus on their potential as biomarkers of cancer and other inflammatory diseases. In addition, we discuss a novel RNA aptamer-based technology, designated ligand–receptor complex-binding aptamers (LIRECAP), that can provide precise measurement of the fraction of a soluble receptor occupied by its ligand. The potential applicability of the LIRECAP technology as a biomarker discovery platform is also described.

Multi-epitope insert modulates solubility-based and chromatographic purification of human papilloma virus 16 L1-based vaccine without inhibiting virus-like particle assembly

The separation of heterogeneous protein mixtures has always been characterized by a trade-off between purity and yield. One way this issue has been addressed in the past is by recombinantly modifying protein to improve separations. Such modifications are mostly employed in the form of tags used specifically for affinity chromatography, though it is also possible to make changes to a protein that will have a sizeable impact on its hydrophobicity and charge/charge distribution. As such, it should also be possible to use protein tags to modulate phase separations and protein-resin binding kinetics when performing ion exchange chromatography. Here, we employed a three-step purification scheme on E. coli expressed, His-tagged, human papilloma virus 16 L1-based recombinant proteins (rHPV 16 L1) that consisted of an inclusion body (IB) wash step, a diethylaminoethyl (DEAE) anion exchange chromatography (AEX) step, and an immobilized metal affinity chromatography (IMAC) polishing step. Purification of the wild type rHPV 16 L1 protein (WT) was characterized by substantial losses during the IB wash but relatively high yield over the DEAE column. In contrast, purification of modified rHPV 16 L1, a chimeric version of the WT protein that had the last 34 amino acids replaced with an MHC class II multi-epitope insert derived from tetanus toxin and diphtheria toxin (WTΔC34-2TEp), was characterized by little to no losses in the IB wash but had a relatively low yield over the DEAE column. Since the fate of these proteins was to be used in vaccine formulations, it is important to note that the modifications made to the WTΔC34-2TEp protein had little to no effect on its ability to assemble into virus-like particles (VLPs). These results demonstrate that modifications of the WT protein via the recombinant insertion of immunofunctional polypeptides can modulate both phase-based separation and charge-based chromatographic processes. Additionally, incorporation of the specific, multi-epitope tag used in this study may prove to be beneficial in recombinant HPV vaccine development due to its potential to improve phase separation yield and vaccine immunogenicity without inhibiting VLP formation.

Pharmaceutical nanotechnology: which products are been designed against COVID-19?

The current pandemic COVID-19, caused by the SARS-CoV-2 virus, has been affecting thousands of people worldwide, promoting high numbers of deaths. With this, the world population is going through a process of changing habits, with social distance, improvement of hygiene techniques, to reduce the spread of the SARS-CoV-2 virus and, consequently, reduce the number of hospitalized people in serious condition, as well as the mortality rate. This scenario has been promoting a continuous search for researchers, in the most varied areas, for possible methods of prevention or cure. Specifically, in the field of pharmaceutical nanotechnology, a variety of products are being developed against SARS-CoV-2. Under these circumstances, we propose here an exposition of some of the nanotechnological products (nanoscale between 1 to 1000 nm) currently designed for the detection of the virus, for the prevention and treatment of COVID-19, in addition to equipment for personal protection. We believe that pharmaceutical nanotechnology will be a valuable tool in the disease from the development of products that guarantee our protection against the SARS-CoV-2 virus.

Enhancement of a Heroin Vaccine through Hapten Deuteration

The United States is in the midst of an unprecedented epidemic of opioid substance use disorder, and while pharmacotherapies including opioid agonists and antagonists have shown success, they can be inadequate and frequently result in high recidivism. With these challenges facing opioid use disorder treatments immunopharmacotherapy is being explored as an alternative therapy option and is based upon antibody-opioid sequestering to block brain entry. Development of a heroin vaccine has become a major research focal point; however, producing an efficient vaccine against heroin has been particularly challenging because of the need to generate not only a potent immune response but one against heroin and its multiple psychoactive molecules. In this study, we explored the consequence of regioselective deuteration of a heroin hapten and its impact upon the immune response against heroin and its psychoactive metabolites. Deuterium (H_dAc) and cognate protium heroin (H_Ac) haptens were compared head to head in an inclusive vaccine study. Strikingly the H_dAc vaccine granted greater efficacy in blunting heroin analgesia in murine behavioral models compared to the H_Ac vaccine. Binding studies confirmed that the H_dAc vaccine elicited both greater quantities and equivalent or higher affinity antibodies toward heroin and 6-AM. Blood-brain biodistribution experiments corroborated these affinity tests. These findings suggest that regioselective hapten deuteration could be useful for the resurrection of previous drug of abuse vaccines that have met limited success in the past.