Strategy of developing nucleic acid-based universal monkeypox vaccine candidates

The unique immune evasion mechanisms of the mpox virus and their implication for developing new vaccines and immunotherapies

Mpox is an infectious and contagious zoonotic disease caused by the mpox virus (MPXV), which belongs to the genus Orthopoxvirus. Since 2022, MPXV has posed a significant threat to global public health. The emergence of thousands of cases across the Western Hemisphere prompted the World Health Organization to declare an emergency. The extensive coevolutionary history of poxviruses with humans has enabled these viruses to develop sophisticated mechanisms to counter the human immune system. Specifically, MPXV employs unique immune evasion strategies against a wide range of immunological elements, presenting a considerable challenge for treatment, especially following the discontinuation of routine smallpox vaccination among the general population. In this review, we start by discussing the entry of the mpox virus and the onset of early infection, followed by an introduction to the mechanisms by which the mpox virus can evade the innate and adaptive immune responses. Two caspase-1 inhibitory proteins and a PKR escape-related protein have been identified as phylogenomic hubs involved in modulating the immune environment during the MPXV infection. With respect to adaptive immunity, mpox viruses exhibit unique and exceptional T-cell inhibition capabilities, thereby comprehensively remodeling the host immune environment. The viral envelope also poses challenges for the neutralizing effects of antibodies and the complement system. The unique immune evasion mechanisms employed by MPXV make novel multi-epitope and nucleic acid-based vaccines highly promising research directions worth investigating. Finally, we briefly discuss the impact of MPXV infection on immunosuppressed patients and the current status of MPXV vaccine development. This review may provide valuable information for the development of new immunological treatments for mpox.

Monkeypox virus protein H3L induces injuries in human and mouse

Monkeypox virus (MPV) is known to inflict injuries and, in some cases, lead to fatalities in humans. However, the underlying mechanisms responsible for its pathogenicity remain poorly understood. We investigated functions of MPV core proteins, H3L, A35R, A29L, and I1L, and discovered that H3L induced transcriptional perturbations and injuries. We substantiated that H3L upregulated IL1A expression. IL1A, in consequence, caused cellular injuries, and this detrimental effect was mitigated when countered with IL1A blockage. We also observed that H3L significantly perturbed the transcriptions of genes in cardiac system. Mechanistically, H3L occupied the promoters of genes governing cellular injury, leading to alterations in the binding patterns of H3K27me3 and H3K4me3 histone marks, ultimately resulting in expression perturbations. In vivo and in vitro models confirmed that H3L induced transcriptional disturbances and cardiac dysfunction, which were ameliorated when IL1A was blocked or repressed. Our study provides valuable insights into comprehensive understanding of MPV pathogenicity, highlights the significant roles of H3L in inducing injuries, and potentially paves the way for the development of therapeutic strategies targeting IL1A.

A novel multi-epitope peptide vaccine targeting immunogenic antigens of Ebola and monkeypox viruses with potential of immune responses provocation in silico

The emergence or reemergence of monkeypox (Mpox) and Ebola virus (EBOV) agents causing zoonotic diseases remains a huge threat to human health. Our study aimed at designing a multi-epitope vaccine (MEV) candidate to target both the Mpox and EBOV agents using immunoinformatics tools. Viral protein sequences were retrieved, and potential nonallergenic, nontoxic, and antigenic epitopes were obtained. Next, cytotoxic and helper T-cell (CTL and HTL, respectively) and B-cell (BCL) epitopes were predicted, and those potential epitopes were fused utilizing proper linkers. The in silico cloning and expression processes were implemented using Escherichia coli K12. The immune responses were prognosticated using the C-ImmSim server. The MEV construct (29.53 kDa) included four BCL, two CTL, and four HTL epitopes and adjuvant. The MEV traits were pertinent in terms of antigenicity, non-allergenicity, nontoxicity, physicochemical characters, and stability. The MEV candidate was also highly expressed in E. coli K12. The strong affinity of MEV-TLR3 was confirmed using molecular docking and molecular dynamics simulation analyses. Immune simulation analyses unraveled durable activation and responses of cellular and humoral arms alongside innate immune responses. The designed MEV candidate demonstrated appropriate traits and was promising in the prediction of immune responses against both Mpox and EBOV agents. Further experimental assessments of the MEV are required to verify its efficacy.

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.

Exploring monkeypox virus proteins and rapid detection techniques

Monkeypox (mpox) is an infectious disease caused by the mpox virus and can potentially lead to fatal outcomes. It resembles infections caused by viruses from other families, challenging identification. The pathogenesis, transmission, and clinical manifestations of mpox and other Orthopoxvirus species are similar due to their closely related genetic material. This review provides a comprehensive discussion of the roles of various proteins, including extracellular enveloped virus (EEV), intracellular mature virus (IMV), and profilin-like proteins of mpox. It also highlights recent diagnostic techniques based on these proteins to detect this infection rapidly.

Breakthrough infection and reinfection in patients with mpox

Recently, patients with Mpox breakthrough infection or reinfection were constantly reported. However, the induction, risk factors, and important clinical symptoms of breakthrough infection and reinfection of Mpox virus (MPXV), as well as the factors affecting the effectiveness of Mpox vaccine are not characterized. Herein, a literature review was preformed to summarize the risk factors and important clinical symptoms of patients with Mpox breakthrough infection or reinfection, as well as the factors affecting the effectiveness of smallpox vaccine against Mpox. Results showed that MSM sexual behavior, condomless sexual behavior, multiple sexual partners, close contact, HIV infection, and the presence of comorbidity are important risk factors for Mpox breakthrough infection and reinfection. Genital ulcers, proctitis, and lymphadenopathy are the important clinical symptoms of Mpox breakthrough infection and reinfection. The effectiveness of emergent vaccination of smallpox vaccine for post-exposure of MPXV is associated with smallpox vaccination history, interval between exposure and vaccination, and history of HIV infection. This review provides a better understanding for the risk factors and important clinical symptoms of Mpox breakthrough infection and reinfection, as well as the formulation of Mpox vaccine vaccination strategies.

T Cell Responses against Orthopoxviruses in HIV-Positive Patients

A global outbreak of predominantly sexually transmitted mpox infections, outside endemic regions, was reported in May 2022. Thereafter, risk groups were vaccinated against smallpox, a structurally related orthopoxvirus. In the current study, we analyzed T cell responses against peptides derived from orthopoxviruses in 33 HIV-positive patients after two vaccinations against smallpox and in 10 patients after mpox infection. We established an ELISpot assay, detecting either the secretion of the pro-inflammatory cytokine interferon (IFN)-γ or interleukin (IL)-2. After vaccination, 21 out of 33 patients (64%) showed specific IFN-γ secretion and 18 (55%) specific IL-2 secretion, defined as >3-fold higher specific value than negative control and at least 4 spots above the negative control. After mpox infection, all patients showed specific IFN-γ secretion and 7 out of 10 (70%) IL-2 secretion. In vaccinated patients, IFN-γ responses were significantly lower than in patients with mpox infection (median response 4.5 vs. 21.0 spots, p < 0.001). The same trend was observed for IL-2 responses. After mpox infection, IL-2 ELISpot results positively correlated with CD8+ T cells (p < 0.05). Thus, T cell responses were detectable in two thirds of HIV-positive patients after vaccination and were even more abundant and vigorous after mpox infection.

Mpox (formerly monkeypox): pathogenesis, prevention, and treatment

In 2022, a global outbreak of Mpox (formerly monkeypox) occurred in various countries across Europe and America and rapidly spread to more than 100 countries and regions. The World Health Organization declared the outbreak to be a public health emergency of international concern due to the rapid spread of the Mpox virus. Consequently, nations intensified their efforts to explore treatment strategies aimed at combating the infection and its dissemination. Nevertheless, the available therapeutic options for Mpox virus infection remain limited. So far, only a few numbers of antiviral compounds have been approved by regulatory authorities. Given the high mutability of the Mpox virus, certain mutant strains have shown resistance to existing pharmaceutical interventions. This highlights the urgent need to develop novel antiviral drugs that can combat both drug resistance and the potential threat of bioterrorism. Currently, there is a lack of comprehensive literature on the pathophysiology and treatment of Mpox. To address this issue, we conducted a review covering the physiological and pathological processes of Mpox infection, summarizing the latest progress of anti-Mpox drugs. Our analysis encompasses approved drugs currently employed in clinical settings, as well as newly identified small-molecule compounds and antibody drugs displaying potential antiviral efficacy against Mpox. Furthermore, we have gained valuable insights from the process of Mpox drug development, including strategies for repurposing drugs, the discovery of drug targets driven by artificial intelligence, and preclinical drug development. The purpose of this review is to provide readers with a comprehensive overview of the current knowledge on Mpox.

Fluorescence-enhanced dual signal lateral flow immunoassay for flexible and ultrasensitive detection of monkeypox virus

The outbreak of the monkeypox virus (MPXV) worldwide in 2022 highlights the need for a rapid and low-cost MPXV detection tool for effectively monitoring and controlling monkeypox disease. In this study, we developed a flexible lateral flow immunoassay (LFIA) with strong colorimetric and enhanced fluorescence dual-signal output for the rapid, on-site, and highly sensitive detection of the MPXV antigen in different scenarios. A multilayered SiO2-Au core dual-quantum dot (QD) shell nanocomposite (named SiO2-Au/DQD), which consists of a large SiO2 core (~ 200 nm), one layer of density-controlled gold nanoparticles (AuNPs, 20 nm), and thousands of small QDs, was fabricated instead of a traditional colorimetric nanotag (i.e., AuNPs) and a fluorescent nanotag (QD nanobead) to simultaneously provide good stability, strong colorimetric ability and superior fluorescence intensity. With the dual-signal output LFIA, we achieved the specific screening of the MPXV antigen (A29L) in 15 min, with detection limits of 0.5 and 0.0021 ng/mL for the colorimetric and fluorometric modes, respectively. Moreover, the colorimetric mode of SiO2-Au/DQD-LFIA exhibits the same sensitivity as the traditional AuNP- LFIA, whereas the overall sensitivity of this method on the basis of the fluorescent signal can achieve 238- and 3.3-fold improvements in sensitivity for MPXV compared with the AuNP-based LFIA and ELISA methods, respectively, indicating the powerful performance and good versatility of the dual-signal method in the point-of-care testing of the MPXV.

Evaluation and comparison of immune responses induced by two Mpox mRNA vaccine candidates in mice

The epidemic of Mpox virus (MPXV) from May 2022 was once declared as a Public Health Emergency of International Concern by the World Health Organization. Vaccines play an important role in prevention of infectious diseases, and mRNA vaccine technology was proved to be a safe and effective platform with successful application in defense of coronavirus disease 2019. In this study, based on A29L, M1R, A35R, and B6R of MPXV, we developed two MPXV mRNA vaccine candidates, designated as MPXfus and MPXmix. The MPXfus was one-component, in which these four antigen proteins were linked in tandem by flexible linker and encoded by an individual mRNA as a fusion protein. The MPXmix was multicomponent containing four mRNA, and each mRNA encoded one antigen protein respectively. Mice were immunized with equal quality of MPXfus or MPXmix, delivered by lipid nanoparticles for evaluation and comparison of the immune responses induced by these two MPXV vaccine candidates. Results of immune response analyses indicated that both MPXfus and MPXmix could elicit high-level of antigen-specific antibodies and robust cellular immune response in mice. Moreover, results of virus neutralization assays suggested that sera from MPXfus- or MPXmix-immunized mice possessed high neutralizing activities against vaccinia virus. In addition, titers of antigen-specific antibody, levels of cellular immune response, and activities of neutralizing antibody against vaccinia virus induced by MPXfus and MPXmix presented no significant difference. In summary, this study provides valuable insights for further clinical development of one-component and multicomponent mRNA vaccine candidates for the prevention of MPXV and other orthomyxoviruses.

A Subunit Vaccine Candidate Composed of Mpox Virus A29L, M1R, A35R, and B6R Elicits Robust Immune Response in Mice

With no specific antiviral drugs and preventive vaccines against Mpox virus (MPXV), the epidemic has led to the declaration of a Public Health Emergency of International Concern. As a developmental direction for new vaccines, studies of subunit vaccines based upon MPXV antigen proteins are lacking. In this study, A29L, M1R, A35R, and B6R of MPXV were expressed and purified from a prokaryotic system. The four MPXV antigen proteins in combination were mixed with aluminum hydroxide or CpG7909 as adjuvant, and subsequently used to inoculate mice. The results of enzyme-linked immunosorbent assay (ELISA), flow cytometry analyses, and enzyme-linked immunospot (ELISPOT) assays indicated that A29L, M1R, A35R, and B6R elicited high-level antigen-specific antibodies and CD4+ T cells-based cellular immune response in mice. Moreover, the results of virus neutralization assays suggested that sera from the mice immunized with four proteins elicited high neutralizing activities against the vaccinia virus. Notably, the results of ELISA, ELISPOT, and virus neutralization assays also showed that the CpG7909 adjuvant was more effective in inducing an immune response compared with the aluminum adjuvant. In summary, this study offers valuable insights for further studies of subunit vaccine candidates for the prevention of MPXV and other orthomyxoviruses.

Rapid Detection of the Monkeypox Virus Genome and Antigen Proteins Based on Surface-Enhanced Raman Spectroscopy

The conventional detection methods cannot satisfy the need for early and rapid detection of monkeypox virus (MPXV) infection. This is due to complicated pretreatment, time consumption, and complex operation of the diagnostic tests. Based on surface-enhanced Raman spectroscopy (SERS), this study attempted to capture the characteristic fingerprints of the MPXV genome and multiple antigenic proteins without the need to design specific probes. The minimum detection limit of this method is 100 copies/mL, with good reproducibility and signal-to-noise ratio. Therefore, the relationship between characteristic peak intensity and the protein and nucleic acid concentration can be used to construct a concentration-dependent spectral line with a good linear relationship. Additionally, principal component analysis (PCA) could identify the SERS spectra of four different MPXV proteins in serum. Therefore, this rapid detection method in the current outbreak of monkeypox control and the future response to possible new outbreaks has broad application prospects.

Design, evaluation, and immune simulation of potentially universal multi-epitope mpox vaccine candidate: focus on DNA vaccine

Monkeypox (mpox) is a zoonotic infectious disease caused by the mpox virus. Mpox symptoms are similar to smallpox with less severity and lower mortality. As yet mpox virus is not characterized by as high transmissibility as some severe acute respiratory syndrome 2 (SARS-CoV-2) variants, still, it is spreading, especially among men who have sex with men (MSM). Thus, taking preventive measures, such as vaccination, is highly recommended. While the smallpox vaccine has demonstrated considerable efficacy against the mpox virus due to the antigenic similarities, the development of a universal anti-mpox vaccine remains a necessary pursuit. Recently, nucleic acid vaccines have garnered special attention owing to their numerous advantages compared to traditional vaccines. Importantly, DNA vaccines have certain advantages over mRNA vaccines. In this study, a potentially universal DNA vaccine candidate against mpox based on conserved epitopes was designed and its efficacy was evaluated via an immunoinformatics approach. The vaccine candidate demonstrated potent humoral and cellular immune responses in silico, indicating the potential efficacy in vivo and the need for further research.

The use of RNA-based treatments in the field of cancer immunotherapy

Over the past several decades, mRNA vaccines have evolved from a theoretical concept to a clinical reality. These vaccines offer several advantages over traditional vaccine techniques, including their high potency, rapid development, low-cost manufacturing, and safe administration. However, until recently, concerns over the instability and inefficient distribution of mRNA in vivo have limited their utility. Fortunately, recent technological advancements have mostly resolved these concerns, resulting in the development of numerous mRNA vaccination platforms for infectious diseases and various types of cancer. These platforms have shown promising outcomes in both animal models and humans. This study highlights the potential of mRNA vaccines as a promising alternative approach to conventional vaccine techniques and cancer treatment. This review article aims to provide a thorough and detailed examination of mRNA vaccines, including their mechanisms of action and potential applications in cancer immunotherapy. Additionally, the article will analyze the current state of mRNA vaccine technology and highlight future directions for the development and implementation of this promising vaccine platform as a mainstream therapeutic option. The review will also discuss potential challenges and limitations of mRNA vaccines, such as their stability and in vivo distribution, and suggest ways to overcome these issues. By providing a comprehensive overview and critical analysis of mRNA vaccines, this review aims to contribute to the advancement of this innovative approach to cancer treatment.

Recombinant proteins A29L, M1R, A35R, and B6R vaccination protects mice from mpox virus challenge

Since May 2022, mutant strains of mpox (formerly monkeypox) virus (MPXV) have been rapidly spreading among individuals who have not traveled to endemic areas in multiple locations, including Europe and the United States. Both intracellular and extracellular forms of mpox virus have multiple outer membrane proteins that can stimulate immune response. Here, we investigated the immunogenicity of MPXV structural proteins such as A29L, M1R, A35R, and B6R as a combination vaccine, and the protective effect against the 2022 mpox mutant strain was also evaluated in BALB/c mice. After mixed 15 μg QS-21 adjuvant, all four virus structural proteins were administered subcutaneously to mice. Antibody titers in mouse sera rose sharply after the initial boost, along with an increased capacity of immune cells to produce IFN-γ alongside an elevated level of cellular immunity mediated by Th1 cells. The vaccine-induced neutralizing antibodies significantly inhibited the replication of MPXV in mice and reduced the pathological damage of organs. This study demonstrates the feasibility of a multiple recombinant vaccine for MPXV variant strains.

Development of a Multi-Epitope Universal mRNA Vaccine Candidate for Monkeypox, Smallpox, and Vaccinia Viruses: Design and In Silico Analyses

Notwithstanding the presence of a smallpox vaccine that is effective against monkeypox (mpox), developing a universal vaccine candidate against monkeypox virus (MPXV) is highly required as the mpox multi-country outbreak has increased global concern. MPXV, along with variola virus (VARV) and vaccinia virus (VACV), belongs to the Orthopoxvirus genus. Due to the genetic similarity of antigens in this study, we have designed a potentially universal mRNA vaccine based on conserved epitopes that are specific to these three viruses. In order to design a potentially universal mRNA vaccine, antigens A29, A30, A35, B6, and M1 were selected. The conserved sequences among the three viral species-MPXV, VACV, and VARV-were detected, and B and T cell epitopes containing the conserved elements were used for the design of the multi-epitope mRNA construct. Immunoinformatics analyses demonstrated the stability of the vaccine construct and optimal binding to MHC molecules. Humoral and cellular immune responses were induced by immune simulation analyses. Eventually, based on in silico analysis, the universal mRNA multi-epitope vaccine candidate designed in this study may have a potential protection against MPXV, VARV, and VACV that will contribute to the advancement of prevention strategies for unpredictable pandemics.

Designing multi-epitope mRNA construct as a universal influenza vaccine candidate for future epidemic/pandemic preparedness

Despite the availability of prevention and treatment strategies and advancing immunization approaches, the influenza virus remains a global threat that continues to plague humanity with unpredictable pandemics. Due to the unusual genetic variability and segmented genome, the reassortment between different strains of influenza is facilitated and the viruses continuously evolve and adapt to the host cell's immunity. This underlies the seasonal vaccine mismatches that decrease the vaccine efficacy and increase the risk of outbreaks. Thus, the development of a universal vaccine covering all the influenza A and B strains would reduce the pervasiveness of the influenza virus. In the current study, a potentially universal influenza multi-epitope vaccine was designed based on the experimentally tested conserved T cell and B cell epitopes of hemagglutinin (HA), neuraminidase (NA), nucleoprotein (NP), and matrix-2 proton channel (M2) of the virus. The immune simulation and molecular docking of the vaccine construct with TLR2, TLR3, and TLR4 elicited the favorable immunogenicity of the vaccine and the formation of stable complexes, respectively. Ultimately, based on the immunoinformatics analysis, the universal mRNA multi-epitope vaccine designed in this study might have a protection potential against the various subtypes of influenza A and B.

The Global Human Monkeypox Outbreak and Management: A Comprehensive Literature Review

Monkeypox (MPX) belongs to the genus Orthopoxvirus (OPV), family Poxviridae, and sub-family Chordopoxvirinae. Human monkeypox (HMPX) is a viral zoonotic illness caused by the monkeypox virus (MPXV). Several non-endemic countries have confirmed MPX cases across the globe. Therefore, consider an outbreak to be a global health emergency. MPXV transmits from animals to humans via infected animals, and there is currently human-to-human transmission, notably among guys who have sexual relations with males. Healthcare interventions are required to stop outbreaks. These include strict isolation and care for MPX patients while they are still contagious or until the skin lesions dry out and crust over. JYNNEOS was approved as a vaccine for the prevention of MPXV. Tecovirimat is licensed to treat severe MPX or risk developing a serious disease. We should encourage international cooperation to conduct clinical trials investigating the effectiveness and safety of MPXV vaccines and antiviral medications. Precautions must be taken at the global level to prevent an MPXV outbreak.