Defining antigen targets to dissect vaccinia virus and monkeypox virus-specific T cell responses in humans

Immune responses associated with mpox viral clearance in men with and without HIV in Spain: a multisite, observational, prospective cohort study

BACKGROUND

Since the emergence of the global mpox outbreak in May, 2022, more than 90 000 cases have been diagnosed across 110 countries, disproportionately affecting people with HIV. The durability of mpox-specific immunity is unclear and reinfections have been reported. We aimed to compare mpox immune responses up to 6 months after diagnosis in participants with and without HIV and assess their effect on disease severity and viral clearance dynamics.

METHODS

This study was embedded within a prospective, observational, multicentre cohort study of viral clearance dynamics among people with mpox in Spain (MoViE). We included women and men aged 18 years or older, who had signs of mpox, and reported having symptom onset within the previous 10 days at the moment of mpox diagnosis from three sex clinics of the Barcelona metropolitan area. Samples from skin ulcers were collected weekly to estimate the time to clear monkeypox virus (MPXV) from skin lesions. Blood samples were taken at diagnosis, 29, 91, and 182 days later for immune analysis. This included quantifying IgG and IgA against three mpox antigens by ELISA, evaluating in-vitro neutralisation, and characterising mpox-specific T-cell responses using interferon γ detecting enzyme-linked immunospot (ELISpot) assay and multiparametric flow cytometry.

FINDINGS

Of the 77 originally enrolled participants, we included 33 participants recruited between July 19, and Oct 6, 2022. Participants without HIV (19 [58%] participants) and participants with HIV (14 [42%] participants) had similar clinical severity and time to MPXV clearance in skin lesions. Participants with HIV had a CD4+ T-cell count median of 777 cells per μL (IQR 484-1533), and 11 (78%) of 14 were virally suppressed on antiretroviral therapy. Nine (27%) of 33 participants were age 49 years or older. 15 (45%) of 33 participants were originally from Spain, and all participants were men. Early humoral responses, particularly concentrations and breadth of IgG and IgA, were associated with milder disease and faster viral clearance. Orthopoxvirus-specific T cells count was also positively correlated with MPXV clearance. Antibody titres declined more rapidly in participants with HIV, but T-cell responses against MPXV were sustained up to day 182 after diagnosis, regardless of HIV status.

INTERPRETATION

Higher breadth and magnitude of B-cell and T-cell responses are important in facilitating local viral clearance, limiting mpox dissemination, and reducing disease severity in individuals with preserved immune system. Antibodies appear to contribute to early viral control and T-cell responses are sustained over time, which might contribute to milder presentations during reinfection.

FUNDING

Fundació Lluita contra les Infeccions, IrsiCaixa, and Consorcio Centro de Investigación Biomédica en Red, Instituto de Salud Carlos III, Ministerio de Ciencia, Innovación e Universidades.

Polyvalent mpox mRNA vaccines elicit robust immune responses and confer potent protection against vaccinia virus

The 2022 mpox outbreak led the World Health Organization (WHO) to declare it a public health emergency of international concern (PHEIC). There is a need to develop more effective and safer mpox virus (MPXV)-specific vaccines in response to the mpox epidemic. The mRNA vaccine is a promising platform to protect against MPXV infection. In this study, we construct two bivalent MPXV mRNA vaccines, designated LBA (B6R-A29L) and LAM (A35R-M1R), and a quadrivalent mRNA vaccine, LBAAM (B6R-A35R-A29L-M1R). The immunogenicity and protective efficacy of these vaccines alone or in combination were evaluated in a lethal mouse model. All mRNA vaccine candidates could elicit potential antigen-specific humoral and cellular immune responses and provide protection against vaccinia virus (VACV) infection. The protective effect of the combination of two bivalent mRNA vaccines and the quadrivalent vaccine was superior to that of the individual bivalent mRNA vaccine. Our study provides valuable insights for the development of more efficient and safer mRNA vaccines against mpox.

Fabrication of label-free immunoprobe for monkeypox A29 detection using one-step electrodeposited molybdenum oxide-graphene quantum rods

Monkeypox is a zoonotic viral infection caused by the monkeypox virus (MPXV), which belongs to the Poxviridae family of the Orthopoxvirus (OPXV) genus. Monkeypox is transmitted from animals to humans and humans to humans; therefore, the accurate and early detection of MPXV is crucial for reducing mortality. A novel graphene-based material, graphene quantum rods (GQRs) was synthesized and confirmed using high-resolution transmission electron microscopy (HR-TEM) and atomic force microscopy (AFM). In this study, molybdenum oxide was electrodeposited and one-pot electrodeposition of MoO3-GQRs composite on carbon fiber paper (CFP) enabled by an antibody (Ab A29)/MoO3-GQRs immunoprobe was developed for the early diagnosis of MPXV protein (A29P). Several studies were conducted to analyze the MoO3-GQRs composite, and the prepared Ab A29/MoO3-GQRs immunoprobe selectively bound to the A29P antigen that was measured using differential pulse voltammetry (DPV) analysis and impedance spectroscopy. The antigen-antibody interaction was analyzed using X-ray photoelectron spectroscopy. DPV analysis showed a wide linear range of detection from 0.5 nM to 1000 nM, a detection limit of 0.52 nM, and a sensitivity of 4.51 µA in PBS. The prepared immunoprobe was used to analyze A29P in serum samples without reducing electrode sensitivity. This system is promising for the clinical analysis of A29P antigen and offers several advantages, including cost-effectiveness, ease of use, accuracy, and high sensitivity.

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.

Identification of differentially recognized T cell epitopes in the spectrum of tuberculosis infection

There is still incomplete knowledge of which Mycobacterium tuberculosis (Mtb) antigens can trigger distinct T cell responses at different stages of infection. Here, a proteome-wide screen of 20,610 Mtb-derived peptides in 21 patients mid-treatment for active tuberculosis (ATB) reveals IFNγ-specific T cell responses against 137 unique epitopes. Of these, 16% are recognized by two or more participants and predominantly derived from cell wall and cell processes antigens. There is differential recognition of antigens, including TB vaccine candidate antigens, between ATB participants and interferon-gamma release assay (IGRA + /-) individuals. We developed an ATB-specific peptide pool (ATB116) consisting of epitopes exclusively recognized by ATB participants. This pool can distinguish patients with pulmonary ATB from IGRA + /- individuals from various geographical locations, with a sensitivity of over 60% and a specificity exceeding 80%. This proteome-wide screen of T cell reactivity identified infection stage-specific epitopes and antigens for potential use in diagnostics and measuring Mtb-specific immune responses.

Long-lasting humoral and cellular memory immunity to vaccinia virus Tiantan provides pre-existing immunity against mpox virus in Chinese population

Investigating immune memory to vaccinia virus and pre-existing immunity to mpox virus (MPXV) among the population is crucial for the global response to this ongoing mpox epidemic. Blood was sampled from vaccinees inoculated with vaccinia virus Tiantan (VTT) strain born before 1981 and unvaccinated control subjects born since 1982. After at least 40 years of the inoculation, 60% or 5% VTT vaccinees possess neutralizing antibodies (NAbs) to VTT or MPXV, with at least 50% having T cell memory to VTT protein antigens. Notably, 46.7% vaccinees show pre-existing T cell responses to MPXV. Broad pre-existing CD8+ T cell reactivities to MPXV are detected not only against conserved epitopes but also against variant epitopes between VTT and MPXV. Persistent NAbs and T cell memory to VTT among vaccinees, along with pre-existing T cells to MPXV among both vaccinees and the unvaccinated population, indicate a particular immune barrier to mpox.

Orthopoxvirus-Specific T-Cell Responses in Convalescent Mpox Patients

Orthopoxvirus-specific T-cell responses were analyzed in 10 patients who had recovered from Mpox including 7 people with human immunodeficiency virus (PWH). Eight participants had detectable virus-specific T-cell responses, including a PWH who was not on antiretroviral therapy and a PWH on immunosuppressive therapy. These 2 participants had robust polyfunctional CD4+ T-cell responses to peptides from the 121L vaccinia virus (VACV) protein. T-cells from 4 of 5 HLA-A2-positive participants targeted at least 1 previously described HLA-A2-restricted VACV epitope, including an epitope targeted in 2 participants. These results advance our understanding of immunity in convalescent Mpox patients.

Pan-pox-specific T-cell responses in HIV-1-infected individuals after JYNNEOS vaccination

People living with human immunodeficiency virus (HIV) are the individuals most affected by the current Monkeypox virus outbreak that was first announced in May 2022. Here we report Pan-pox-specific T-cell responses in a cohort of HIV-1-infected individuals after receiving the nonreplicative, attenuated smallpox vaccine JYNNEOS from Bavarian Nordic. Intradermal (i.d.) and subcutaneous (s.c.) vaccination was safe without major side effects. Dose-sparing i.d. vaccination was superior to s.c. vaccination and promoted T-cell polyfunctionality, and the expression of the gut-homing marker α4β7 integrin on lymphocytes. HIV-1-infected individuals with CD4 T-cell counts ≤500/mm3 blood required at least a booster vaccination to exhibit efficient virus-specific T-cell responses. The magnitude of the Th1 response after this booster directly correlated with the CD4 T-cell count of the vaccinees. Further studies with a larger number of participants are warranted to confirm and expand our observations.

Characterizing the acute antibody response of monkeypox and MVA-BN vaccine following an Australian outbreak

In response to the emergence of the monkeypox virus (MPXV) in Australia in May 2022, we developed and evaluated indirect immunofluorescence assays (IFA) for MPXV and Vaccinia virus (VACV) IgG and IgM antibodies using serum samples from patients with nucleic acid amplification test (NAAT)-confirmed mpox and uninfected unvaccinated controls. Additionally, 47 healthcare workers receiving two doses of the third-generation smallpox vaccine Modified Vaccinia Ankara-Bavarian Nordic (MVA-BN) undertook serial serum collection to describe the serological response to vaccination. MPXV antibodies were detected in 16/18 individuals with NAAT-confirmed mpox (sensitivity 0.89, specificity 1.00), and VACV antibodies were detected in 28/29 individuals who received two doses of MVA-BN vaccine (sensitivity 0.97, specificity 1.00). Detectable antibody in subjects historically vaccinated with early-generation vaccines against smallpox was found in 7/7 subjects, at a median of 48 years following vaccination. MPXV NAAT-positive patients with serum samples collected within the first 14 days after rash onset had detectable IgG and IgM in 9/12 and 5/12 of patients, respectively, with maintenance of IgG and disappearance of IgM titers after 60 days. While specificity was high when testing unvaccinated and uninfected subjects, significant cross-reactivity between MPXV and VACV antibodies was observed.

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.

Exploring the whole proteome of monkeypox virus to design B cell epitope-based oral vaccines using immunoinformatics approaches

In the last few months 85,536 cases and 91 deaths were reported for monkeypox disease from 110 and 71 locations from all over the world, correspondingly. The vaccines of other viruses that belong to the Poxviridae family were recommended for monkeypox. There is no licensed vaccine available for monkeypox that originated from monkeypox virus. In the present study, using the reverse vaccinology approach we have performed whole proteome analysis of monkeypox virus to screen out the potential antigenic proteins that can be used as vaccine candidates. We have also designed 12 B cell epitopes-based vaccine candidates using immunoinformatics approach. We have found a total 15 potential antigenic proteins out of which 14 antigens are novel and can be used for further vaccine development against monkeypox. We have performed the physicochemical properties, antigenic, immunogenic and allergenicity prediction of the designed vaccine candidates MPOXVs (MPOXV1-MPOXV12). Further, we have performed molecular docking, in silico immune simulation and cloning of MPOXVs. All MPOXVs are potential vaccine candidate that can potentially activate the innate, cellular, and humoral immune response. However, further experimental validation is required before moving to clinical trials. This is the first oral vaccine reported for monkeypox virus derived from monkeypox proteins.

Determination of seroprevalence and kinetics of humoral response using mpox virus A29 protein

BACKGROUND

Mpox virus (MPXV), previously known as monkeypox virus, has spread globally in 2022. An accurate and convenient antibody test is essential for the determination of seroprevalence and for studying immune response after natural infection or vaccination. Most seroprevalence or vaccine studies used either live MPXV (or vaccinia virus [VACV]) or inactivated MPXV (or VACV) culture lysate for serological assays, but MPXV culture can only be performed in biosafety level 3 (BSL-3) facilities. Here, we developed and evaluated an enzyme immunoassay (EIA) based on the MPXV A29 surface envelope protein.

METHODS

We compared the specificity of the MPXV A29, VACV A27, and VACV lysate EIA using serum specimens collected prior to the global spread of MPXV. Next, we performed these EIAs for serum specimens collected from two mpox patients and an MVA-BN vaccine recipient. We also assessed the kinetics of plasmblast and MPXV A29-specific B-cell response.

RESULTS

Using sera collected from different age groups in Hong Kong, we found that most individuals, including those born before 1981 who have received the smallpox vaccine, tested negative using the MPXV A29 protein. MPXV A29-specific antibody could be detected in the serum of mpox patients and an MVA-BN recipient. In a mpox patient, the frequency of plasmablast and MPXV A29-specific B cell peaked on day 8 post-symptom onset and gradually decreased. Finally, we demonstrated that antibodies against the A29 protein can be used for immunofluorescence staining of MPXV-infected cells.

CONCLUSIONS

MPXV A29 protein is suitable for studying the immune response against MPXV infection.

Serosurvey of Immunity to Monkeypox (Mpox) Virus Antigens in People Living with HIV in South Florida

Mpox is an infectious disease caused by the monkeypox virus (MPXV) belonging to the Orthopoxvirus (OPXV) genus, which includes smallpox and vaccinia virus (VACV). A global mpox outbreak which began in May 2022 has infected more than 88,000 people. VACV-based vaccines provide protection against mpox disease but complicate the use of serological assays for disease surveillance. We tested the reactivity of serum IgG from Modified Vaccinia Ankara-Bavarian Nordic (MVA-BN)-vaccinated (n = 12) and convalescent mpox-infected (n = 5) individuals and uninfected, non-vaccinated controls (n = 32) to MPXV/VACV proteins A27, A29, A30, A35, B16, B21, C19, D6, E8, H3, I1, and L1. Using a subset of MPXV antigen-based assays (A35, B16, E8, H3, and I1), we conducted a mpox antibody survey of serum from 214 individuals, including 117 (54.7%) people with HIV (PWH) collected between June 2022 and January 2023, excluding individuals who reported recent mpox vaccination or infection, and 32 young, pre-pandemic controls. The convalescent sera reacted strongly to most tested antigens. Vaccine sera responses were limited to A35, E8, H3, and I1. IgG antibody to E8 was markedly elevated in all vaccinated individuals. B16 IgG showed high sensitivity (100% [95% CI: 56.55-100.0%]) and specificity (91.67% [64.61-99.57%]) for distinguishing infection from MVA-BN vaccination, while E8 IgG showed 100% [75.75-100] sensitivity and 100% [79.61-100] specificity for detecting and distinguishing vaccinated individuals from controls. We identified 11/214 (5.1%) recent serum samples and 1/32 (3.1%) young, pre-pandemic controls that were seropositive for ≥2 MPXV antibodies, including 6.8% of PWH. Seropositivity was 10/129 (7.8%) among males compared to 1/85 (1.2%) among females. Our findings provide insight into the humoral immune response to mpox and demonstrate the usefulness of inexpensive, antigen-based serosurveillance in identifying asymptomatic or unreported infections.

The MegaPool Approach to Characterize Adaptive CD4+ and CD8+ T Cell Responses

Epitopes recognized by T cells are a collection of short peptide fragments derived from specific antigens or proteins. Immunological research to study T cell responses is hindered by the extreme degree of heterogeneity of epitope targets, which are usually derived from multiple antigens; within a given antigen, hundreds of different T cell epitopes can be recognized, differing from one individual to the next because T cell epitope recognition is restricted by the epitopes' ability to bind to MHC molecules, which are extremely polymorphic in different individuals. Testing large pools encompassing hundreds of peptides is technically challenging because of logistical considerations regarding solvent-induced toxicity. To address this issue, we developed the MegaPool (MP) approach based on sequential lyophilization of large numbers of peptides that can be used in a variety of assays to measure T cell responses, including ELISPOT, intracellular cytokine staining, and activation-induced marker assays, and that has been validated in the study of infectious diseases, allergies, and autoimmunity. Here, we describe the procedures for generating and testing MPs, starting with peptide synthesis and lyophilization, as well as a step-by-step guide and recommendations for their handling and experimental usage. Overall, the MP approach is a powerful strategy for studying T cell responses and understanding the immune system's role in health and disease. © 2023 Wiley Periodicals LLC. Basic Protocol 1: Generation of peptide pools ("MegaPools") Basic Protocol 2: MegaPool testing and quantitation of antigen-specific T cell responses.

Mpox vaccine and infection-driven human immune signatures: an immunological analysis of an observational study

BACKGROUND

Monkeypox virus has recently infected more than 88 000 people, raising concerns about our preparedness against this emerging viral pathogen. Licensed and approved for mpox, the JYNNEOS vaccine has fewer side-effects than previous smallpox vaccines and has shown immunogenicity against monkeypox in animal models. This study aims to elucidate human immune responses to JYNNEOS vaccination compared with mpox-induced immunity.

METHODS

Peripheral blood mononuclear cells and sera were obtained from ten individuals vaccinated with one or two doses of JYNNEOS and six individuals diagnosed with monkeypox virus infection. Samples were obtained from seven individuals before vaccination to serve as a baseline. We examined the polyclonal serum (ELISA) and single B-cell (heavy chain gene and transcriptome data) antibody repertoires and T-cell responses (activation-induced marker and intracellular cytokine staining assays) induced by the JYNNEOS vaccine versus monkeypox virus infection.

FINDINGS

All participants were men between the ages of 21 and 60 years, except for one woman in the group of mpox-convalescent individuals, and none had previous orthopoxvirus exposure. All mpox cases were mild. Vaccinee samples were collected 6-33 days after the first dose and 5-40 days after the second dose. Mpox-convalescent samples were collected 20-102 days after infection. In vaccine recipients, gene-level plasmablast and antibody responses were negligible and sera displayed moderate binding to recombinant orthopoxviral proteins (A29L, A35R, E8L, A30L, A27L, A33R, B18R, and L1R) and native proteins from the 2022 monkeypox outbreak strain. By contrast, recent monkeypox virus infection (within 20-102 days) induced robust serum antibody responses to monkeypox virus proteins and to native monkeypox virus proteins from a viral isolate obtained during the 2022 outbreak. JYNNEOS vaccine recipients presented robust orthopoxviral CD4+ and CD8+ T-cell responses.

INTERPRETATION

Infection with monkeypox virus resulted in robust B-cell and T-cell responses, whereas immunisation with JYNNEOS elicited more robust T-cell responses. These data can help to inform vaccine design and policies for preventing mpox in humans.

FUNDING

National Cancer Institute (National Institutes of Health), National Institute of Allergy and Infectious Diseases (National Institutes of Health), and Icahn School of Medicine.

Evaluation of Cross-Immunity to the Mpox Virus Due to Historic Smallpox Vaccination

When the Mpox virus (MPXV) began spreading globally in 2022, it became critical to evaluate whether residual immunity from smallpox vaccination provided cross-protection. To assess the cross-immune response to MPXV, we collected serum samples (n = 97) and PBMCs (n = 30) from healthy-donors, either born before 1974 and reporting smallpox vaccination during childhood or born after 1975 and not vaccinated with Vaccinia virus (VACV)-based vaccines. We evaluated the levels of anti-MPXV IgG and neutralizing antibodies (Nabs) and the presence of a T cell response against MPXV. We found anti-MPXV IgG and Nabs in 60 (89.6%) and 40 (70.1%) vaccinated individuals, respectively. We observed a T cell response to Orthopoxviruses and MPXV peptide pools in 30% of vaccinated individuals. We thus show that a high proportion of subjects who received the smallpox vaccine 40 to 60 years ago have humoral cross-immunity, while the T-cell-specific response against MPXV was observed in a smaller group (30%) of vaccinated individuals. This study, combined with information on immunity developed during natural infection or the administration of current vaccines, will contribute to a better understanding of humoral and cellular responses against MPXV.

Monkeypox virus-infected individuals mount comparable humoral immune responses as Smallpox-vaccinated individuals

In early 2022, a cluster of monkeypox virus (MPXV) infection (mpox) cases were identified within the UK with no prior travel history to MPXV-endemic regions. Subsequently, case numbers exceeding 80,000 were reported worldwide, primarily affecting gay, bisexual, and other men who have sex with men (GBMSM). Public health agencies worldwide have offered the IMVANEX Smallpox vaccination to these individuals at high-risk to provide protection and limit the spread of MPXV. We have developed a comprehensive array of ELISAs to study poxvirus-induced antibodies, utilising 24 MPXV and 3 Vaccinia virus (VACV) recombinant antigens. Panels of serum samples from individuals with differing Smallpox-vaccine doses and those with prior MPXV infection were tested on these assays, where we observed that one dose of Smallpox vaccination induces a low number of antibodies to a limited number of MPXV antigens but increasing with further vaccination doses. MPXV infection induced similar antibody responses to diverse poxvirus antigens observed in Smallpox-vaccinated individuals. We identify MPXV A27 as a serological marker of MPXV-infection, whilst MPXV M1 (VACV L1) is likely IMVANEX-specific. Here, we demonstrate analogous humoral antigen recognition between both MPXV-infected or Smallpox-vaccinated individuals, with binding to diverse yet core set of poxvirus antigens, providing opportunities for future vaccine (e.g., mRNA) and therapeutic (e.g., mAbs) design.

Monkeypox Virus: A Comprehensive Overview of Viral Pathology, Immune Response, and Antiviral Strategies

BACKGROUND

The years 2022-2023 witnessed a monkeypox virus (mpox) outbreak in some countries worldwide, where it exists in an endemic form. However, the number of infectious cases is continuously on the rise, and there has been an unexpected, drastic increase in cases that result from sustained transmission in non-endemic regions of the world. Under this scenario, it is pertinent for the world to be aware of healthcare threats to mpox infection. This review aimed to compile advanced data regarding the different aspects of mpox disease.

METHODS

A comprehensive strategy for the compilation of recent data was adopted to add data regarding mpox, biology, viral pathology, immune response, and brief details on the antiviral strategies under trial; the search was limited to 2016-2023. The aim is to make the scientific community aware of diverse aspects of mpox.

RESULTS

Consequently, detailed insights have been drawn with regard to the nature, epidemiology, etiology, and biological nature of mpox. Additionally, its host interaction and viral infectious cycle and immune interventions have been briefly elaborated. This comprehensively drawn literature review delivers brief insights into the biological nature, immune responses, and clinical developments in the form of therapeutics against mpox. This study will help scientists understand the biological nature and responses in hosts, which will further help clinicians with therapeutic handling, diagnosis, and treatment options.

CONCLUSIONS

This study will provide updated information on mpox's pathology, immune responses, and antiviral strategies. Moreover, it will also help the public to become educated on the healthcare-associated threat and take timely mitigation measures against expected mpox outbreaks in the future.

Memory profiles distinguish cross-reactive and virus-specific T cell immunity to mpox

Mpox represents a persistent health concern with varying disease severity. Reinfections with mpox virus (MPXV) are rare, possibly indicating effective memory responses to MPXV or related poxviruses, notably vaccinia virus (VACV) from smallpox vaccination. We assessed cross-reactive and virus-specific CD4+ and CD8+ T cells in healthy individuals and mpox convalescent donors. Cross-reactive T cells were most frequently observed in healthy donors over 45 years. Notably, long-lived memory CD8+ T cells targeting conserved VACV/MPXV epitopes were identified in older individuals more than four decades after VACV exposure and exhibited stem-like characteristics, defined by T cell factor-1 (TCF-1) expression. In mpox convalescent donors, MPXV-reactive CD4+ and CD8+ T cells were more prevalent than in controls, demonstrating enhanced functionality and skewing toward effector phenotypes, which correlated with milder disease. Collectively, we report robust effector memory MPXV-specific T cell responses in mild mpox and long-lived TCF-1+ VACV/MPXV-specific CD8+ T cells decades after smallpox vaccination.

Characterization of immune response against monkeypox virus in cohorts of infected patients, historic and newly vaccinated subjects

Monkeypox virus (MPXV) is a zoonotic disease endemic in the rainforest countries of Central and West Africa. Understanding the immune response in zoonosis is fundamental to prevent and contrast viral spreading. MPXV is a close relative of Variola (smallpox) virus and vaccination with vaccinia virus gives approximatively 85% of protection against MPXV. With the emergence of the recent MPXV outbreak, JYNNEOS vaccine has been proposed to individuals at high-risk of exposure. Comparative data on MPXV immune response in vaccinated or infected subjects are still limited. Here we set-up an immunofluorescence method for the evaluation of humoral response elicited by natural infection and healthy vaccinated subjects, including historically smallpox-vaccinated individuals and newly vaccinated subjects. Neutralization assay was also included, and in vaccinated subjects, cell-mediated response was evaluated. We observed that the natural infection produces a strong immune response that can control the disease. In naïve subjects, a second dose boosts the serological response to levels similar to those of the MPXV patients. Last, smallpox-vaccinated controls retain a degree of protection, even after years from vaccination, most visible in the t-cellular response.

Monkeypox (Mpox) requires continued surveillance, vaccines, therapeutics and mitigating strategies

The widespread outbreak of the monkeypox virus (MPXV) recognized in 2022 poses new challenges for public healthcare systems worldwide. With more than 86,000 people infected, there is concern that MPXV may become endemic outside of its original geographical area leading to repeated human spillover infections or continue to be spread person-to-person. Fortunately, classical public health measures (e.g., isolation, contact tracing and quarantine) and vaccination have blunted the spread of the virus, but cases are continuing to be reported in 28 countries in March 2023. We describe here the vaccines and drugs available for the prevention and treatment of MPXV infections. However, although their efficacy against monkeypox (mpox) has been established in animal models, little is known about their efficacy in the current outbreak setting. The continuing opportunity for transmission raises concerns about the potential for evolution of the virus and for expansion beyond the current risk groups. The priorities for action are clear: 1) more data on the efficacy of vaccines and drugs in infected humans must be gathered; 2) global collaborations are necessary to ensure that government authorities work with the private sector in developed and low and middle income countries (LMICs) to provide the availability of treatments and vaccines, especially in historically endemic/enzootic areas; 3) diagnostic and surveillance capacity must be increased to identify areas and populations where the virus is present and may seed resurgence; 4) those at high risk of severe outcomes (e.g., immunocompromised, untreated HIV, pregnant women, and inflammatory skin conditions) must be informed of the risk of infection and be protected from community transmission of MPXV; 5) engagement with the hardest hit communities in a non-stigmatizing way is needed to increase the understanding and acceptance of public health measures; and 6) repositories of monkeypox clinical samples, including blood, fluids, tissues and lesion material must be established for researchers. This MPXV outbreak is a warning that pandemic preparedness plans need additional coordination and resources. We must prepare for continuing transmission, resurgence, and repeated spillovers of MPXV.

Identification of differentially recognized T cell epitopes in the spectrum of Mtb infection

Tuberculosis caused by Mycobacterium tuberculosis is one of the leading causes of death from a single infectious agent. Identifying dominant epitopes and comparing their reactivity in different tuberculosis (TB) infection states can help design diagnostics and vaccines. We performed a proteome-wide screen of 20,610 Mtb derived peptides in 21 Active TB (ATB) patients 3-4 months post-diagnosis of pulmonary TB (mid-treatment) using an IFNγ and IL-17 Fluorospot assay. Responses were mediated exclusively by IFNγ and identified a total of 137 unique epitopes, with each patient recognizing, on average, 8 individual epitopes and 22 epitopes (16%) recognized by 2 or more participants. Responses were predominantly directed against antigens part of the cell wall and cell processes category. Testing 517 peptides spanning TB vaccine candidates and ESAT-6 and CFP10 antigens also revealed differential recognition between ATB participants mid-treatment and healthy IGRA+ participants of several vaccine antigens. An ATB-specific peptide pool consisting of epitopes exclusively recognized by participants mid-treatment, allowed distinguishing participants with active pulmonary TB from healthy interferon-gamma release assay (IGRA)+/- participants from diverse geographical locations. Analysis of longitudinal samples indicated decreased reactivity during treatment for pulmonary TB. Together, these results show that a proteome-wide screen of T cell reactivity identifies epitopes and antigens that are differentially recognized depending on the Mtb infection stage. These have potential use in developing diagnostics and vaccine candidates and measuring correlates of protection.

Rational development of multicomponent mRNA vaccine candidates against mpox

The re-emerging mpox (formerly monkeypox) virus (MPXV), a member of Orthopoxvirus genus together with variola virus (VARV) and vaccinia virus (VACV), has led to public health emergency of international concern since July, 2022. Inspired by the unprecedent success of coronavirus disease 2019 (COVID-19) mRNA vaccines, the development of a safe and effective mRNA vaccine against MPXV is of high priority. Based on our established lipid nanoparticle (LNP)-encapsulated mRNA vaccine platform, we rationally constructed and prepared a panel of multicomponent MPXV vaccine candidates encoding different combinations of viral antigens including M1R, E8L, A29L, A35R and B6R. In vitro and in vivo characterization demonstrated that two immunizations of all mRNA vaccine candidates elicit a robust antibody response as well as antigen specific Th1-biased cellular response in mice. Importantly, the penta- and tetra-component vaccine candidates AR-MPXV5 and AR-MPXV4a showed superior capability of inducing neutralizing antibodies as well as of protecting from VACV challenge in mice. Our study provides critical insights to understand the protection mechanism of MPXV infection and direct evidence supporting further clinical development of these multicomponent mRNA vaccine candidates.

Mpox vaccine and infection-driven human immune signatures

Background

Mpox (formerly known as monkeypox) outbreaks outside endemic areas peaked in July 2022, infecting > 85,000 people and raising concerns about our preparedness against this emerging viral pathogen. Licensed and approved for mpox, the JYNNEOS vaccine has fewer side effects than previous smallpox vaccines and demonstrated efficacy against mpox infection in humans. Comparing JYNNEOS vaccine- and mpox-induced immunity is imperative to evaluate JYNNEOS' immunogenicity and inform vaccine administration and design.

Methods

We examined the polyclonal serum (ELISA) and single B cell (heavy chain gene and transcriptome data) antibody repertoires and T cells (AIM and ICS assays) induced by the JYNNEOS vaccine as well as mpox infection.

Findings

Gene-level plasmablast and antibody responses were negligible and JYNNEOS vaccinee sera displayed minimal binding to recombinant mpox proteins and native proteins from the 2022 outbreak strain. In contrast, recent mpox infection (within 20-102 days) induced robust serum antibody responses to A29L, A35R, A33R, B18R, and A30L, and to native mpox proteins, compared to vaccinees. JYNNEOS vaccine recipients presented comparable CD4 and CD8 T cell responses against orthopox peptides to those observed after mpox infection.

Interpretation

JYNNEOS immunization does not elicit a robust B cell response, and its immunogenicity may be mediated by T cells.

Funding

Research reported in this publication was supported, in part, by the National Cancer Institute of the National Institutes of Health under Award Number U54CA267776, U19AI168631(VS), as well as institutional funds from the Icahn School of Medicine.

T cells are ready for the fight against monkeypox

In this issue of Cell Host & Microbe, Grifoni et al. provide reassuring evidence that the majority of epitopes induced by vaccinia virus vaccines are conserved in monkeypox virus and can elicit memory T cell responses, while also providing an extensive list of potential T cell epitopes.