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Vaccinia-specific CD4 and CD8 memory cells. CD8-depleted PBMCs (grey bars) compared with total PBMCs (black bars) were tested by ELISpot assay (a) and proliferation assay (b). Results are shown for two representative individuals.
Source publication
Residual immunity to the smallpox virus raises key questions about the persistence of long-term immune memory in the absence of antigen, since vaccination ended in 1980. IFN-gamma-producing effector-memory and proliferative memory T cells were compared in 79 vaccinees 13-25 yr after their last immunization and in unvaccinated individuals. Only 20%...
Context in source publication
Context 1
... of Long-Term Memory T Cells Specific for Vaccinia. To assess the cell populations involved in these vaccinia-specific responses, we first assayed IFN-produc- tion and proliferation after CD8 cell depletion (Fig. 2, a and b). Residual vaccinia-specific effector and proliferative responses were still observed in most vaccinated individu- als; this suggests that CD4 T cells were the major compo- nent of these persistent effector-memory T cell responses. That absolute numbers of vaccinia-specific SFCs in the CD4-enriched PBMC fractions did not increase ...
Citations
... A mouse model of VACV infection suggested that CD4+ T-cell-dependent anti-VACV antibody production plays an important role in clearing the virus following acute infection, while in the absence of antibodies, CD8+ T cells can contribute to protection against the disease [3]. It is believed that the smallpox vaccine confers lifelong protection against severe disease [10], and studies carried out after smallpox eradication tried to estimate the waning effect by measuring the levels of immunological markers at different time-points post-immunization [11][12][13][14][15][16][17][18][19][20][21]. Nowadays, after smallpox eradication and the discontinuation of the vaccination campaign, the human population is largely unvaccinated. ...
... In previous publications, variable percentages (from 0 to about 80%) of responsive T cells upon stimulation with VACV or VACV-derived peptides have been described, and this variability may certainly depend on the laboratory protocol used and the assay selected [12,[17][18][19]21,29,30]. The analysis of the T cell response was restricted to a subset of individuals because of the availability of whole blood samples for PBMC preparation from only 20 vaccinated and 10 unvaccinated participants. ...
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.
... However, parallel comparisons of the lung transplant recipients and controls reveal clear differences in the CD8 + T cell compartment, and assay variability would serve to reduce the power to see differences between these groups. Similar methodology using stimulation with peptides [28][29][30][31] or live vaccinia vaccine [32,33] to enhance detection of low frequency memory responses has also been used in several vaccine studies. This methodology does not distinguish whether observed difference in the CD8 + T cell compartment is due to lower starting frequency and/or reduced proliferative capacity in the lung transplant recipients, and whether the difference predicts less vaccine protection. ...
Background:
Although mRNA vaccines have overall efficacy preventing morbidity/mortality from SARS-CoV-2 infection, immunocompromised persons remain at risk. Antibodies mostly prevent early symptomatic infection, but cellular immunity, particularly the virus-specific CD8+ T cell response, is protective against disease. Defects in T cell responses to vaccination have not been well characterized in immunocompromised hosts; persons with lung transplantation are particularly vulnerable to vaccine failure with severe illness.
Methods:
Comparison groups included persons with lung transplantation and no history of COVID-19 (21 and 19 persons after initial mRNA vaccination and a third booster vaccination respectively), 8 lung transplantation participants recovered from COVID-19, and 22 non-immunocompromised healthy control individuals after initial mRNA vaccination (without history of COVID-19). Anti-spike T cell responses were assayed by stimulating peripheral blood mononuclear cells (PBMCs) with pooled small overlapping peptides spanning the SARS-CoV-2 spike protein, followed by intracellular cytokine staining (ICS) and flow cytometry for release of cytokines in response to stimulation, including negative controls (no peptide stimulation) and positive controls (phorbol myristate acetate [PMA] and ionomycin stimulation). To evaluate for low frequency memory responses, PBMCs were cultured in the presence of the mRNA-1273 vaccine for 14 days before this evaluation.
Results:
Ionophore stimulation of PBMCs revealed a less inflammatory milieu in terms of interleukin (IL)-2, IL-4, and IL-10 profiling in lung transplantation individuals, reflecting the effect of immunosuppressive treatments. Similar to what we previously reported in healthy vaccinees, spike-specific responses in lung transplantation recipients were undetectable (< 0.01%) when tested 2 weeks after vaccination or later, but were detectable after in vitro culture of PBMCs with mRNA-1273 vaccine to enrich memory T cell responses. This was also seen in COVID-19-recovered lung transplantation recipients. Comparison of their enriched memory responses to controls revealed relatively similar CD4+ T cell memory, but markedly reduced CD8+ T cell memory both after primary vaccination or a booster dose. These responses were not correlated to age or time after transplantation. The vaccine-induced CD4+ and CD8+ responses correlated well in the healthy control group, but poorly in the transplantation groups.
Conclusions:
These results reveal a specific defect in CD8+ T cells, which have key roles both in transplanted organ rejection but also antiviral effector responses. Overcoming this defect will require strategies to enhance vaccine immunogenicity in immunocompromised persons.
... Memory CD4 1 T-cells, including CM, transitional memory (TM), and EM T-cells, are key cellular reservoirs for HIV-1 infection (2,7). CM CD4 1 T-cells contribute substantially to HIV persistence, given that this subset can survive for decades and represents a long-lasting reservoir in immunological responders (IR) receiving ART (2,8). Our group recently showed that maintenance of HIV-1 infection was increased despite several years of ART for immunological suboptimal responders (ISR), compared with IR, with the largest difference being observed in the TM and long-lived CM CD4 1 T-cell subsets due to a greater abundance of immune checkpoint molecules and expression of homeostatic cytokines (9). ...
Elucidating the mechanisms underlying the persistence and location of the HIV reservoir is critical for developing cure interventions. While it has been shown that levels of T-cell activation and the size of the HIV reservoir are greater in rectal tissue and lymph nodes (LN) than in blood, the relative contributions of T-cell subsets to this anatomic difference are unknown. We measured and compared HIV-1 DNA content, expression of the T-cell activation markers CD38 and HLA-DR, and expression of the exhaustion markers programmed cell death protein 1 (PD-1) and T-cell immunoreceptor with immunoglobulin and immunoreceptor tyrosine-based inhibitory motif domains (TIGIT) in naive, central memory (CM), transitional memory (TM), and effector memory (EM) CD4+ and CD8+ T-cells in paired blood and LN samples among 14 people with HIV who were receiving antiretroviral therapy. HIV-1 DNA levels, T-cell immune activation, and TIGIT expression were higher in LN than in blood, especially in CM and TM CD4+ T-cell subsets. Immune activation was significantly higher in all CD8+ T-cell subsets, and memory CD8+ T-cell subsets from LN had higher levels of PD-1 expression, compared with blood, while TIGIT expression levels were significantly lower in TM CD8+ T-cells. The differences seen in CM and TM CD4+ T-cell subsets were more pronounced among participants with CD4+ T-cell counts of <500 cells/μL within 2 years after antiretroviral therapy initiation, thus highlighting increased residual dysregulation in LN as a distinguishing feature of and a potential mechanism for individuals with suboptimal CD4+ T-cell recovery during antiretroviral therapy. IMPORTANCE This study provides new insights into the contributions of different CD4+ and CD8+ T-cell subsets to the anatomic differences between LN and blood in individuals with HIV who have optimal versus suboptimal CD4+ T-cell recovery. To our knowledge, this is the first study comparing paired LN and blood CD4+ and CD8+ T-cell differentiation subsets, as well as those subsets in immunological responders versus immunological suboptimal responders.
... Survivors from VARV infections had low levels of circulating CD4 + T cells responding to VACV antigen stimulation up to more than 40 years after infection. These data show the mechanisms of the persistence of long-memory against OPXVs in the absence of antigens [186,189]. ...
The eradication of smallpox was an enormous achievement due to the global vaccination program launched by World Health Organization. The cessation of the vaccination program led to steadily declining herd immunity against smallpox, causing a health emergency of global concern. The smallpox vaccines induced strong, humoral, and cell-mediated immune responses, protecting for decades after immunization, not only against smallpox but also against other zoonotic orthopoxviruses that now represent a significant threat to public health. Here we review the major aspects regarding orthopoxviruses’ zoonotic infections, factors responsible for viral transmissions, as well as the emerging problem of the increased number of monkeypox cases recently reported. The development of prophylactic measures against poxvirus infections, especially the current threat caused by the monkeypox virus, requires a profound understanding of poxvirus immunobiology. The utilization of animal and cell line models has provided good insight into host antiviral defenses as well as orthopoxvirus evasion mechanisms. To survive within a host, orthopoxviruses encode a large number of proteins that subvert inflammatory and immune pathways. The circumvention of viral evasion strategies and the enhancement of major host defenses are key in designing novel, safer vaccines, and should become the targets of antiviral therapies in treating poxvirus infections.
... Given the eradication of smallpox and cessation of vaccinia vaccination, vaccinia reactivity has been studied to address the issue of cellular immune memory. While antibody responses against vaccinia appear to be stable for many decades after vaccination (76), the cellular immune response including CTLs appears to wane to undetectable levels by sensitive ELISpot assays within about two to three decades (77)(78)(79). However, in vitro enrichment assays using vaccinia stimulation of PBMC demonstrated durable memory lasting five decades or more (77,80). ...
... While antibody responses against vaccinia appear to be stable for many decades after vaccination (76), the cellular immune response including CTLs appears to wane to undetectable levels by sensitive ELISpot assays within about two to three decades (77)(78)(79). However, in vitro enrichment assays using vaccinia stimulation of PBMC demonstrated durable memory lasting five decades or more (77,80). The degree to which memory detected in this manner would be protective against infection is unknown, although evaluations of vaccinees during smallpox outbreaks PBMC cultured with the mRNA-1273 vaccine in vitro reveal enrichment of spike-specific memory CD4+ and CD8+ T cell responses . ...
... Our methodology for detecting memory T cell responses against SARS-CoV-2 spike protein is novel for its use of the mRNA-1273 as an in vitro stimulus, but the general strategy of antigen-specific stimulation to enrich memory T cells for ELISpot detection has been utilized widely. As mentioned above, vaccinia infection of PBMC has been employed to reveal memory responses against vaccinia (77,80), and this approach has been applied for other indications typically using small peptide antigens (84)(85)(86)(87). While the generation of de novo T cell responses from naïve T cells rather than expansion of low-level memory responses by such protocols is a theoretical caveat to our approach, experimentally doing so purposely has been a technically challenging goal that requires dedicated enrichment and differentiation of specialized dendritic cells (88)(89)(90)(91). ...
Introduction
While antibodies raised by SARS-CoV-2 mRNA vaccines have had compromised efficacy to prevent breakthrough infections due to both limited durability and spike sequence variation, the vaccines have remained highly protective against severe illness. This protection is mediated through cellular immunity, particularly CD8+ T cells, and lasts at least a few months. Although several studies have documented rapidly waning levels of vaccine-elicited antibodies, the kinetics of T cell responses have not been well defined.
Methods
Interferon (IFN)-γ enzyme-linked immunosorbent spot (ELISpot) assay and intracellular cytokine staining (ICS) were utilized to assess cellular immune responses (in isolated CD8+ T cells or whole peripheral blood mononuclear cells, PBMCs) to pooled peptides spanning spike. ELISA was performed to quantitate serum antibodies against the spike receptor binding domain (RBD).
Results
In two persons receiving primary vaccination, tightly serially evaluated frequencies of anti-spike CD8+ T cells using ELISpot assays revealed strikingly short-lived responses, peaking after about 10 days and becoming undetectable by about 20 days after each dose. This pattern was also observed in cross-sectional analyses of persons after the first and second doses during primary vaccination with mRNA vaccines. In contrast, cross-sectional analysis of COVID-19-recovered persons using the same assay showed persisting responses in most persons through 45 days after symptom onset. Cross-sectional analysis using IFN-γ ICS of PBMCs from persons 13 to 235 days after mRNA vaccination also demonstrated undetectable CD8+ T cells against spike soon after vaccination, and extended the observation to include CD4+ T cells. However, ICS analyses of the same PBMCs after culturing with the mRNA-1273 vaccine in vitro showed CD4+ and CD8+ T cell responses that were readily detectable in most persons out to 235 days after vaccination.
Discussion
Overall, we find that detection of spike-targeted responses from mRNA vaccines using typical IFN-γ assays is remarkably transient, which may be a function of the mRNA vaccine platform and an intrinsic property of the spike protein as an immune target. However, robust memory, as demonstrated by capacity for rapid expansion of T cells responding to spike, is maintained at least several months after vaccination. This is consistent with the clinical observation of vaccine protection from severe illness lasting months. The level of such memory responsiveness required for clinical protection remains to be defined.
... Vaccination could provide immunological memory, which can persist for several years to several decades [116][117][118]. Stimulation of both B and T lymphocyte-mediated immunity is considered vital for any successful vaccination strategy by providing a faster and more efficient immune response in the host upon encountering the target pathogen in the future. ...
Human polyomavirus type 1, or BK virus (BKV), is a ubiquitous pathogen belonging to the polyomaviridae family mostly known for causing BKV-associated nephropathy (BKVN) and allograft rejection in kidney transplant recipients (KTRs) following the immunosuppression regimens recommended in these patients. Reduction of the immunosuppression level and anti-viral agents are the usual approaches for BKV clearance, which have not met a desired outcome yet. There are also debating matters such as the effect of this pathogen on emerging various comorbidities and the related malignancies in the human population. In this study, a reverse vaccinology approach was implemented to design a mRNA vaccine against BKV by identifying the most antigenic proteins of this pathogen. Potential immunogenic T and B lymphocyte epitopes were predicted through various immunoinformatic tools. The final epitopes were selected according to antigenicity, toxicity, allergenicity, and cytokine inducibility scores. According to the obtained results, the designed vaccine was antigenic, neutral at the physiological pH, non-toxic, and non-allergenic with a world population coverage of 93.77%. Since the mRNA codon optimization ensures the efficient expression of the vaccine in a host cell, evaluation of different parameters showed our designed mRNA vaccine has a stable structure. Moreover, it had strong interactions with toll-like receptor 4 (TLR4) according to the molecular dynamic simulation studies. The in silico immune simulation analyses revealed an overall increase in the immune responses following repeated exposure to the designed vaccine. Based on our findings, the vaccine candidate is ready to be tested as a promising novel mRNA therapeutic vaccine against BKV.
... In our study, we observed that some participants born in the early 1940s still had high neutralization titers for orthopoxviruses. This result is consistent with previous reports that smallpox vaccination generates long-term splenic memory lymphocytes that can lead to the production of antibodies against the vaccine >80 years after vaccination (30)(31)(32)(33)(34)(35)(36)(37)(38)(39). However, we also show a low seroprevalence among participants born before 1960 (≈12.5%). ...
To determine a demographic overview of orthopoxvirus seroprevalence, we tested blood samples collected during 2003-2019 from France (n = 4,876), Bolivia (n = 601), Laos (n = 657), and Mali (n = 255) for neutralizing antibodies against vaccinia virus. In addition, we tested 4,448 of the 4,876 samples from France for neutralizing antibodies against cowpox virus. We confirmed extensive cross-immunity between the 2 viruses. Seroprevalence of antibodies was <1% in Bolivia, <5% in Laos, and 17.25% in Mali. In France, we found low prevalence of neutralizing antibodies in persons who were unvaccinated and vaccinated for smallpox, suggesting immunosenescence occurred in vaccinated persons, and smallpox vaccination compliance declined before the end of compulsory vaccination. Our results suggest that populations in Europe, Africa, Asia, and South America are susceptible to orthopoxvirus infections, which might have precipitated the emergence of orthopoxvirus infections such as the 2022 spread of monkeypox in Europe.
... Spike Glycoprotein-Specific CD4 + and CD8 + T-Cell Immunity, Which Is Significantly Decreased Six Months After the Administration of the Second Dose of the Vaccine Cellular immunity against SARS-CoV-2 is important for efficient protection against the virus (38). Unlike humoral immunity, which is mediated by antibodies that immediately neutralize the virus, cellular immunity can only mobilize against a virus after antigen challenge (39)(40)(41). This mobilization relies on both CD4 + T cells and CD8 + T cells recognizing appropriate target antigens and effectively proliferating after antigen recognition. ...
Coronavirus disease 2019 (COVID-19) vaccines effectively elicit humoral and cellular immunity against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in healthy populations. This immunity decreases several months after vaccination. However, the efficacy of vaccine-induced immunity and its durability in patients with severe asthma on biological therapy are unknown. In this study, we evaluated the effectiveness and durability of mRNA vaccine-induced SARS-CoV-2-specific humoral and cellular immunity in severe asthma patients on biological therapy. The study included 34 patients with severe asthma treated with anti-IgE (omalizumab, n=17), anti-IL5 (mepolizumab, n=13; reslizumab, n=3), or anti-IL5R (benralizumab, n=1) biological therapy. All patients were vaccinated with two doses of the BNT162b2 mRNA vaccine with a 6-week interval between the doses. We found that this COVID-19 vaccination regimen elicited SARS-CoV-2-specific humoral and cellular immunity, which had significantly declined 6 months after receipt of the second dose of the vaccine. The type of biological treatment did not affect vaccine-elicited immunity. However, patient age negatively impacted the vaccine-induced humoral response. On the other hand, no such age-related impact on vaccine-elicited cellular immunity was observed. Our findings show that treatment of patients with severe asthma with biological therapy does not compromise the effectiveness or durability of COVID-19 vaccine-induced immunity.
... The cellular immunity against SARS-CoV-2 is important for efficient protection against the virus (35). Unlike humoral immunity, where antibodies immediately neutralize the virus, cellular immunity needs to mobilize against the virus after the antigen challenge (36)(37)(38). This mobilization relies on both CD4 + and CD8 + T cells to recognize the target antigen and their effective proliferation after the antigen recognition. ...
The COVID-19 vaccines effectively elicit humoral and cellular immunity against the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in a healthy population. This immunity decreases several months after the vaccination. However, the efficacy of the vaccine-induced immunity and its durability in patients with severe asthma on biological therapy is unknown. In this study, we evaluated the effectiveness and durability of the mRNA vaccine-induced SARS-CoV-2-specific humoral and cellular immunity in severe asthma patients on biological therapy. The study included 37 patients with severe asthma treated with anti-IgE (omalizumab, n=18), anti-IL5 (mepolizumab, n=14; reslizumab, n=4), or anti-IL5R (benralizumab, n=1) biological therapy. All patients were vaccinated with two doses of BNT162b2 mRNA vaccine (Comirnaty) at a 6-week period between the doses. We found that the COVID-19 vaccination elicited SARS-CoV-2-specific humoral and cellular immunity, which significantly declined 6 months after the second dose of the vaccine. The type of biological treatment did not affect the vaccine-elicited immunity. However, the patients' age negatively impacted the vaccine-induced humoral response. On the other hand, no such age-related impact was observed on the vaccine-elicited cellular immunity. Our findings showed that biological therapy of patients with severe asthma does not compromise the effectiveness and durability of the COVID-19 vaccine-induced immunity.
... Par ailleurs, une étude sur la vaccination antivariolique montre qu'une réexposition au vaccin de personnes déjà vaccinées depuis 25 ans est bénéfique afin de stimuler des réponses mémoires effectrices. Cependant il est montré que le pool résiduel de cellules mémoires effectrices, mesuré une dizaine d'année après, n'est pas augmenté après réexposition périodique au vaccin, ce qui indique que la première injection (l'amorçage) exerce une influence plus forte que les expositions ultérieures sur la persistance à long terme (Combadiere et al., 2004). ...
... Des vaccins non vivants comme les vaccins inactivés ou sous-unitaires confèrent une immunité beaucoup moins longue après la première injection. Par exemple, pour le vaccin contre le virus de la variole (Dryvax) qui est conçue à base du virus de la vaccine, les réponses T mémoires prolifératives ainsi que les cellules B mémoires sont détectées 50 ans après l'injection(Combadiere et al., 2004).Cependant le MVA, la version très atténuée, non réplicative du vaccin contre le virus de la variole, ne présente pas la même réponse mémoire. Pour avoir une immunité protectrice et persistance, il faut une dose plus élevée de vaccin et trois injections. ...
Les stratégies vaccinales sont au cœur du développement d’un vaccin. Elles s’orientent autour de l’administration et de la formulation d’un antigène (Ag). Par exemple, l’environnement immunitaire de la peau est très riche en cellules présentatrices d’Ag (CPA) contrairement au muscle, ce qui la rend très prometteuse pour l’injection d’un vaccin. Cependant, la méthode conventionnelle Mantoux est difficile à utiliser, elle demande une injection très minutieuse, parallèle à l’épiderme. Les premiers travaux de cette thèse consistent à mettre en avant l’utilisation de nouvelles microaiguilles Bella-muTM, qui permet une application simple de la voie ID. Elle induit un ciblage des CPA de la peau avec l’activation des cellules de Langerhans et la prise en charge de l’Ag par les CPA du derme. Par ailleurs, la vaccination VIH est très complexe à cause de son extrême variabilité, ce qui bloque le développement d’un vaccin capable d’induire une réponse protectrice. Une formulation à base d’un peptide très conservé entre les souches formulées avec du Squalène montre une bonne qualité de réponse immunitaire adaptative avec la production d’anticorps neutralisant à large spectre contrairement à l’aluminium. Le deuxième projet de la thèse utilise la microscopie 3D pour étudier les différents éléments de la réponse immunitaire innée induits par ces deux adjuvants qui impactent la réponse humorale dans le ganglion. En conclusion, le choix des stratégies vaccinales tel que la voie d’administration et la formulation qui va déterminer les évènements de la réponse innée mise en place après l’injection qui impact la qualité de la réponse adaptative et donc l’efficacité du vaccin.
