Vaccine adjuvants are thought to work by stimulating innate immunity in the draining lymph node (LN), although this has not been proven in humans. To bridge data obtained in animals to humans, we have developed an in situ human LN explant model to investigate how adjuvants initiate immunity. Slices of explanted LNs were exposed to vaccine adjuvants and revealed responses that were not detectable in LN cell suspensions. We used this model to compare the liposome-based AS01 with its components MPL and QS-21, and TLR ligands. Liposomes were predominantly taken up by subcapsular sinus-lining macrophages, monocytes and dendritic cells. AS01 induced dendritic cell maturation and a strong pro-inflammatory cytokine response in intact LN slices but not in dissociated cell cultures, in contrast to R848. This suggests the onset of the immune response to AS01 requires a coordinated activation of LN cells in time and space. Consistent with the robust immune response observed in older adults with AS01-adjuvanted vaccines, the AS01 response in human LNs was independent of age, unlike R848. This human LN explant model is a valuable tool for studying the mechanism of action of adjuvants in humans and for screening new formulations to streamline vaccine development.
Vicki V. Stylianou, Kirstie M. Bertram, Van Anh Vo, Elizabeth B. Dunn, Heeva Baharlou, Darcii J. Terre, James Elhindi, Elisabeth Elder, James French, Farid Meybodi, Stéphane T. Temmerman, Arnaud M. Didierlaurent, Margherita Coccia, Kerrie J. Sandgren, Anthony L. Cunningham
BACKGROUND. There is uncertainty around the timing of booster vaccination against COVID-19 in highly vaccinated populations during the present endemic phase of COVID-19. Studies focused on primary vaccination have previously suggested improved immunity after delaying immunisation. METHODS. We conducted a randomised controlled trial (Nov 2022 – Aug 2023) and assigned 52 fully vaccinated adults to an immediate or a 3-month delayed bivalent Spikevax mRNA booster vaccine. Follow-up visits were completed for 48 participants (n = 24 per arm), with saliva and plasma samples collected following each visit. RESULTS. The rise in neutralising antibody responses to ancestral and Omicron strains were almost identical between the immediate and delayed vaccination arms. Analyses of plasma and salivary antibody responses (IgG, IgA), plasma antibody-dependent phagocytic activity, and the decay kinetics of antibody responses were similar between the 2 arms. Symptomatic and asymptomatic SARS-CoV-2 infection occurred in 49% (21/49) participants over the median 11.5 months of follow up and were also similar between the 2 arms. CONCLUSIONS. Our data suggests no benefit from delaying COVID-19 mRNA booster vaccination in pre-immune populations during the present endemic phase of COVID-19 TRIAL REGISTRATION. Australian New Zealand Clinical Trials Registry number 12622000411741. FUNDING. National Health and Medical Research Council, Australia, Program Grant App1149990 and Medical Research Future Fund App2005544.
Wen Shi Lee, Jennifer Audsley, Mai-Chi Trieu, Arnold Reynaldi, L. Carissa Aurelia, Palak H. Mehta, Joanne Patterson, Helen E. Kent, Julie Nguyen, Thakshila Amarasena, Robyn Esterbauer, Ebene R. Haycroft, Pradhipa Ramanathan, Miles P. Davenport, Timothy E. Schlub, Joseph Sasadeusz, Adam K. Wheatley, Amy W. Chung, Jennifer A. Juno, Kevin J. Selva, Stephen J. Kent
Viral vectors are being used for the treatment of cancer. Yet their efficacy varies among tumors and their use poses challenges in immunosuppressed patients, underscoring the need for alternatives. We report striking antitumoral effects by a nonlytic viral vector based on attenuated lymphocytic choriomeningitis virus (r3LCMV). We show in multiple tumor models that injection of tumor-bearing mice with this vector results in improved tumor control and survival. Importantly, r3LCMV improved tumor control in immunodeficient Rag1–/– mice and MyD88–/– mice, suggesting that multiple pathways contributed to the antitumoral effects. The antitumoral effects of r3LCMV were also observed when this vector was administered several weeks before tumor challenges, suggesting the induction of trained immunity. Single cell RNA-Seq analyses, antibody blockade experiments, and KO models revealed a critical role for host-intrinsic IFN-I in the antitumoral efficacy of r3LCMV vectors. Collectively, these data demonstrate potent antitumoral effects by r3LCMV vectors and unveil multiple mechanisms underlying their antitumoral efficacy.
Young Rock Chung, Bakare Awakoaiye, Tanushree Dangi, Nahid Irani, Slim Fourati, Pablo Penaloza-MacMaster
BACKGROUND. Malaria transmission blocking vaccines aim to interrupt the transmission of malaria from one person to another. METHODS. The candidates, R0.6C and ProC6C, share the Plasmodium falciparum sexual stage antigen, Pfs48/45 “6C” domain. R0.6C utilizes the Glutamate Rich Protein (GLURP) as a carrier and ProC6C includes a second domain (Pfs230-Pro) and a short 36 amino acids CSP sequence. Healthy adults (n = 125) from a malaria endemic area of Burkina Faso were immunized with three intramuscular injections, four weeks apart, of 30 μg or 100 μg R0.6C or ProC6C each adsorbed to Alhydrogel adjuvant (AlOH) alone or in combination with Matrix-M (15 μg or 50 μg, respectively). The allocation was random and double blind for this Phase 1 trial. RESULTS. The vaccines were safe and well tolerated with no vaccine-related serious adverse events. A total of seven adverse events, mild to moderate in intensity and considered possibly related to the study vaccines were recorded. Vaccine-specific antibodies were highest in volunteers immunized with 100 μg ProC6C-AlOH with Matrix-M, and 13/20 (65%) subjects in the group showed greater than 80% transmission reducing activity (TRA) when evaluated in the standard membrane feeding assay at 15 mg/mL IgG. In contrast, R0.6C induced sporadic TRA. CONCLUSIONS. All formulations were safe and well tolerated in a malaria endemic area of Africa in healthy adults. The ProC6C-AlOH/Matrix-M vaccine elicited the highest levels of functional antibodies, meriting further investigation. TRIAL REGISTRATION. Pactr.org PACTR202201848463189. FUNDING. The study was funded by the European Union and Developing Countries Clinical Trials Partnership (Grant number RIA2018SV-2311).
B. Alfred Tiono, Jordan L. Plieskatt, Alphonse Ouedraogo, Ben Idriss Soulama, Kazutoyo Miura, Edith C. Bougouma, Mohammad Naghizadeh, Aissata Barry, Jean Baptiste B. Yaro, Sem Ezinmegnon, Noelie B. Henry, Ebenezer Ofori, Bright Adu, Susheel K. Singh, Augustin Konkobo, Karin Lövgren Bengtsson, Amidou Diarra, Cecilia Carnrot, Jenny M. Reimer, Amidou Z. Ouedraogo, Moussa Tienta, Carole A. Long, Issa N. Nebie, Issaka Sagara, Sodiomon B. Sirima, Michael Theisen
BACKGROUND. Sanaria PfSPZ Vaccine, composed of attenuated Plasmodium falciparum (Pf) sporozoites (SPZ), protects against malaria. We conducted this clinical trial to assess the safety and efficacy of PfSPZ Vaccine in HIV positive (HIV+) individuals since the HIV infection status of participants in mass vaccination programs may be unknown. METHODS. This randomized, double blind, placebo-controlled trial enrolled 18-45-year-old HIV negative (HIV-) and well-controlled HIV+ Tanzanians (HIV viral load < 40 copies/mL, CD4 counts > 500 cells/µL). Participants received 5 doses of PfSPZ Vaccine or normal saline over 28 days followed by controlled human malaria infection (CHMI) 3 weeks later. RESULTS. There were no solicited adverse events in the 9 HIV- and 12 HIV+ participants. After CHMI, 6/6 normal saline (NS) controls, 1/5 HIV- vaccinees and 4/4 HIV+ vaccinees were Pf positive by qPCR. Post-immunization, anti-PfCSP (isotype and IgG subclass) and anti-PfSPZ antibodies, anti-PfSPZ CD4 T cell responses and Vδ2+ γδ CD3+ T cells were non-significantly higher in HIV- than HIV+ vaccinees. Sera from HIV- vaccinees had significantly higher inhibition of PfSPZ invasion of hepatocytes in vitro, and antibody-dependent complement deposition (ADCD) and Fcγ3B binding by anti-PfCSP and ADCD by anti-PfCelTOS antibodies. CONCLUSIONS. PfSPZ Vaccine was safe and well tolerated in HIV+ vaccinees, but not protective. Vaccine efficacy was 80% in HIV- vaccinees (P = 0.012), whose sera had significantly higher inhibition of PfSPZ invasion of hepatocytes and enrichment of multi-functional PfCSP antibodies. A more potent PfSPZ vaccine or regimen is needed to protect those living with HIV against Pf infection in Africa.
Said Jongo, L.W. Preston Church, Florence Milando, Munira Qassim, Tobias Schindler, Mohammed Rashid, Anneth Tumbo, Gloria Nyaulingo, Bakari M. Bakari, Thabit Athuman Mbaga, Latipha Mohamed, Kamaka Kassimu, Beatus S. Simon, Maxmillian Mpina, Irfan Zaidi, Patrick E. Duffy, Phillip A. Swanson II, Robert Seder, Jonathan D. Herman, Maanasa Mendu, Yonatan Zur, Galit Alter, Natasha KC, Pouria Riyahi, Yonas Abebe, Tooba Murshedkar, Eric R. James, Peter F. Billingsley, B. Kim Lee Sim, Thomas L. Richie, Claudia Daubenberger, Salim Abdulla, Stephen L. Hoffman
Intranasal vaccines are anticipated to be powerful tools for combating many infectious diseases, including SARS-CoV-2, because they induce not only systemic immunity but also mucosal immunity at the site of initial infection. However, they are generally inefficient in inducing an antigen-specific immune response without adjuvants. Here, we developed an adjuvant-free intranasal vaccine platform that utilizes the preexisting immunity induced by previous infection or vaccination to enhance vaccine effectiveness. We made RBD-HA, a fusion of the receptor-binding domain (RBD) of spike derived from SARS-CoV-2 as a vaccine target with HA derived from influenza A virus (IAV) as a carrier protein. Intranasal immunization of previously IAV-infected mice with RBD-HA without an adjuvant elicited robust production of RBD-specific systemic IgG and mucosal IgA by utilizing both HA-specific preexisting IgG and CD4+ T cells. Consequently, the mice were efficiently protected from SARS-CoV-2 infection. Additionally, we demonstrated the high versatility of this intranasal vaccine platform by assessing various vaccine antigens and preexisting immunity associated with a variety of infectious diseases. The results of this study suggest the promising potential of this intranasal vaccine platform to address problems associated with intranasal vaccines.
Atsushi Kawai, Nagisa Tokunoh, Eigo Kawahara, Shigeyuki Tamiya, Shinya Okamura, Chikako Ono, Jessica Anindita, Hiroki Tanaka, Hidetaka Akita, Sho Yamasaki, Jun Kunisawa, Toru Okamoto, Yoshiharu Matsuura, Toshiro Hirai, Yasuo Yoshioka
Even with the prolific clinical use of next-generation cancer therapeutics, many tumors remain unresponsive or become refractory to therapy, creating a medical need. In cancer, DCs are indispensable to T cell activation, so there is a restriction on cytotoxic T cell immunity if DCs are not present in sufficient numbers in the tumor and draining lymph nodes to uptake and present relevant cancer antigens. To address this bottleneck, we developed a Flt3L-based therapeutic named Alb-Flt3L that demonstrated superior pharmacokinetic properties compared to Flt3L, including significantly longer half-life, accumulation in tumor and lymph node, and cross-presenting DCs expansion following a single injection. We demonstrated that Alb-Flt3L, in combination with standard-of-care chemotherapy and radiation therapy, serves as an in situ vaccination strategy capable of engendering polyclonal tumor neoantigen-specific immunity spontaneously. In addition, Alb-Flt3L-mediated tumor control synergized with immune checkpoint blockade delivered as anti-PD-L1. The mechanism of action of Alb-Flt3L treatment revealed a dependency on Batf3, type-I-interferons, and plasmacytoid DCs. Finally, the ability of Alb-Flt3L to expand human DC was explored in humanized mice. We observed significant expansion of human cross-presenting DC subsets, supporting the notion that Alb-Flt3L could be used clinically to modulate human DC populations in future cancer therapeutic regimens.
Brandon Lam, Yu Jui Kung, John Lin, Ssu-Hsueh Tseng, Hsin-Fang Tu, Claire Huang, Brandon Lee, Esteban Velarde, Ya Chea Tsai, Rafael Villasmil, Sung Taek Park, Deyin Xing, Chien-Fu Hung, T.-C. Wu
Tissue-resident lymphocytes provide organ-adapted protection against invading pathogens. Whereas their biology has been examined in great detail in various infection models, their generation and functionality in response to vaccination has not been comprehensively analyzed in humans. We therefore studied SARS-CoV2 mRNA-vaccine-specific T cells in surgery specimens of kidney, liver, lung, bone marrow and spleen in comparison to paired blood samples from largely virus-naïve individuals. As opposed to lymphoid tissues, non-lymphoid organs harbored significantly elevated frequencies of Spike-specific CD4+ T cells compared to blood showing hallmarks of tissue residency and an expanded memory pool. Organ-derived CD4+ T cells further exhibited increased polyfunctionality over those detected in blood. Single-cell RNA sequencing together with T cell receptor repertoire analysis indicated that the clonotype rather than organ origin is a major determinant of transcriptomic state in vaccine-specific CD4+ T cells. In summary, our data demonstrate that SARS-CoV2 vaccination entails acquisition of tissue memory and residency features in organs distant from the inoculation site, thereby contributing to our understanding of how local tissue protection might be accomplished.
Vanessa Proß, Arne Sattler, Söeren Lukassen, Laura Tóth, Linda Marie Laura Thole, Janine Siegle, Carolin Stahl, An He, Georg Damm, Daniel Seehofer, Christina Götz, Christian Bayerl, Pia Jäger, Alexander Macke, Stephan Eggeling, Bernadette Kirzinger, Thomas Mayr, Hermann Herbst, Katharina Beyer, Dominik Laue, Jan Krönke, Jan Braune, Friederike Rosseck, Beatrice Kittner, Frank Friedersdorff, Mandy Hubatsch, Sarah Weinberger, Nils Lachmann, Veit Maria Hofmann, Eva Schrezenmeier, Carolin Ludwig, Hubert Schrezenmeier, Katharina Jechow, Christian Conrad, Katja Kotsch
Herpes zoster (HZ) is a substantial problem for people with decreased cell-mediated immunity, including older adults. The first vaccine approved for HZ prevention, the zoster vaccine live (ZVL), which provided limited and short-lived protection, has been supplanted by the superior recombinant zoster vaccine (RZV), which provides robust and durable protection. To understand the mechanisms underlying the differential immunologic characteristics of the two vaccines, we used T cell receptor beta sequencing and peptide-MHC class II tetramer staining to analyze gE-specific CD4+ T cell clonotypes in RZV and ZVL recipients. Compared to ZVL, RZV expanded more gE-specific CD4+ clonotypes with greater breadth and higher frequency of public clonotypes. RZV recruited a higher proportion of clonotypes from the naïve than from memory cells, while ZVL recruited equally from memory and naïve compartments. Compared to memory-, naïve-derived clonotypes were more likely to last ≥ 5 years post-immunization. Moreover, the frequency of tetramer+ persistent clones correlated with the frequency of tetramer+ naïve CD4+ T cells pre-vaccination. We conclude that the ability of RZV to recruit naive CD4+ T cells into the response may contribute to the durability of its effect. The abundance, breadth, and the frequency of public clonotypes may further add to its protective effect.
Kerry J. Laing, Emily S. Ford, Michael J. Johnson, Myron J. Levin, David M. Koelle, Adriana Weinberg
Christoph Strumann, Otavio T. Ranzani, Jeanne Moor, Reinhard Berner, Nicole Toepfner, Cho-Ming Chao, Matthias B. Moor
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