Browsing by Subject "Vaccine"

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Open Access
Assessment of immune potency of SARS-CoV-2 VLP vaccine in mice, enhanced through different adjuvants and liposome complexation
(2023-08) Abraş, İrem Fatma
SARS-CoV-2, emerging in December 2019 in Wuhan, China, led to a swift global pandemic declaration in March 2020, prompting widespread vaccine development. Most vaccines target specific regions, mainly the spike protein. In our lab, we have employed an innovative virus-like particle (VLP) vaccine approach encompassing all four structural proteins of the virus: spike, nucleocapsid, membrane, and envelope. Our study utilizes sterically stabilized cationic liposomes (SSCL) to encapsulate VLPs expressing the Delta variant spike protein, along with various adjuvants: CpG ODN, poly(I:C), and 2’3’-cGAMP. We characterized liposomes using tunable resistive pulse sensing for size and concentration. In C57BL/6 mice, we administered primary and two booster injections on Day 0, Day 15, and Day 73, respectively, collecting blood samples at intervals (Day 14, Day 28, Day 42, Day 72, and Day 90). To assess vaccine impact on mouse humoral immunity, we conducted ELISAs for total IgG, IgG1, and IgG2c antibodies against recombinant Spike and the receptor-binding domain (RBD). IgG titers increased until Day 42, remained stable or slightly decreased on Day 72, and significantly rose on Day 90. We calculated IgG2c/IgG1 ratios, reflecting Th1 immune responses, revealing enhanced cellular immunity potential in groups with adjuvants compared to the VLP-only group. This study underscores the effectiveness of our VLP vaccine strategy in stimulating robust immune responses and opens avenues for further research and development.
Open Access
Biotin functionalized self‐assembled peptide nanofiber as an adjuvant for immunomodulatory response
(Wiley-VCH Verlag, 2020-12) Demircan, Muhammed Burak; Tohumeken, Sehmus; Gündüz, Nuray; Khalily, Mohammad Aref; Tekinay, T.; Güler, M. O.; Tekinay, Ayşe B.
Biotinylated peptide amphiphile (Biotin‐PA) nanofibers, are designed as a noncovalent binding location for antigens, which are adjuvants to enhance, accelerate, and prolong the immune response triggered by antigens. Presenting antigens on synthetic Biotin‐PA nanofibers generated a higher immune response than the free antigens delivered with a cytosine‐phosphate‐guanine oligodeoxynucleotides (CpG ODN) (TLR9 agonist) adjuvant. Antigen attached Biotin‐PA nanofibers trigger splenocytes to produce high levels of cytokines (IFN‐γ, IL‐12, TNF‐α, and IL‐6) and to exhibit a superior cross‐presentation of the antigen. Both Biotin‐PA nanofibers and CpG ODN induce a Th‐1‐biased IgG subclass response; however, delivering the antigen with Biotin‐PA nanofibers induce significantly greater production of total IgG and subclasses of IgG compared to delivering the antigen with CpG ODN. Contrary to CpG ODN, Biotin‐PA nanofibers also enhance antigen‐specific splenocyte proliferation and increase the proportion of the antigen‐specific CD8(+) T cells. Given their biodegradability and biocompatibility, Biotin‐PA nanofibers have a significant potential in immunoengineering applications as a biomaterial for the delivery of a diverse set of antigens derived from intracellular pathogens, emerging viral diseases such as COVID‐19, or cancer cells to induce humoral and cellular immune responses against the antigens.
Open Access
Development & characterization of CpG adjuvanted SARS-CoV-2 Virus-Like Particle vaccine
(2022-06) Turay, Nilsu
Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) appeared in late 2019, led to countless cases and deaths and eventually regarded as one of the severe pandemics of modern times. To reduce hospitalization and mortality rates against COVID-19 an immediate need for effective vaccines has emerged. SARS-CoV-2 contains 4 structural proteins; Nucleocapsid (N), Envelope (E), Membrane (M) and Spike (S). Numerous vaccine platforms targeting Spike antigen were developed and tested on healthy volunteers. Among vaccine platforms, Virus-Like Particles (VLPs) capable of mimicking the structure, morphology and conformation of authentic and variant viruses offer a selective advantage for a better protection. VLPs, due to multivalent antigen display capabilities and ease of expressing different Spike variants can elicit cellular, as well as humoral immune responses and were expected to be superior to that of other COVID-19 vaccine platforms. Herein, we produced, purified and characterized the first mammalian derived, 4 structural protein containing SARS-CoV-2 VLP vaccine. Various animal models were used to assess the immunogenicity and immuno-protective potential of the candidate VLP vaccine that was formulated with two different CpG ODN adjuvants. Following cloning of four viral structural proteins to two separate dual expression plasmids and transiently transfecting them to adherent HEK293-FT cells, VLP yields were monitored daily from cell culture supernatant. Presence of SARS-CoV-2 structural proteins on VLPs were verified via immunoblotting. Furthermore, the size of VLPs was investigated and was shown to resemble to that of authentic SARS-CoV-2. To assess in vivo immunogenicity of the adjuvanted VLPs, BALB/c mice were subcutaneously (sc) immunized and end point titer ELISA was studied from sera. For the toxicity assay of the candidate VLP vaccine, the selected highest human dose was sc injected to female Sprague Dawley rats. Lastly, to show the immunoprotective effect of the VLP vaccine, challenge studies were conducted with transgenic K18-hACE2. Results demonstrated that VLPs induce robust antiviral humoral and Th1-biased cellular responses when adjuvanted with CpG ODNs. Furthermore, VLP immunization did not lead to any significant systemic effect during repeated dose toxicity studies on rats. A robust immuno-protection against the live SARS-CoV-2 virus was observed with the challenge experiments. Collectively, the results provide the rationale for using this vaccine candidate in human clinical trials. In the second part of the thesis, SARS-CoV-2 recombinant RBD and Nucleocapsid proteins were produced and purified via affinity chromatography. After 6X Histidinetagged RBD and N were produced in HEK293-FT cells, supernatant passed through the immobilized metal affinity chromatography (IMAC) column. Quality of the recombinant proteins was investigated using silver staining and western blotting. Afterward, immunized mice sera were used to find an optimal coating concentration of the purified recombinant proteins. Finally, purified recombinant proteins were used in in-house ELISA experiments.
Open Access
Development and preclinical evaluation of virus-like particle vaccine against COVID-19 infection
(Wiley-Blackwell Publishing Ltd., 2021-09-14) Yılmaz, İsmail Cem; İpekoğlu, E. M.; Bülbül, Artun; Turay, Nilsu; Yıldırım, Muzaffer; Evcili, İrem; Yılmaz, N. S.; Güvençli, N.; Aydın, Y.; Güngör, Bilgi; Saraydar, Berfu; Bartan, Aslı Gülce; İbibik, Bilgehan; Bildik, Tuğçe; Baydemir, İ.; Şanlı, H. A.; Kayaoğlu, B.; Ceylan, Yasemin; Yıldırım, Tuğçe; Abraş, İrem; Ayanoğlu, C.; Cam, S. B.; Dede, E. C.; Gizer, M.; Erganis, O.; Saraç, F.; Uzar, S.; Enul, H.; Adıay, C.; Aykut, Gamze; Polat, H.; Yıldırım, İ. S.; Tekin, S.; Körüklüoğlu, G.; Zeytin, H. E.; Korkusuz, P.; Gürsel, İhsan; Gürsel, M.
Background Vaccines that incorporate multiple SARS-CoV-2 antigens can further broaden the breadth of virus-specific cellular and humoral immunity. This study describes the development and immunogenicity of SARS-CoV-2 VLP vaccine that incorporates the four structural proteins of SARS-CoV-2. Methods VLPs were generated in transiently transfected HEK293 cells, purified by multimodal chromatography, and characterized by tunable-resistive pulse sensing, AFM, SEM, and TEM. Immunoblotting studies verified the protein identities of VLPs. Cellular and humoral immune responses of immunized animals demonstrated the immune potency of the formulated VLP vaccine. Results Transiently transfected HEK293 cells reproducibly generated vesicular VLPs that were similar in size to and expressing all four structural proteins of SARS-CoV-2. Alum adsorbed, K3-CpG ODN-adjuvanted VLPs elicited high titer anti-S, anti-RBD, anti-N IgG, triggered multifunctional Th1-biased T-cell responses, reduced virus load, and prevented lung pathology upon live virus challenge in vaccinated animals. Conclusion These data suggest that VLPs expressing all four structural protein antigens of SARS-CoV-2 are immunogenic and can protect animals from developing COVID-19 infection following vaccination.
Open Access
Differential immune activation following encapsulation of immunostimulatory CpG oligodeoxynucleotide in nanoliposomes
(Elsevier, 2011) Erikçi, E.; Gursel, M.; Gürsel, T.
The immunogenicity of a vaccine formulation is closely related to the effective internalization by the innate immune cells that provide prolonged and simultaneous delivery of antigen and adjuvant to relevant antigen presenting cells. Endosome associated TLR9 recognizes microbial unmethylated CpG DNA. Clinical applications of TLR9 ligands are significantly hampered due to their pre-mature in vivo digestion and rapid clearance. Liposome encapsulation is a powerful tool to increase in vivo stability as well as enhancing internalization of its cargo to relevant immune cells. The present study established that encapsulating CpG motifs in different liposomes having different physicochemical properties altered not only encapsulation efficiency, but also the release and delivery rates that ultimately impacted in vitro and ex-vivo cytokine production rates and types. Moreover, different liposomes encapsulating CpG ODN significantly increased Th1-biased cytokines and chemokines gene transcripts Additional studies demonstrated that co-stimulatory and surface marker molecules significantly upregulated upon liposome/CpG injection. Finally, co-encapsulating model antigen ovalbumin with CpG ODN adjuvant in nanoliposomes profoundly augmented Th1 and cell mediated anti-Ova specific immune response. Collectively, this work established an unappreciated immunoregulatory property of nanoliposomes mediating immunity against protein antigen and could be harnessed to design more effective therapeutic vaccines or stand alone immunoprotective agents targeting infectious diseases, as well as cancer or allergy. © 2010 Elsevier Ltd.
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Erken Cumhuriyet ve II. Dünya Savaşı yıllarında Türkiye’de görülen salgın hastalıklar ve mücadele yöntemleri
(Bilkent University, 2020) Eken, Zeynep Başak; Erdem, Müge; Özkan, Öykü; Kuş, Kerem; Uzun, Gökay
Türkiye Cumhuriyeti kurulduğunda, uzun süren savaşlar sebebiyle harabe haline gelen Anadolu’da bir yandan verem, tifüs, sıtma, trahom, frengi gibi bulaşıcı hastalıklarla mücadele ediliyordu. Cumhuriyet’in ilanıyla birlikte bu hastalıklarla mücadele etmek için seferber olundu ve ilk yıllarda salgın hastalıklar kontrol altına alınabildi. Bu salgınlarla mücadele için önemli aşılar Türkiye’de devlet eliyle üretilirken, üretilmeyen ilaçlar ve aşılar yurt dışından ithal edildi, heyetler ve sağlık kuruluşları kuruldu. İkinci Dünya Savaşı için ilan edilen seferberlik ve savaşın neden olduğu ekonomik koşullarda salgın hastalıklar yaygınlaştı ve maddi yetersizlikler mücadeleyi olumsuz şekilde etkiledi.
Open Access
Immunomodulatory effects of TLR ligands and polysaccharide combinations : strategies to augment innate immune response
(2007) Tincer, Gizem
Microbial infection initiates multiple TLR ligand mediated signaling cascade on innate immune cells. While some TLRs trigger a Th1 biased immune activation, others may lead to a Th2 dominant immune response. Extracellular (TLR1, 2, 4, 5, 6, 10, and 11) vs endosome-associated TLRs (TLR3, 7/8, and 9) display differential immune activation and cytokine milieu. Understanding contrasting and synergistic behaviors of these TLR subclasses when mixed together may lead to more potent formulations for immunotherapy. Delivery and retaining the stability of nucleic acid based labile TLR ligands to the site of immunologically relevant cells is also a challenge. In the first part of the thesis, optimum TLR combinations with differential immune effects will be brought into light. Next, immunomodulatory effect of a natural polysaccharide (PS) will be characterized. Finally the ability of a PS carrier to form complex with ligands of nucleic acid sensing TLRs and its potential as a controlled delivery vehicle to stimulate the immune cells will be documented. In brief, our results suggest that different PS types extracted from various mushroom sources are immunostimulatory and are targeted to TLR2/6 for delivery of other relevant stimulants. Moreover, certain TLR ligand combinations can be harnessed to induce more robust immune activation compared to their stand alone counterparts. This knowledge will pave the way for establishing an effective PS based carrier of DNA/RNA ligands thus, more effective immunotherapeutic strategies for treating infectious and other local or systemic diseases be possible.
Open Access
Immunoregulatory activities of nanoparticle-forming oligodeoxynucleotides
(2009) Karatepe, Kutay
Innate immune system is activated by a wide range of microbial by products leading to an immediate immune activation primarily designed to neutralize and control the invading insult. The cells of the innate immune system also instruct the development of antigen-specific adaptive immunity. While TLR9 is triggered by bacterial DNA, extended and over-exuberant immune response poses a threat since it may exacerbate cell and tissue destruction leading to organ failure. Telomeric TTAGGG conserved motifs are previously reported to antagonize TLR mediated events. The down-regulatory effect of these motifs may help to restore the desired homeostatic balance of the immune system. While CpG ODN patterned after bacterial DNA can be harnessed in different clinical settings to provide an advantage to host to resist infectious diseases, control tumor growth or alleviate allergic symptoms, the immunosuppressive telomeric motifs could be effectively applied in controlling systemic anti-inflammatory or autoimmune related disorders. Several challenges exist in the utilization of synthetic ODNs in the clinic. The first challenge is that conventional classes of synthetic ODNs exhibit different properties. K-type ODNs are more effective in proliferation and activation of B cells and DC. D-type ODNs are in nanoparticle forms, lead to anti-viral type I IFN production and mature monocytes into DCs. Of note, the efficacy of these synthetic ODNs is reduced under physiological conditions due to premature clearance and low levels of internalization. Moreover, D-ODNs as one of the most potent IFNα inducing TLR9 ligands possess a large-scale production problem due to 3’polyGruns, which hamper their entry into the clinic. We have designed a novel class of ODN, designated as ODN420, devoid of polyGs that can undergo nanoparticle formation necessary for its IFNα induction. Ex vivo stimulation of mouse splenocytes and in vivo administration of ODN420 have revealed that this ODN exhibits higher immunostimulatory potential and is more stable than most commonly used ODNs due to its nanoparticle-forming ability. Another interesting finding is that ODN420 with the natural phosphodiester (PO) backbone is at least as potent as its more stable counterpart with the modified phosphorothioate backbone. Furthermore, it combines superior properties of conventional classes of K and D-ODNs. These results have been reproduced in human peripheral blood mononuclear cells by various assays. Next, we have analyzed whether this ODN could be utilized as a vaccine adjuvant and an anti-cancer agent with two independent experiments. Our immunization results demonstrate that ODN420 induces a higher level of Th1-mediated response than conventional ODNs and is a promising candidate as a vaccine adjuvant. This response is hampered when ODN420 is used in combination with ODN-A151. In the tumor xenograft model, ODN420 has promoted partial remission of the tumors or delayed the tumor growth. This knowledge will pave the way for more effective immunotherapeutic approaches.
Open Access
In vivo applications of liposomal vaccines encapsulating single or dual pathogenassociated molecular patterns
(2017-03) Bayyurt Kocabaş, Banu
Nucleic acid-based pattern recognition receptor (PRR) agonists are promising adjuvants and immunotherapeutic agents. Combination of PRR ligands potentiates immune response by providing synergistic immune activity via triggering different signaling pathways and may impact antigen dependent T-cell immune memory. However, the duration of short circulation due to nuclease attacks is hampering their clinical performance. Liposomes enable protein and nucleic acid based compounds to have high encapsulation efficiency. Herein, we aimed to develop liposomal carrier systems that co-encapsulating single TLR9 or combinations with TLR3 or STING ligands and assess their potential as adjuvants and immunostimulatory agents in in vivo applications. Liposomal dual nucleic acid formulations induced synergistic innate immune activation, enhanced cytokine production along with internalization capacity of ligands. In anti-cancer vaccine study, CpG ODN and poly(I:C) coencapsulation significantly increased OVA-specific Th1-biased immune even after eight months post-booster injection. Challenge with OVA-expressing tumor cell line, E.G7, demonstrated that mice immunized with liposomes co-encapsulating CpG ODN and poly(I:C) had significantly slower tumor progression dependent on OVAspecific cytotoxic memory T-cells. In our second in vivo application, liposomal CDN and TLR9 therapy led to 80% remission of established melanoma tumor. Increased IgG2c/IgG1 ratio in mice treated with liposomal formulations indicating the development of antigen specific Th1-biased immunity was observed. Furthermore, along with the treatment, IFN-dual ligands into liposomes enhanced the anti-tumor activity of single ligands. In the third part, immunization with CpG ODN loaded liposomal formulations together with antigens increased antigen-specific humoral response against FMDV and Helicobacter. In addition, the liposomal CpG ODN reduced bacterial gastric colonization by antigen-dependent Th1 and Th17 immune responses after helicobacter challenging.
Open Access
Induction of potent protection against acute and latent herpes simplex virus infection in mice vaccinated with dendritic cells
(2013) Ghasemi, M.; Erturk, M.; Buruk, K.; Sonmez, M.
Background aims. Dendritic cells (DCs) are the most potent antigen presenting cells of the immune system and have been under intense study with regard to their use in immunotherapy against cancer and infectious disease agents. In the present study, DCs were employed to assess their value in protection against live virus challenge in an experimental model using lethal and latent herpes simplex virus (HSV) infection in Balb/c mice. Methods. DCs obtained ex vivo in the presence of granulocyte-macrophage colony-stimulating factor and interleukin-4 were loaded with HSV-1 proteins (DC/HSV-1 vaccine). Groups of mice were vaccinated twice, 7 days apart, via subcutaneous, intraperitoneal or intramuscular routes with DC/HSV-1 and with mock (DC without virus protein) and positive (alum adjuvanted HSV-1 proteins [HSV-1/ALH]) control vaccines. After measuring anti-HSV-1 antibody levels in blood samples, mice were given live HSV-1 intraperitoneally or via ear pinna to assess the protection level of the vaccines with respect to lethal or latent infection challenge. Results. Intramuscular, but not subcutaneous or intraperitoneal, administration of DC/HSV-1 vaccine provided complete protection against lethal challenge and establishment of latent infection as assessed by death and virus recovery from the trigeminal ganglia. It was also shown that the immunity was not associated with antibody production because DC/HSV-1 vaccine, as opposed to HSV-1/ALH vaccine, produced very little, if any, HSV-1-specific antibody. Conclusions. Overall, our results may have some impact on the design of vaccines against genital HSV as well as chronic viral infections such as hepatitis B virus, hepatitis C virus and human immunodeficiency virus. © 2013, International Society for Cellular Therapy.
Open Access
Investigation of cellular and humoral immune responses induced by SARS-CoV-2 VLP vaccine in Pre-clinical and clinical studies
(2022-08) Bildik, Kadriye Tuğçe
COVID-19 pandemic, caused by SARS-CoV-2, emerged in China in late 2019, and as of March 2020 has become a serious concern for the whole world due to severe progression of the disease especially in the elderly and high transmission rate of the virus. The ravages of pandemic on health sector, economy and social life accelerated the vaccine race as vaccination is the most critical measure to hamper the pace of the pandemic and the most important step for acquiring herd immunity. Various vaccine studies are registered by WHO most of which target Spike protein or a certain region of Spike protein, such as receptor binding domain (RBD) for inducing immune reactions. Alternatively, the use of virus-like particle (VLP) technology for vaccine development broadens the magnitude of immune responses as the four main structural proteins of the virus, Spike, Nucleocapsid, Membrane and Envelope, are incorporated. Therefore, we developed a VLP vaccine against SARS-CoV-2 and adjuvanted it using Alum and K3 CpG ODN. Herein, we investigated the humoral and cellular immune responses induced by SARS-CoV-2 VLP vaccine in pre-clinical and clinical studies. The results from pre-clinical experiments conducted on vaccinated BALB/c mice indicated that VLP vaccine triggered effective antibody response against Spike, Nucleocapsid, Wild Type RBD, Alpha RBD and Delta RBD proteins as shown by ELISA. Additionally, it was proven that the diminishing antibody responses can be boosted and a prolonged immune response was achieved by a third dose of VLP vaccine. For the clinical studies, the humoral and cellular immune responses of Phase II clinical trial volunteers were analyzed by employing ELISA and CBA methods respectively. The results obtained from ELISA demonstrated that the Phase II volunteers developed effective antibody titers against Spike, Nucleocapsid, Wild Type RBD, Alpha RBD and Delta RBD proteins. Analysis of the cellular immune responses by CBA showed that VLP vaccine induced a Th1-skewed immune reaction with coexistence of Th2-, Th17- and Treg related responses owing to its formulation with K3 CpG ODN and Alum. Taken together, our results indicated that SARS-CoV-2 VLP accine triggered effective cellular and humoral immune reactions against Spike and Nucleocapsid along with RBD variants which proved the cross-protective response achieved. Elicitation of multi-functional immune response and adoptability of the VLP technology to newly emerging variants makes VLP vaccine a promising candidate for the future booster injections.
Open Access
Investigation of improved immunostimulatory activity of D and K type CpG ODNs in liposomes
(2013) Dereli, İhsan
CpG ODNs are potent immunotherapeutic agents. In human, two major classes of CpG ODNs were shown to induce differential immune activation. D ODNs are strong IFNα inducers, thus promising antiviral agents, whereas K ODNs are effective against bacterial infections. However, their effects cannot be combined. When K and D type ODNs are used simultaneously, K ODN cancels D specific effect, a phenomenon known as K and D ODN dichotomy. The prime reason for this counter acting K ODN action was subcellular compartmentalization of K type CpG ODNs upon internalization. Besides, CpG ODNs have labile nature. When investigated in clinical trials, these nucleic acid based ligands are eliminated upon administration and displayed limited bio-availability due to nuclease digestion. Hence, efforts to protect in vivo performance, and increase stability and accumulation near target cells became a crucial task. Liposome technology offers a simple and mild approach to harbor these ODNs within membrane bilayers and protect them. We also reasoned that, if we use liposomes that alter subcellular fate of K and D ODNs, we can retain both K and D effect when liposomal ODNs are co-administered and the breadth of immunotherapeutic spectrum could be improved. This thesis was designed to understand and characterize different types of CpG ODNs loaded into different liposomes and aimed to determine their activities in different in vitro and in vivo settings. Our results revealed that when two different classes of clinically important CpG ODNs were encapsulated within proper liposome types, it is possible to recapitulate both K and D type ODN effect in PBMCs. Furthermore, in a vaccine model against H. felis, although initially did not induce significantly higher anti H.felis immunity, liposomal CpG ODNs improved persisting antibody levels for extended periods compared to free counterparts. Collectively, our results demonstrate that this platform allows more effective in vivo utilization of CpG ODNs and can be formulated to develop more efficient means to combat several health problems, ranging from cancer to allergy.
Open Access
Investigation of Pre-clinical and clinical results against SARS-COV-2 wild-type and Alpha variants combination of VLP-58-1023-AL-K3 vaccine
(2022-08) Bartan, Aslı Gülce
The SARS-CoV-2 virus, which first appeared in Wuhan, China and had a pandemic effect at the end of 2019, has urgently created need of suitable vaccine candidates’ development with its quick spread. Scientists in different laboratories from all over the world, including Turkey, have started the studies of vaccine development with different methods based on the basic proteins of the SARS-CoV-2 virus. Most of these vaccines are based on the Spike protein, which allows the virus to enter the host and survive. Although the Spike protein, which has high antigenic properties and contains the RBD region to bind ACE2 receptor in the host, is effective in the formation of neutralizing antibodies in the person, the virus essentially has 4 structural proteins, not only spike. Our vaccine strategy containing virus-like particles (VLP) was based on the self-assembly property of Spike, Membrane, Envelope and Nucleocapsid proteins, and these protein structures were transformed into plasmids with his-tag labels, and the products were collected in mammalian cells in vitro by the transfection method. VLPs were purified by affinity chromatography and formulated with 2 different adjuvants which are Alum and CpG. Since the virus, which has changed rapidly in the last 2 years, is open to new mutations over spreading, it is very important that our vaccine should be editable and adaptable to new virus variants. Due to the alpha variant effect in the world, which was first seen in the UK and has become widespread all over the world recent years, WT VLP formed with a more stable Spike protein containing a thermostable sub-proline (6p; HexaPro) mutation was used in the first dose of our vaccine, but UK VLP containing alpha variant mutations was used in the second dose. Alum and CpG adjuvants were used together for both injection formulations. Our vaccine has successfully completed Phase 2 studies. As a result of these studies, approximately 115 vaccinated volunteers were followed up for 90 days and immunological analyzes were performed with samples taken at certain day intervals (Day 21, Day 35, Day49 and Day90). As a result of these analyzes, moderate and high levels of neutralizing and non-neutralizing antibody responses were observed in many patients, and a humoral immune response was induced until day 90. In addition, it was observed that the cellular responses of the volunteers are progressed in tendency with the Th1 cell response.
Open Access
Large-scale manufacturing and characterization of a Sars Cov-2 virus-like particle vaccine adsorbed onto alhydrogel and adjuvanted with K3 CpG oligodeoxynucleotide for use in phase 1/2 clinical trials
(2022-04-28) Bülbül, Artun
Emergence of COVID-19 pandemic has been met by an exceptionally fast response from vaccine makers around the globe. Vaccines that elicit excellent immunological responses against SARS-CoV-2 are now widely utilized. Existing platforms include mRNA-lipid nanoparticle-based vaccines, adenovirus vectored vaccines, various inactivated virus vaccines and subunit vaccines. We have previously described a novel virus-like particle (VLP) platform expressing the hexaproline prefusion stabilized Spike protein along with the nucleocapsid, membrane and envelope structural proteins. In mice, ferrets and rats, VLPs adjuvanted with K3 CpG Oligodeoxynucleotide (ODN) and adsorbed onto 2% Aluminum Hydroxide (Alum), induced robust humoral and cellular immune response against Spike and Nucleocapsid proteins. Herein, we have expanded our work to manufacture the virus like particles in a GMP compliant facility intended for testing in phase I/II clinical trials. The technology transfer comprises i) VLP production from suspension adapted HEK293 cells, ii) purification with multimodal fast protein liquid chromatography (FPLC) and iii) concentration and diafiltration using tangential flow filtration (TFF). We have successfully scaled up our production from 50 mL of HEK293 cell culture to 5 L bioreactor, achieving yields reaching up to 40 mg VLPs per L of cell culture. Furthermore, several methods were developed to determine protein identity, purity, functionality, stability and immunopotency of VLP vaccine that was finally formulated with Alum + CpG ODN. Moreover, we investigated the immunogenicity of VLPs decorated either with Wuhan (Hu-1) or with Alpha (B.1.1.7) variant Spike against receptor binding domains (RBD) specific to other variants of concern (VoC). Although our vaccine platform, could further benefit from process optimization to improve VLP yield, this study presents the first pilot scale production and purification of variant specific hexaproline prefusion stabilized SARS-CoV-2 VLPs. VLP preparations complying with our quality control parameters were released for fill and finish and were used for subsequent Phase 1 (NCT04818281) and Phase 2 clinical trials (NCT04962893).
Open Access
Modulation of immune responses using adjuvants to facilitate therapeutic vaccination
(Wiley, 2020) Schijns, V.; Fernández‐Tejada, A.; Barjaktarović, Ž.; Bouzalas, I.; Brimnes, J.; Chernysh, S.; Gizurarson, S.; Gürsel, İhsan; Jakopin, Ž.; Lawrenz, M.; Nativi, C.; Paul, S.; Pedersen, G. K.; Rosano, C.; Ruiz‐de‐Angulo, A.; Slütter, B.; Thakur, A.; Christensen, D.; Lavelle, Ed. C.
Therapeutic vaccination offers great promise as an intervention for a diversity of infectious and non‐infectious conditions. Given that most chronic health conditions are thought to have an immune component, vaccination can at least in principle be proposed as a therapeutic strategy. Understanding the nature of protective immunity is of vital importance, and the progress made in recent years in defining the nature of pathological and protective immunity for a range of diseases has provided an impetus to devise strategies to promote such responses in a targeted manner. However, in many cases, limited progress has been made in clinical adoption of such approaches. This in part results from a lack of safe and effective vaccine adjuvants that can be used to promote protective immunity and/or reduce deleterious immune responses. Although somewhat simplistic, it is possible to divide therapeutic vaccine approaches into those targeting conditions where antibody responses can mediate protection and those where the principal focus is the promotion of effector and memory cellular immunity or the reduction of damaging cellular immune responses as in the case of autoimmune diseases. Clearly, in all cases of antigen‐specific immunotherapy, the identification of protective antigens is a vital first step. There are many challenges to developing therapeutic vaccines beyond those associated with prophylactic diseases including the ongoing immune responses in patients, patient heterogeneity, and diversity in the type and stage of disease. If reproducible biomarkers can be defined, these could allow earlier diagnosis and intervention and likely increase therapeutic vaccine efficacy. Current immunomodulatory approaches related to adoptive cell transfers or passive antibody therapy are showing great promise, but these are outside the scope of this review which will focus on the potential for adjuvanted therapeutic active vaccination strategies.
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Osmanlı’da ve Türkiye’de aşı tarihi
(Bilkent University, 2020) Seyitoğlu, Deniz Ege; Aksoy, Taylan Özgür; Şakiroğulları, Deniz; Köse, Zeynep; Kösterit, Demir
Aşılar toplum sağlığının korunmasının önemli bir parçasıdır. Aşılanmış bir toplum salgınlara karşı da bağışıklık kazanmış olur. Hem Osmanlı devletinde hem de Türkiye Cumhuriyeti'nde toplum sağlığını korumak ve salgınlarla mücadele etmek adına birçok aşı çalışması yapılmış, çeşitli kurumlar ve yasalar faaliyete geçirilmiştir. 19. yüzyıl ve sonrasında Osmanlı yüzünü Avrupa'ya dönmüş ve aşı alanındaki çalışmaları yakından takip etmiştir. Tüm bu çalışmaların sonucunda çiçek, kuduz ve verem aşısı gibi birçok aşının üretimi yapılmış ve bu alandaki bilgi birikimi arttırılmıştır. Tüm bu bilgi ve deneyimler Türkiye Cumhuriyeti'ne kalmış, 1997'ye kadar çalışmalar sürdürülmüş ve aşı üretimine devam edilmiştir. Bu proje kapsamında salgın hastalıklarla mücadele konusunda büyük bir önem teşkil eden aşı üretimi Osmanlı döneminden başlayarak günümüz Türkiye'sine kadar incelenecektir. 1885’te çiçek aşısı kanunu çıkarılmasından, 1997’ de aşı üretiminin sonlandırılmasına kadar olan bu dönemde üretilen aşılar, üretim yerleri ve toplum sağlığına olan etkileri incelenecektir.
Open Access
Rational vaccine design in times of emerging diseases: The critical choices of immunological correlates of protection, vaccine antigen and immunomodulation
(MDPI AG, 2021-04-06) Schijns, V.; Majhen, D.; Ley, P.; Thakur, A.; Summerfield, A.; Berisio, R.; Nativi, C.; Fernández-Tejada, A.; Alvarez-Dominguez, C.; Gizurarson, S.; Zamyatina, A.; Molinaro, A.; Rosano, C.; Jakopin, Z.; McClean, S.; Gürsel, İhsan
Vaccines are the most effective medical intervention due to their continual success in preventing infections and improving mortality worldwide. Early vaccines were developed empirically however, rational design of vaccines can allow us to optimise their efficacy, by tailoring the immune response. Establishing the immune correlates of protection greatly informs the rational design of vaccines. This facilitates the selection of the best vaccine antigens and the most appropriate vaccine adjuvant to generate optimal memory immune T cell and B cell responses. This review outlines the range of vaccine types that are currently authorised and those under development. We outline the optimal immunological correlates of protection that can be targeted. Finally we review approaches to rational antigen selection and rational vaccine adjuvant design. Harnessing current knowledge on protective immune responses in combination with critical vaccine components is imperative to the prevention of future life-threatening diseases.