Abstracts of the 2nd International Electronic Conference on Vaccines (IECV 2024), 27–29 November 2024

Abstract

The 2nd International Electronic Conference on Vaccines (IECV 2024) took place online from 27 to 29 November 2024. This conference report is a collection of abstracts from six different sessions of IECV 2024.

1. Introduction

There are currently major challenges to developing new vaccines and improving existing platforms for both infectious diseases and cancer. Novel methods of vaccine delivery for both human and different animal species are required. Advances in vaccine design to give broad protection to mitigate against the mutation of antigens and to provide both good humoral and cellular immunity are a priority. For flaviviruses, particularly dengue, there are major hurdles to producing vaccines, which not only cover all the serotypes but also prevent the induction of antibody-dependent enhancement. Inactivated and subunit vaccines need to be combined with effective long-acting adjuvants to optimize their potential. In all cases, novel assays, in particular omics-based approaches, are necessary to evaluate in-depth and early responses to vaccination.

The IECV 2024 invited researchers from academia, as well as vaccine practitioners, to contribute original findings, novel ideas, scientific concepts, and new technologies and experiences to deal with immunology mechanisms, animal models for immunologic diseases, viral immunology, immunopathogenesis, vaccine development and efficacy evaluation, immune responses to vaccines, vaccine technology, vaccine vectors, adjuvants, and immunomodulators, with reference to the following topics:

S1. Cancer Vaccines, Immunotherapy, and Immunoprevention;

S2. Challenges of Developing a Dengue Vaccine;

S3. Vaccine Adjuvants;

S4. mRNA Vaccines;

S5. Advancement in Vaccine Design for Broad Protection;

S6. Novel Assays for Evaluating Responses to Vaccination.

2. Session 1: Cancer Vaccines, Immunotherapy, and Immunoprevention

2.1. An Evaluation of the Humoral Immune Response Generated by the Inoculation of a Multi-Peptide-Based Vaccine Prototype Derived from Tumoral Antigens of Breast Cancer in Balb/C Mice

Edgar Hurtado-Ortega ¹, María Lilia Nicolás-Morales ¹, Amalia Vences-Velázquez ¹, Juan Miguel Mendoza-Bello ², Mónica Espinoza-Rojo ², Karen Cortés-Sarabia ³

• Laboratorio de Investigación en Inmunobiología y Diagnóstico Molecular, Facultad de Ciencias Químico Biológicas, UAGro, Chilpancingo de los Bravo, Guerrero, México
• Laboratorio de Biología Molecular y Genómica, Facultad de Ciencias Químico Biológicas, UAGro, Chilpancingo de los Bravo, Guerrero, México
• Universidad Autónoma de Guerrero, Guerrero, México

• Introduction

Breast cancer is the most diagnosed type of cancer in women and the leading cause of death by cancer worldwide. In recent years, active immunotherapy using vaccines has been raised as a novel approach to conventional treatments. Peptide-based vaccines are developed using overexpressed proteins in the tumor, commonly known as tumor antigens, that can stimulate the humoral immune response.

• Objective

To evaluate in Balb/c mice the production of antibodies induced by inoculation with doses of 30, 50, and 100 µg of the multi-peptide-based vaccine prototype derived from tumoral antigens.

• Material and Methods

The vaccine prototype included the peptides derived from the following proteins: mammaglobin-α, NY-ESO-1, PLAC-1, Syntenin-1, and MAGE-A3. These were selected by in silicio analysis. Peptides were mixed with Freund incomplete adjuvant and inoculated subcutaneously during days 1, 15, 45, and 60 in twelve Balb/C mice classified into four experimental groups (three experimental groups and a placebo group). The mice were bled during days 0, 40, and 80, and serum samples were used to detect the presence of antibodies (IgM, IgG1, IgG2a, IgG2b, and IgG3) and the recognition of each individual peptide by assays of Indirect ELISA and Dot blot.

• Results

We observed the production of IgM and subclasses of IgG in the three experimental groups (30, 50, and 100 µg), mainly the subclasses IgG2a and IgG2b. In the Dot blot, we observed that immunized mice produce antibodies against all the peptides; particularly, the peptides derived from Syntenin-1, PRAME, mammaglobin-α, and PLAC-1 were the most immunogenic. Conclusion: The multi-peptide-based vaccine prototype induced antibody production against each peptide. The results can contribute to the development of future in vivo experiments focused on the effect of the administration of peptides on avoiding tumoral growth.

2.2. An In Silico and In Vivo Analysis of a Novel Multi-Epitope Peptide Vaccine Against Hepatocellular Carcinoma

Yusra Zarlashat ¹, Hassan Mushtaq ²

• Government College University, Faisalabad, Pakistan
• Health Biotechnology Division, National Institute for Biotechnology and Genetic Engineering (NIBGE-C), Faisalabad, Pakistan

Hepatocellular carcinoma (HCC) is becoming more prevalent, making it one of the most serious worldwide health challenges. Several studies have focused on designing effective multi-epitope peptide vaccines against HCC in recent years. An in silico approach was used in prior investigations to create a multi-epitope peptide vaccine against HCC. Glypican-3 (GPC-3), melanoma-associated antigen-C2 (MAGE-C2), aspartyl-β-hydroxylase (ASPH), and New York esophageal squamous cell carcinoma 1 (NY-ESO-1) are four overexpressed antigens in HCC patients that we used in the vaccine’s design. A multi-epitope peptide vaccine against HCC was designed through in silico antigen selection, physicochemical characterization, epitope prediction, structural analysis, cloning optimization, immune simulation, bacterial expression, protein purification, and immunological evaluation in rats. Four B-cells, nine MHC-I restricted, and eleven MHC-II restricted epitopes were selected based on their antigenicity score > 0.5 and non-allergenicity with an adjuvant that included a segment of the microbial heat shock protein (HSP70) peptide 407–426 for vaccine construction. The relevant linkers were used to link each of the vaccine components and the cloned-in vector. This vector was successfully transformed into the Escherichia coli strain to further evaluate itsimmunological response and efficacy. The primary aim of this study is to design a vaccine and subsequently conduct laboratory experiments to evaluate its efficacy and safety profiles. It covers 90% of the global population, hence it is very effective. The vaccine’s easily soluble nature was shown by its physicochemical properties, such as its hydropathicity index (−0.457) and aliphatic index (75.63). The vaccine has a high probability of being soluble in E. coli, with a solubility of 0.680. The ongoing results will provide insights into the efficacy of the vaccine against HCC.

2.3. Comprehensive Review on Vaccination Approaches in Triple-Negative Breast Cancer

Nishant Mahendra Patel ¹, Zubair Saghir Ahmed Shaikh ², Sulbha G Patil ², Amitkumar Dhankani ³, Palak Mahendra Patel ⁴

• College of Professional Studies, Northeastern University, 02115, Boston, USA
• Department of Pharmaceutics, P.S.G.V.P.M’S College of Pharmacy, Shahada, 425409, India
• Department of Pharmaceutical Analysis, P.S.G.V.P.M’S College of Pharmacy, Shahada, 425409, India
• KM Shah Dental College and Hospital, Sumandeep Vidyapeeth, Vadodara, 391760, India

Triple-Negative Breast Cancer (TNBC) represents a formidable subtype of breast cancer, characterized by the absence of estrogen receptors, progesterone receptors, and HER2 protein. This phenotype presents significant treatment challenges due to its aggressive nature and lack of targeted therapies. Consequently, there has been an intensified focus on novel therapeutic strategies, including vaccination approaches, which hold promise in eliciting robust anti-tumor immune responses. This review provides a comprehensive analysis of current vaccination strategies employed in the management of TNBC. It explores various vaccine platforms, such as peptide-based, dendritic cell-based, viral vector-based, and virus-like nanoparticle (VLP)-based vaccines, highlighting their mechanisms of action. Furthermore, this review examines the role of neoantigen vaccines, which leverage tumor-specific mutations to enhance immune specificity and efficacy, and combination strategies that integrate vaccines with other modalities, including immune checkpoint inhibitors and conventional chemotherapies, to potentiate anti-tumor responses and overcome immunosuppressive tumor microenvironments. Emerging trends, such as personalized vaccination approaches tailored to individual patient tumor profiles, are evaluated for their potential to revolutionize TNBC treatment paradigms. Additionally, we address the challenges and limitations faced in vaccine development, including antigen selection, delivery methods, and the heterogeneity of TNBC. This review concludes with future perspectives on optimizing vaccine-based therapies and their integration into standard TNBC treatment regimens. By synthesizing current research and clinical advancements, this review aims to provide a detailed understanding of vaccination strategies in TNBC, underscoring their potential to improve patient outcomes and contribute to the ongoing battle against this aggressive cancer subtype.

2.4. Development of Nanobodies Targeting TIGIT for Cancer Immunotherapy

Shipeng Wang, Jixiang Gu, Chunhui Li, Huimin Ma, Xiangyu Xie, Wenxiao Sun, Xinyue Chang, Lisha Zha

College of Animal Science and Technology, Anhui Agricultural University, Hefei 230036, China

TIGIT, a T-cell immunoreceptor with Ig and ITIM domains, has been recognized as a critical inhibitory receptor on T cells and natural killer (NK) cells. It plays an important role in immune suppression mediated by tumors. Tumor cells express CD155, which engages TIGIT and hampers T cell or NK cell activation to perform cytotoxicity, thus facilitating tumor progression. Releasing TIGIT on immune cells from CD155 binding to target tumor cells is one promising strategy for cancer immunotherapy. To this end, TIGIT-specific nanobodies were generated by immunizing camels with the TIGIT protein, from which a library of nanobodies was built. Then, Monoclonal nanobodies were screened by phage display, and high-affinity nanobodies for TIGIT were identified. Competitive ELISA assays were performed to demonstrate that nanobodies effectively inhibited the binding of TIGIT to CD155. Furthermore, the cytotoxicity activities of NK-92MI cells were significantly enhanced by adding TIGIT antibodies; meanwhile, higher cell degranulation was determined. At the same time, the viability of tumor cells after mixing with NK-92MI cells was detected, showing that the viabilities of K562 cells were as high as 90%, suggesting the limited cytotoxicity of NK-92MI cells. In contrast, the viabilities of K562 cells were significantly reduced when the nanobodies were added, indicating that nanobodies effectively block TIGIT on NK cells from binding to CD155 on tumor cells. These findings suggest that the screened nanobodies have promising potential for further evaluation in tumor-bearing mouse models. These nanobodies might offer significant benefits in clinical settings by improving patient selection and therapeutic outcomes in cancer immunotherapy.

3. Session 2: Challenges of Developing a Dengue Vaccine

A Comparison of Humanized Mice Models Using NOD-Derived Strains for Dengue Virus Infection

Hector Hernando Gutierrez Barbosa ¹, Sandra Medina-Moreno ¹, Federico Perdomo-Celis ², Harry Davis ¹, Joel Chua ¹, Juan C Zapta ¹

• Institute of Human Virology, University of Maryland School of Medicine, Baltimore, MD 21201, USA
• Instituto de Genética Humana, Facultad de Medicina, Pontificia Universidad Javeriana, Bogotá 110231, Colombia

Dengue, a major public health issue in tropical and subtropical regions, currently has no specific treatment and only one licensed vaccine, with limited use in endemic areas. The lack of antiviral drugs and the challenges in understanding dengue’s pathophysiology stem from the absence of an effective animal model that mirrors human infection in terms of viraemia peaks, clinical presentation, and immune response. Humanized mouse models have been useful in viral disease research, but dengue studies often use NOD-scid IL2R gamma null (NSG) immunodeficient mice, which focus on preventing graft rejection rather than fully developing human hematopoiesis. In this study, we compare four humanized mouse models derived from NOD mice expressing human cytokines, which were xenotransplanted and infected with DENV-2 (New Guinea C) intravenously. The models (Hu-NSG, hu-EXL, hu-SGM3) received xenotransplants of CD34+ fetal cord blood, while one model (Hu-SGM3-PBMCs) was transplanted with human PBMCs. We found that models expressing human cytokines had higher viremia compared to the NSG model. All the models showed infectious virus during viremia, confirmed by means of indirect plaque assays. The Hu-SGM3-PBMCs model, in particular, developed a severe infection with signs of bleeding and intestinal necrosis, leading to the death of all mice by day 18 post-infection, with viremia levels twice as high as in the other models according to RT-qPCR. The models using hCD34+ cells showed low or undetectable levels of human proinflammatory cytokines during infection, measured by means of flow cytometry Bead Arrays. In contrast, the hu-mice model with human PBMCs exhibited detectable and decreasing levels of IFN-g, IL-10, IP10, and TNF, which is consistent with the immune modulation seen in DENV-2 New Guinea C strain infections. These results indicate that humanized mice models derived from NOD mice expressing human cytokines enhance viremia and offer a relevant platform for studying dengue and potential treatments.

4. Session 3: Vaccine Adjuvants

4.1. Efficacy, Safety, and Molecular Mechanism of Sublingual Poly(I:C)-Adjuvanted Vaccine Formulated with SARS-CoV-2 RBD or Influenza HA Antigen in Non-Human Primates, Macaque Monkeys

Tetsuro Yamamoto ^1,2,3, Fusako Mitsunaga ^4,5, Kunihiko Wasaki ^1,2, Atsushi Kotani ^1,3, Kazuki Tajima ^1,3, Shin Nakamura ^4,5

• Innovation Research Center, EPS Holdings, Inc.; 2-1 Tsukudohachimancho, Shinjuku-ku, Tokyo, 162-0815, Japan
• EP Mediate Co., LTD; 1–8 Tsukudocho, Shinjuku-ku, Tokyo162-0821, Japan
• Research Center, EPS Innovative Medicine Co., Ltd.; 1-8 Tsukudocho, Shinjuku-ku, Tokyo, 162-0821, Japan
• Intelligence & Technology Lab, Inc.; 52-1 Fukue, Kaizu-cho, Kaizu 503-0628, Japan
• Biomedical Institute, NPO Primate Agora; 52-2 Fukue, Kaizu-cho, Kaizu 503-0628, Japan

The sublingual vaccine introduced in this study induces mucosal antibody-mediated protection against SARS-CoV-2 and influenza viruses, which infect via the upper respiratory tract, mouth, and nose. Poly(I:C) is an adjuvant used to activate TLR3-mediated immune responses, but it remains unapproved due to its proinflammatory side effects. The mucosae of the oral cavity are the primary target of the sublingual vaccination, although this poses a practical limitation due to the inhibitory mucin barrier.

We developed a sublingual SARS-CoV-2 vaccine using the SARS-CoV-2 RBD antigen and Poly(I:C) adjuvant, as well as an influenza vaccine including the HA antigen. These vaccines were tested in non-human primates, macaque monkeys, utilizing N-acetyl cysteine to disintegrate the mucus layer. The sublingual Poly(I:C)-adjuvanted vaccine (SPAV) elicited mucosal and systemic immune responses, including antigen-specific secretory IgA in saliva and nasal washing, as well as specific IgA and IgG in blood. These antibodies neutralized SARS-CoV-2, suggesting that the SPAV protects against the SARS-CoV-2 virus.

SPAV appeared to be safe judging from the results of the blood tests, the plasma inflammatory cytokines, the gene expression of the proinflammatory factor in the WBC, and a direct comparison to AddaS03, which is an emulsion adjuvant viewed as being safe. In mice, an intranasally administrated Poly(I:C)-adjuvanted vaccine had a potent unfavorable effect in the olfactory bulb, causing the upregulated expression of nine proinflammatory genes, but the same was not true in monkeys. Thus, the previously reported detrimental effects of Poly(I:C)-adjuvanted vaccines in mice are overstated due to differences in nose structure and function, as well as immune response, between mice/rodents and macaques/primates.

DNA microarray analysis revealed that the SPAV mediates atypical up- or down-regulated gene expression associated with immune suppression/tolerance, leading to incomplete Treg differentiation and T-cell exhaustion. Possibly, the PASV could induce previously unknown effects on balancing stimulation and inhibition, like the “Yin and Yang” concept, in immune responses.

4.2. Enhancing Adjuvant Efficacy with Dispersed Ascorbyl Palmitate (ASC16)

Franco Maslovski ¹, David Hernández ², Gisela Yaccuzzi ¹, Laura Leiva ³, Luciano Fusco ¹

• Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Instituto de Química Básica y Aplicada del Nordeste Argentino (IQUIBA), Corrientes, Argentina
• Facultad de Ciencias Veterinarias, Universidad Nacional del Nordeste (UNNE), Corrientes, Argentina
• Instituto de Química Básica y Aplicada del Nordeste Argentino (IQUIBA), Corrientes, Argentina

Today, an ideal adjuvant must meet several essential criteria: it must be safe, biocompatible, and capable of directing the immune response and enhancing antigen presentation. ASC16 (GRAS and FDA Inactive Ingredients Database) is a derivative of vitamin C that can form viscoelastic hydrogels or act as a toxin inhibitor depending on whether it is present at high or low concentrations, respectively. For these reasons, we proposed to evaluate the effect of dispersed ASC16 (low concentration; Mo) as an additive in a hydrogel (high concentration; Pa40) to produce experimental antivenom. For the formation of the hydrogel, first, ASC16 (25 mg) and PEG₄₀₀ solution (0.750 mL) were mixed and heated to 63 °C until complete solubilization. Then, this dispersion was cooled to 40 °C, and then it was incorporated into 0.250 mL of PBS solution with or without dispersed ASC16 (120 µM) and finally venom proteins (6–10 µg/mice). Afterward, BALB/c mice were inoculated with hydrogel in the absence or presence of additive (Pa40 and Pa40Mo). Fourteen days after the inoculation, skin and blood samples were taken for histological analysis of local injury and to determine the titre and specificity of the antibodies by ELISA and Immunoblotting tests. We used t-tests for two independent samples to verify whether there were significant differences. Our results show that Pa40Mo induced the highest titres (3.75) and had the highest Western blot signal, followed by Pa40 (3.27), with significant differences (p ≤ 0.05). Histological analyses indicate that both formulations caused tissue alterations by the observation of regenerating muscle cells. This study shows that both formulations provide evidence of acute injury and that formulations with dispersed ASC16 as an additive induce higher antibody titres and have greater specificity than formulations without the additive. However, future studies are needed to determine the signalling mechanism of dispersed ASC16.

5. Session 4: mRNA Vaccines

Regulating the Use of AI in mRNA Vaccine Development Through Policy Coherence

Rabaï Bouderhem ^1,2

• Prince Mohammad Bin Fahd University, Saudi Arabia
• Research Associate, CREDIMI FRE 2003, CNRS—University of Burgundy, Dijon, France

Artificial intelligence (AI) has become a game-changer in advancing mRNA vaccine development, bringing unparalleled speed and efficiency to research. AI-driven tools play a crucial role in enhancing vaccine potency and stability by optimizing gene sequences. This results in vaccines that provoke stronger immune responses and are more resistant to degradation. Such progress could enhance health equity and global vaccine distribution, especially in areas lacking adequate cold storage facilities. However, integrating AI into vaccine development poses several technical, ethical and regulatory challenges. One significant hurdle is accurately identifying antigens that can trigger effective immune responses. Additionally, the swift pace of AI-driven research often surpasses current regulatory frameworks, necessitating a delicate balance between innovation and oversight. Ethical issues such as data privacy, algorithmic bias, safety, explainability and transparency in decision-making processes must be tackled to maintain public trust. Regulatory agencies are addressing these obstacles by formulating guidelines covering data authenticity, reliability, transparency, and real-world patient monitoring. A risk-based AI regulation approach is being explored, requiring robust governance structures and collaborative efforts among global regulatory bodies. While AI shows great potential in transforming mRNA vaccine development, concerted efforts are crucial to navigate challenges and ensure the safe and equitable realization of its benefits worldwide.

6. Session 5: Advancement in Vaccine Design for Broad Protection

6.1. Identification of Neutralizing Epitopes in Avian Leukosis Virus

Xiangyu Xie, Shipeng Wang, Xinyue Chang, Lisha Zha

College of Animal Science and Technology, Anhui Agricultural University, Hefei 230036, China

Neoplasms and reduced productivity in chickens caused by avian leukosis viruses (ALVs) have led to significant economic losses in the poultry industry. Due to the frequent genomic mutations that give rise to new viral variants, traditional whole-virus vaccines have demonstrated inadequate protection. With the high prevalence of ALV in farms in China, it is urgent to develop novel vaccines to control ALV. The capsid protein p27 is highly conserved across all current ALV subtypes, and studies have shown that p27-specifc antibodies in ALV-infected chickens were able to neutralize ALV, making it a promising target for vaccine design. We screened anti-p27 monoclonal antibodies using phage display technology from antibodies 111C and 86C that could neutralize ALVs. To identify neutralizing epitopes, antibody–antigen docking simulation was first used to predict epitopes that might interact with neutralizing antibodies. Then, the predicted peptides were generated, which were then identified by ELISA and Western blot to bind to neutralizing monoclonal antibodies. The affinities of the neutralizing antibodies in binding to the identified epitopes were as high as 10⁻⁹ M, validating the neutralizing epitopes were correct. These epitopes were found to be highly conserved among most ALV variants and could be displayed on virus-like particles (VLPs) to form vaccine candidates. These vaccines will be tested in chickens to assess both their immunogenicity and protection against ALVs. The reverse vaccinology used in this study provides an excellent paradigm for the development of protective vaccines against ALV, with broader implications for future vaccine research.

6.2. Lysosome-Associated Membrane Protein Targeting Strategy Improved Immunogenicity of Glycoprotein-Based DNA Vaccine for Hantaan Virus

Zilu Ma, Yuanhang Chang, Shuaishuai Fu, Yuanzhe Li, Zejin Li, Bingquan Zhou, Weijie Ding, Yulin Yang, Yiming Xue, Zhuoyi Lv, Baozeng Sun, Kun Yang, DongBo Jiang

Department of Immunology, Basic Medicine School, Air-Force Medical University (the Fourth Military Medical University), China

• Background and Aims

Hemorrhagic fever with renal syndrome (HFRS) is a viral zoonotic disease primarily caused by the Hantaan virus (HTNV). This illness is prevalent in over 70 countries worldwide, posing a significant public health challenge due to its high endemicity. The glycoprotein (GP) of HTNV is a key structural protein that is crucial for triggering both humoral and cellular immune responses, making GP-specific immunoprophylaxis a promising therapeutic approach for HFRS.

• Methods

Lysosome-associated membrane protein 1 (LAMP1) has the ability to target antigens to lysosomes and endosomes, thereby enhancing the immunogenicity of nucleic acid vaccines. In this study, we developed a recombinant DNA vaccine for HTNV GP that utilizes LAMP1 to direct the vaccine to the major histocompatibility complex (MHC) class II compartment. We conducted thorough computational analyses to evaluate the properties of the vaccine molecule and its potential immune responses in the body. Initial animal studies confirmed the effectiveness of GP-derived Th epitopes and multi-epitope vaccines.

• Results

We designed two vaccines based on Gnc molecules and optimized them using a LAMP-targeting approach. Following three immunizations, mice receiving the pVAX-LAMP/Gnc vaccine exhibited increased splenocyte-specific IFN-γ secretion and higher serum antibody titers, particularly in terms of neutralizing activity. Furthermore, the efficacy of these molecular therapies was supported by preliminary in silico findings and laboratory animal experiments. By facilitating lysosomal trafficking and antigen presentation, the LAMP1 targeting strategy significantly enhanced both humoral and cellular immune responses specific to EBOV-GP.

• Conclusions

Our research expands the strategic framework for improving DNA vaccine design and presents a promising candidate for HFRS prevention, establishing a foundation for future antiviral vaccine strategies.

6.3. A Virus-like-Particle-Derived Vaccine Induces Neutralizing Antibodies Against Novel Duck Reovirus (NDRV)

Wenxiao Sun, Shipeng Wang, Jixiang Gu, Chunhui Li, Huimin Ma, Xiangyu Xie, Xinyue Chang, Lisha Zha

College of Animal Science and Technology of Anhui University of Agriculture, China

Novel duck reovirus (NDRV) causes high morbidity in ducklings, and the recovered individuals often show stunted growth. There is currently no commercial vaccine available for effectively controlling NDRV. The capsid protein σC in NDRV is responsible for virus–cell attachment and thus plays a key role in viral infection. In this study, we aimed to develop a new vaccine candidate presenting σC on the virus-like particle AP205 according to specific binding with SpyCatcher and SpyTag. Firstly, σC-SpyTag was expressed in E. coli and purified, which was then coupled to AP205-SpyCatcher to generate AP205-σC. Then, AP205-σC was characterized, and the results demonstrated that it remained intact and had a homogenous viral particle structure, which packaged prokaryotic ssRNA inside. After immunizing ducklings with it, AP205-σC induced σC-specific IgY antibodies that could effectively recognize NDRV. Importantly, these antibodies were able to block the virus from infecting duck embryo fibroblasts in vitro, suggesting the vaccine successfully elicited neutralizing antibodies in ducklings. Consistently, the clinical pathologic features like lesions or listlessness in the AP205-σC-immunized ducklings were drastically reduced compared to those in the control group. Moreover, the viral loads in the AP205-σC-immunized ducklings were strikingly reduced, indicating that the vaccine contributed to viral clearance. These results suggested that AP205-σC exhibited excellent immunogenicity and posed protection against NDRV infection in ducks. In conclusion, AP205-σC has the potential to induce neutralizing antibody responses against NDRV and is worthwhile to develop for large-scale application.

6.4. Challenges in Developing Universal Influenza Vaccine: Progress and Hurdles in Creating Broad Protection Against the Rapidly Mutating Virus

Hafiza Nimra Tariq

Faculty of Veterinary Science, University of Agriculture Faisalabad, Faisalabad, Pakistan

Influenza remains a persistent global threat, with the rapid mutation of its surface proteins, particularly hemagglutinin (HA), challenging the effectiveness of seasonal vaccines. Universal vaccination seems to be a promising way of combatting the influenza virus’s rapid mutation rate. The concept of a universal vaccine aims to provide broad protection against diverse strains by targeting conserved viral epitopes. In this review, I explored some of the major hurdles in achieving this goal, focusing on antigen selection, immunodominance, and the challenges posed by nanoparticle-based and T-cell-mediated vaccine platforms. The pursuit of a universal influenza vaccine faces numerous challenges despite advancements in the identification of conserved antigens and innovative technologies. Different types of vaccines have been put into clinical trials, such as viral vector and mRNA-based vaccines, non-replicating viral vector vaccines, and broadly neutralized antibodies (bnAbs), which have been proven to meet the research demands of the universal influenza vaccine. While promising, these approaches face significant barriers, including issues of antigen stability, delivery, and struggles of eliciting durable cross-reactive immune responses in mucosal tissues. Novel platforms like mRNA vaccines and viral vector vaccines show promise in providing broad protection against virus mutations. Breakthroughs in vaccine design continue to be made, aiming to enhance cross-protective efficacy and defense against potential pandemics. The results highlight that although significant progress has been made, overcoming the scientific, technical, and regulatory challenges is essential for achieving a truly universal influenza vaccine. In conclusion, ongoing global collaboration and innovative research are crucial for overcoming these barriers. However, the mutation rate of the influenza virus presents a significant obstacle in the path towards a commercially available universal vaccine.

6.5. Comparative Immunogenicity of 10 µg Versus 20 µg of Hepatitis B Vaccine Booster Dose in Healthcare Workers

Emma Borrelli ¹, Francesca Barbagli ², Giulia De Vuono ², Giovanni Battista Miceli ², Antonietta Gerardina Sisinni ², Simonetta Fabrizi ²

• Department of Medical Biotechnologies University of Siena, Siena, Italy
• Unit of Preventive Medicine and Health Surveillance, University Hospital Le Scotte, Siena, Italy

Healthcare workers (HCWs) are at increased risk of occupational exposure to hepatitis B virus (HBV) infection, even if they have received a complete immunization schedule of three doses of hepatitis B vaccine in infancy. According to our Hospital Immunization Program, Hepatitis B surface (anti—HBs) antibody serum levels were determined in all HCWs at the time of hospital admission in order to investigate the HBV immunity state. HCWs with low anti-HBs serum levels (10 mIU/mL) usually received a booster dose of 20 µg/1 mL Engerix B (GlaxoSmithKline Biologicals, Rixensart, Belgium) vaccine. However, due to a temporary shortage of the 20 µg Engerix B vaccine, we wondered if 10 µg/0.5 mL (pediatric dose) could be equally effective to elicit the immunogenicity in our HCWs. For this reason, we conducted a pilot study on forty homogeneous HCWs with a non-immune level of anti HBs antibody (10 mIU/mL) who were previously vaccinated in infancy. Twenty HCWs (Group A) received a booster dose of Engerix B vaccine 10 µg/0.5 mL, and twenty HCWs (Group B) received the standard dose of 20 µg/1 mL of Engerix B vaccine. One month after the vaccination, the anti-HBs antibody serum levels in all participants in the study were determined. The results showed a significant increase in anti-HBs antibody serum levels both after 10 micrograms and 20 micrograms of Engerix B vaccine. All but two healthcare workers were immunized after their booster dose; no statistically significant difference was found in the mean of anti-HBs antibody serum levels between groups A and B. If confirmed in a large clinical trial, the use of 10 micrograms Engerix B booster dose in adults could represent a preferred choice in terms of cost efficacy, particularly in specific situations, for example in vaccination programs in low-income countries.

6.6. Designing a Novel Multi-Epitope Cocktail Vaccine Candidate for Lymphatic Filariasis: An Immuno-Informatics Approach

Anchal Singh, Vipin Kumar, Sunil Kumar

Department of Biochemistry, Institute of Science, Banaras Hindu University, Varanasi, 221005, U.P., India

• Background

Lymphatic filariasis is a neglected tropical disease (NTD) affecting more than 863 million people in 47 countries across the world. A multi-epitope prophylactic/therapeutic vaccination targeting filarial defense proteins would be invaluable in achieving the current goal of LF elimination.

• Method

In this study, a combination of immunomics and immune-informatics was applied to construct a multi-epitope vaccine candidate. The antigenic proteins were identified by immune blotting against different categories of Wuchereria bancrofti-infected LF sera.

• Result

The major antigenic proteins were heat shock protein 70, Tubulin beta chain, Enolase, Galectin, and 14-3-3 zeta. The five antigens were combined together to construct a multi-epitope vaccine after predicting the linear B-cell and T-cell epitopes of individual antigens. A three-dimensional model of the candidate vaccine was predicted, followed by refinement, and was validated using RAMPAGE and PROCHECK servers. A Toll-like receptor (TLR) agonist, a 50S ribosomal subunit of Mycobacterium tuberculosis, was included in the candidate vaccine to enhance vaccine immunogenicity. The docking of the chimeric peptide vaccine against the TLR5 resulted in high binding efficiency for the docked complex. The in silico immune simulation provided a significant increase in CD4⁺ T-cell and CD8⁺ T-cell populations.

• Conclusions

In summary, the recombinant putative vaccine showed high immunogenicity which could be experimentally validated in the future for the development of a potent LF vaccine. Furthermore, by employing multi-epitope structures and constructing a cocktail vaccine for LF, this study has the potential to represent an important milestone in the development of an anti-filarial vaccine.

6.7. Evaluation of Chicken Astrovirus Breeder Vaccine Candidate

Victoria Jane Smyth ¹, Kerry McIlwaine ², Pauline Sheridan ³

• Virology Branch, Veterinary Sciences Division, Agri-Food and Biosciences Institute, Stormont, Belfast BT4 3SD, UK
• School of Biological Sciences, Queen’s University, Belfast BT9 5DL, UK
• Disease Surveillance Investigation Branch, Veterinary Sciences Division, Agri-Food and Biosciences Institute, Omagh, BT78 5NF, UK

Introduction: Chicken astrovirus (CAstV) is a ubiquitous agent infecting global broiler production, mainly affecting embryos and neonates, with some highly pathogenic (hp) strains causing hatchery losses (up to 69%) and fatal kidney disease with visceral gout. There are two serogroups of CAstV, A and B; most diseases have been associated with the B serogroup, which is subdivided into subgroups via capsid gene genotyping.

Methods: The CAstV-11672 (subgroup Bi) strain was administered to in-lay broiler breeder hens as a live breeder vaccine candidate. Sera were monitored weekly for seroconversion via ELISA. Eggs were collected from seroconverted and control hens, and were synchronised and incubated to hatch. Hatchlings in isolators were challenged with one of three hp strains belonging to subgroups Bi, Biii and Biv. The chicks were visually monitored for disease development; their CAstV levels were monitored by real time RT-qPCR; and their weight and development of kidney lesions by days four and ten (termination) were monitored.

Results: Thelevels of CAstV seroconversion in hens were low after oral inoculation but increased significantly after intramuscular inoculation. The levels of anti-CAstV antibodies detected in egg yolks were approximately half that of the hens. The weights of chicks with maternally-derived antibodies (matABs) were significantly higher at day 10 after being challenged with hp strains from the Bi and Biii subgroups. The chicks with matABs showed no kidney lesions at day 4 from any of the hp strains, whereas the chicks without matABs had substantial numbersof kidney lesions at day 4, which were statistically significant by day 10.

Conclusions: The CAstV-11672 strain elicited a strong immune response in adult birds, with successful the transmission of matABs that protected the hatchlings from challenges with hp strains of CAstV, resulting in the prevention of kidney damage and higher body mass compared to chicks without anti-CAstV matABs. CAstV-11672 appears to be a successful candidate for a CAstV breeder vaccine.

6.8. Exploiting Surface-Exposed Proteins to Develop New Therapeutic Strategies Against Bcc and Pseudomonas aeruginosa Infections

Silvia A. Sousa ^1,2, Antonio M.M. Seixas ^1,2, Jeremias Muazeia ^1,2, Jorge H. Leitao ^1,2

• iBB—Institute for Bioengineering and Biosciences, Instituto Superior Tecnico, Universidade de Lisboa, Av. Rovisco Pais, 1049-001 Lisbon, Portugal
• Associate Laboratory i4HB—Institute for Health and Bioeconomy at Instituto Superior Tecnico, Universidade de Lisboa, Av. Rovisco Pais, 1049-001 Lisbon, Portugal

Respiratory infections caused by Burkholderia cepacia complex (Bcc) and Pseudomonas aeruginosa remain life-threatening to Cystic Fibrosis (CF) patients. Immunotherapies are attractive alternatives to protect CF patients against these infections. In order to identify new targets for the development of immunoprotective therapies, we used a surfomics approach to find putative surface-exposed proteins. This methodology combined with immunoinformatics tools allowed the identification of surface-exposed proteins containing B-cell epitopes [1]. The OmpA-like protein BCAL2645 was chosen and demonstrated by Western blotting and ELISA assays to be immunoreactive against sera from CF patients with a record of Bcc infections. The protein was characterized as multifunctional and important in the infection process. An anti-BCAL2645 polyclonal antibody was produced and was found to decrease the number of adhered and invading B. cenocepacia bacteria to human cells in vitro by more than 70% [2]. A cross-effect against P. aeruginosa and B. multivorans using this antibody was also observed, strongly decreasing the adhesion and invasion of these species to the human bronchial epithelial cell line CFBE41o- [3]. Using the animal model Galleria mellonella, the antibody was found to confer protection against these infections. These results highlight the potential of anti-BCAL2645 antibodies for passive immunization therapies to prevent infections against two of the most problematic bacterial species infecting CF patients. Preliminary results from passive immunization strategies under study using anti-BCAL2645 antibodies will be presented.

6.9. Exploring the Oral Route of Vaccine Delivery Using Recombinant Secretory IgA as a Vehicle to Boost Immune Responses Against Tuberculosis in BCG-Primed Mice

Mohd Hatimi Tukiman ¹, Maryam Azlan ¹, Mohd Nor Norazmi ¹, Frank Camacho ²

• School of Health Sciences, Universiti Sains Malaysia, Kubang Kerian, 16150, Malaysia
• Pharmacology Department, Biological Sciences School, Universidad de Concepcion, Concepcion, 4070409, Chile

An improved vaccine against tuberculosis (TB) is urgently needed to enhance the impact of TB immunisation offered by BCG, the only licensed TB vaccine, which is currently unable to substantially reduce the number of TB cases globally. Most new TB vaccine candidates use the parenteral and invasive route of immunisation without showing significant superiority to BCG. Wide-ranging vaccination strategies should be considered to improve the chances of finding an ideal TB vaccine. Here, we explore the potential of treating TB with a non-invasive immunisation route, specifically looking at the oral route of vaccination as a potential strategy for developing a new TB vaccine, which is arguably the most preferred route of vaccination due to its ease of administration at a lower cost compared to injectable vaccines. The downstream hostile gut environment poses a major challenge to oral vaccine development. Several strategies for overcoming this challenge have been studied, such as using live-attenuated vectors and nanoparticles. Our group is at an early stage of developing an oral TB vaccine candidate based on a chimeric secretory IgA-Ag85B subunit vaccine constructed to withstand the gut environment and reach the mucosal immune cells to initiate immune responses. We are currently evaluating the immunogenicity of the vaccine candidate as a booster to BCG in a mouse model to further assess its potential. BALB/c mice primed with BCG were given the vaccine candidate orally, with subsequent collection of samples from the euthanised mice 4 weeks post-booster to determine the T-cell responses in the spleen using flow cytometry and the anti-Ag85B IgG levels in serum and the anti-Ag85B IgA levels in bronchoalveolar lavage using ELISA. The findings from this study can offer new knowledge regarding oral immunisation using a recombinant secretory IgA construct that could potentially become a candidate vaccine for future TB vaccine development.

6.10. Flagellin-Displayed HBc Virus-like Particles for Hemagglutinin Stem-Based Universal Influenza Vaccine Development

Elise M VanLuinen ^1,2,3, Xinyuan Chen ¹

• Department of Pharmaceutical Sciences, University of Rhode Island, USA
• MARC U*STAR Program, University of Rhode Island, USA
• Department of Cell and Molecular Biology, University of Rhode Island, USA

Influenza vaccination faces challenges due to viral mutagenicity, necessitating a shift towards universal vaccine approaches. Many current vaccinations target the globular head region of the hemagglutinin (HA) surface protein of the Influenza virus. However, despite the widespread use of this technique, it does not offer broad protection against possible mutations or variations that naturally occur in the Influenza virus. Our study focuses on creating a broadly effective influenza vaccine by targeting the conserved hemagglutinin stem using virus-like particles (VLPs). Through innovative Spy Catcher/Spy Tag technology, we engineered VLPs presenting the HA stem on their surface adjuvanted with the VLP composition containing the Hepatitis B core protein and Flagellin, enhancing immunogenicity. The virus-like particle is made up of two components. The first component is the core of the particle, in which the HBc-flagellin particle assembles into a spherical particle, displaying the Spy Catcher protein on the surface of this particle. This is then combined in solution with a custom HA stem peptide, conjugated with Spy Tag to complete the VLP, with the HA stem displayed on the surface. Preliminary results demonstrating the successful assembly of VLPs into spherical particles visualized by transmission electron microscopyproved the remaining ability of Spy Tag binding to the virus core, and completed gene cloning for the HA stem protein. This project offers insights into universal vaccine design and holds promise for advancing influenza prevention strategies, as well as a theoretical platform for other virus-like particle vaccines.

6.11. Immunogenicity Study in Development of Mucosal Vaccine Against Tuberculosis Using Chimeric Secretory IgA: TB Multi-Epitopes Protein in Milk Samples

Min Xuan Keh ¹, Nur Ain Mohd Asri ¹, Mohd Nor Norazmi ^1,2, Rapeah Suppian ¹, Maryam Azlan ¹, Frank Camacho ^3,4

• School of Health Sciences, Universiti Sains Malaysia, Kubang Kerian, Kelantan, Malaysia
• Malaysia Genome and Vaccine Institute, National Institutes of Biotechnology Malaysia, Kajang, Selangor Darul Ehsan, Malaysia
• Recombinant Biopharmaceuticals Laboratory, Pharmacology Department, School of Biological Sciences, Universidad de Concepcion, Concepcion, Chile
• Center for Biotechnology and Biomedicine Spa, Concepcion, Chile

• Introduction

Tuberculosis (TB) remains one of the leading infectious diseases worldwide. The Bacillus Calmette-Guérin (BCG) vaccine, the only currently available TB vaccine, offers limited protection in adults. Therefore, it is critical to develop new effective vaccines. Considering Mycobacterium tuberculosis (Mtb) primarily infects the lungs, mucosal vaccines may be a promising strategy, as they can stimulate both systemic and mucosal immunity. This study explores the development and evaluation of a novel mucosal TB vaccine utilizing TB multi-epitopes by producing a recombinant chimeric protein in the mammary gland of goat, and in vivo mucosal immunization by utilizing the stable properties of the chimeric protein.

• Methods

An AAV vector carrying TB multi-epitopes and secretory IgA-J chain were co-transduced into the mammary gland of goat, and milk was collected daily. The chimeric protein containing the TB multi-epitopes antigen and secretory components in milk was detected by Western blot against anti-His and anti-Ag85b. The protein was then purified from the milk using the Akta Prime purification system. The mice were immunized using purified protein intranasally, and their immunogenicity responses were evaluated by flow cytometry.

• Results

In milk containing chimeric protein, bands corresponding to murine secretory component (75 kDa) and multi-epitopes Antigen Fc-alpha (75 kDa) could be detected against anti-His and anti-Ag85b, respectively. After the chimeric protein was purified, a purity of 95% of chimeric protein was obtained and detected at 75 kDa. Mice immunized with the vaccine candidate were shown to elicit immune response by producing a higher level of activated and memory T cells compared to the control group.

• Conclusions

The protein complex formed by TB multi-epitopes-Fc alpha and the murine secretory component can be obtained, purified and detected in milk samples, provided that the mammary gland acts as a potential bioreactor for the production of the recombinant vaccine candidate. The immune response was shown to be induced by the protein complex in mice by producing more activated and memory T cells.

6.12. Novel Tuberculosis (TB) Oral Vaccine Candidate: Enhancing Mucosal Immunity with Recombinant Secretory IgA (SIgA) in Goat Milk

Nur Ain Mohd Asri ¹, Keh Min Xuan ¹, Frank Camacho ^2,3, Maryam Azlan ¹, Mohd Nor Norazmi ^1,4, Rapeah Suppian ¹

• School of Health Sciences, Universiti Sains Malaysia, Health Campus, Kubang Kerian, Kelantan Darul Naim, Malaysia
• Recombinant Biopharmaceuticals Laboratory, Pharmacology Department, School of Biological Sciences, Universidad de Concepcion, Concepcion, Chile
• Center for Biotechnology and Biomedicine Spa, Concepcion, Chile
• Malaysia Genome and Vaccine Institute, National Institutes of Biotechnology Malaysia, Kajang, Selangor Darul Ehsan, Malaysia

The Bacillus Calmette–Guérin (BCG) vaccine, the only licensed tuberculosis (TB) vaccine, has limited effectiveness in preventing pulmonary TB in adults. Our study explores using the mammary gland of non-transgenic goats to produce an oral vaccine candidate, combining secretory IgA (SIgA) with epitopes from TB. This approach aims to enhance mucosal immunity and provide comprehensive protection across different stages of TB infection. The vaccine candidate was developed by engineering recombinant epitopes including Antigen 85b (Ag85b) for active TB, alpha-crystallin (Acr) for latent TB, and resuscitation-promoting factor E (RpfE) for reactivated TB combined with SIgA. We evaluated the immunological response by administering goat milk containing the recombinant protein directly as oral immunization. Five groups of Balb/C mice (n = 5) were categorized as follows: recombinant milk (RM), normal milk (NM), BCG prime with RM boost (BCG-RM), BCG prime with NM boost (BCG-NM), and BCG alone (BCG). The RM and NM groups received daily oral immunizations with RM or NM for two weeks. The BCG-primed groups received booster doses of RM or NM daily for two weeks, one month after the initial BCG vaccination. Two weeks after the final immunization, the mice were sacrificed, and IgA levels in the saliva and lung lavage were measured using enzyme-linked immunosorbent assay (ELISA). Mice immunized with recombinant vaccine-containing milk, especially those primed with BCG, showed a significant increase in IgA levels in the saliva and lung lavage compared to the normal milk and BCG-only groups. These results indicate that the recombinant vaccine-containing milk can effectively induce a strong mucosal immune response against TB. The significant increase in IgA levels in mice, particularly in BCG-primed groups, highlights the potential of this vaccine as a booster candidate with BCG priming.

6.13. Peptides from PfEMP1 Interacting with Cytoadherence Receptor gC1qR May Provide Broader Protection Against Severe Malaria

Abdul Hafiz

Department of Microbiology and Parasitology, Faculty of Medicine, Umm Al-Qura University, Makkah, Saudi Arabia

Malaria is a major public health problem. Estimates suggestthat there were over 249 million cases of malaria in the year 2022. Most of the severe malaria cases and almost all the malaria-related deaths are caused by malaria parasite Plasmodium falciparum. The malaria parasite P. falciparum has unique cytoadherence properties through which it sequesters in the host’s microvascular endothelial cells. The P. falciparum-infected erythrocytes can bind to the host’s microvascular endothelial cells, platelets, uninfected erythrocytes and other immune cells, such as dendritic cells, and sequester in the host’s blood vasculature. The cytoadherence of P. falciparum-infected erythrocytes in the brain and placenta has been associated with severe malaria disease. Cytoadherence to microvascular endothelial cells causes obstruction in blood flow, endothelial cell activation, and the release of proinflammatory cytokines. Studies have also shown that the gC1qR-mediated cytoadherence of P. falciparum-infected erythrocytes to dendritic cells can lead to the inhibition of the dendritic cells and therefore may contribute to the immune suppression of the innate immune system of the host. Cytoadherence is mediated by specific receptor–ligand interactions. Earlier, we identified a novel receptor gC1qR for cytoadherence to brain microvascular endothelial cells and platelets. The P. falciparum-infected erythrocytes can bind to dendritic cells, platelets and brain microvascular endothelial cells via gC1qR as a receptor. Cytoadherence to gC1qR has been implicated in the pathogenesis of severe malaria by several studies. We have also mapped the interacting domain of PfEMP1 interacting with gC1qR. Since gC1qR has an important role in severe malaria pathogenesis and the inhibition of dendritic cells have a role in innate and adaptive immunity, a vaccine targeting gC1qR and its PfEMP1 ligand interaction will likely have a broader protection, eliciting a longer-lasting immunity against P. falciparum infections.

6.14. The Dynamics of the Incidence of Vaccine-Controlled Infections in the Southern Federal District of the Russian Federation from 2010 to 2023

Dudnikova Ekaterina Nikolaevna ¹, Sergeev Andrey Alexeyevich ², Krisyak Olesya Igorevna ³, Redko Elizaveta Igorevna ⁴

• Faculty of Medicine, Kuban State Medical University, Krasnodar, 350063, Russia
• Faculty of History, Sociology and International Relations, Kuban State University, Krasnodar, 350000, Russia
• Faculty of Pediatrics, Kuban State Medical University, Krasnodar, 350063, Russia
• Fomin Clinic, Krasnodar, 350049, Russia

• Introduction

An uncontrolled flow of migration and powerful anti-vaccination propaganda have led to an outbreak of vaccine-controlled infections among the Russian population in recent years.

The purpose of this study is to assess the dynamics of the incidence of whooping cough, measles, and rubella among the population in the Southern Federal District of the Russian Federation in the period of 2010 to 2023.

• Methods

Thi study is based on data from the federal statistical observation form “Information on the number of diseases registered in patients living in the service area of a medical organization” for the period of 2015 to 2023.

• Results

Between 2010 and 2023, the number of whooping cough cases amounted to 9199. The lowest number of whooping cough cases in the Southern Federal District was registered in 2021 and amounted to 15 (0.16%). The largest number of whooping cough cases was registered in 2023 and amounted to 4511 (49.04% of all detected cases since 2010). Krasnodar had the highest number of cases (2027—24.7%), followed by Rostov in second place (635 cases—6.9%) and Volgograd in third place (473 cases—5.14%).

The number of cases of rubella in the period from 2010 to 2023 in the Southern Federal District amounted to 108. The smallest number of cases was 0, and this was registered in the period from 2017 to 2023. The largest number was 30 cases, and thiswas registered in 2013 (27.78% of all detected cases since 2010). In first place for the number of cases of rubella was Krasnodar (23 cases—21.3%) in 2013, in second place was Volgograd (13 cases—12.04%) in 2010, and in third place was Astrakhan (12 cases—11.11%) in 2014.

• Conclusions

During the studied period, the largest number of cases of whooping cough and rubella was registered in the Krasnodar region. The lowest number of cases of all nosologies was registered in 2020—2021, which was probably due to social isolation during the COVID-19 pandemic.

6.15. Therapeutic Effects of Neutralizing Antibodies to Protect Chickens from Fowl Adenovirus Serotype 4 (FAdV-4) Infection

Huimin Ma, Shipeng Wang, Jixiang Gu, Chunhui Li, Xiangyu Xie, Wenxiao Sun, Xinyue Chang, Lisha Zha

College of Animal Science and Technology, Anhui Agricultural University, Hefei 230036, China

Fowl adenovirus serotype 4 (FAdV-4), leading to Hepatitis-hydropericardium syndrome (HHS) in chickens, has caused huge economic losses to the poultry industry in China since 2015. Therefore, effective therapeutic approaches to prevent FAdV-4 is critical for HHS control. In this study, we identified two monoclonal antibodies, 27A-5 and 42A-10, to specifically bind to and neutralize FAdV-4 viruses in vitro. Pre-incubation of both antibodies with FAdV-4 hindered the viruses from infecting LMH cells, with the complete blocking concentrations being 33.3 μg/mL for 27A-5 and 16.6 μg/mL for 42A-10. In addition, whether these antibodies pose viral neutralization abilities in vivo was determined, as was whether they could be used as therapeutic antibodies in the future. In chickens, the survival rates were 100% after administration with both antibodies (10 mg/kg), while the fatality rates of untreated chickens were 100%. In addition, a low dose (5 mg/kg) of the 27A-5 antibody could save all animals. Moreover, pathologic changes such as pericardial sac liquid and liver damages in survivors were remarkably reduced. Further analysis demonstrated that inflammation caused by FAdV-4 infection was decreased in antibody treated animals. More importantly, the viral loads in treated chickens were almost cleared, indicating that the antibodies were effectively neutralizing the FAdV-4 viruses in vivo. In conclusion, the two antibodies could neutralize FAdV-4 in vitro and in vivo, which means that they have the potential to be therapeutic antibodies for HHS treatment. This study lays a foundation for the development of safe and effective therapeutic methods against FAdV-4.

7. Session 6: Novel Assays for Evaluating Responses to Vaccination

7.1. Post-Vaccination COVID-19 Spike-Specific IgA Antibody Levels in Vaccinee Nasopharyngeal Samples

Mohamed Ibrahim Saeed ¹, Mohammed Ibrahim Mohammed Salih ², Salma mohamed garham Omer ², Montaser Ibrahim Abdalgader Ibrahim ², Esameldeen Ahmed Adam Abdoelkarim ², Mayada Osman Ali Mohammed ², Omnia Mustafa mohamed Salih ², Sakina Abdelmouneim hassan Elfadil ²

• Microbiology, Medical Laboratory science Department, Gulf Medical University, Jurf1, Ajman, United Arab Emirates
• Faculty of Medical Laboratory science, National Ribat University, Burri, Khartoum, Sudan

Increased COVID-19-specific secretary IgA antibody levels in the respiratory tract are required for inhibiting early COVID-19 virion particle attachment to ACE-2 receptors and primary virus replication. Because all COVID-19 vaccines are administered parenterally, it has been thought that the vaccine might not elicit sufficient mucosal immunity (1). The purpose of this study was to determine the level of IgA antibodies in respiratory samples from vaccinees. Twenty-ninenasopharyngeal swabs were collected from healthy participants who had received at least two doses of a different COVID-19 vaccination. Rt-PCR confirmed that all samples were negative for COVID-19. A quantitative ELISA kit with defined calibrators (0–25) ng/mL coated with recombinant 2019-nCoV Spike protein (antigen) was used to measure IgA antibody concentrations per sample. The results revealed that COVID-19 spike IgA was present at a lower level in the majority of the samples (86.2%), with a mean IgA level of 0.01 ng/mL. Only four samples had higher IgA levels, which accounted for 13.8%. Three subjects had elevated IgA levels, ranging from 0.5 to 1.5 ng/m. One individual had a boosted IgA level of 3.4 ng/mL, which retested negative in COVID-19 Rt-PCR and appeared to be a recently recovered asymptomatic COVID-19case. The result explains why COVID-19 vaccines failed to prevent virus transmission and infection, because the vaccines failed to elicit protective mucosal immunity in the form of highly protective secretary IgA antibodies in vaccinees. This is because the current COVID-19 vaccines are administered parentally rather than through the mucosal portal via oral immunization or nasal spray delivery. Thus, there is a need for second or third mucosal (nasal/oral) COVID-19 vaccine doses which might imitate natural infection by boosting mucosal IgA levels. This would help in reducing the number of healthy carriers and, in the long run, in eradicating the existing circulating virus.

7.2. Th1-Dominant Immune Response Induced by Foot-and-Mouth Disease Vaccine Confers Protection in Cattle

Suresh H Basagoudanavar, Uzma Jabeen, Kailash Singh Bisht, D C Nidhi, B P Sreenivasa, Madhusudan Hosamani, H J Dechamma, Pallab Chaudhuri

ICAR-Indian Veterinary Research Institute, Hebbal, Bengaluru 560 024, India

• Introduction

Foot-and-mouth disease (FMD) is a highly contagious viral infection affecting cattle, pigs, and other cloven-hoofed animals. The disease, caused by FMD virus (FMDV), poses a severe threat to the livestock industry due to its ability to spread rapidly and cause high productivity losses. In India, to prevent outbreaks and safeguard animal health and productivity, a trivalent vaccine containing the inactivated virus antigens of three serotypes (O, A, and Asia-1) is employed. While humoral immunity, characterized by antibody production, is essential for defending against FMDV, a comprehensive understanding of protection also requires an investigation of cell-mediated immune (CMI) responses.

• Methods

Indian cattle aged 6 to 9 months were immunized with a trivalent FMD vaccine in a water-in-oil-in-water (W/O/W) formulation. We evaluated the virus neutralizing antibody and CMI responses following vaccination. The cattle were challenged with homologous FMDV serotype O at six months post vaccination.

• Results

The vaccine elicited potent humoral and cellular immune responses. The vaccine-induced virus-neutralizing antibody response peaked around two to four weeks post-vaccination and was maintained for up to six months. Elevated IFN-γ and reduced IL-4 cytokine levels by 14 days post-vaccination (dpv) and the dominance of the IgG2 isotype antibody at 30 dpv suggested a predominantly Th1-type cellular immune response. Interestingly, IFN-γ and IL-4 expression exhibited inverse patterns of regulation, highlighting the precise regulation of Th1 and Th2 responses. The challenging of vaccinated cattle with the homologous FMDV serotype O at six months post-vaccination showed 100% protective efficacy.

• Conclusions

The study findings demonstrated that humoral, as well as CMI, responses with a predominant Th1 immune response contributed to the vaccine’s efficacy against the FMDV challenge in cattle.