Systemic Antibody Responses Research Articles

Robust efficacy and long-lasting humoral immunity induced by a respiratory syncytial virus prefusion F-based nanoparticle vaccine in genetically diverse animal models

Abstract Respiratory syncytial virus (RSV) is the leading cause of lower respiratory tract infections in children, accounting for 7% of deaths in those less than one year of age. Despite multiple exposures to RSV throughout life, natural infection affords only partial protection and there is currently no licensed vaccine against RSV. We developed a vaccine candidate, RSVNanoVax, composed of polyanhydride nanoparticles encapsulating the RSV prefusion F protein and a CpG1668 adjuvant. To assess the efficacy of RSVNanoVax we utilized two model systems with increased genetic variability, Swiss Webster mice and the cotton rat. Following an intranasal prime-boost vaccination with RSVNanoVax, Swiss Webster mice exhibited robust titers of RSV F-directed IgG antibodies in both the serum and lung tissue that were sustained out to at least 1-year post-vaccination. RSV F-directed IgA was also induced within the lung tissue and nasal passages, suggesting that RSVNanoVax stimulates long-lasting systemic and mucosal antibody responses in outbred mice. Serum antibodies maintained robust neutralizing activity against both RSV A and B virus strains. Following RSV challenge, vaccinated mice exhibited complete viral clearance in the lungs as early as day 2 post-infection. Further studies performed in cotton rats demonstrated that RSVNanoVax conferred protection from both viral replication in the lungs as well as RSV-induced pulmonary immunopathology following viral challenge. Vaccinated cotton rats also exhibited robust titers of RSV F-directed serum antibodies with neutralizing capacity. Overall, RSVNanoVax represents a promising RSV vaccine candidate capable of providing long-term protection and immunity in genetically diverse populations. Supported by grants from NIH (R01 AI124093, T32 CA078586, T32 AI007485)

Intranasal administration of a virus like particles-based vaccine induces neutralizing antibodies against SARS-CoV-2 and variants of concern.

BackgroundThe highly contagious SARS‐CoV‐2 is mainly transmitted by respiratory droplets and aerosols. Consequently, people are required to wear masks and maintain a social distance to avoid spreading of the virus. Despite the success of the commercially available vaccines, the virus is still uncontained globally. Given the tropism of SARS‐CoV‐2, a mucosal immune reaction would help to reduce viral shedding and transmission locally. Only seven out of hundreds of ongoing clinical trials are testing the intranasal delivery of a vaccine against COVID‐19.MethodsIn the current study, we evaluated the immunogenicity of a traditional vaccine platform based on virus‐like particles (VLPs) displaying RBD of SARS‐CoV‐2 for intranasal administration in a murine model. The candidate vaccine platform, CuMVTT‐RBD, has been optimized to incorporate a universal T helper cell epitope derived from tetanus‐toxin and is self‐adjuvanted with TLR7/8 ligands.ResultsCuMVTT‐RBD vaccine elicited a strong systemic RBD‐ and spike‐IgG and IgA antibodies of high avidity. Local immune response was assessed, and our results demonstrate a strong mucosal antibody and plasma cell production in lung tissue. Furthermore, the induced systemic antibodies could efficiently recognize and neutralize different variants of concern (VOCs).ConclusionOur data demonstrate that intranasal administration of CuMVTT‐RBD induces a protective systemic and local specific antibody response against SARS‐CoV‐2 and its VOCs.

Longitudinal Systemic and Mucosal Immune Responses to SARS-CoV-2 Infection.

BackgroundA longitudinal study was performed to determine the breadth, kinetics, and correlations of systemic and mucosal antibody responses to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection.MethodsTwenty-six unvaccinated adults with confirmed coronavirus disease 2019 (COVID-19) were followed for 6 months with 3 collections of blood, nasal secretions, and stool. Control samples were obtained from 16 unvaccinated uninfected individuals. SARS-CoV-2 neutralizing and binding antibody responses were respectively evaluated by pseudovirus assays and multiplex bead arrays.ResultsNeutralizing antibody responses to SARS-CoV-2 were detected in serum and respiratory samples for 96% (25/26) and 54% (14/26), respectively, of infected participants. Robust binding antibody responses against SARS-CoV-2 spike protein and S1, S2, and receptor binding (RBD) domains occurred in serum and respiratory nasal secretions, but not in stool samples. Serum neutralization correlated with RBD-specific immunoglobulin (Ig)G, IgM, and IgA in serum (Spearman ρ = 0.74, 0.66, and 0.57, respectively), RBD-specific IgG in respiratory secretions (ρ = 0.52), disease severity (ρ = 0.59), and age (ρ = 0.40). Respiratory mucosal neutralization correlated with RBD-specific IgM (ρ = 0.42) and IgA (ρ = 0.63).ConclusionsSustained antibody responses occurred after SARS-CoV-2 infection. Notably, there was independent induction of IgM and IgA binding antibody and neutralizing responses in systemic and respiratory compartments. These observations have implications for current vaccine strategies and understanding SARS-CoV-2 reinfection and transmission.

Respiratory mucosal delivery of next-generation COVID-19 vaccine provides robust protection against both ancestral and variant strains of SARS-CoV-2

The emerging SARS-CoV-2 variants of concern (VOCs) threaten the effectiveness of current COVID-19 vaccines administered intramuscularly and designed to only target the spike protein. There is a pressing need to develop next-generation vaccine strategies for broader and long-lasting protection. Using adenoviral vectors (Ad) of human and chimpanzee origin, we evaluated Ad-vectored trivalent COVID-19 vaccines expressing spike-1, nucleocapsid, and RdRp antigens in murine models. We show that single-dose intranasal immunization, particularly with chimpanzee Ad-vectored vaccine, is superior to intramuscular immunization in induction of the tripartite protective immunity consisting of local and systemic antibody responses, mucosal tissue-resident memory T cells and mucosal trained innate immunity. We further show that intranasal immunization provides protection against both the ancestral SARS-CoV-2 and two VOC, B.1.1.7 and B.1.351. Our findings indicate that respiratory mucosal delivery of Ad-vectored multivalent vaccine represents an effective next-generation COVID-19 vaccine strategy to induce all-around mucosal immunity against current and future VOC.

Compensatory intestinal antibody response against pro-inflammatory microbiota after bariatric surgery

ABSTRACT Obesity and type 2 diabetes (T2D) are growing burdens for individuals and the health-care system. Bariatric surgery is an efficient, but drastic treatment to reduce body weight, normalize glucose values, and reduce low-grade inflammation. The gut microbiome, which is in part controlled by intestinal antibodies, such as IgA, is involved in the development of both conditions. Knowledge of the effect of bariatric surgery on systemic and intestinal antibody response is limited. Here, we determined the fecal antibody and gut microbiome response in 40 T2D and non-diabetic (ND) obese individuals that underwent bariatric surgery (N = 40). Body weight, fasting glucose concentrations and inflammatory parameters decreased after bariatric surgery, whereas pro-inflammatory bacterial species such as lipopolysaccharide (LPS), and flagellin increased in the feces. Simultaneously, concentrations of LPS- and flagellin-specific intestinal IgA levels increased with the majority of pro-inflammatory bacteria coated with IgA after surgery. Finally, serum antibodies decreased in both groups, along with a lower inflammatory tone. We conclude that intestinal rearrangement by bariatric surgery leads to expansion of typical pro-inflammatory bacteria, which may be compensated by an improved antibody response. Although further evidence and mechanistic insights are needed, we postulate that this apparent compensatory antibody response might help to reduce systemic inflammation by neutralizing intestinal immunogenic components and thereby enhance intestinal barrier function after bariatric surgery.

Immunogenicity and Protective Capacity of a Virus-like Particle Vaccine against Chlamydia trachomatis Type 3 Secretion System Tip Protein, CT584.

An effective vaccine against Chlamydia trachomatis is urgently needed as infection rates continue to rise and C. trachomatis causes reproductive morbidity. An obligate intracellular pathogen, C. trachomatis employs a type 3 secretion system (T3SS) for host cell entry. The tip of the injectosome is composed of the protein CT584, which represents a potential target for neutralization with vaccine-induced antibody. Here, we investigate the immunogenicity and efficacy of a vaccine made of CT584 epitopes coupled to a bacteriophage virus-like particle (VLP), a novel platform for Chlamydia vaccines modeled on the success of HPV vaccines. Female mice were immunized intramuscularly, challenged transcervically with C. trachomatis, and assessed for systemic and local antibody responses and bacterial burden in the upper genital tract. Immunization resulted in a 3-log increase in epitope-specific IgG in serum and uterine homogenates and in the detection of epitope-specific IgG in uterine lavage at low levels. By contrast, sera from women infected with C. trachomatis and virgin controls had similarly low titers to CT584 epitopes, suggesting these epitopes are not systemically immunogenic during natural infection but can be rendered immunogenic by the VLP platform. C. trachomatis burden in the upper genital tract of mice varied after active immunization, yet passive protection was achieved when immune sera were pre-incubated with C. trachomatis prior to inoculation into the genital tract. These data demonstrate the potential for antibody against the T3SS to contribute to protection against C. trachomatis and the value of VLPs as a novel platform for C. trachomatis vaccines.

Intranasal Delivery of Thermostable Subunit Vaccine for Cross-Reactive Mucosal and Systemic Antibody Responses Against SARS-CoV-2

Intranasal Delivery of Thermostable Subunit Vaccine for Cross-Reactive Mucosal and Systemic Antibody Responses Against SARS-CoV-2

Immunogenicity and Protective Potential of Mucosal Vaccine Formulations Based on Conserved Epitopes of Influenza A Viruses Fused to an Innovative Ring Nanoplatform in Mice and Chickens.

Current inactivated vaccines against influenza A viruses (IAV) mainly induce immune responses against highly variable epitopes across strains and are mostly delivered parenterally, limiting the development of an effective mucosal immunity. In this study, we evaluated the potential of intranasal formulations incorporating conserved IAV epitopes, namely the long alpha helix (LAH) of the stalk domain of hemagglutinin and three tandem repeats of the ectodomain of the matrix protein 2 (3M2e), as universal mucosal anti-IAV vaccines in mice and chickens. The IAV epitopes were grafted to nanorings, a novel platform technology for mucosal vaccination formed by the nucleoprotein (N) of the respiratory syncytial virus, in fusion or not with the C-terminal end of the P97 protein (P97c), a recently identified Toll-like receptor 5 agonist. Fusion of LAH to nanorings boosted the generation of LAH-specific systemic and local antibody responses as well as cellular immunity in mice, whereas the carrier effect of nanorings was less pronounced towards 3M2e. Mice vaccinated with chimeric nanorings bearing IAV epitopes in fusion with P97c presented modest LAH- or M2e-specific IgG titers in serum and were unable to generate a mucosal humoral response. In contrast, N-3M2e or N-LAH nanorings admixed with Montanide™ gel (MG) triggered strong specific humoral responses, composed of serum type 1/type 2 IgG and mucosal IgG and IgA, as well as cellular responses dominated by type 1/type 17 cytokine profiles. All mice vaccinated with the [N-3M2e + N-LAH + MG] formulation survived an H1N1 challenge and the combination of both N-3M2e and N-LAH nanorings with MG enhanced the clinical and/or virological protective potential of the preparation in comparison to individual nanorings. Chickens vaccinated parenterally or mucosally with N-LAH and N-3M2e nanorings admixed with Montanide™ adjuvants developed a specific systemic humoral response, which nonetheless failed to confer protection against heterosubtypic challenge with a highly pathogenic H5N8 strain. Thus, while the combination of N-LAH and N-3M2e nanorings with Montanide™ adjuvants shows promise as a universal mucosal anti-IAV vaccine in the mouse model, further experiments have to be conducted to extend its efficacy to poultry.

Peritoneal Administration of a Subunit Vaccine Encapsulated in a Nanodelivery System Not Only Augments Systemic Responses against SARS-CoV-2 but Also Stimulates Responses in the Respiratory Tract.

The COVID-19 pandemic has currently created an unprecedented threat to human society and global health. A rapid mass vaccination to create herd immunity against SARS-CoV-2 is a crucial measure to ease the spread of this disease. Here, we investigated the immunogenicity of a SARS-CoV-2 subunit vaccine candidate, a SARS-CoV-2 spike glycoprotein encapsulated in N,N,N-trimethyl chitosan particles or S-TMC NPs. Upon intraperitoneal immunization, S-TMC NP-immunized mice elicited a stronger systemic antibody response, with neutralizing capacity against SARS-CoV-2, than mice receiving the soluble form of S-glycoprotein. S-TMC NPs were able to stimulate the circulating IgG and IgA as found in SARS-CoV-2-infected patients. In addition, spike-specific T cell responses were drastically activated in S-TMC NP-immunized mice. Surprisingly, administration of S-TMC NPs via the intraperitoneal route also stimulated SARS-CoV-2-specific immune responses in the respiratory tract, which were demonstrated by the presence of high levels of SARS-CoV-2-specific IgG and IgA in the lung homogenates and bronchoalveolar lavages of the immunized mice. We found that peritoneal immunization with spike nanospheres stimulates both systemic and respiratory mucosal immunity.

IL-21 enhances influenza vaccine responses in aged macaques with suppressed SIV infection.

Natural aging and HIV infection are associated with chronic low-grade systemic inflammation, immune senescence, and impaired antibody responses to vaccines such as the influenza (flu) vaccine. We investigated the role of IL-21, a CD4+ T follicular helper cell (Tfh) regulator, on flu vaccine antibody response in nonhuman primates (NHPs) in the context of age and controlled SIV mac239 infection. Three doses of the flu vaccine with or without IL-21–IgFc were administered at 3-month intervals in aged SIV+ NHPs following virus suppression with antiretroviral therapy. IL-21–treated animals demonstrated higher day 14–postboost antibody responses, which associated with expanded CD4+ T central memory cells and peripheral Tfh–expressing (pTfh–expressing) T cell immunoreceptor with Ig and ITIM domains (TIGIT), expanded activated memory B cells, and contracted CD11b+ monocytes. Draining lymph node (LN) tissue from IL-21–treated animals revealed direct association between LN follicle Tfh density and frequency of circulating TIGIT+ pTfh cells. We conclude that IL-21 enhances flu vaccine–induced antibody responses in SIV+ aged rhesus macaques (RMs), acting as an adjuvant modulating LN germinal center activity. A strategy to supplement IL-21 in aging could be a valuable addition in the toolbox for improving vaccine responses in an aging HIV+ population.

Pathology and Immunity After SARS-CoV-2 Infection in Male Ferrets Is Affected by Age and Inoculation Route.

Improving COVID-19 intervention strategies partly relies on animal models to study SARS-CoV-2 disease and immunity. In our pursuit to establish a model for severe COVID-19, we inoculated young and adult male ferrets intranasally or intratracheally with SARS-CoV-2. Intranasal inoculation established an infection in all ferrets, with viral dissemination into the brain and gut. Upon intratracheal inoculation only adult ferrets became infected. However, neither inoculation route induced observable COVID-19 symptoms. Despite this, a persistent inflammation in the nasal turbinates was prominent in especially young ferrets and follicular hyperplasia in the bronchi developed 21 days post infection. These effects -if sustained- might resemble long-COVID. Respiratory and systemic cellular responses and antibody responses were induced only in animals with an established infection. We conclude that intranasally-infected ferrets resemble asymptomatic COVID-19 and possibly aspects of long-COVID. Combined with the increasing portfolio to measure adaptive immunity, ferrets are a relevant model for SARS-CoV-2 vaccine research.

Nasopharyngeal and serological anti SARS-CoV-2 IgG/IgA responses in COVID-19 patients

BackgroundThe systemic antibody responses to SARS-CoV-2 in COVID-19 patients has been extensively studied. However, less is known about the mucosal responses in the upper airways, the site of initial SARS-CoV-2 replication. MethodsThe IgG and IgA antibody responses were analysed in plasma and nasopharyngeal swabs from the first four confirmed COVID-19 patients in France. Two were pauci-symptomatic while two developed severe disease. We characterized their antibody profiles by using an in-house ELISA to detect antibodies directed against SARS-CoV-2 Nucleoprotein and Spike. ResultsAnti-N IgG and IgA antibodies were detected in the NPS of severe patients only. The levels of antibodies in the plasma markedly differed amongst the patients. The most distinctive features are a strong anti-N IgG response in the severe patient who recovered, and a high anti-N IgA response specifically detected in the fatal case of COVID-19. ConclusionsAnti-N IgG and IgA antibodies are detected in NPS only for severe patients, with levels related to serological antibodies. The severe patients showed different antibody profiles in the plasma, notably regarding the IgA and IgG response to the N antigen, that may reflect different disease outcome. By contrast, pauci-symptomatic patients did not exhibit any mucosal antibodies in NSP, which is associated with a low or absent serological response against both N and S.

Variants of SARS Coronavirus-2 and Their Potential Impact on the Future of the COVID-19 Pandemic

The emergence of SARS-CoV-2 variants of concern (VOCs), especially the sweeping spread of the delta variant, and differing public health management strategies, have rendered global eradication of SARS-CoV-2 unlikely. The currently available COVID-19 vaccines, including the inactivated whole virus vaccines, mRNA vaccines, and adenovirus-vectored vaccines, are effective in protecting people from severe disease and death from COVID-19, but they may not confer good mucosal immunity to prevent the establishment of infection and subsequent viral shedding and transmission. Mucosal vaccines delivered via intranasal route may provide a promising direction, which, if given as a third dose after a two-dose series of intramuscular vaccination, likely promotes mucosal immunity in addition to boosting the systemic cell-mediated immunity and antibody response. However, immunity induced by vaccination, and natural infection as well, is likely to wane followed by re-infection as in the case of human coronaviruses OC43, 229E, NL63, and HKU1. It is a challenge to prevent and control COVID-19 worldwide with the increasing number of VOCs associated with increased transmissibility and changing antigenicity. Nevertheless, we may seek to end the current pandemic situation through mass vaccination and gradual relaxation of non-pharmaceutical measures, which would limit the incidence of severe COVID-19. Repeated doses of booster vaccine will likely be required, similar to influenza virus, especially for the elderly and the immunocompromised patients who are most vulnerable to infection.

Predictors of Nonseroconversion after SARS-CoV-2 Infection.

Not all persons recovering from severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection develop SARS-CoV-2–specific antibodies. We show that nonseroconversion is associated with younger age and higher reverse transcription PCR cycle threshold values and identify SARS-CoV-2 viral loads in the nasopharynx as a major correlate of the systemic antibody response.

Protection against Mycoplasma bovis infection in calves following intranasal vaccination with modified-live Mannheimia haemolytica expressing Mycoplasma antigens

Novel live vaccine strains of Mannheimia haemolytica serotypes (St)1 and St6, expressing and secreting inactive yet immunogenic leukotoxin (leukotoxoid) fused to antigenic domains of Mycoplasma bovis Elongation Factor Tu (EFTu) and Heat shock protein (Hsp) 70 were constructed and tested for efficacy in cattle. Control calves were administered an intranasal mixture of M. haemolytica St1 and St6 mutants (ΔlktCAV4) expressing and secreting leukotoxoid while vaccinated calves were administered an intranasal mixture of like M. haemolytica St1 and St6 leukotoxoid mutants coupled to M. bovis antigens (EFTu-Hsp70-ΔlktCAV4). Both M. haemolytica strains were recovered from palatine tonsils up to 34 days post intranasal exposure. On day 35 all calves were exposed to bovine herpes virus-1, four days later lung challenged with virulent M. bovis, then euthanized up to 20 days post-challenge. Results showed all cattle produced systemic antibody responses against M. haemolytica. The vaccinates also produced systemic antibody responses to M. bovis antigen, and concurrent reductions in temperatures, middle ear infections, joint infection and lung lesions versus the control group. Notably, dramatically decreased lung loads of M. bovis were detected in the vaccinated cattle. These observations indicate that the attenuated M. haemolytica vaccine strains expressing Mycoplasma antigens can control M. bovis infection and disease symptoms in a controlled setting.

Use of blood matrices and alternative biological fluids for antibody detection in animal tuberculosis

Bovine tuberculosis (bTB) control programs can be improved by implementation of advanced ante-mortem testing algorithms. Serodiagnostic methods using traditional blood or blood-derived specimens may benefit from the use of less invasive alternative biological fluids, provided those mirror systemic antibody responses. In the present study, we used Dual Path Platform (DPP) and Multiantigen Print Immunoassay (MAPIA) to compare antibody levels in ten sample types including whole blood (fresh and hemolyzed), plasma (fresh and leftover from Bovigam testing), serum, saliva, broncho-alveolar lavage, urine, diaphragm extract, and bile collected from cattle aerosol-infected with Mycobacterium bovis. High correlation (r = 0.97−0.99) in measurements of IgG antibodies to MPB70/MPB83 fusion antigen by DPP assay was found between all blood-derived specimens, supporting matrix equivalency. Broncho-alveolar lavage and diaphragm extract yielded positive results in all the infected animals tested, showing high correlation with matching serum data (r = 0.94 and r = 0.95, respectively) and suggesting their potential use in antibody assays. Characterized by MAPIA, the antigen reactivity patterns obtained with paired sera and alternative specimens were nearly identical, with slight differences in intensity. Antibodies were also found by DPP assay in saliva, urine, and bile from some of the infected animals, but the titers were relatively low, thus reducing the diagnostic value of such specimens. The proposed approach was evaluated in a pilot field study on warthogs diagnosed with M. bovis infection. Relative levels of antibody in tissue fluid obtained from lymph nodes or lungs were consistent with those detected in sera and detectable in all infected warthogs. The findings support the diagnostic utility of non-traditional biological fluids and tissue samples when used as alternative test specimens in serologic assays for bTB.

Population-wide diversity and stability of serum antibody epitope repertoires against human microbiota.

Serum antibodies can recognize both pathogens and commensal gut microbiota. However, our current understanding of antibody repertoires is largely based on DNA sequencing of the corresponding B-cell receptor genes, and actual bacterial antigen targets remain incompletely characterized. Here we have profiled the serum antibody responses of 997 healthy individuals against 244,000 rationally selected peptide antigens derived from gut microbiota and pathogenic and probiotic bacteria. Leveraging phage immunoprecipitation sequencing (PhIP-Seq) based on phage-displayed synthetic oligo libraries, we detect a wide breadth of individual-specific as well as shared antibody responses against microbiota that associate with age and gender. We also demonstrate that these antibody epitope repertoires are more longitudinally stable than gut microbiome species abundances. Serum samples of more than 200 individuals collected five years apart could be accurately matched and could serve as an immunologic fingerprint. Overall, our results suggest that systemic antibody responses provide a non-redundant layer of information about microbiota beyond gut microbial species composition.

Antibodies induced by oral immunization of mice with a recombinant protein produced in tobacco plants harboring Bordetella pertussis epitopes.

Bordetella pertusis causes whooping cough or pertussis, disease that has not been eradicated and is reemerging despite the availability and massive application for decades of vaccines, such as Boostrix® which is an acellular vaccine harboring two regions of S1 subunit of the pertussis toxin, one region of filamentous hemagglutinin and one region of pertactin. In 2008, the World Health Organization estimated 16 million new cases and 95% occurred in developing countries with 195,000 children’s deaths. We attempt to improve the vaccine against whooping cough and reduce its production costs by obtaining plants and bacteria expressing a heterologous protein harboring pertactin, pertussis toxin, and filamentous hemagglutinin epitopes from B. pertussis and assessing its immunogenicity after oral administration to mice. First, we designed a synthetic gene that encodes a multiepitope, then it was cloned into a vector for transient transformation by infiltration of tobacco plants with low amounts of nicotine; the codon bias-optimized construct was also cloned into an Escherichia coli expression vector. Recombinant proteins from E. coli cells (PTF) and tobacco leaves (PTF-M3ʹ) were purified by nickel affinity with a yield of 0.740 mg of recombinant protein per g dry weight. Purified recombinant proteins were administered orally to groups of Balb/c mice using the Boostrix® vaccine and vehicle (PBS) as positive and negative controls, respectively. A higher mucosal and systemic antibody responses were obtained in mice receiving the PTF and PTF-M3ʹ proteins than Boostrix® or PBS. These findings prove the concept that oral administration of multiepitope recombinant proteins expressed in plants may be a potential edible vaccine.Supplementary InformationThe online version contains supplementary material available at 10.1007/s11240-021-02107-1.

Intranasal Administration of RBD Nanoparticles Confers Induction of Mucosal and Systemic Immunity against SARS-CoV-2.

Mucosal immunity plays a significant role in host defense against viruses in the respiratory tract. Because the upper respiratory airway is a primary site of SARS-CoV-2 entry, immunization at the mucosa via the intranasal route could potentially lead to induction of local sterilizing immunity that protects against SARS-CoV-2 infection. In this study, we evaluated the immunogenicity of a receptor-binding domain (RBD) of SARS-CoV-2 spike glycoprotein loaded into N,N,N-trimethyl chitosan nanoparticles (RBD-TMC NPs). We showed that intranasal delivery of RBD-TMC NPs into mice induced robust local mucosal immunity, as evidenced by the presence of IgG and IgA responses in BALs and the lungs of immunized mice. Furthermore, mice intranasally administered with this platform of immunogens developed robust systemic antibody responses including serum IgG, IgG1, IgG2a, IgA and neutralizing antibodies. In addition, these immunized mice had significantly higher levels of activated splenic CD4+ and CD8+ cells compared with those that were administered with soluble RBD immunogen. Collectively, these findings shed light on an alternative route of vaccination that mimics the natural route of SARS-CoV-2 infection. This route of administration stimulated not only local mucosal responses but also the systemic compartment of the immune system.

Association of systemic antibody response against polyethylene terephthalate with inflammatory serum cytokine profile following implantation of differently coated vascular prostheses in a rat animal model.

Experimental studies demonstrated antibodies against matrix and coating of polyester-based vascular prostheses. Thus, this study examined associations of these antibodies with serum cytokines (IL-2, IL-4, and IL-10) and local inflammatory reactions. Rats (n=8/group) intramuscularly received prosthesis segments [PET-C, PET-G, and PET-A groups: polyethylene terephthalate (PET)-based prostheses coated with bovine collagen and gelatin or human serum albumin, respectively; uncoated polytetrafluoroethylene-based (PTFE) prosthesis], with sham-operated controls. Blood was drawn pre-operatively and weekly until day 22. Polymer-specific or coating-specific antibodies and cytokines were detected by enzyme immunoassays, inflammatory reactions were immunohistochemically evaluated on day 23. Polymer-specific antibodies were detected in all PET-groups using uncoated PET as antigenic target, but not for PTFE or controls, coating-specific antibodies only for PET-A. IL-10 was increased in all PET-groups and correlated with polymer-specific antibodies for PET-G and PET-A. IL-2 was increased for PET-A, but overall correlated with PET-specific antibodies. IL-4 remained unchanged in all groups. Intense local inflammatory reactions (ED1+ /ED2+ macrophages and T lymphocytes) were found within all PET-groups, but only minor for PTFE or controls. In conclusion, PET-specific antibodies were associated with increased IL-10 and along with concurrent coating-specific antibodies also with increased IL-2, indicating a specific T cell response. Thus, matrix and/or coating of polymeric vascular prostheses elicit distinct systemic immune reactions, probably influencing local inflammatory reactions.