[Pharmacovigilance guidelines for clinical application of Chinese patent medicines for mucosal administration].

The group standard Pharmacovigilance guidelines for clinical application of Chinese patent medicines for mucosal administration was released on January 16, 2024, on the national group standards information platform by the Institute of Basic Research in Clinical Medicine of China Academy of Chinese Medical Sciences and School and Hospital of Stomatology of Peking University, under the centralized management by the China Association of Chinese Medicine. The standard number is T/CACM 1563.6-2024. It aims to propose key elements and specify technical methods for safety monitoring and reporting, signal identification, risk assessment, and risk control based on the Drug administration law of the People's Republic of China(revised in 2019), which establishes normative pharmacovigilance guideline of Chinese patent medicine for mucosal administration that is in line with the characteristics of traditional Chinese Medicine(TCM) based on the pharmacovigilance content for clinical application of Chinese patent medicine for mucosal administration. The group standard has been discussed by internal and external experts through multiple rounds of consultation. It serves as a guiding document for stakeholders involved in pharmacovigilance activities, including pharmaceutical license holders, drug manufacturers, medical institutions, research institutes, and pharmaceutical trading enterprises.

Immunization-related stress and stress-related responses of mucosal versus intramuscular COVID-19 vaccination among adults in China.

BACKGROUND: In late 2022, China became the first country to roll out mucosal COVID-19 vaccines. No prior study has yet compared the immunization stress-related responses (ISRR) among different routes of COVID-19 vaccine delivery. We aimed to compare the immunization-related psychological stress and ISRR between mucosal and intramuscular COVID-19 vaccines. METHODS: A cross-sectional questionnaire survey using a biopsychosocial framework design was performed from January 11 to 20, 2023. Adults with COVID-19 vaccination were eligible for the study, and a total of 1073 adults participated with community-based sample. Primary outcomes were the psychological stress levels and prevalence of ISRR. Multivariate regression models were employed to compare these outcomes between the two vaccination groups. The potential mediating effects of stress on vaccination and ISRR were examined using bootstrap sampling method. To further ensure the robustness of our results, sensitivity analysis with propensity score matching was performed. FINDINGS: In the univariate analysis, participants who received mucosal vaccination reported significantly lower stress levels compared to those who received intramuscular vaccination (3.39 ± 3.02 vs. 3.93 ± 3.24, P = .006). The prevalence of overall ISRR was significantly lower in the mucosal group compared to the intramuscular group (38.4% vs. 47.9%, P = .002). Multivariate regression models revealed that participants who received mucosal vaccination had a significantly lower stress level (ß = -0.516, 95% CI: -0.852 to -0.180; P = .003) and 38.7% fewer overall ISRR (OR = 0.613, 95% CI: 0.427 to 0.881; P = .008), particularly in terms of neurological symptoms. The immunization-related stress mediated the association between vaccination type and ISRR, with indirect effects estimated at 0.0663 (95% CI: 0.0195 to 0.1346) for overall ISRR. CONCLUSIONS: Mucosal COVID-19 vaccination was associated with reduced psychological stress and physical responses, as compared to intramuscular vaccination, which may contribute to increased trust and compliance with routine or mass vaccination efforts in the future.

Mucosal delivery of a prefusogenic-F, glycoprotein, and matrix proteins-based virus-like particle respiratory syncytial virus vaccine induces protective immunity as evidenced by challenge studies in mice.

RSV infection remains a serious threat to the children all over the world, especially, in the low-middle income countries. Vaccine delivery via the mucosa holds great potential for inducing local immune responses in the respiratory tract. Previously, we reported the development of highly immunogenic RSV virus-like-particles (RSV-VLPs) based on the conformationally stable prefusogenic-F protein (preFg), glycoprotein and matrix protein. Here, to explore whether mucosal delivery of RSV-VLPs is an effective strategy to induce RSV-specific mucosal and systemic immunity, RSV-VLPs were administered via the nasal, sublingual and pulmonary routes to BALB/c mice. The results demonstrate that immunization with the VLPs via the mucosal routes induced minimal mucosal response and yet facilitated modest levels of serum IgG antibodies, enhanced T cell responses and the expression of the lung-homing marker CXCR3 on splenocytes. Immunization with VLPs via all three mucosal routes provided protection against RSV challenge with no signs of RSV induced pathology.

Ionic liquid-based formulation approaches for enhanced transmucosal drug delivery.

The utilization of ionic liquids (ILs) in pharmaceutical drug delivery applications has seen significant expansion in recent years, owing to their distinctive characteristics and inherent adjustability. These innovative compounds can be used to tackle challenges associated with traditional dosage forms, such as polymorphism, inadequate solubility, permeability, and efficacy in topical drug delivery systems. Here, we provide a brief classification of ILs, and their effectiveness in augmenting transmucosal drug delivery approaches by improving the solubility and permeability of active pharmaceutical ingredients (APIs) by temporary mucus modulation aiding the paracellular transport of APIs, prolonging drug retention, and, thus, aiding controlled drug release across various mucosal surfaces. We also highlight potential advances in, and future perspectives of, IL-based formulations in mucosal drug delivery.

Induction of protective immune responses at respiratory mucosal sites.

Many pathogens enter the host through mucosal sites. Thus, interfering with pathogen entry through local neutralization at mucosal sites therefore is an effective strategy for preventing disease. Mucosally administered vaccines have the potential to induce protective immune responses at mucosal sites. This manuscript delves into some of the latest developments in mucosal vaccination, particularly focusing on advancements in adjuvant technologies and the role of these adjuvants in enhancing vaccine efficacy against respiratory pathogens. It highlights the anatomical and immunological complexities of the respiratory mucosal immune system, emphasizing the significance of mucosal secretory IgA and tissue-resident memory T cells in local immune responses. We further discuss the differences between immune responses induced through traditional parenteral vaccination approaches vs. mucosal administration strategies, and explore the protective advantages offered by immunization through mucosal routes.

Transmucosal administration of pentobarbital and phenytoin solution induces euthanasia in bearded dragons (Pogona vitticeps).

OBJECTIVE: To assess the efficacy of transmucosal euthanasia solution to induce euthanasia. ANIMALS: 6 bearded dragons (Pogona vitticeps). METHODS: An initial dose of euthanasia solution containing pentobarbital and phenytoin sodium was administered transmucosally in conscious lizards (100 mg/kg pentobarbital dose), followed by a second dose 20 minutes later (400 mg/kg pentobarbital dose). The presence of movement, leakage of euthanasia solution, behaviors consistent with oral irritation, respiratory rate, heart rate, palpebral and corneal reflex, and response to noxious stimuli were recorded until death, confirmed by the absence of Doppler cardiac flow and cardiac electrical activity. The time to loss of all parameters was calculated. Postmortem evaluation allowed for histopathologic evaluation of the oral cavity and gastrointestinal tract to detect potential mucosal damage from the alkaline euthanasia solution. RESULTS: The median time to death was 300 minutes (range, 300 to 360 minutes), median time to respiratory arrest was 30 minutes (range, 30 to 50 minutes), and median time to loss of deep pain response was 30 minutes (range, 20 to 50 minutes). Signs consistent with oral irritation occurred in 4 of 6 (66.7%) lizards, including 2 lizards that exhibited whole-body spasms after euthanasia solution administration. Histopathologic changes indicating peracute mucosal ulceration, suspected to be from caustic causes, were identified in 1 (1/6 [16.7%]) lizard. CLINICAL RELEVANCE: Transmucosal euthanasia solution administration resulted in clinical euthanasia within 6 hours. This method should be utilized only after premedication with analgesic and/or anesthetic medications due to the potential for acute mucosal ulceration and behaviors that may be distressing in client-owned animals.

Cell-penetrating peptides for transmucosal delivery of proteins.

Enabling non-invasive delivery of proteins across the mucosal barriers promises improved patient compliance and therapeutic efficacies. Cell-penetrating peptides (CPPs) are emerging as a promising and versatile tool to enhance protein and peptide permeation across various mucosal barriers. This review examines the structural and physicochemical attributes of the nasal, buccal, sublingual, and oral mucosa that hamper macromolecular delivery. Recent development of CPPs for overcoming those mucosal barriers for protein delivery is summarized and analyzed. Perspectives regarding current challenges and future research directions towards improving non-invasive transmucosal delivery of macromolecules for ultimate clinical translation are discussed.

Mucosal Administration of Lactobacillus casei Surface-Displayed HA1 Induces Protective Immune Responses against Avian Influenza A Virus in Mice.

Avian influenza is a serious threat to both public health and the poultry industry worldwide. This respiratory virus can be combated by eliciting robust immune responses at the site of infection through mucosal immunization. Recombinant probiotics, specifically lactic acid bacteria, are safe and effective carriers for mucosal vaccines. In this study, we engineered recombinant fusion protein by fusing the hemagglutinin 1 (HA1) subunit of the A/Aquatic bird/Korea/W81/2005 (H5N2) with the Bacillus subtilis poly γ-glutamic acid synthetase A (pgsA) at the surface of Lactobacillus casei (pgsA-HA1/L. casei). Using subcellular fractionation and flow cytometry we confirmed the surface localization of this fusion protein. Mucosal administration of pgsA-HA1/L. casei in mice resulted in significant levels of HA1-specific serum IgG, mucosal IgA and neutralizing antibodies against the H5N2 virus. Additionally, pgsA-HA1/L. casei-induced systemic and local cell-mediated immune responses specific to HA1, as evidenced by an increased number of IFN-γ and IL-4 secreting cells in the spleens and higher levels of IL-4 in the local lymphocyte supernatants. Finally, mice inoculated with pgsA-HA1/L. casei were protected against a 10LD50 dose of the homologous mouse-adapted H5N2 virus. These results suggest that mucosal immunization with L. casei displaying HA1 on its surface could be a potential strategy for developing a mucosal vaccine against other H5 subtype viruses.

In vivo tracing of immunostimulatory raw starch microparticles after mucosal administration.

Raw starch microparticles (SMPs) proved efficient antigen carriers with adjuvant properties when administered via the mucosal route; however, the underlying mechanisms associated with this bioactivity are unknown. In the present study, we explored the mucoadhesion properties, fate, and toxicity of starch microparticles after mucosal administration. Nasally administered microparticles were mainly retained in nasal turbinates, reaching the nasal-associated lymphoid tissue; this step is facilitated by the ability of the microparticles to penetrate through the mucous epithelium. Likewise, we found intraduodenally administered SMPs on the small intestinal villi, follicle-associated epithelium, and Peyer's patches. Furthermore, under simulated gastric and intestinal pH conditions, we detected mucoadhesion between the SMPs and mucins, regardless of microparticle swelling. SMPs' mucoadhesion and translocation to mucosal immune responses induction sites explain the previously reported role of these microparticles as vaccine adjuvants and immunostimulants.

Mucosal administration of anti-bacterial antibodies provide long-term cross-protection against Pseudomonas aeruginosa respiratory infection.

Bacterial respiratory infections, either acute or chronic, are major threats to human health. Direct mucosal administration, through the airways, of therapeutic antibodies (Abs) offers a tremendous opportunity to benefit patients with respiratory infections. The mode of action of anti-infective Abs relies on pathogen neutralization and crystallizable fragment (Fc)-mediated recruitment of immune effectors to facilitate their elimination. Using a mouse model of acute pneumonia induced by Pseudomonas aeruginosa, we depicted the immunomodulatory mode of action of a neutralizing anti-bacterial Abs. Beyond the rapid and efficient containment of the primary infection, the Abs delivered through the airways harnessed genuine innate and adaptive immune responses to provide long-term protection, preventing secondary bacterial infection. In vitro antigen-presenting cells stimulation assay, as well as in vivo bacterial challenges and serum transfer experiments indicate an essential contribution of immune complexes with the Abs and pathogen in the induction of the sustained and protective anti-bacterial humoral response. Interestingly, the long-lasting response protected partially against secondary infections with heterologous P. aeruginosa strains. Overall, our findings suggest that Abs delivered mucosally promotes bacteria neutralization and provides protection against secondary infection. This opens novel perspectives for the development of anti-infective Abs delivered to the lung mucosa, to treat respiratory infections.

Evaluation of Oral Transmucosal Administration of Pentobarbital for Euthanasia of Conscious Wild Birds.

This prospective study evaluated oral transmucosal pentobarbital sodium at three doses in 110 wild-caught wild birds requiring euthanasia. Birds received transmucosal pentobarbital at five (430 mg/kg), six (516 mg/kg), and seven times (602 mg/kg) the intravenous dose for mammals. Time to first effects and loss of consciousness, presence of pupillary light and corneal reflexes, apnea, and asystole were recorded each minute. When asystole was not achieved at 5 minutes, IV pentobarbital was administered. Combining data for all doses, loss of consciousness occurred at a median (range) of 2 minutes (0-4.75 min), apnea at 3 minutes (0-6 min), and asystole at 4 minutes (0.5-5 min). Loss of consciousness and apnea occurred significantly faster in the 602 mg/kg dose group than in the 430 mg/kg group (p = 0.009, difference of 0.6 ± 0.2 min; p = 0.024, difference of 0.7 ± 0.3 min), respectively. Apnea and asystole were achieved in 80/110 birds within 5 minutes. Oral transmucosal pentobarbital results in rapid loss of consciousness and respiratory arrest and provides a reliable alternative euthanasia method compared to intravenous administration.

Oromucosal products - Market landscape and innovative technologies: A review.

Strategies that rely on oral mucosal administration have increased in the last decade and oromucosal products are paving the way to overcome specific challenges, namely improving drug bioavailability when compared with the conventional oral route, due to a reduction of the hepatic first-pass metabolism and pre-systemic degradation. Overall, the advantages of these products make oromucosal route of administration attractive for the development of value-added medicines, which can address more properly the unmet medical needs of specific patients. Generally, such products have an easy and convenient administration since they do not require water for ingestion, which may be particularly relevant for geriatric and pediatric groups, or non-cooperative patients. Usually, the development of these products aims to provide a faster onset of action, critical for acute or emergency treatments. Although oriented to achieve better therapeutic outcomes, today's drug development is primarily focused on patient-centered care, meaning that patients' specific characteristics/needs are an important driving force behind product-development efforts. In accordance, pharmaceutical innovation can rely not only on new drug substances but also on re-formulation of already approved ones or alternative routes of administration, enhancing patient convenience, treatment efficacy and/or safety. Throughout this review, the oromucosal drug products, approved in the last decade, and a retrospective analysis of their critical quality attributes and specifications will be described. Furthermore, trends and opportunities of the latest technologies in this field, as well as the number of ongoing clinical studies, will be presented and discussed.

Pharmacokinetics of intravenous, oral transmucosal, and intranasal buprenorphine in healthy male dogs.

Effective management of pain in animals is of critical importance but options are limited for treating acute pain in dogs on an outpatient basis. The objective of this study was to compare the plasma concentrations and pharmacokinetics of a concentrated solution of buprenorphine, 1.8 mg/ml (Simbadol™) administered intravenously, intranasally, and via the oral transmucosal (OTM) route in healthy male dogs. Five healthy castrated adult male Beagle-cross dogs were included in this randomized blocked crossover study. The dogs received 0.03 mg/kg body weight buprenorphine intravenously, intranasally, or via the OTM route, with a minimum 72-h washout period between treatments. Blood samples were collected at multiple intervals up to 24 h post administration and buprenorphine plasma concentrations were determined by liquid chromatography tandem mass spectrometry. Non-compartmental pharmacokinetic analysis revealed that the area under the curve of intravenous, intranasal, and OTM routes were 28.0 (15.1-41.3) h × ng/ml, 16.1 (3.4-28.7) h × ng/ml and 10.8 (8.8-11.8) h × ng/ml, respectively. The bioavailability of intranasal and OTM routes were 57.5 (22.7-93.7)% and 41.1 (25.5-69.4)%, respectively. Intranasal and OTM routes of administration of concentrated buprenorphine in dogs may allow for the provision of analgesic care at home.

Immunoadjuvant and Humoral Immune Responses of Garlic (Allium sativum L.) Lectins upon Systemic and Mucosal Administration in BALB/c Mice.

Dietary food components have the ability to affect immune function; following absorption, specifically orally ingested dietary food containing lectins can systemically modulate the immune cells and affect the response to self- and co-administered food antigens. The mannose-binding lectins from garlic (Allium sativum agglutinins; ASAs) were identified as immunodulatory proteins in vitro. The objective of the present study was to assess the immunogenicity and adjuvanticity of garlic agglutinins and to evaluate whether they have adjuvant properties in vivo for a weak antigen ovalbumin (OVA). Garlic lectins (ASA I and ASA II) were administered by intranasal (50 days duration) and intradermal (14 days duration) routes, and the anti-lectin and anti-OVA immune (IgG) responses in the control and test groups of the BALB/c mice were assessed for humoral immunogenicity. Lectins, co-administered with OVA, were examined for lectin-induced anti-OVA IgG response to assess their adjuvant properties. The splenic and thymic indices were evaluated as a measure of immunomodulatory functions. Intradermal administration of ASA I and ASA II had showed a four-fold and two-fold increase in anti-lectin IgG response, respectively, vs. the control on day 14. In the intranasal route, the increases were 3-fold and 2.4-fold for ASA I and ASA II, respectively, on day 50. No decrease in the body weights of animals was noticed; the increases in the spleen and thymus weights, as well as their indices, were significant in the lectin groups. In the adjuvanticity study by intranasal administration, ASA I co-administered with ovalbumin (OVA) induced a remarkable increase in anti-OVA IgG response (~six-fold; p < 0.001) compared to the control, and ASA II induced a four-fold increase vs. the control on day 50. The results indicated that ASA was a potent immunogen which induced mucosal immunogenicity to the antigens that were administered intranasally in BALB/c mice. The observations made of the in vivo study indicate that ASA I has the potential use as an oral and mucosal adjuvant to deliver candidate weak antigens. Further clinical studies in humans are required to confirm its applicability.

Mannose-anchored quaternized chitosan/thiolated carboxymethyl chitosan composite NPs as mucoadhesive carrier for drug delivery.

There are various challenges for the mucosal delivery of drug, which is largely attributed to the absence of effective drug carriers that can make delivery to mucosal sites. In the present study, we aimed to synthesize bifunctional mucoadhesive nanoparticles (NPs) that could be used for mucosal delivery. N-2-Hydroxypropyl trimethyl ammonium chloride chitosan (M-N-2-HACC) was modified with D-mannose, and N-acetyl-L-cysteine (NAC) was immobilized on the carboxymethyl chitosan (N-CMCS). The electrostatic interaction between the two substances was used to produce mannose-modified thiolated chitosan NPs (M-N-2-HACC/N-CMCS NPs). The NPs showed a particle size of 196.72 ± 0.45 nm and zeta potential of 17.12 ± 0.50 mV. Moreover, it demonstrated high hydrophilicity, enduring drug release, stability, safety, and mucosal adhesion, which contributed to the effectiveness of mucosal administration. Additionally, the NPs could be instantly absorbed by macrophages. Collectively, these results suggested that M-N-2-HACC/N-CMCS NPs could be used as a promising candidate for mucosal delivery.

Development of novel mucoadhesive gels containing nanoparticle for buccal administration of dexamethasone

Abstract This study aimed to develop promising and innovative mucoadhesive gel systems containing dexamethasone-loaded nanoparticle to increase the effectiveness of treatment for oral precancerous lesions and to reduce side effects. In this respect, a dexamethasone-loaded nanoparticle formulation was prepared by using emulsification/solvent evaporation method. The nanoparticle has high zeta potential (-10.3±0.5 mV), low particle size (218.42±2.1), low polydispersity index (0.070±0.014) and high encapsulation efficiency (95.018±2.982%). To improve the mucosal retention time, the dexamethasone-loaded nanoparticle was dispersed in mucoadhesive gel using gellan gum. The developed gels offered appropriate pH value, high drug content, suitable mechanical and mucoadhesive performance and appropriate viscosity for mucosal administration. All formulations exhibited plastic flow and typical gel-type mechanical spectra after the determined frequency value. The developed formulations exhibited extended drug release as intended for these systems. Cytotoxicity was tested by MTT assay in human epithelioid carcinoma cell (HeLa) in vitro. The MTT assay showed that the blank formulations were non-toxic to cells. It was observed that the bioactivity of the free dexamethasone was potentiated by mucoadhesive gels containing dexamethasone-loaded nanoparticle in HeLa cells. Results from this study indicate that mucoadhesive gels are effective for the local treatment of precancerous lesions. Our findings showed that the developed formulations were worthy of further studies.

The Bacterial Mucosal Immunotherapy MV130 Protects Against SARS-CoV-2 Infection and Improves COVID-19 Vaccines Immunogenicity.

COVID-19-specific vaccines are efficient prophylactic weapons against SARS-CoV-2 virus. However, boosting innate responses may represent an innovative way to immediately fight future emerging viral infections or boost vaccines. MV130 is a mucosal immunotherapy, based on a mixture of whole heat-inactivated bacteria, that has shown clinical efficacy against recurrent viral respiratory infections. Herein, we show that the prophylactic intranasal administration of this immunotherapy confers heterologous protection against SARS-CoV-2 infection in susceptible K18-hACE2 mice. Furthermore, in C57BL/6 mice, prophylactic administration of MV130 improves the immunogenicity of two different COVID-19 vaccine formulations targeting the SARS-CoV-2 spike (S) protein, inoculated either intramuscularly or intranasally. Independently of the vaccine candidate and vaccination route used, intranasal prophylaxis with MV130 boosted S-specific responses, including CD8+-T cell activation and the production of S-specific mucosal IgA antibodies. Therefore, the bacterial mucosal immunotherapy MV130 protects against SARS-CoV-2 infection and improves COVID-19 vaccines immunogenicity.

Pharmacokinetic Characterisation and Comparison of Bioavailability of Intranasal Fentanyl, Transmucosal, and Intravenous Administration through a Three-Way Crossover Study in 24 Healthy Volunteers.

BACKGROUND: For more than 60 years, the synthetic opioid fentanyl has been widely used in anaesthesia and analgesia. While the intravenous formulation is primarily used for general anaesthesia and intensive care settings, the drug's high lipophilic properties also allow various noninvasive routes of administration. Published data suggest that intranasal administration is also attractive for use as intranasal patient-controlled analgesia (PCA). A newly developed intranasal fentanyl formulation containing 47 µg fentanyl, intravenous fentanyl, and oral transmucosal fentanyl citrate were characterised, and bioavailability was compared to assess the suitability of the intranasal formulation for an intranasal PCA product. METHODS: 27 healthy volunteers were enrolled in a single-centre, open-label, randomised (order of treatments), single-dose study in a three-period crossover design. The pharmacokinetics of one intranasal puff of fentanyl formulation (47 µg, 140 mL per puff), one short intravenous infusion of 50 µg fentanyl, and one lozenge with an integrated applicator (200 µg fentanyl) were studied, and bioavailability was calculated. Blood samples were collected over 12 hours, and plasma concentrations of fentanyl were determined by HPLC with MS/MS detection. RESULTS: 24 volunteers completed the study. The geometric mean of AUC0-tlast was the highest with oral transmucosal administration (1106 h ∗ pg/ml, CV% = 32.86), followed by intravenous (672 h ∗ pg/ml, CV% = 32.18) and intranasal administration (515 h ∗ pg/ml, CV% = 30.10). C max was 886 pg/ml (CV% = 59.38) for intravenous, 338 pg/ml (CV% = 45.61) for intranasal, and 310 pg/ml (CV% = 29.58) for oral transmucosal administration. t max was shortest for intravenous administration (0.06 h, SD = 0.056), followed by intranasal (0.21 h, SD = 0.078) and oral transmucosal administration (1.20 h, SD = 0.763). Dose-adjusted absolute bioavailability was determined to be 74.70% for the intranasal formulation and 41.25% for the oral transmucosal product. In total, 38 adverse events (AEs) occurred. Fourteen AEs were potentially related to the investigational items. No serious AE occurred. CONCLUSION: Pharmacokinetic parameters and bioavailability of the investigated intranasal fentanyl indicated suitability for its intended use as an intranasal PCA option.

Mucosal Administration of Recombinant Baculovirus Displaying Toxoplasma gondii ROP4 Confers Protection Against T. gondii Challenge Infection in Mice.

Pathogens require physical contact with the mucosal surface of the host organism to initiate infection and as such, vaccines eliciting both mucosal and systemic immune responses would be promising. Studies involving the use of recombinant baculoviruses (rBVs) as mucosal vaccines are severely lacking despite their inherently safe nature, especially against pathogens of global importance such as Toxoplasma gondii. Here, we generated rBVs displaying T. gondii rhoptry protein 4 (ROP4) and evaluated their protective efficacy in BALB/c mice following immunization via intranasal (IN) and oral routes. IN immunization with the ROP4-expressing rBVs elicited higher levels of parasite-specific IgA antibody responses compared to oral immunization. Upon challenge infection with a lethal dose of T. gondii ME49, IN immunization elicited significantly higher parasite-specific antibody responses in the mucosal tissues such as intestines, feces, vaginal samples, and brain than oral immunization. Marked increases in IgG and IgA antibody-secreting cell (ASC) responses were observed from intranasally immunized mice. IN immunization elicited significantly enhanced induction of CD4+, CD8+ T cells, and germinal center B (GC B) cell responses from secondary lymphoid organs while limiting the production of the inflammatory cytokines IFN-γ and IL-6 in the brain, all of which contributed to protecting mice against T. gondii lethal challenge infection. Our findings suggest that IN delivery of ROP4 rBVs induced better mucosal and systemic immunity against the lethal T. gondii challenge infection compared to oral immunization.

Methods to improve the immunogenicity of plasmid DNA vaccines.

DNA vaccines have emerged as innovative approaches that have great potential to overcome the limitations of current conventional vaccines. Plasmid DNA vaccines are often safer than other vaccines because they carry only antigen genetic information, are more stable and easier to produce, and can stimulate both humoral and cellular immune responses. Although the results of ongoing clinical trials are very promising, some limitations compromise the immunogenicity of these vaccines. Thus, this review describes different strategies that can be explored to improve the immunogenicity of plasmid DNA vaccines, including the optimization of the plasmid vector backbone, the use of different methods for vaccine delivery, the use of alternative administration routes and the inclusion of adjuvants. In combination, these improvements could lead to the successful clinical use of plasmid DNA vaccines.