Vaccine Carrier Research Articles

A Study on Knowledge of Health Workers on Vaccine Storage, Distribution, and Cold Chain Management in Yemen

The success of the Expanded Programme on Immunization (EPI) over the years is attributed to the immunization supply chain, effective logistics systems, and the health professionals who run them. Gaps in knowledge and practices still exist in developing countries and countries with conflict. Due to the paucity of information regarding the subject in humanitarian settings, this study was carried out. This descriptive cross-sectional study was carried out among health workers at the four levels of the healthcare system in 6 governorates in Yemen. A total of 536 health workers provided responses to the online questionnaire between February and May 2022. The study showed that 515(96.1%) and 521(97.2%) of the respondents, respectively, knew the recommended temperature range for storage of Rota and pentavalent vaccines at the health facility. Most respondents, 415(77.4%) and 413(77.0%) knew the recommended storage temperature for measles and BCG, respectively, and 466(86.9%) knew they could be stored at a negative temperature when the need arises. Over two-thirds of respondents only receive vaccines 411(76.7%), and 124(23.1%) receive and distribute vaccines. Vaccine distribution included the use of refrigerated vehicles (15.2%), cold boxes (32.8%), and vaccine carriers (41.6%), both with conditioned ice packs. Despite the protracted and complex humanitarian situation in Yemen, Health workers demonstrated good knowledge and practices of vaccine storage, distribution, and cold chain management, which contributed to the sustenance of immunization services. There is a need for required investment in a cost-effective and sustainable last-mile vaccine distribution approach to ensure equitable availability of vaccines at health facilities and prevent any missed opportunity. Keywords: Cold chain, Distribution, Vaccine storage, Knowledge.

Dendrimer-Mediated Delivery of DNA and RNA Vaccines.

DNA and RNA vaccines (nucleic acid-based vaccines) are a promising platform for vaccine development. The first mRNA vaccines (Moderna and Pfizer/BioNTech) were approved in 2020, and a DNA vaccine (Zydus Cadila, India), in 2021. They display unique benefits in the current COVID-19 pandemic. Nucleic acid-based vaccines have a number of advantages, such as safety, efficacy, and low cost. They are potentially faster to develop, cheaper to produce, and easier to store and transport. A crucial step in the technology of DNA or RNA vaccines is choosing an efficient delivery method. Nucleic acid delivery using liposomes is the most popular approach today, but this method has certain disadvantages. Therefore, studies are actively underway to develop various alternative delivery methods, among which synthetic cationic polymers such as dendrimers are very attractive. Dendrimers are three-dimensional nanostructures with a high degree of molecular homogeneity, adjustable size, multivalence, high surface functionality, and high aqueous solubility. The biosafety of some dendrimers has been evaluated in several clinical trials presented in this review. Due to these important and attractive properties, dendrimers are already being used to deliver a number of drugs and are being explored as promising carriers for nucleic acid-based vaccines. This review summarizes the literature data on the development of dendrimer-based delivery systems for DNA and mRNA vaccines.

Monomeric crystal structure of the vaccine carrier protein CRM197 and implications for vaccine development.

CRM197 is a genetically detoxified mutant of diphtheria toxin (DT) that is widely used as a carrier protein in conjugate vaccines. Protective immune responses to several bacterial diseases are obtained by coupling CRM197 to glycans from these pathogens. Wild-type DT has been described in two oligomeric forms: a monomer and a domain-swapped dimer. Their proportions depend on the chemical conditions and especially the pH, with a large kinetic barrier to interconversion. A similar situation occurs in CRM197, where the monomer is preferred for vaccine synthesis. Despite 30 years of research and the increasing application of CRM197 in conjugate vaccines, until now all of its available crystal structures have been dimeric. Here, CRM197 was expressed as a soluble, intracellular protein in an Escherichia coli strain engineered to have an oxidative cytoplasm. The purified product, called EcoCRM, remained monomeric throughout crystallization. The structure of monomeric EcoCRM is reported at 2.0 Å resolution with the domain-swapping hinge loop (residues 379-387) in an extended, exposed conformation, similar to monomeric wild-type DT. The structure enables comparisons across expression systems and across oligomeric states, with implications for monomer-dimer interconversion and for the optimization of conjugation.

Inulin acetate as a novel recombinant subunit vaccine carrier for immunization of tilapia against tilapia lake virus

Tilapia lake virus (TiLV) is highly contagious and pathogenic to tilapia, causing enormous economic losses in tilapia industry. Up to now, there is no commercial vaccine is available for against TiLV infection. Therefore, a novel vaccine with high immune efficacy is urgently-needed. In this study, we examined the efficacy of subunit vaccine against TiLV through intramuscular injection using inulin acetate (InAc) nanoparticles encapsulation. The S2 protein (encoded by segment 2 gene of TiLV) was used as the antigen and the delivery system was named as InAc-S2. The toxicity analysis showed InAc-S2 had no significant influence on fishes growing and development. Meanwhile, we found InAc-S2 has a dual-release pattern (initial burst release and sustained release) in antigen release. Subsequently, tilapia was injected intramuscularly by different treatments (PBS, InAc, S2, and InAc-S2), and the immune protective effect induced by these treatments was analyzed. We found a powerful and long-lasting humoral or cellular immune response (serum antibody production, immune-related parameters and immune-related genes expression) can be induced in fishes by injected with InAc-S2 in comparison with those injected with S2 antigen alone. Moreover, a relative higher survival rate was observed in fish vaccinated with InAc-S2 at the dose of 4 μg protein/g of fish (with the relative percentage survival of 58.6%). Overall, this study for the first time demonstrated the potential of InAc as subunit vaccine carrier against TiLV infection and provide a reference to novel vaccine development in aquaculture.

Evaluation of vaccine storage and distribution practices in rural healthcare facilities in Kenya

BackgroundVaccines require cold chain storage conditions, and good distribution practices throughout the supply chain to maintain their quality and potency. However, in the last mile of the vaccines supply chain, these requirements may not be guaranteed resulting in reduced effectiveness which could lead to an upsurge in vaccine preventable morbidity and mortality. The aim of this research was to evaluate vaccine storage and distribution practices in the last mile of vaccine supply chain in Turkana County.MethodsA descriptive cross-sectional study was conducted from January 2022 to February 2022 across seven sub-counties in Turkana County, Kenya, to assess vaccine storage and distribution practices. The study sample size was 128 county health professionals across 4 hospitals, 9 health centers, and 115 dispensaries. The respondents were selected using simple random sampling within the facilities strata. Data were collected using a structured questionnaire, adapted, and adopted from a standardized WHO questionnaire on effective vaccines management and administered to one healthcare personnel working in the immunization supply chain per facility. Data were analyzed using excel and presented as percentages in table forms.ResultsA total of 122 health care workers participated in the study. Most respondents (89%, n = 109) had utilized a vaccine forecasting sheet, but only 81% did have an established maximum–minimum level inventory control system. Many of the respondents had sufficient knowledge of ice pack conditioning although 72% had adequate vaccine carriers and ice packs. Only 67% of respondents had a complete set of twice-daily manual temperature records at the facility. Most refrigerators complied with the WHO specifications but only 80% of them had functional fridge-tags. The number of facilities that had a routine maintenance plan was below average while only 65% had an adequate contingency plan.ConclusionRural health facilities have suboptimal supply of vaccine carriers and icepacks for effective storage and distribution of vaccines. In addition, some vaccine fridges lack functional fridge-tags for proper temperature monitoring. Routine maintenance and contingency plans remain a challenge to ensure optimal service delivery.

Adenoviral Vector-Based Vaccine Platform for COVID-19: Current Status.

The coronavirus disease (COVID-19) breakout had an unimaginable worldwide effect in the 21st century, claiming millions of lives and putting a huge burden on the global economy. The potential developments in vaccine technologies following the determination of the genetic sequence of SARS-CoV-2 and the increasing global efforts to bring potential vaccines and therapeutics into the market for emergency use have provided a small bright spot to this tragic event. Several intriguing vaccine candidates have been developed using recombinant technology, genetic engineering, and other vaccine development technologies. In the last decade, a vast amount of the vaccine development process has diversified towards the usage of viral vector-based vaccines. The immune response elicited by such vaccines is comparatively higher than other approved vaccine candidates that require a booster dose to provide sufficient immune protection. The non-replicating adenoviral vectors are promising vaccine carriers for infectious diseases due to better yield, cGMP-friendly manufacturing processes, safety, better efficacy, manageable shipping, and storage procedures. As of April 2022, the WHO has approved a total of 10 vaccines around the world for COVID-19 (33 vaccines approved by at least one country), among which three candidates are adenoviral vector-based vaccines. This review sheds light on the developmental summary of all the adenoviral vector-based vaccines that are under emergency use authorization (EUA) or in the different stages of development for COVID-19 management.

Using <i>Bacillus subtilis</i> as an oral vaccine carrier against <i>Streptococcus suis</i>

Due to the progressive growth of the bacteria caused by the widespread use of antibiotics, treatment of streptococcosis is becoming increasingly difficult. Reliable vaccination against Streptococcus suis is necessary. Modern molecular diagnostic and genetic engineering capabilities create prospects for direct cloning of the protective epitopes of the Lmb gene of the local S. suis strain into the proposed delivery system of the pig immune system antigen. Among oral vaccine carriers, Bacillus subtilis is recognized as a relatively environmentally friendly carrier with an efficient protein secretion system and adaptive metabolism capable of spore production under relatively harsh conditions. This spore property can be used to increase the stability and reusability of vaccines. The possibility of using the protective Lmb epitopes of S. suis in B. subtilis as a carrier of an oral recombinant vaccine against Streptococcus suis was studied. The nucleotide sequences of S. suis were obtained from the GenBank database after a preliminary analysis of literature data on the known protective antigens of S. suis of various serotypes. Nucleotide sequence analysis was performed using Unipro UGENE v. 43.0. The Immune Epitope Database (IEDB) was used to search for T (CTL and Th) and B dependent epitopes of the Lmb gene. A computer-designed vaccine in which localization of CTL, B, and Th epitopes is predicted is described. The results of cloning the sequence of the antigenically active epitope of the S. suis Lmb protein in B. subtilis for subsequent oral administration and study of changes in immunological reactions and adverse reactions in animals are described. The possibility to clone the epitopes of recombinant S. suis Lmb protein into the pBE-S polylinker vector was revealed. In the long term, it seems possible to create a new inexpensive and easy-to-use vaccine against S. suis that does not require injection.

Mannose-modified erythrocyte membrane-encapsulated chitovanic nanoparticles as a DNA vaccine carrier against reticuloendothelial tissue hyperplasia virus.

The erythrocyte membranes used in nanovaccines include high membrane stability, long circulation life, adaptability and extremely good bio compatibility. Nanoparticles encapsulated by erythrocyte membranes are widely used as ideal drug delivery vehicles because of their high drug loading, long circulation time, and excellent biocompatibility. The mannose modification of delivery materials can help target mannose receptors (MRs) to deliver antigens to antigen-presenting cells (APCs). In this study, the antigen gene gp90 of avian reticuloendotheliosis virus (REV) was encapsulated with carboxymethyl chitosan (CS) to obtain CSgp90 nanoparticles, which were coated with mannose-modied fowl erythrocyte membranes to yield CS-gp90@M-M nanoparticles. The physicochemical characterization and immune response of the CS-gp90@M-M nanoparticles were investigated in vitro and in vivo. CS-gp90@M-M nanoparticles were rapidly phagocytized in vitro by macrophages to induce the production of cytokines and nitric oxide. In vivo, CS-gp90@M-M nanoparticles increased cytokine levels, the CD4+/8+ ratio, REV-specific antibodies in the peripheral blood of chicks, and the mRNA levels of immune-related genes in the spleen and bursa of immunized chicks. CS-gp90@M-M nanoparticles could be targeted to lymphoid organs to prolong the retention time of the nanoparticles at the injection site and lymphatic organs, leading to a strong, sustained immune response. Moreover, the CS-gp90@M-M nano-vaccine showed a lasting immunoprotective effect and improved the body weight of chicks after the challenge. Overall, CS-gp90@M-M nanoparticles can be used in vaccine designs as an effective delivery carrier with immune response-enhancing effects.

Vaccine Management Knowledge and Practice of Health workers in Yemen

Vaccine management comprises of estimation of vaccine needs, ordering, storage, distribution, monitoring vaccines use and limiting vaccine wastage. Yemen has been in conflict situation for over 7 years and remains one of the world’s worst humanitarian crises, with an estimated 23.4 million people in need of humanitarian assistance. This descriptive cross-sectional study to assess the vaccine management knowledge and practice in Yemen was carried out among health workers in 6 governorates. 536 health workers at different levels provided responses to the online questionnaire which were imported into the Statistical Package for Social Sciences (SPSS) platform for relevant descriptive and inferential analysis. Chi square test was used to determine statistical significance of observed difference in knowledge and vaccine management practice against relevant socio-demographic and work-related variables. The level of significance was set at p value <0.05. The study showed that 429(80%) had good knowledge while 63(11.8%) and 44(8.2%) had fair and poor knowledge of vaccine management respectively. More than two-thirds of respondents only receive vaccines 411(76.7%), 124(23.1%) receive and distribute vaccines. Vaccine distribution included use of refrigerated vehicles (15.2%), cold boxes (32.8%) and vaccine carrier (41.6%) both with conditioned ice packs. A total of 432(63.8%) have experienced vaccine stock-out and mostly for 1-2weeks (75.6%). Association between age and vaccine management knowledge was statistically significant with p-value of 0.006. The vaccine management knowledge and practice as shown from the findings of the study are commendable. However, there is need to address the artificial stock-out of vaccines to avoid missed opportunities. Keywords: Knowledge, Practice, Vaccine Management.

Ag85A, As an S2 Vaccine Carrier, Reduces the Toxicity of the S2 Vaccine and Enhances the Protective Ability of Mice against Brucella.

Brucella is a globally distributed zoonotic disease that can cause abortion and changes in immune function in humans and animals. At present, there is no good treatment plan for Brucella, and animals can only be treated harmlessly once they become ill, resulting in huge economic losses. Therefore, the prevention of Brucella infection is a very crucial step. Although a variety of Brucella vaccines have been widely used, they have varying degrees of shortcomings. For example, some Brucella vaccines have residual virulence, which leads to the emergence of Brucella in animals during the immunization process. Bacillus infection and other conditions occur. To further reduce the toxicity of the Brucella vaccine and enhance its protective effect on animals, this study used Antigen 85A (Ag85A) as a carrier of the Brucella vaccine to fuse with the Brucella S2 vaccine. The results of the study found that the S2-Ag85A oral Brucella vaccine could effectively reduce the toxicity residue of the S2 vaccine, stimulate the mice to produce a better immunogenic response, and effectively activate the expression levels of Brucella heterozygous IgG1 and IgG2a. Experiments have shown that the expression of IFN-γ in the peripheral blood serum and spleen of mice is significantly increased, and the expression levels of IL-1β, TNF-α, and IL-6 are significantly reduced, which may indicate that S2-Ag85A oral Brucella vaccine could induce the expression of IFN-γ, thus downregulating the expression levels of IL-6 and TNF-α in the spleen tissue. The above results indicate that the S2-Ag85A oral vaccine is an effective attenuated vaccine for preventing Brucella infection.

Cost, health impacts and cost effectiveness of iceless refrigeration in India's last-mile vaccine cold chain delivery.

Compared with ice-based vaccine carriers (IBVCs), iceless vaccine carrier (ILVC) last-mile delivery could optimize vaccine effectiveness by reducing spoilage. We estimated ILVC-associated spoilage costs averted and cost effectiveness. IBVC vaccine spoilage costs were estimated for six vaccines. ILVC incremental costs were based on yearly ILVC cost over total doses. Cost effectiveness was estimated via Markov modeling of rotavirus vaccine. The spoilage cost using IBVCs was US$9 603 294. Using ILVCs, the incremental cost per vaccine dose was US$0.026, the cost-benefit ratio was 0.28, the number of averted disability-adjusted life years was 0.03 per child and there was a saving of US$0.80 per child vaccinated. ILVCs may bring cost savings and health gains compared with IBVCs.

A REVIEW ON NANO/MICROPARTICLES FORMULATION OF VACCINE DELIVERY FOR UNIVERSAL INFLUENZA

Worldwide, influenza affects millions of individuals and has the potential to cause serious illness or even death. The most effective approach of prophylaxis is vaccination, but due to strain and viral mutation changes, the seasonal influenza vaccine frequently has limited efficiency and needs to be administered annually. Although they have been employed clinically, more conserved universal influenza antigens like the M2 ectodomain (M2e) and the hemagglutinin stalk region (HA stalk) frequently have poor antigenicity. Universal antigens have been created employing nano/microparticles as influenza vaccine carriers to boost their antigenicity. Indicators of immunity and protection against influenza have been demonstrated in mouse, pig, ferret, and chicken models using polymers, liposomes, metal, and protein-based particles. This review focuses on the physiochemical characteristics, production, characterization, and biologic responses in vivo of the formulations of the seasonal and universal influenza vaccines made from these materials. The assessment concludes with future perspectives for nano/microparticles as carrier systems and other factors to take into account within the perspective of the landscape for the administration of the universal influenza vaccine. KEYWORDS: Influenza; Polymeric Nanoparticles; Liposomes; Gold Nanoparticles; Protein Nanoparticles

Engineering probiotic-derived outer membrane vesicles as functional vaccine carriers to enhance immunity against SARS-CoV-2

Because of the continued emergence of SARS-CoV-2 variants, there has been considerable interest in how to display multivalent antigens efficiently. Bacterial outer membrane vesicles (OMVs) can serve as an attractive vaccine delivery system because of their self-adjuvant properties and the ability to be decorated with antigens. Here we set up a bivalent antigen display platform based on engineered OMVs using mCherry and GFP and demonstrated that two different antigens of SARS-CoV-2 could be presented simultaneously in the lumen and on the surface of OMVs. Comparing immunogenicity, ClyA-NG06 fusion and the receptor-binding domain (RBD) of the spike protein in the OMV lumen elicited a stronger humoral response in mice than OMVs presenting either the ClyA-NG06 fusion or RBD alone. Taken together, we provided an efficient approach to display SARS-CoV-2 antigens in the lumen and on the surface of the same OMV and highlighted the potential of OMVs as general multi-antigen carriers.

Meet changes with constancy: Defence, antagonism, recovery, and immunity roles of extracellular vesicles in confronting SARS-CoV-2.

Coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has wrought havoc on the world economy and people's daily lives. The inability to comprehensively control COVID-19 is due to the difficulty of early and timely diagnosis, the lack of effective therapeutic drugs, and the limited effectiveness of vaccines. The body contains billions of extracellular vesicles (EVs), which have shown remarkable potential in disease diagnosis, drug development, and vaccine carriers. Recently, increasing evidence has indicated that EVs may participate or assist the body in defence, antagonism, recovery and acquired immunity against SARS-CoV-2. On the one hand, intercepting and decrypting the general intelligence carried in circulating EVs from COVID-19 patients will provide an important hint for diagnosis and treatment; on the other hand, engineered EVs modified by gene editing in the laboratory will amplify the effectiveness of inhibiting infection, replication and destruction of ever-mutating SARS-CoV-2, facilitating tissue repair and making a better vaccine. To comprehensively understand the interaction between EVs and SARS-CoV-2, providing new insights to overcome some difficulties in the diagnosis, prevention and treatment of COVID-19, we conducted a rounded review in this area. We also explain numerous critical challenges that these tactics face before they enter the clinic, and this work will provide previous 'meet change with constancy' lessons for responding to future similar public health disasters. Extracellular vesicles (EVs) provide a 'meet changes with constancy' strategy to combat SARS-CoV-2 that spans defence, antagonism, recovery, and acquired immunity. Targets for COVID-19 diagnosis, therapy, and prevention of progression may be found by capture of the message decoding in circulating EVs. Engineered and biomimetic EVs can boost effects of the natural EVs, especially anti-SARS-CoV-2, targeted repair of damaged tissue, and improvement of vaccine efficacy.

Understanding the research advances on lumpy skin disease: A comprehensive literature review of experimental evidence.

Lumpy skin disease is caused by lumpy skin disease virus (LSDV), which can induce cattle with high fever and extensive nodules on the mucosa or the scarfskin, seriously influencing the cattle industry development and international import and export trade. Since 2013, the disease has spread rapidly and widely throughout the Russia and Asia. In the past few decades, progress has been made in the study of LSDV. It is mainly transmitted by blood-sucking insects, and various modes of transmission with distinct seasonality. Figuring out how the virus spreads will help eradicate LSDV at its source. In the event of an outbreak, selecting the most effective vaccine to block and eliminate the threat posed by LSDV in a timely manner is the main choice for farmers and authorities. At present, a variety of vaccines for LSDV have been developed. The available vaccine products vary in quality, protection rate, safety and side effects. Early detection of LSDV can help reduce the cost of disease. In addition, because LSDV has a huge genome, it is currently also used as a vaccine carrier, forming a new complex with other viral genes through homologous recombination. The vaccine prepared based on this can have a certain preventive effect on many kinds of diseases. Clinical detection of disease including nucleic acid and antigen level. Each method varies in convenience, accuracy, cost, time and complexity of equipment. This article reviews our current understanding of the mode of transmission of LSDV and advances in vaccine types and detection methods, providing a background for further research into various aspects of LSDV in the future.

Development and biological evaluation of pNIPAM-based nanogels as vaccine carriers

“Smart” nanogels are an attractive tool for the development of new strategies of immunization in veterinary medicine. Here, we reported the synthesis and physicochemical characterization of thermoresponsive nanogels based on poly(N-isopropylacrylamide) (pNIPAM) and theirin vitro, ex vivoand in vivo (mice model) performance. Smart nanogels of ca. 250 nm, with a transition temperature of 32 °C were obtained by precipitation polymerization. Assays to evaluatepNIPAM nanogels cytotoxicity were performed in different cell lines showing high biocompatibility (>70 %). The efficient internalization of the system was studied by confocal microscopy as well as flow cytometry. The ability to protect and deliver antigens was analyzed using the outer membrane lipoprotein A (OmlA), an important virulence factor ofActinobacillus pleuropneumoniae(App)cause of porcine pleuropneumonia. This lipoprotein was synthesized by recombinant technology and its technique was also described. The biodistribution ofpNIPAM nanogels administered intranasally was performedinvivo and ex vivo through Pearl Imaging System, which showed that nanogels were kept mostly in the lungs during the evaluated time. Besides, the efficacy of the proposal nanogel-based vaccine was studiedin vivoby measuring the antibody titers of BALB/c mice inoculated with OmlA encapsulated intopNIPAM nanogels compared to OmlA plus aluminum hydroxide adjuvant. The results proved the ability of nanogels to stimulate a humoral immune response. Therefore, we have demonstrated thatpNIPAM nanogels can be used as an efficient platform for vaccine nanocarriers.

Involvement of Bacterial Extracellular Membrane Nanovesicles in Infectious Diseases and Their Application in Medicine.

Bacterial extracellular membrane nanovesicles (EMNs) are attracting the attention of scientists more and more every year. These formations are involved in the pathogenesis of numerous diseases, among which, of course, the leading role is occupied by infectious diseases, the causative agents of which are a range of Gram-positive and Gram-negative bacteria. A separate field for the study of the role of EMN is cancer. Extracellular membrane nanovesicles nowadays have a practical application as vaccine carriers for immunization against many infectious diseases. At present, the most essential point is their role in stimulating immune response to bacterial infections and tumor cells. The possibility of nanovesicles' practical use in several disease treatments is being evaluated. In our review, we listed diseases, focusing on their multitude and diversity, for which EMNs are essential, and also considered in detail the possibilities of using EMNs in the therapy and prevention of various pathologies.

Polyanhydride Chemistry.

Polyanhydrides (PAs) are a class of synthetic biodegradable polymers employed as controlled drug delivery vehicles. They can be synthesized and scaled up from low-cost starting materials. The structure of PAs can be manipulated synthetically to meet desirable characteristics. PAs are biocompatible, biodegradable, and generate nontoxic metabolites upon degradation, which are easily eliminated from the body. The rate of water penetrating into the polyanhydride (PA) matrix is slower than the anhydride bond cleavage. This phenomenon sets PAs as "surface-eroding drug delivery carriers." Consequently, a variety of PA-based drug delivery carriers in the form of solid implants, pasty injectable formulations, microspheres, nanoparticles, etc. have been developed for the sustained release of small molecule drugs, and vaccines, peptide drugs, and nucleic acid-based active agents. The rate of drug delivery is often controlled by the polymer erosion rate, which is influenced by the polymer structure and composition, crystallinity, hydrophobicity, pH of the release medium, device size, configuration, etc. Owing to the above-mentioned interesting physicochemical and mechanical properties of PAs, the present review focuses on the advancements made in the domain of synthetic biodegradable biomedical PAs for therapeutic delivery applications. Various classes of PAs, their structures, their unique characteristics, their physicochemical and mechanical properties, and factors influencing surface erosion are discussed in detail. The review also summarizes various methods involved in the synthesis of PAs and their utility in the biomedical domain as drug, vaccine, and peptide delivery carriers in different formulations are reviewed.

Oral vaccination for sustainable disease prevention in aquaculture-an encapsulation approach.

The prevalence of infectious diseases in the aquaculture industry and a limited number of safe and effective oral vaccines has imposed a challenge not only for fish immunity but also a threat to human health. The availability of fish oral vaccines has expanded recently, but little is known about how well they work and how they affect the immune system. The unsatisfactory efficacy of existing oral vaccinations is partly attributable to the antigen degradation in the adverse gastrointestinal environment of fishes, the highly tolerogenic gut environment, and inferior vaccine formulation. To overcome such challenges in designing: an easier, cost-efficient, and effective vaccination method, several encapsulation methods are being adopted to safeguard antigens from the intestinal atmosphere for their immunogenic functions. Oral vaccination is easily degraded by gastric acids and enzymes before reaching the immunological site; however, this issue can be solved by encapsulating antigens in poly-biodegradable nanoparticles, transgenic designed bacteria, plant systems, and live feeds. To enhance the immunological impact, each antigen delivery method operates at a different level. Utilizing nanotechnology, it has been possible to regulate vaccination parameters, target particular cells, and lower the antigen dosage with potent nanomaterials such as chitosan, poly D,L-lactic-co-glycolic acid (PLGA) as vaccine carriers. Live feeds such as Artemia salina can be utilized as bio-carrier, owing to their appropriate size and non-filter feed system, through a process called bio-encapsulation. It ensures the protection of antigens over the fish intestine and ensures complete uptake by immune cells in the hindgut for increased immune response. This review comprises recent advances in oral vaccination in aquaculture in terms of an encapsulation approach that can aid in future research.

Chitosan-Based Nanomaterial as Immune Adjuvant and Delivery Carrier for Vaccines.

With the support of modern biotechnology, vaccine technology continues to iterate. The safety and efficacy of vaccines are some of the most important areas of development in the field. As a natural substance, chitosan is widely used in numerous fields-such as immune stimulation, drug delivery, wound healing, and antibacterial procedures-due to its good biocompatibility, low toxicity, biodegradability, and adhesion. Chitosan-based nanoparticles (NPs) have attracted extensive attention with respect to vaccine adjuvants and delivery systems due to their excellent properties, which can effectively enhance immune responses. Here, we list the classifications and mechanisms of action of vaccine adjuvants. At the same time, the preparation methods of chitosan, its NPs, and their mechanism of action in the delivery system are introduced. The extensive applications of chitosan and its NPs in protein vaccines and nucleic acid vaccines are also introduced. This paper reviewed the latest research progress of chitosan-based NPs in vaccine adjuvant and drug delivery systems.