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Applications of Antiviral Nanoparticles in Cancer Therapy
Published in Devarajan Thangadurai, Saher Islam, Charles Oluwaseun Adetunji, Viral and Antiviral Nanomaterials, 2022
Anusha Konatala, Sai Brahma Penugonda, Fain Parackel, Sudhakar Pola
Nanoparticles (NPs) have a scope for application in delivery systems for cancer vaccines as they potentiate the co-delivery of tumor-associated antigens and proteins to the specific cells to generate a stronger immune response. Moreover, several sophisticated NP systems are used for optimisation of vaccines to improve efficiency. Synthetic vaccines using nanomaterials have been explored for a long time because of properties like biocompatibility, biodegradability, and improved bioavailability for a long-lasting immune response (Sulczewski et al. 2018). Unlike viral vaccines, nanoparticle vaccines show improved safety and efficacy. These nanoformulations are not only similar to the viruses’ size and shape but are also consistent with their ability to deliver antigen and activate immunological response (Shen et al. 2018; Sulczewski et al. 2018).
Introduction
Published in F. Y. Liew, Vaccination Strategies of Tropical Diseases, 2017
Studies of many globular proteins have concluded that there is on an average only one antigenic determinant per 5000 Da of protein (equivalent to about 40 amino acids). Subunit vaccines which are macromolecules of various sizes carry a large number of sites that determine their antigenic specificity. It is apparent that of these only a few are important in provoking protective immunity whereas others may frequently induce the opposite effect of suppression which could be detrimental to the host defense mechanism. Thus, provided an individual protective determinant can be identified, isolated, and retain its immunogenicity, it would be possible to produce a highly specific vaccine free from competing and nonessential components. The basis for synthetic peptide vaccines was laid by the pioneering work of Anderer8 who showed that short fragments of the protein from tobacco mosaic virus could inhibit the precipitation of the virus by antiserum and that a hexapeptide from the fragment, when coupled to bovine serum albumin, induced specific virus precipitating and neutralizing antibodies. Since then and particularly recently, synthetic peptide vaccine is a popular area of study. In spite of rapid progress in the past few years, synthetic vaccines are still at their early developmental stage. So far, they are confined to peptides with sequential antigenic determinants only. Other types of antigen, such as nucleic acids, polysaccharides, or lipids, are currently being explored. Quite apart from identifying immunogenic determinants, other obstacles such as a requirement for adjuvants and the regulation of immune reponse have yet to be overcome. The background and the current state-of-the-art of peptide vaccine is presented in Chapter 5.
Antibodies and Antisera
Published in Lars-Inge Larsson, Immunocytochemistry: Theory and Practice, 2020
Experiments with synthetic peptides, as well as with protein antigens, reveal that the antigenic site or epitope is very small indeed and usually consists of only three to eight amino acid residues. These residues may form part of a continuous stretch of a peptide sequence (continuous antigenic site). In other cases they may be separated from each other in the primary protein sequence, but may be brought together in the native folded protein by the protein conformation (discontinuous antigenic site).1,2 It has proven possible to synthesize short peptides that mimic the antigenic sites of proteins. In cases of discontinuous antigenic sites such synthetic peptides may include “spacer amino acids” to fill the gap between the residues brought together by conformation. In this way, antigenic sites in several proteins have been mapped and identified.2 A somewhat different approach has been taken by Lerner’s group, which has used small synthetic peptides as antigens to elicit antibodies that can react with large proteins incorporating the peptide sequence.41,69,71 Interestingly, not only known antigenic regions in the whole protein, but also regions that would not have elicited immune responses in animals injected with the whole protein may be reactive with antisynthetic peptide antibodies. Again, antibodies made to highly mobile peptide regions react well with the native protein, whereas those against well-ordered regions do not.71 This approach holds considerable promise for many avenues of research, including the development of synthetic vaccines and production of antibodies to proteins where only the DNA or RNA sequence is known.41
An overview of in silico vaccine design against different pathogens and cancer
Published in Expert Review of Vaccines, 2020
Kimia Kardani, Azam Bolhassani, Ali Namvar
The development of a strong and effective antibody response is more complicated to treat and prevent infections and tumors. The inability of synthetic linear peptides to effectively mimic the discontinuous epitopes is one of the reasons for the failure of many B cell synthetic vaccines. These results illustrate why more than a thousand synthetic B cell peptides have been determined, but only 125 and 30 of them have achieved to phases I and II trials, respectively. Moreover, none of them have achieved success in phase III or licensed for human use [53]. Generally, the lack of clinical efficacy of some epitope-based vaccines against different pathogens may happen due to these reasons including (A) the restricted conserved sequence, (B) the limited number of epitopes, (C) the restricted population coverage of HLA, (D) insignificant delivery, and (E) existence of the epitopes which stimulate regulatory T cell responses [54]. Thus, in order to develop strong and potent epitope-based vaccines, scientists must try to eliminate and solve the problems mentioned earlier. For example, the number of epitopes needed for complete protection was known as a definable and small subset (lower than 50) [55,56]. In this review, we will briefly describe immuno-informatics approaches to design an efficient multiepitope vaccine candidate in preclinical and clinical trials performed up to now. Figure 1 illustrates the total steps of designing and prediction of an efficient multiepitope-based vaccine.
Progress in the overall understanding of typhoid fever: implications for vaccine development
Published in Expert Review of Vaccines, 2020
Peter J O’Reilly, Dikshya Pant, Mila Shakya, Buddha Basnyat, Andrew J Pollard
A new synthetic Vi polysaccharide vaccine has been developed. The polygalacturonic acid-base of this synthetic vaccine shares the same backbone as the Vi polysaccharide antigen. Studies in mice have shown higher immunogenicity than seen with the standard Vi vaccine. The synthetic vaccine demonstrated a booster response when a second dose was given, which the authors hope will make the vaccine effective in children under 2 years of age [82].
How far have we reached in development of effective influenza vaccine?
Published in International Reviews of Immunology, 2018
Qi Hao Looi, Jhi Biau Foo, May Teng Lim, Cheng Foh Le, Pau Loke Show
Influenza vaccine manufacturers are trying their best effort to balance the desire to delay vaccine strain selection to gather data for the recently circulating viruses and the desire to make the selection earlier to allow an efficient vaccine production. Selection of the appropriate strains plays a vital role as it represents the beginning of the manufacturing pipeline. Current influenza vaccines are predominantly produced by egg-based production methods. Being dependent on the supply of vaccine-quality eggs, vaccine manufacturers are constrained by the number of doses produced, especially in less developing countries. This phenomenon may lead to vaccine shortages, especially during pandemic situations. Alternative production platforms, such as cell culture-based vaccine production, plant-based vaccine production or synthetic vaccines, could increase the flexibility of manufacturers and ensure a consistency in production. It is often thought that these alternative production methods decrease the time needed to develop and release an influenza vaccine. However, the aforementioned production methods often required strain-specific reagents for vaccine potency, release tests such as the single radial immunodiffusion (SRID) assay, subsequent clinical trials, and regulatory approval procedure which significantly delay the commercial release of the influenza vaccines. To speed up these procedures, mock-up vaccines are developed to generate a registration dossier, which can subsequently be used for the licensing of an actual seasonal or pandemic influenza vaccine. Furthermore, current influenza vaccines induce neutralizing antibodies against the viral membrane surface proteins HA and NA. Due to antigenic shift and drift of HA and NA genes, neutralizing antibodies elicited by influenza vaccines lack cross-reactivity against nonmatching influenza strains. While seasonal adjustments to the vaccine strains are made, it is not as convenient and fast as a potential cross-protective influenza vaccine.