**1. Introduction**

The goal of this chapter is to review the importance of synthetic peptide-based vaccination, providing a brief knowledge about their new generation prototypes. In the first stage, relation to immunity and peptide vaccine with importance of using biopolymers was given under the title of solid-phase peptide synthesis including microwave system. After that, this review was focused on the established methods for peptide loaded nanoparticles or conjugated biopolymers preparation of peptidebased vaccine prototypes and nanotechnological particles as delivery system with touching on different methods. In addition, the impact of Contemporary Advancements in Peptide Based Vaccine like Liposome Based Subunit Vaccines was explained. In the last part, peptide-based vaccine prototypes studies *in vivo and in vitro* were given with their future perspective and development.

## **2. Peptide vaccines prototype and immunity**

All vaccines generally are developed by using live or attenuated microorganisms. However, the use of whole microorganisms, their components or the biological

process for vaccine production has many weaknesses and a variety of approaches for synthetic peptide vaccination remain under investigation for the infectious diseases [1]. Peptides play an important role in a biological process, including the stimulate the immune response [2].

Peptide-based vaccination is an immunotherapy where a peptide is applied often with the use of an immunoadjuvant (nanoparticle or biopolymers) to stimulate T-cell and sometimes B-cell immunity. Peptide-based vaccinations are present in major histocompatibility complexes (MHC) the ultimate target for T cells in infection recognition and infection immune responses [3, 4]. Sometimes peptide-based vaccines play a role to stimulate innate and adaptive immunity both (**Figure 1**) and peptides are immunogen components of peptide-based vaccine and memory responses of peptide is weak in immune responses [1] without the biopolymer or nanoparticle system.

When producing a new generation of synthetic peptide vaccines, components of the pathogenic pathogen of interest are generally used. These components are linear peptides and produced by solid phase peptide synthesis (SPPS) method with high efficiency and purity [5–9]. When peptides are used in combination with a vaccine system, if they are used without a drug delivery system, there are risks of degradation by protease enzymes that break down proteins and phagocytosis by immune system cells such as antibodies [10]. In addition, drug delivery systems should be preferred as nanoparticles and biopolymers. A higher immune response

**27**

*New Generation Peptide-Based Vaccine Prototype DOI: http://dx.doi.org/10.5772/intechopen.89115*

vaccine administration for the use of synthetic peptides [18].

response was obtained in BALB/c mice from experimental animals [23].

A historical overview of peptide chemistry from T. Curtius (who achieved the first synthesis of peptide in 1882) and Fischer (who synthesized the first dipeptide in 1901) to M. Bergmann and L. Zervas is first in presenting the Solid-Phase peptide synthesis. Next, the fundamentals of peptide synthesis with a focus on SPPS by R. B. Merrifeld are described. Although the peptides can be synthesized in three methods: in a solution medium, on a solid support, or as a combination of the solid and the solution synthesis, this chapter emphasizes an overview of peptide synthesis giving importance on SPPS. Currently, most of the peptides for research,

**3. Solid-phase peptide synthesis (SPPS)**

and to protect peptides from harmful effects of degrading enzymes and aggressive antibodies, it is generally necessary to use nanosystems such as protein, biopolymer conjugations or nanoparticles (NPs). Peptide delivery systems based on nanoparticles are developing more and more for the development of peptide-based vaccines. Especially, biodegradable polymers offer very popular and patented vaccines [11]. For instance, poly(amino acid) and polylactic acid (PLA) are used for NPs and when antigenic peptides are encapsulated by them in order to vaccinate mice can provide significantly higher levels of total the antibodies like immunoglobulins (IgGs); IgG, IgG1, IgG2. This means they can able to stimulate humoral immune responses and also CD4+ and CD8+, T and B cell activation and for the cellular immune responses; interferon γ (IFNγ) which induce Ig class switching to IgG2a [12–14]. In another study, Murine model was used in an immunization study. An antigen of Hepatitis B disease loaded on Poly (lactic-co-glycolic acid) (PLGA) NPs (300 nm) provided better immune responses compared to the antigen alone. Immunization with PLA NPs (200–600 nm) can also provide higher levels of IFNγ production related to a Th1 response. In contrast, immunization of PLA microparticles (2–8 μm) promoted IL-4 secretion due to Th2 response [15]. Both PLGA NPs and liposomes are phagocytosed efficiently by cells to localize intracellular localizations and produce an immune response [16, 17]. Carbon NPs are promising in oral

Different approaches are available to develop synthetic peptide-based vaccines, using metal ions in combination with peptide sequences. In particular, the investigation of the complex formation biopolymer by peptide in the presence of metal ions contributes greatly to the technological development of peptide-based vaccine prototypes [19]. The contact of the peptides with the polyelectrolyte (PE) is found at the interface. Solubility of polyplexes and complexes with NPs and peptides; it depends on the structure of the peptides (such as hydrophilic and lipophilic) and correlates with the isoelectric points in this system. Metal ions such as copper (Cu+2) generally promote two effects: (1) conjugation of polyelectrolyte to peptide molecules and (2) aggregation of polyplex particles in the intermolecular region. Some of these polyplexes exhibit strong immunogenicity and provide a high level of immunological protection for peptide vaccine prototypes, making them more efficient, but the solubility, composition and stability of these polycomplexes depend on pH, metal/PE and protein/PE ratios. These systems are based on conjugation of PE and antigen molecules with covalent bonds to NPs or biopolymers, which induce an immune response to the immunizing agent. The hydrophobic interactions in such a complex create an adjuvant effect for prototyping technology in vaccination. [19–22]. In the studies on the development of peptide vaccine prototypes previously made by our study group, it was observed that the purification of characterization of binding of synthetic peptides to various adjuvants and subsequent high immune

**Figure 1.** *Cellular representation of immune cells after vaccination [1].*

#### *New Generation Peptide-Based Vaccine Prototype DOI: http://dx.doi.org/10.5772/intechopen.89115*

*Current and Future Aspects of Nanomedicine*

stimulate the immune response [2].

nanoparticle system.

process for vaccine production has many weaknesses and a variety of approaches for synthetic peptide vaccination remain under investigation for the infectious diseases [1]. Peptides play an important role in a biological process, including the

with the use of an immunoadjuvant (nanoparticle or biopolymers) to stimulate T-cell and sometimes B-cell immunity. Peptide-based vaccinations are present in major histocompatibility complexes (MHC) the ultimate target for T cells in infection recognition and infection immune responses [3, 4]. Sometimes peptide-based vaccines play a role to stimulate innate and adaptive immunity both (**Figure 1**) and peptides are immunogen components of peptide-based vaccine and memory responses of peptide is weak in immune responses [1] without the biopolymer or

Peptide-based vaccination is an immunotherapy where a peptide is applied often

When producing a new generation of synthetic peptide vaccines, components of the pathogenic pathogen of interest are generally used. These components are linear peptides and produced by solid phase peptide synthesis (SPPS) method with high efficiency and purity [5–9]. When peptides are used in combination with a vaccine system, if they are used without a drug delivery system, there are risks of degradation by protease enzymes that break down proteins and phagocytosis by immune system cells such as antibodies [10]. In addition, drug delivery systems should be preferred as nanoparticles and biopolymers. A higher immune response

**26**

**Figure 1.**

*Cellular representation of immune cells after vaccination [1].*

and to protect peptides from harmful effects of degrading enzymes and aggressive antibodies, it is generally necessary to use nanosystems such as protein, biopolymer conjugations or nanoparticles (NPs). Peptide delivery systems based on nanoparticles are developing more and more for the development of peptide-based vaccines. Especially, biodegradable polymers offer very popular and patented vaccines [11]. For instance, poly(amino acid) and polylactic acid (PLA) are used for NPs and when antigenic peptides are encapsulated by them in order to vaccinate mice can provide significantly higher levels of total the antibodies like immunoglobulins (IgGs); IgG, IgG1, IgG2. This means they can able to stimulate humoral immune responses and also CD4+ and CD8+, T and B cell activation and for the cellular immune responses; interferon γ (IFNγ) which induce Ig class switching to IgG2a [12–14]. In another study, Murine model was used in an immunization study. An antigen of Hepatitis B disease loaded on Poly (lactic-co-glycolic acid) (PLGA) NPs (300 nm) provided better immune responses compared to the antigen alone. Immunization with PLA NPs (200–600 nm) can also provide higher levels of IFNγ production related to a Th1 response. In contrast, immunization of PLA microparticles (2–8 μm) promoted IL-4 secretion due to Th2 response [15]. Both PLGA NPs and liposomes are phagocytosed efficiently by cells to localize intracellular localizations and produce an immune response [16, 17]. Carbon NPs are promising in oral vaccine administration for the use of synthetic peptides [18].

Different approaches are available to develop synthetic peptide-based vaccines, using metal ions in combination with peptide sequences. In particular, the investigation of the complex formation biopolymer by peptide in the presence of metal ions contributes greatly to the technological development of peptide-based vaccine prototypes [19]. The contact of the peptides with the polyelectrolyte (PE) is found at the interface. Solubility of polyplexes and complexes with NPs and peptides; it depends on the structure of the peptides (such as hydrophilic and lipophilic) and correlates with the isoelectric points in this system. Metal ions such as copper (Cu+2) generally promote two effects: (1) conjugation of polyelectrolyte to peptide molecules and (2) aggregation of polyplex particles in the intermolecular region. Some of these polyplexes exhibit strong immunogenicity and provide a high level of immunological protection for peptide vaccine prototypes, making them more efficient, but the solubility, composition and stability of these polycomplexes depend on pH, metal/PE and protein/PE ratios. These systems are based on conjugation of PE and antigen molecules with covalent bonds to NPs or biopolymers, which induce an immune response to the immunizing agent. The hydrophobic interactions in such a complex create an adjuvant effect for prototyping technology in vaccination. [19–22]. In the studies on the development of peptide vaccine prototypes previously made by our study group, it was observed that the purification of characterization of binding of synthetic peptides to various adjuvants and subsequent high immune response was obtained in BALB/c mice from experimental animals [23].
