Adjuvants in Veterinary Vaccines: Modes of Action and Adverse Effects

Abstract

Vaccine adjuvants are chemicals, microbial components, or mammalian proteins that enhance the immune response to vaccine antigens. Interest in reducing vaccine-related adverse effects and inducing specific types of immunity has led to the development of numerous new adjuvants. Adjuvants in development or in experimental and commercial vaccines include aluminum salts (alum), oil emulsions, saponins, immune-stimulating complexes (ISCOMs), liposomes, microparticles, nonionic block copolymers, derivatized polysaccharides, cytokines, and a wide variety of bacterial derivatives. The mechanisms of action of these diverse compounds vary, as does their induction of cell-mediated and antibody responses. Factors influencing the selection of an adjuvant include animal species, specific pathogen, vaccine antigen, route of immunization, and type of immunity needed.

Assessment of local reaction to vaccines in live piglets with magnetic resonance imaging compared to histopathology

“…These are mostly small and transient in the case of live viral vaccines but are often more pronounced in case of inactivated vaccines owing to the use of adjuvants. Adjuvant-induced local inflammatory reactions at the injection site are common but vary in extent depending on adjuvant type (Day, 2006;Patel and Heldens, 2009;Spickler and Roth, 2003).…”

Microparticle Vaccines Against Toxoplasma gondii

“…These subunit vaccines require effective adjuvants to aid them to elicit strong protective immune responses [10,11]. Therefore, one of the current important issues in vaccinology is the urgent need for the development of new or improved adjuvants to enhance the immunogenicity or effectiveness of vaccines [9,10,12].…”

“…Adjuvants are special substances used in combination with an antigen to generate a more robust immune response than the antigen alone [11,14,15]. This broad definition encompasses a very wide range of materials for adjuvant development.…”

“…This broad definition encompasses a very wide range of materials for adjuvant development. Actually, adjuvants can be broadly separated into two classes, vaccine delivery systems and immunostimulatory agents, based on their main mechanisms of action [11]. Vaccine delivery systems are generally particulate, such as emulsions [16], micro/nano particles [17], iscoms, and liposomes [18], and their main function is to deliver antigens into antigen-presenting cells (APCs) [11].…”

“…Vaccine delivery systems are generally particulate, such as emulsions [16], micro/nano particles [17], iscoms, and liposomes [18], and their main function is to deliver antigens into antigen-presenting cells (APCs) [11]. In contrast, immunostimulatory agents are predominantly derived from pathogens and often represent pathogen-associated molecular patterns (PAMP), such as lipopolysaccharides (LPS) [19], monophosphoryl Lipid A (MPL-A) [20], and CpG oligodeoxynucleotides (CpG-ODN) [21], which activate cells of the innate immune system to induce the following acquired immune response [11].…”