Novel Vaccine Adjuvants

Hindawi Publishing Corporation BioMed Research International Volume 2013, Article ID 835105, 2 pages http://dx.doi.org/10.1155/2013/835105 Editorial Novel Vaccine Adjuvants Anshu Agrawal, 1 Mohammad Owais, 2 and Udai P. Singh 3 Division of Basic and Clinical Immunology, Department of Medicine, University of California, Irvine, CA 92697, USA Interdisciplinary Biotechnology Unit, Aligarh Muslim University, Aligarh, Uttar Pradesh 202002, India Department of Pathology, Microbiology and Immunology, University of South Carolina, School of Medicine, Building 1, Room B 42, 6439 Garners Ferry Road, Columbia, SC 29208, USA Correspondence should be addressed to Anshu Agrawal; aagrawal@uci.edu Received 11 September 2013; Accepted 11 September 2013 Copyright © 2013 Anshu Agrawal et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Vaccines still remain the most successful method for pro- tection and eradication against diseases. However, to avoid harmful effects associated with whole organism vaccines, new vaccine candidates are composed of parts of an organism, and therefore these are weakly immunogenic. Adjuvants are essential components of vaccines that nonspecifically stim- ulate the immune system, particularly the innate immune system cells, to enhance the immunogenicity of vaccines. Initially the major function of adjuvants such as alum was to allow sustained presence of antigens by preventing their degradation in vivo. Recent advances have, however, demonstrated that success of alum as an adjuvant is also due to its ability to activate the innate immune system cells. Significant progress in the last decade has increased our understanding of the innate immune system which is highly complex and can be activated via a wide array of receptors to generate different immune responses. The nature of adaptive immune response, quality, and quantity are governed by how the innate immune responses are activated. Novel adjuvants are therefore targeted to receptors expressed on antigen-presenting cells (APCs) such as dendritic cells (DCs) to activate the innate immune system. DCs express an array of pathogen recognition receptors (PRRs) so that they can recognize any threat to the body. Examples of PRRs include the TLRs, CLRs, and NLRs. Apart from preventing infections, vaccinations are also being used as therapy against tumors. Targeting antigens to APCs along with adjuvants allows the induction of immune response against tumors. The manuscript by L. Arribillaga et al., in this tissue, demonstrates that fusion of an antigen to the extra domain A from fibronectin (EDA) targets antigens to TLR4-expressing cells such as DCs leading to their activation. The approach is also effective for cross-presentation as well as the induction of antiviral/tumor immunity. Furthermore, the approach is universal as conjugation of EDA to streptavidin allows any biotinylated antigens to be used as immunogen for vaccination purposes. In contrast to the approach above, N. Kojima et al. use oligomannose-coated liposomes to target and stimulate APCs. The oligomannose on the liposomes targets antigens to the C-type lectin receptor (CLR) and is effective in inducing CTLs and/or Th1 cells. This approach is also universal because both lipophilic and hydrophilic antigens can be incorporated in the liposomes. Contrary to these surface receptor targeting methodologies, C. A. Colaco et al. discuss the merits of using heat shock proteins (HSPs) as vaccine adjuvants because HSPs are not just stimulators of innate immunity but can also traffic antigens into APCs, facil- itating the induction of specific acquired immune responses. Since the new generations of adjuvants being developed are highly specific in the type of CD4T, CD8T, or B-cell response they can stimulate, therefore, recent approaches for vaccine development are focused on utilizing a combi- nation of adjuvants to activate the various components of immune system to generate an effective memory response. The manuscript by E. Mata et al. provides an excellent example of a combinatorial approach in which they discuss that a successful malaria vaccine may require a combination of adjuvants which can activate different parts of the immune system. The review also provides an excellent overview of various types and properties of adjuvants in both preclinical