FA16 Immunization Module’s Updates

Adjuvants in Vaccine Formulations

An adjuvant is a substance that serves the function of being an immune system potentiator in vaccines. This is achieved by triggering an early response by the innate immune system. The desired innate immune responses that adjuvants induce are an inflammatory response as well as the activation of antigen-presenting cells (APCs). These activated APCs will then produce cytokines necessary for the activation and differentiation of T cells much more rapidly and in larger quantities than would otherwise occur.

Currently there are two adjuvants that are utilized in vaccines in the U.S. The first are aluminum salts which include aluminum hydroxide, aluminum phosphate, potassium aluminum sulfate, and mixed aluminum salts. These aluminum salts are used in DTAP, pneumococcal conjugate, Haemophihlus influenza type b, and hepatitis A and B vaccines. The other adjuvant that has been approved for use in the U.S. is monophosphoryl lipid A (MPL), a purified fat-like substance. MPL is used in the Cervarix vaccine that is administered to protect against the human papillomavirus types 16 and 18.

It should also be mentioned that not all vaccines contain or even require an adjuvant because many vaccines are able to elicit an adequate immune response without the presence of an artificial adjuvant due to the presence of naturally occurring immune potentiators naturally present within the vaccine. There are many types of adjuvants that have potential use, including: mineral salts, bacterial products, toxins, lipids, nucleic acids, peptidoglycans, carbohydrates, peptides, cytokines, hormones, and small organic molecules to name a few. Many of these are current subjects of adjuvant research. One being heavily researched are the small organic molecules due to their ability to act as Toll-like receptor (TLR) agonists. An example of this are various synthetic adenine derivatives which act as TLR7 agonists. These adenine derivatives can potentially play an important role in viral vaccines because they have been found to have interferon-inducing (IFN-inducing) activities. TLR7 plays an important role in the immune response to viruses because it recognizes single stranded RNA, small interfering RNA, as well as these adenine derivatives leading to IFN production.

References:

https://www.ncbi.nlm.nih.gov/pubmed/15812492

http://www.cdc.gov/vaccinesafety/concerns/adjuvants.html

http://www.fda.gov/biologicsbloodvaccines/safetyavailability/vaccinesafety/ucm187810.htm

https://www.ncbi.nlm.nih.gov/pubmed/17275323

https://www.ncbi.nlm.nih.gov/pubmed/16539397

https://www.ncbi.nlm.nih.gov/pubmed/22481916

  • Noah Huh
  • Andy Guo