ABSTRACT
For an adjuvant to succeed in guiding an immune response, we have to intervene in the development o f the immune response along the lines shaped by nature. Thus, a main target for adjuvants is the innate immune system which recognizes molecules with structures divergent from those in the host, thereby leading to inflammatory responses and eventually acquired immune responses. Some vaccine antigens from microorganisms have immunomodulating activity, e.g., in respiratory syncytial virus (RSV) the G envelope protein promotes a T h 2 type o f response that may exacerbate disease, while the F envelope protein promotes a T h l type of response.4 Therefore the G antigen in its native form should be avoided as an immunogen; despite harboring protective properties, it may enhance disease or subsequent natural infec tion .5 Likewise experimental vaccination o f mice with Trypanosoma cruzi whole-cell antigens exacerbated disease following subsequent challenge of mice, while deletion o f one antigen resulted in a protective experimental vaccine.6 Thus the parasite has learned evolutionarily to use the reaction o f the host to evade a protective immune response. Adjuvants are often o f bacterial origin; well-known examples are lipopolysaccharide (LPS), muramyldipeptide (M DP), various
New Vaccine Technologies, edited by Ronald W. Ellis. ©2001 Eurekah.com.
