The immunopotentiating activities of
colloidal iron hydroxide, a novel, experimental
mineral adjuvant, and of
aluminium hydroxide. the licensed adjuvant for human
vaccines, were compared. Our studies revealed that
colloidal iron hydroxide and
aluminium hydroxide behaved comparably with respect to supporting induction of an antibody response to
tetanus toxoid. Furthermore, mice immunized with both, the experimental
vaccine (tick-borne encephalitis virus (TBEV)
antigen adsorbed to
colloidal iron hydroxide) or with a commercially available TBEV
vaccine (adjuvanted with
aluminium hydroxide), developed long-lasting antibody responses which protected the animals from TBEV
infection even one year after vaccination. The use of
colloidal iron hydroxide as adjuvant had the additional advantage to reproducibly support induction of HIV-1 envelope-specific cytotoxic T lymphocytes (CTL), when used as adjuvant for a HIV-1 env-carrying recombinant fowlpox virus and being applied via the subcutaneous route.
Aluminium hydroxide was much less active in this respect. Non-adjuvanted recombinant
fowlpox elicited CTLs only when given intravenously or intraperitoneally, vaccination routes considered not to be suitable for routine use in humans. Further studies to evaluate the use of colloidal
iron as possible alternative and/or supplement for routinely used
mineral adjuvants may therefore be warranted.