Other cells act as HIV reservoirs, harboring intact viruses that may remain undetected by the immune system. Understanding how HIV disease evolves, especially during early infection, is a high priority for the Institute. After entering the body, the virus rapidly disseminates, homing to the lymph nodes and related organs where it replicates and accumulates in large quantities. Basic research in immunology, epidemiology studies of long-term survivors, and vaccine trials in animal models and humans all contribute to a greater understanding of the immune system breakdown and ways vaccines may be designed to prevent or slow down the progress of HIV disease. To augment the immune responses elicited by these and other vaccines, scientists use immunologic adjuvants , which can increase the type, strength and durability of immune responses evoked by a vaccine.
Some adjuvants also stimulate mucosal immunity.
An adjuvant may work well with one experimental vaccine but not another. Therefore, the FDA licenses the vaccine formulation, or the antigen-adjuvant combination, rather than the adjuvant alone. Alum primarily increases the strength of antibody responses generated by the vaccine antigen . Because of alum's limited activity, other adjuvants now being evaluated in animal models and human studies may be better suited for the newer candidate HIV vaccines. A different way to enhance immune responses to HIV is the prime-boost vaccine strategy.