In the hunt for a safe and effective HIV vaccine, many combinations of vaccine types have been tested. Aside from the different vaccine vector types and the pieces of HIV DNA or protein used in the primary vaccine, various other molecules have been tested as adjuvants, which aim to enhance the vaccine’s effect by boosting the immune system. The immune signaling molecule (cytokine) interleukin-2, or IL-2, may be an effective adjuvant for HIV and other vaccines. The HIV Vaccine Trials Network trial 044 tested the timing of IL-2 as an adjuvant in conjunction with a candidate HIV DNA vaccine. Led by Dr. Lindsey Baden, associate professor at the Harvard School of Medicine, along with VIDD co-director Dr. Julie McElrath, staff scientists Drs. Cecilia Morgan and Olivier Defawe, and senior staff scientist Dr. Yunda Huang, the study researchers tested the use of IL-2 simultaneously with or 2 days after administration of the vaccine or a placebo in 70 volunteers.
The researchers found that volunteers who received the IL-2 adjuvant 2 days after vaccination had significantly increased T-cell immune responses as compared to those who received both adjuvant and vaccine at the same time. The group also looked at the study participants’ T cells 1 year after vaccination, and found that those who received IL-2 two days after vaccination seemed to have a more durable T-cell response than those who received both vaccine and adjuvant simultaneously. These findings are the first demonstration that the timing of this type of adjuvant affects immune response, and imply that adjuvant timing should be taken into consideration in future vaccine study design.
Baden LR, Blattner WA, Morgan C, Huang Y, Defawe OD, Sobieszczyk ME, Kochar N, Tomaras GD, McElrath MJ, Russell N, Brandariz K, Cardinali M, Graham BS, Barouch DH, Dolin R; NIAID HIV Vaccine Trials Network 044 Study Team. Timing of plasmid cytokine (IL-2/Ig) administration affects HIV-1 vaccine immunogenicity in HIV-seronegative subjects. J Infect Dis. 2011 Nov;204(10):1541-9.