Transfer of the ability of HIV-1 Tat to raise an adjuvant-free humoral immune response to unrelated antigens

► HIV-1 Tat raises an adjuvant-free antibody response depending on Tat oligomerization. ► Adjuvanticity is a T-cell dependent phenomenon in which a Th2 profile predominates. ► Three model antigens become adjuvant-free immunogenic when coupled to fragment Tat1-57 or Tat37-57. ► Tat1-57 and Tat37-57 might represent an alternative to the adjuvants in vaccination.