Purpose of review: Recombinant adenovirus (rAd) vectors have emerged as promising vaccine platform technologies due to their capacity to elicit potent humoral and cellular immune responses to encoded antigens. These vectors are being explored as potential vaccine candidates for a variety of pathogens. This review summarizes current efforts to develop rAd vector-based vaccines for HIV-1.
Recent findings: In the phase 2b Step study, rAd5 vectors expressing clade B HIV-1 Gag, Pol, and Nef antigens failed to afford protection and may have resulted in increased HIV-1 acquisition in certain subgroups. Recent studies have explored the potential reasons for this failure and the utility of novel rAd vectors derived from non-Ad5 serotypes.
Summary: Current areas of active investigation include the development of alternative serotype rAd vectors, the incorporation of rAd vectors into heterologous vector prime-boost regimens, and the use of rAd vectors to express novel HIV-1 antigens. These HIV-1 vaccine candidates will be evaluated in clinical trials over the next several years.