Two of the world's most prevalent infectious diseases — HIV and malaria — are the subject of review articles this month.

The generation of an HIV-1 vaccine has proved a difficult challenge, with researchers initially focusing on the induction of HIV-1-specific antibodies, and then on inducing cell-mediated immunity. It now seems probable that an effective vaccine will need to elicit both humoral and cellular immunity, and Susan Zolla-Pazner focuses on some of the problems facing the selection of antibody-inducing HIV-1 epitopes on page 199.

Malaria researchers have tended to focus on ways of promoting an adaptive immune response to Plasmodium. On page 169, Mary Stevenson and Eleanor Riley discuss a role for innate immunity in generating a protective response towards malaria and the implications of such studies for vaccine development.

The interface between innate and adaptive immune responses is of crucial importance at barrier surfaces such as the skin, as discussed by Thomas Kupper and Robert Fuhlbrigge on page 211. The bridge between innate and adaptive immunity is also the topic of an Opinion article on page 223. Matthew Albert examines the evidence that apoptotic cells taken up by antigen-presenting cells not only provide antigen to initiate an adaptive immune response, but also provide signals that influence the context in which the antigen is presented.

Some T-cell subsets have phenotypic characteristics of both the innate and adaptive immune systems. In a review article on page 190, Eric Vivier and Nicolas Anfossi describe a population of αβ-T-cell receptor+ CD8+ T cells that co-express inhibitory natural killer (NK)-cell receptors, and on page 231, several key investigators in the NKT cell field provide a revised classification for this heterogeneous T-cell population.