Identifying an immune signature against invasive Salmonella.

S ystemic typhoidal Salmonella enterica (serovars Typhi and Paratyphi) has been a major focus of study in the scientific community for the last several decades. Significant progress has been made regarding vaccine development against these serovars, which led to the production of two commercially available typhoid vaccines (1). However, there is still room for improvement regarding the efficacy of these vaccines, especially for targeting younger children. More recently, nontyphoidal S. enterica (NTS; other serovars) infections emerged as a significant, clinically important disease in developing countries, being a major cause of invasive infections, particularly in Africa, where it can be isolated from up to 50% of all bacteremias. Recently, NTS have been shown to be as commonly isolated from bacteremias as Haemophilus influenzae type b and pneumococcus in sub-Saharan Africa (2), highlighting the importance of vaccine development to control this disease in endemic areas. In PNAS, Lee et al. (3) make a significant contribution toward the future development of effective vaccines against Salmonella. The authors describe the construction and use of a Salmonella proteomic array to identify a common immune signature of bacterial antigens in mice and humans with bacteremia caused by Salmonella, defining an approach to identify potential candidates for a subunit vaccine.